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Earth Observer Earth Home Earth Observer Home Editor’s Corner Feature Articles Meeting Summaries News Science in the News Calendars In Memoriam More Archives 18 min read
Summary of the 2023 Sun – Climate Symposium
Introduction
Observations of the Sun and Earth from space continue to revolutionize our view and understanding of how solar variability and other natural and anthropogenic forcings impact Earth’s atmosphere and climate. For more than four decades (spanning four 11-year solar cycles and now well into a fifth), the total and spectral solar irradiance and global terrestrial atmosphere and surface have been observed continuously, providing an unprecedented, high-quality time series of data for Sun–climate studies, such as the Total Solar Irradiance (TSI) composite record – see Figure 1.
Figure 1. The Total Solar Irradiance (TSI) composite record spans almost 5 decades and includes measurements from 13 different instruments (9 NASA and 4 international). Figure credit: Greg Kopp, Laboratory for Atmospheric and Space Physics (LASP)/University of Colorado (UC). Sun–Climate Symposia, originally called SOlar Radiation and Climate Experiment (SORCE) Science Team Meetings, have been held at a regular cadence since 1999 – before the launch of SORCE in 2003. These meetings provide an opportunity for experts from across the solar, Earth atmosphere, climate change, stellar, and planetary communities to present and discuss their research results about solar variability, climate influences and the Earth-climate system, solar and stellar variability comparative studies, and stellar impacts on exoplanets.
The latest iteration was the eighteenth in the series and occurred in October 2023. (As an example of a previous symposium, see Summary of the 2022 Sun–Climate Symposium, in the January–February 2023 issue of The Earth Observer [Volume 35, Issue 1, pp. 18–27]). The 2023 Sun–Climate Symposium took place October 17–20 in Flagstaff, AZ – with a focus topic of “Solar and Stellar Variability and its Impacts on Earth and Exoplanets.” The Sun–Climate Research Center – a joint venture between NASA’s Goddard Space Flight Center (GSFC) and the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado (UC) with the Lowell Observatory hosting the meeting. The in-person meeting had 75 attendees – including 7 international participants – with diverse backgrounds covering a wide range of climate change and solar-stellar variability research topics – see Photo.
Photo. Attendees at the 2023 Sun–Climate Symposium in Flagstaff, AZ. Photo credit: Kelly Boden/LASP Update on NASA’s Current and Planned TSIS Missions
The current NASA solar irradiance mission, the Total and Spectral Solar Irradiance Sensor (TSIS-1), marks a significant advance in our ability to measure the Sun’s energy input to Earth across various wavelengths. Following in the footsteps of its predecessors, most notably SORCE, TSIS-1 contributes to the continuous time series of solar energy data dating back to 1978 – see Figure 1. The two instruments on TSIS-1 improve upon those on previous missions, enabling scientists to study the Sun’s natural influence on Earth’s ozone layer, atmospheric circulation, clouds, and ecosystems. These observations are essential for a scientific understanding of the effects of solar variability on the Earth system.
TSIS-1 launched to the International Space Station (ISS) in December 2017 and is deployed on the Station’s EXpedite the PRocessing of Experiments to Space Station (ExPRESS) Logistics Carrier–3 (ELC-3). Its payload includes the Total Irradiance Monitor (TIM) for observing the TSI and the Spectral Irradiance Monitor (SIM) for measuring the Solar Spectral Irradiance (SSI) – see comparison in Figure 2. The mission completed its five-year prime science mission in March 2023. SIM measures from 200–2400 nm with variable spectral resolution ranging from about 1 nm in the near ultraviolet (NUV) to about 10 nm in the near infrared (NIR). TSIS-1 has been extended by at least three more years as part of the Earth Sciences Senior Review process.
TSIS-2 is intended as the follow-on to TSIS-1. The mission is currently in development at LASP and GSFC with a planned launch around mid 2025. The TSIS-2 payload is nearly identical to that of TSIS-1, except that the payload will ride on a free-flying spacecraft rather than be mounted on a solar pointing platform on the ISS. NASA hopes to achieve 1–2 years of overlap between TSIS-1 and TSIS-2. Achieving such measurement overlap between missions is crucial to the continuity of the long-term records of the TSI and SSI without interruption and improving the solar irradiance composite.
In addition to the current solar irradiance mission and its planned predecessor, NASA is always looking ahead to plan for the inevitable next solar irradiance mission. Two recent LASP CubeSat missions – called Compact SIM (CSIM) and Compact TIM (CTIM) – have tested miniaturized versions of the SIM and TIM instruments, respectively. Both CSIM and CTIM have performed extremely well in space – with measurements that correlate well with the larger instruments – and are being considered as continuity options for the SSI and TSI measurements. Based on the success of CSIM and CTIM, LASP has developed a concept study report about the Compact-TSIS (CTSIS) as a series of small satellites viable for a future TSIS-3 mission.
Figure 2. The Solar Spectral Irradiance (SSI) variability from TSIS-1 Spectral Irradiance Monitor (SIM) is compared to the Total Solar Irradiance (TSI) variability from TSIS-1 Total Irradiance Monitor (TIM). The left panel shows the SIM SSI integrated over its wavelength range of 200–2400 nm, which is in excellent agreement with the TSI variability during the rising phase of solar cycle 25. The right panels show comparison of SSI variability at individual wavelengths to the TSI variability, revealing linear relationships with ultraviolet variability larger than TSI variability, visible variability similar to TSI variability, and near infrared variability smaller than TSI variability. Figure credit: Erik Richard/LASP Meeting Overview
After an opening plenary presentation in which Erik Richard [LASP] covered the information on TSIS-1, TSIS-2, CSIM, and CTIM presented in the previous section on “NASA’s Current and Planned Solar Irradiance Missions,” the remainder of the four-day meeting was divided into five science sessions each with oral presentations, and a poster session featuring 23 contributions.
The five session topics were:
Solar and Stellar Activity Cycles Impacts of Stellar Variability on Planetary Atmospheres Evidence of Centennial and Longer-term Variability in Climate Change Evidence of Short-term Variability in Climate Change Trending of Solar Variability and Climate Change for Solar Cycle 25 (present and future) There was also a banquet held on the final evening of the meeting (October 19) with special presentations focusing on the water drainage system and archaeology of the nearby Grand Canyon – see Sun-Climate Symposium Banquet Special Presentation on the Grand Canyon National Park.
The remainder of this report summarizes highlights from each of the science sections. To learn more, the reader is referred to the full presentations from the 2023 Sun–Climate Symposium, which can be found on the Symposium website by clicking on individual presentation titles in the Agenda tab.
Session 1: Solar and Stellar Activity Cycles
Sun-like stars (and solar analogs, solar twins) provide a range of estimates for how the Sun’s evolution may affect its solar magnetic cycle variability. Recent astrophysics missions (e.g., NASA’s Kepler mission) have added thousands of Sun-like stars to study, compared to just a few dozen from a couple decades ago when questions remained if the Sun is a normal G star or not.
Tom Ayres [UC Center for Astrophysics and Space Astronomy (CASA)] gave the session’s keynote presentation on Sun-like stars. He pointed out that the new far ultraviolet (FUV) and X-ray stellar observations have been used to clarify that our Sun is a normal G-type dwarf star with low activity relative to most other G-type dwarf stars.
Travis Metcalfe [White Dwarf Research Corporation (WDRC)] discussed the recent progress in modeling of the physical processes that generate a star’s magnetic field – or stellar dynamo. He explained how the presence of stellar wind can slow down a star’s rotation, which in turn lengthens the period of the magnetic cycle. He related those expectations to the Sun and to the thousands of Sun-like stars observed by Kepler.
Continuing on the topic of solar dynamo, Lisa Upton [Space Systems Research Corporation (SSRC)] and Greg Kopp [LASP] discussed their recent findings using a solar surface magnetic flux transport model, which they can use to reconstruct an estimated TSI record back in time to the anomalously low activity during the Maunder Minimum in the 1600s. Dan Lubin [University of California San Diego (UCSD)] described efforts to identify grand-minimum stars – which exhibit characteristics similar to our Sun during the Maunder Minimum. Using Hamilton Echelle Spectrograph observations, they have identified about two dozen candidate grand-minimum stars.
In other presentations and posters offered during this session, Adam Kowalski [LASP]) discussed stellar and solar flare physics and revealed that the most energetic electrons generated during a flare are ten times more than previously thought, while Moira Jardine [University of St. Andrews, Scotland]) discussed the related subject of space weather on the Sun and stars and how the coronal extent was likely much larger for the younger Sun. Three presenters – Debi Choudhary [California State University, Northridge], Garrett Zills [Augusta University], and Serena Criscuoli [National Solar Observatory] –discussed how solar emission line variability from both line intensity and line width are good indicators of magnetic activity on the Sun and thus relevant for studies of Sun-like star variability. Andres Munoz-Jaramillo [Southwest Research Institute (SWRI)] highlighted the importance of archiving large datasets showing the Harvard dataverse as an example. Juan Arjona [LASP] discussed the solar magnetic field observations made using the Max Planck Institute for Solar System Research’s GREGOR solar telescope.
Session 2: Impacts of Stellar Variability on Planetary Atmospheres
Presenters in this session focused on how the stellar variability can impact exoplanet evolution and climate. By analyzing data from NASA’s Kepler mission, scientists have discovered numerous Earth-like planets orbiting other stars – or exoplanets, which has enabled comparative studies between planets in our Solar System and exoplanets.
Aline Vidotto [University of Leiden, Netherlands] gave this session’s keynote presentation in which he discussed the impact of stellar winds on exoplanets. In general, younger stars rotate faster and thus have more stellar variability. The evolution of the exoplanet’s atmosphere is dependent on its star’s variability and also modulated by the exoplanet’s own magnetic field. Robin Ramstad [LASP] further clarified a planetary magnetic field’s influences on atmospheric evolution for planets in our solar system.
Vladimir Airapetian [GSFC] presented an overview of how laboratory measurements used to simulate pre-biosignatures – characteristics that precede those elements, molecules, or substances that would indicate past or present life – could be created in an exoplanet atmosphere by highly energetic particles and X-rays from stars with super flares, very large-scale magnetic eruptions on a star that can be thousands of times brighter than a typical solar flare. While the probability of a super flare event is low for our Sun (perhaps 1 every 400 years), super flares are routinely observed on more active stars.
The stellar flares and the spectral distribution of the flare’s released energy can have large impacts on exoplanet’s atmospheres. Laura Amaral [Arizona State University] presented on the super-flare influences on the habitable zone of exoplanets and explained how the flare’s significantly enhanced X-ray emissions would greatly accelerate water escape from the exoplanet’s atmosphere. Ward Howard [ UC CASA] showed that exoplanet transits can also provide information about starspots (akin to the dark sunspots on the Sun) when a transit event happens to occult a starspot – see Figure 3. Ward also explained the importance of observing the transit events at multiple wavelengths, referred to as transit spectroscopy, to understand the physical characteristics of the starspots. Yuta Notsu [LASP] compared the energetics observed in many different stars using X-ray and far ultraviolet (FUV) observations to estimate stellar magnetic field strengths, which in turn can be used to estimate the stellar extreme ultraviolet (EUV) spectra. Those results provide new information on how the stellar spectra could evolve during the lifetime of Sun-like stars, and how those spectral changes can affect the atmospheric escape rates on their exoplanets.
Nina-Elisabeth Nemec [University of Göttingen, Germany] described how Kepler observations of exoplanets rely on tracking their transits across its host star’s disk. She explained some of the challenges that arise with analyzing such transits when there are large starspots present.
Figure 3. Illustration of an exoplanet transit that will occult a starspot. The transit light curve can provide information about the size of the starspot, and transit observations at multiple wavelengths can reveal physical parameters, such as temperature, of the starspot. Figure credit: Ward Howard, CASA/University of Colorado Session 3: Evidence of Centennial and Longer-term Variability in Climate Change
Venkatachalam “Ram” Ramaswamy [National Oceanic and Atmospheric Administration’s (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL)] gave the keynote for this session in which he discussed Earth’s variable climate change over the past two centuries. He explained in detail Earth’s energy budget and energy imbalance, which leads to less land and sea ice, warmer temperatures at the surface and in the atmosphere and ocean, and more extreme weather. These weather changes have different regional impacts, such as more floods in some regions and more drought in different regions – see Figure 4.
Figure 4. The rainfall amount has shifted over the past fifty years (red is less and blue is more) with strong regional impacts on droughts and floods. Figure credit: Ram Ramaswamy/NOAA/GFDL Bibhuti Kumar Jha [SWRI], Bernhard Hofer [Max Planck Institute for Solar System Research, Germany], and Serena Criscuoli [National Solar Observatory] discussed long-term solar measurements from the Kodaikanal Solar Observatory and showed that the chromospheric plages (Ca K images) have 1.6% faster solar rotation rate than sunspots (white light images). Timothy Jull [University of Arizona (UA)], Fusa Miyake [Nagoya University, Japan], Georg Fueulner [Potsdam Institute for Climate Impact Research, Germany], and Dan Lubin discussed the impact that solar influences (i.e., solar flares, solar energetic particles) have had on Earth’s climate over hundreds of years through their impact on phenomena such as the natural distribution of carbon dioxide in the atmosphere and fluctuations in the North Atlantic Oscillation.
Hisashi Hayawawa [Nagoya University] and Kalevi Mursula [University of Oulu, Finland] discussed the influence that ever-changing sunspots and magnetic fields on the Sun are having on climate – with a focus on the Maunder Minimum period. Irina Panyushkina [UA] and Timothy Jull presented tree ring radioisotope information as it relates to climate change trends as well as long-term, solar variability trends. According to Lubin, if a reduction in solar input similar to what happened during the Maunder Minimum would happen today, the resulting reduction in temperature would be muted due to the higher concentration of greenhouse gases (GHG) in the atmosphere.
Session 4: Evidence of Short-term Variability in Climate Change
Session 4 focused on discussions that examined shorter-term variations of solar irradiance and climate change. Bill Collins [Lawrence Berkeley National Laboratory (LBNL)] started off the session with a presentation on Earth albedo asymmetry across the hemispheres from Nimbus-7 observations, and then showed some important differences when looking at the Clouds and the Earth’s Radiant Energy System (CERES) record – shown in Figure 5. Lon Hood [UA] discussed the changes in atmospheric circulation patterns which might be the consequence of Arctic sea ice loss increasing the sea level pressure over northern Eurasia. Alexi Lyapustin [GSFC] described how higher temperatures are causing an extension of the wildfire season in the Northern hemisphere by 1–3 months.
Figure 5. The albedo difference between the visible and near-infrared bands are shown for the southern hemisphere (red line) and the northern hemisphere (blue lines) for CERES [left] and Nimbus 7 [right]. The southern hemisphere albedo difference is higher than the northern hemisphere albedo difference, both for the 1980s as measured by Nimbus-7 and for the recent two decades as measured by CERES. These hemispheric differences are related mostly to differences in cloud coverage. The seasonal effect on the albedo difference values is about 2%, but the changes from 1980s to 2010s appear to be about 10%. Figure credit: Bill Collins/Lawrence Berkeley National Laboratory Jae Lee [GSFC/University of Maryland, Baltimore County] discussed changes in the occurrence and intensity of the polar mesosphere clouds (PMCs), showing high sensitivity to mesospheric temperature and water, and fewer PMCs for this solar cycle. In addition, some presenters discussed naturally driven climate changes. Luiz Millan [JPL], whose research has found that the water-laden plume from the Hunga-Tonga-Hunga-Ha’apai (HT-HH) volcano eruption in January 2022 has had a warming effect on the atmosphere as well as the more typical cooling effect at the surface from the volcanic aerosols. In another presentation, Jerry Raedar [University of New Hampshire, Space Science Center] showed results from his work indicating about 5% reductions in temperature and pressure following major solar particle storms, but noted differences in dependence between global and regional effects.
Session 5: Trending of Solar Variability and Climate Change for Solar Cycle 25 (present and future)
Session 5 focused on trends during Solar cycle 25 (SC-25), which generated lively discussions about predictions. It appears the SC-25 maximum sunspot number could be about 15% higher than the original SC-25 maximum predictions. Those differences between the sunspot observations and this prediction may be related to the timing of SC-25 ramp up. Lisa Upton started off Session 5 by presenting both the original and latest predictions from the NASA–NOAA SC-25 Prediction Panel. Her assessment of the Sun’s polar magnetic fields and different phasing of magnetic fields over the Sun’s north and south poles suggests that the SC-25 maximum will be larger than the prediction – see Figure 6.
The next several speakers – Matt DeLand [Science Systems and Applicatons Inc. (SSAI)], Sergey Marchenko [SSAI], Dave Harber [LASP], Tom Woods [LASP], and Odele Coddington [LASP] – showed a variety of TSI and SSI (NUV, visible, and NIR) variability observations during SC-25. The group consensus was that the difference between the SC-24 and SC-25 maxima may be due to the slightly higher solar activity during SC-25 as compared to the time of the SC-24 maximum – which was an anomalously low cycle. The presenters all agreed that SC-25 maximum may not have been reached yet (and SC-25 maximum may not have occurred yet in 2024).
Figure 6. The sunspot number progression (black) during solar cycle 25 is higher than predicted (red). The original NASA–NOAA panel prediction was for a peak sunspot number of 115 in 2025. Lisa Upton’s updated prediction is for a sunspot number peak of 134 in late 2024. Figure credit: NOAA Space Weather Prediction Center On the climate change side, Don Wuebbles [University of Illinois, Urbana-Champaign] provided a thorough overview of climate change science showing that: the largest impacts result from the activities of humans, land is warming faster than the oceans, the Arctic is warming two times faster than rest of the world, and 2023 was the hottest year on record with an unprecedented number of severe weather events.
There were several presentations about the solar irradiance observations. Leah Ding [American University] presented new analysis techniques using machine learning with Solar Dynamics Observatory (SDO) solar images to study irradiance variability. Steve Penton [LASP] discussed new SIM algorithm improvements for TSIS-1 SIM data product accuracy. Margit Haberreiter [Physikalisch-Meteorologisches Observatorium Davos (PMOD), Switzerland] discussed new TSI observations from the Compact Lightweight Absolute Radiometer (CLARA) on the Norwegian NorSat-1 microsatellite. Marty Snow [South African National Space Agency] discussed a new TSI-proxy from the visible light (green filter) Solar Position Sensor (SPS) flown on the NOAA Geostationary Operational Environmental Satellites (GOES-R). (The first of four satellites in the GOES-R series launched in 2016 (GOES-16) followed by GOES-17 and GOES-18 in 2018 and 2022 respectively. The final satellite in the series – GOES-U – launched June 25, 2024 will become GOES-19 after checkout is complete.)
Peter Pilewskie [LASP] discussed future missions, focusing on the Libera mission for radiative energy budget, on which he is Principal Investigator. Selected as the first Earth Venture Continuity mission (EVC-1), Libera will record how much energy leaves our planet’s atmosphere on a day-by-day basis providing crucial information about how Earth’s climate is evolving. In Roman mythology, Libera was Ceres’ daughter. The mission name is thus fitting as Libera will act as a follow-on mission to maintain the decades long data record of observation from NASA’s suite of CERES instruments. Figure 7 shows the CERES climate data record trends over the past 20 years.
Figure 7. The CERES Earth Radiation Budget (ERB) climate data record shows a positive trend for the absorbed solar radiation [left] and the net radiation [right] and a small negative trend for the emitted terrestrial radiation [middle]. Figure credit: Peter Pilewskie/adapted from a 2021 paper in Geophysical Research Letters Susan Breon [GSFC] discussed the plans for and status of TSIS-2 , and Tom Patton [LASP] discussed CTSIS as an option for TSIS-3 – both of these topics were discussed earlier in this article in the section on “NASA’s Current and Planned Solar Irradiance Missions.”
Angie Cookson [California State University, San Fernando Observatory (SFO)] shared information about the SFO’s 50-year history, and how analyses of solar image observations taken at SFO are used to derive important indicators of solar irradiance variability – see Figure 8.
Figure 8. The San Fernando Observatory (SFO) [left] has been making visible [middle] and near ultraviolet (NUV) [right] solar images from the ground for more than 50 years. Those solar images have been useful for understanding the sources of solar irradiance variability. Figure credit: Angie Cookson/SFO Sun-Climate Symposium Banquet Special Presentation on the Grand Canyon National Park
At the Thursday evening banquet, two speakers – Mark Nebel and Anne Millar – from the National Park Service (NPS) presented some of their geological research on the nearby Grand Canyon. Nebel discussed the water drainage systems surrounding the Grand Canyon while Millar described the many different fossils that have been found in the surrounding rocks. Nebel explained how the Grand Canyon’s water drainage system into the Colorado River is complex and has evolved over the past few decades – see map and photo below. Millar brought several samples of the plant and insect fossils found in the Grand Canyon to share with banquet participants. Those fossils ranged in time from the Bright Angel Formation ocean period 500 million years ago to the Hermit Formation period 285 million years ago – when the Grand Canyon was semi-arid land with slow-moving rivers.
Map and photo credit: Mark Nebel/NPS Conclusion
Altogether, 80 presentations during the 2023 Sun–Climate Symposium spread across 6 sessions about solar analogs, exoplanets, long-term climate change, short-term climate change, and solar/climate recent trending. The multidisciplinary group of scientists attending made for another exciting conference for learning more about the TSIS solar irradiance observations. Sun–Climate recent results have improved perception of our Sun’s variability relative to many other Sun-like stars, solar impact on Earth and other planets and similar type impacts of stellar variability on exoplanets, and better characterization of anthropogenic climate drivers (e.g., increases in GHG) and natural climate drivers (Sun and volcanoes).
The next Sun–Climate Symposium will be held in spring 2025 with a potential focus on polar climate records, including polar ice trends and long-term solar variabilities derived from ice-core samples. Readers who may be interested in participating in the 2025 science organizing committee should contact Tom Woods and/or Dong Wu [GSFC].
Acknowledgments
The three co-authors were all part of the Science Organizing Committee for this meeting and wish to acknowledge the other members for their work in planning for and participating in another successful Sun–Climate Symposium. They include: Odele Coddington, Greg Kopp, and Ed Thiemann [all at LASP]; Jae Lee, Doug Rabin, and Dong Wu [all at GSFC]; Jeff Hall, Joe Llama, and Tyler Ryburn [all at Lowell Observatory]; Dan Lubin [UCSD’s Scripps Institution of Oceanography (SIO)]; and Tom Stone [U.S. Geological Survey’s Astrogeology Science Center]. The authors and other symposium participants are also deeply grateful to Kelly Boden [LASP] for organizing the logistics and management of the conference, and to the Lowell Observatory, the Drury Inn conference center staff, and the LASP data system engineers for their excellent support in hosting this event.
Tom Woods
University of Colorado, Laboratory for Atmospheric and Space Research
tom.woods@lasp.colorado.edu
Peter Pilewskie
University of Colorado, Laboratory for Atmospheric and Space Research
peter.pilewskie@lasp.colorado.edu
Erik Richard
University of Colorado, Laboratory for Atmospheric and Space Research
erik.richard@lasp.colorado.edu
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Earth Observer Earth Home Earth Observer Home Editor’s Corner Feature Articles Meeting Summaries News Science in the News Calendars In Memoriam More Archives 23 min read
Summary of the 2023 GEDI Science Team Meeting
Introduction
The 2023 Global Ecosystem Dynamics Investigation (GEDI) Science Team Meeting (STM) took place October 17–19, 2023, at the University of Maryland, College Park (UMD), in College Park, MD. Upwards of 80 people participated in the hybrid meeting (around 50 in-person and the rest virtually). Included among them were GEDI Science Team (ST) members, collaborators, and stakeholders – see Photo. The primary goals of the meeting included providing a status update on the GEDI instrument aboard the International Space Station (ISS), receiving final project updates from the inaugural cohort of the GEDI completed ST, and understanding the present status and future goals of data product development.
After a short mission status update, the remainder of this article will summarize the content of the STM. For those desiring more information on these topics, some of the full meeting presentations are posted online. Readers can also contact the GEDI ST with specific questions.
Photo. GEDI Science Team Meeting in-person and virtual attendees. Photo credit: Talia Schwelling Mission Status Update: GEDI Given New Lease on Life
A lot has changed since the publication of the last GEDI STM summary. (See Summary of the GEDI Science Team Meeting in the July–August 2022 issue of The Earth Observer [Volume 34, issue 4, pp. 20–24]). When the GEDI ST convened in November 2022, the fate of GEDI was hanging in the balance, with the plan being to release GEDI from the ISS at the end of its second extension period.
NASA saved the instrument, however, and a new plan went into effect: in order to extend its tenure on the ISS, the GEDI mission entered a temporary period of “hibernation” in March 2023 after nearly four years in orbit. This hibernation period and movement of the instrument from Exposed Facility Unit (EFU)-6 (operating location) to EFU-7 (storage location) made way for another mission – see Figure 1. (UPDATE: After being in storage for roughly 13 months, the GEDI instrument was returned to its original location on the Japanese Experiment Module–Exposed Facility (JEM–EF) on Earth Day this year, April 22, 2024, and is now once again back to normal science operations using its three lasers.)
Figure 1. NASA’s GEDI instrument was moved from EFU-6 to EFU-7 on the ISS on March 17, 2023, where it remained in hibernation for 13 months until its recent reinstallation to EFU-6 on April 22, 2024. The instrument is once again back to normal science operations using its three lasers. Figure credit: NASA As The Earth Observer reported in 2023, data from GEDI are being used for a wide range of applications, including biomass estimation, habitat characterization, and wildfire prediction (See page 4 of The Editor’s Corner in the March–April 2023 issue of The Earth Observer [Volume 35,Issue 2, pp. 1–4]. This section also reports on GEDI’s extension via out-of-cycle Senior Review in 2022). GEDI data is used to develop maps to quantify biomass that are unique in both their accuracy and their explicit characterization of uncertainty and are a key component in the estimation of aboveground carbon stocks, as absorbed carbon is used to drive plant growth and is stored as biomass – see Figure 2. These estimations help quantify the impacts of deforestation and subsequent regrowth on atmospheric carbon dioxide (CO2) concentration. NASA’s choice to extend the GEDI mission has significantly broadened the capacity to collect more of these important data.
Figure 2. Country-wide estimates of total aboveground biomass in petagrams (Pg) using GEDI Level-4B Version 2.1 dataset (GEDI_L4B_AGB). Figure credit: ORNL DAAC DAY ONE
GEDI Mission Operations, Instrument Status, and Data Level Updates
Ralph Dubayah [UMD—GEDI Principal Investigator (PI)] opened the meeting with a summary of the current status of the mission and GEDI data products. After reviewing the details of GEDI’s hibernation (described in the previous section) he went on to describe what GEDI has accomplished over the past 4.5 years of operations, noting that the instrument collected over 26 billion footprints over the land surface.
All the data collected by GEDI during its first epoch (i.e., before its hibernation) have been processed and released to the appropriate Distributed Active Archives Centers (DAACs) as Version 2 (V2) products. (To learn more about the DAACs and other aspects of Earth Science data collection and processing, see Earth Science Data Operations: Acquiring, Distributing, and Delivering NASA Data for the Benefit of Society, in the March–April 2017 issue of The Earth Observer, [Volume 29, Issue 2, pp. 4–18]. The DAACs – including URL links to each – are listed in a Table on page 7–8 of this issue). The two DAACs directly involved with GEDI data processing are the Land Processes DAAC (LP DAAC) and Oak Ridge National Laboratory (ORNL) DAAC. The LP DAAC houses GEDI Level-1 (L1) data, which consists of geolocated waveforms, and L2 data, which is broken down into L2A and L2B. L2A data includes ground elevation, canopy height, and relative height metrics. (Waveform measurements are described in detail in a sidebar on page 32 of the Summary of the Second GEDI Science Team Meeting in the November–December 2016 issue of The Earth Observer [Volume 28, Issue 6, pp. 31–36].) L2B data includes canopy cover fraction (CCF) and leaf area index (LAI). The ORNL DAAC houses GEDI L3 gridded land surface metrics data, L4A footprint level aboveground biomass density data, and L4B gridded aboveground biomass density data – e.g., see Figure 2.
Dubayah went on to explain that while GEDI hibernated, the mission team would work to enhance existing data products as well as produce new products. Version 3 (V3) datasets for all data products are expected to be released by the fall of 2024, and new data products are in development, including a waveform structural complexity index (WSCI) and a topography and canopy height product that blends data from GEDI and the Ice, Clouds, and land Elevation Satellite–2 (ICESat–2) mission. A new dataset, the GEDI L4C footprint level waveform structural complexity index (WSCI) product, was added to the ORNL DAAC catalogue in May 2024. To further improve data quality and coverage, the GEDI team is hoping to organize an airborne lidar field campaign to southeast Asia in the coming years. Dubayah concluded his updates by highlighting a set of six papers published in 2023 in Nature and Science family or partner journals that focused on the use of GEDI data. Visit our website for a comprehensive list of publications related to GEDI.
After receiving a general update from the mission PI, the next several presentations gave meeting participants a more in-depth look at GEDI science data planning and individual data products. Scott Luthcke [NASA’s Goddard Space Flight Center (GSFC)—GEDI Co-Investigator (Co-I)] presented status updates for the GEDI Science Operating Center (SOC), including the Science Planning System (SPS) and Science Data Processing System (SDPS) automation, development, and processing. In addition, he reported on the status of the L1 geolocated waveform data product and the L3 gridded land surface metrics product. At the time of this meeting, the SPS had completed operations through mission week 223 – almost 4.5 years of data – and was beginning to transition to improving processes on the back end while GEDI hibernates. The SDPS had completed processing and delivery of all V2 data products to the LP DAAC and ORNL DAAC.
Luthcke reported on GEDI’s current observed and estimated geolocation performance, including detailed summaries of component analysis and steps towards improving Precision Orbit Determination (POD), Precision Attitude Determination (PAD), Pointing Calibration, time-tag correction, and Oven Controlled Crystal Oscillator (OCXO) calibration. GEDI passes over Salar de Uyuni, the world’s largest salt flat located in Bolivia – see Figure 3, are being used to assess the PAD high-frequency and low-frequency errors. Estimated errors are shown to be consistent with observed geolocation errors. Finally, Luthcke gave a summary of completed L3 products and new wall-to-wall 1-km (0.62-mi) resolution and high-resolution products.
Figure 3. Salar de Uyuni, the world’s largest salt flat as seen from the International Space Station. Figure credit: Samantha Cristoforetti/ESA/NASA John Armston [UMD—GEDI Co-I] updated attendees on GEDI L2 products. L2A consists of elevation and height metrics, and L2B consists of canopy cover and vertical profile metrics. To assess GEDI ground and canopy top measurement accuracy and improve algorithm performance, the mission team is using data collected from NASA Land, Vegetation, and Ice Sensor (LVIS) campaigns from 2016 to present. Armston reported that L2B estimates of canopy and ground reflectance were completed for the first mission epoch (April 2019–March 2023) and the GEDI team continues to work on algorithm improvements for cover estimates in challenging conditions (e.g., steep slopes). Data users can expect improved waveform processing for ground elevation and canopy height, new reflectance estimation, and revised quality metrics and flags in the L2A and L2B not-yet-released V3 products.
Jim Kellner [Brown University—GEDI Co-I] shared the current status of and planned algorithm improvements to the L4A data product, or the footprint-level aboveground biomass density product. The algorithm theoretical basis document for L4A data products was published in November 2022; it describes how models were developed and the importance of quality filtering. L4A data product development continues in tandem with updates to L2A data and improvements to existing calibration and validation data and ingestion of new data.
Sean Healey [U.S. Forest Service—GEDI Co-I] reviewed coverage and uncertainties of the recently produced V2 L4B data products – see Figure 4. Ongoing GEDI-relevant research includes:
investigating a statistical method called bootstrapping, which may allow more complex types of models; conducting theoretical statistical studies aimed at decomposing mean square error for model-based methods; and developing ways to estimate biomass change over time – which will become more important as the extended mission potentially stretches to a decade. Figure 4. Gridded mean aboveground biomass density [top] and standard error of the mean [bottom] from Version 2.1 of the GEDI L4B Gridded Aboveground Biomass Density product, published on October 29, 2023. Figure credit: ORNL DAAC Competed Science Team Presentations—Session 1
This GEDI STM was the last convergence of the first iteration of the GEDI competed ST. Attendees received final in-person updates on the cohort’s projects and plans for future research. Over the course of the three-day meeting, there were several sections dedicated to Competed ST Presentations. For purposes of organization in this report, each section has been given a session number.
Taejin Park [NASA’s Ames Research Center (ARC) and Bay Area Environmental Research Institute (BAERI)] kicked off the ST presentations with an overview of his group’s progress in enhancing the predictions of forest height and aboveground biomass by incorporating GEDI L2, L3, and L4 data products into a process-based model, called Allometric Scaling Resource Limitation (ASRL), over the contiguous United States (CONUS). The ASRL model effectively captures large-scale, maximum tree size distribution and facilitates prognostic applications for predicting future aboveground biomass changes under various climate scenarios. Park also described collaborative research efforts with international partners to map changes in aboveground biomass in tropical and temperate forests using a carbon management systems (CMS).
Kerri Vierling [University of Idaho] shared the results from her team’s projects demonstrating the use of GEDI data fusion products to describe patterns of bird and mammal distributions in western U.S. forests. The focal species for these projects include a suite of vertebrate forest carnivores, prey, and ecosystem engineer species that modify their environments in ways that create habitat for other creatures, e.g., woodpeckers – see Figure 5. Many of these species are of interest for management by a variety of state and federal agencies. Vierling also discussed ongoing analyses identifying biodiversity hotspots and land ownership patterns.
Figure 5. A Female downy woodpecker creates a tree cavity that other organisms may use in the future for habitat. Woodpecker species are great examples of ecosystem engineers. Figure credit: Doug Swartz/Macaulay Library at the Cornell Lab or Ornithology (ML 58304661) Sean Healey presented on his competed ST research on Online Biomass Inference using Waveforms and iNventory (OBI-WAN), a Google Earth Engine application. This forest-carbon reporting tool harnesses GEDI waveforms, biomass models, and statistics to make estimates of mean biomass and biomass change for areas specified by online users. Healey explained the statistical methods applied to operate OBI-WAN and gave context for the use of sensor fusion to provide biomass change information that is critical for monitoring, reporting, and verification.
Keith Krause [Battelle] presented his work evaluating vertical structural similarity of LVIS classic and GEDI large-footprint waveforms. At the GEDI and LVIS footprint scale (20–23 m, or 65–75 ft, spot on the ground), lidar waveforms over forests represent canopies of leaves and branches from several trees. Krause presented results comparing waveforms against each other to show similarities in shape (i.e., if the trees in their footprints have a similar vertical structure). He also described how he used data clustering techniques to group similar waveforms into distinct structural classes. From there, he could map waveforms with similar vertical structure to better understand the spatial distribution of the structural groups.
Breakout Sessions—Session 1
GEDI STMs offer a rare opportunity for members of the competed and mission STs, a variety of stakeholders, and other individuals to convene and discuss ideas and goals for their own research and for the GEDI mission. Toward that end, breakout sessions were held on the first and second day of the meeting – referred to as Session 1 and Session 2 in this report. The individual breakout meetings used a hybrid format allowing in-person and online participants to join the discussion that was most relevant to their interests and expertise.
Chris Hakkenberg [Northern Arizona University (NAU)] led a breakout session on structural diversity, including the horizontal and vertical components. Different structural attributes, (e.g., stand structure, height, cover, and vegetation density) have different – but related – metrics and measurement approaches. Participants discussed biodiversity-structure relationships (BSRs), how to better characterize horizontal structural diversity, and how to define which metrics (i.e., scale, sampling unit, and spatial resolution) are most meaningful in different situations.
Jim Kellner led a session that focused on biomass calibration and validation and how to create the best data products given global environmental variation. Special cases – e.g., mangroves – pose challenges for calibration and validation because they don’t always have as much plot-level data as other environments. Participants discussed how to determine strata while considering climactic and environmental covariates as well as constraints of data availability and consistency.
Competed Science Team Presentations—Session 2
The FORest Carbon Estimation (FORCE) Project is exploring the use of GEDI-derived canopy structure metrics to map forest biomass in the U.S. and Canada. Daniel Hayes [University of Maine] presented comparisons of GEDI metrics and canopy height models derived from airborne lidar and photo point clouds over different forest types and disturbance history in managed forests of Maine. Co-PI Andy Finley [Michigan State University] presented new work that adjusts GEDI L4B biomass estimates to plot data over the continental U.S. from Forest Inventory and Analysis (FIA) program of the U.S. Department of Agriculture’s Forest Research and Development Branch. The project’s next steps are to fuse GEDI canopy structure metrics with other covariates in a spatial model to produce wall-to-wall estimates of biomass for boreal–temperate transition forests in northeast North America.
GEDI data is also being used to study tropical forests. Chris Doughty [NAU] described how he and his team analyzed GEDI L2A data across all tropical forests and found that tropical forest structure was less stratified and more exposed to sunlight than previously thought. Most tropical forests (80% of the Amazon and 70% of southeast Asia and the Congo Basin) have a peak in the number of leaves at 15 m (49 ft) instead of at the canopy top. Doughty and his team have found that deviation from more ideal conditions (i.e., lower fertility or higher temperatures) lead to shorter, less-stratified tropical forests with lower biomass.
Paul Moorcroft [Harvard University] reported on studies of current and future carbon dynamics across the Pacific Coast region based on forest structure and rates of carbon uptake. Moorcroft’s group examined how these ecosystems will behave in the future under different climate scenarios and have plans to conduct similar studies in other regions.
DAY TWO
Naikoa Aguilar-Amuchastegui [World Bank] kicked off day two with his perspective on the importance of streamlining the monitoring, reporting, and validation (MRV) process from scientific estimation to actual use of the data. Once scientific data is generated, end users are often faced with challenges related to transparency and understandability. Scientists can better communicate how to use their datasets properly, by familiarizing themselves with who wants to use their data, why they want to use it, and what their needs are. With this information in mind, data can be presented in more practical ways that allow for a variety of institutions with different standards and frameworks to integrate GEDI data more easily into their reporting. As the GEDI team continues to produce high-quality maps, efforts are underway to connect with end users and provide tutorials, workshops, and other resources.
GEDI Demonstrative Products
Demonstrative products show how GEDI data can be used in practice and in combination with other resources. Ecosystem modeling is one way that GEDI data are being used to address questions about aboveground carbon balance, future atmospheric CO2 concentrations, and habitat quality and biodiversity. George Hurtt [UMD—GEDI Co-I] shared his progress on integrating GEDI canopy height measurements with the Ecosystem Demography model to estimate current global forest carbon stocks and project future sequestration gaps under climate change – see Figure 6. Hurtt emphasized that this unprecedented volume of lidar data significantly enhances the ability of carbon models to capture spatial heterogeneity of forest carbon dynamics at 1 km (0.6 mi) scale, which is crucial for local policymaking regarding climate mitigation.
Figure 6. [Top] Average lidar canopy height at 0.01° resolution, computed by gridding both GEDI and ICESat-2 together, and carbon stocks [middle] and fluxes [bottom] from ED-Lidar (GEDI and ICESat-2 combined). The insets highlight fine-scale spatial distribution and coverage gaps at selected regions (1.5° × 1.5°). Note that the three maps show grid-cell averages aggregated from sub-grid scale heterogeneity for each variable. Figure credit: From a 2023 article in Global Change Biology. There is also great potential for the development and application of methods for mapping forest structure, carbon stocks, and their changes by fusing data from GEDI and the Deutsches Zentrum für Luft- und Raumfahrt’s (DLR) [German Space Operations Center] TerraSAR-X Add-oN for Digital Elevation Measurement (TanDEM-X) satellite mission, which uses synthetic aperture radar (SAR) to gather three-dimensional (3D) images of Earth’s surface. This fusion product is being spearheaded by Wenlu Qi [UMD], who presented on efforts to create maps of pantropical canopy height, biomass, forest structure, and biomass change using the fusion product as well as maps of forests in temperate U.S. and Hawaii.
Data from the GEDI mission are also being used to quantify the spatial and temporal distribution of habitat structure, which influences habitat quality and biodiversity. Scott Goetz [NAU—GEDI Deputy PI] presented on biodiversity-related activities, citing a 2023 paper in Nature that examined the effectiveness of protected areas (PAs) across southeast Asia using GEDI data to compare canopy structure within and outside of PAs – see Figure 7. He also presented an analysis of tree and plant diversity across U.S. National Ecological Observation Network (NEON) sites that showed similar capabilities of GEDI with airborne laser scanning (ALS) for tree diversity.
Figure 7. [Top] Protected Areas (PAs) such as national parks can reduce habitat loss and degradation (from logging) and extractive behaviors such as hunting (shown in red circle), but this figure shows there are a wide range of real-world outcomes based on management effectiveness. [Middle] PAs are aimed at safeguarding multiple facets of biodiversity, including species richness (SR), functional richness (FR) and phylogenetic diversity (PD). PAs often focus on vertebrate conservation, owing to their threat levels and value to humans – including for tourism. This study focused on wildlife in southeast Asia, with mammals shown here representing a variation of feeding guilds and sizes. The same approach is repeated for birds. [Bottom] Wildlife communities inside PAs and in the surrounding landscape may exhibit distinct levels and types of diversity. Figure credit: From a 2023 article in Nature. Competed Science Team Presentations—Session 3
One unique application of GEDI data is using lidar height to improve radiative transfer models for snow processes. Steven Hancock [University of Edinburgh, Scotland] reported on his group’s work studying snow, forest structure, and heterogeneity in forests, explaining that the majority of land surface models used for climate and weather forecasting use one-dimensional (1D) radiative transfer (RT) models driven by leaf area alone. Heterogeneous forests cast shadows and cause the surface albedo to depend upon sun angle and tree height for moderate leaf area indices (LAI), i.e., LAI values from 1-3 – which are common in snow-affected areas. This complexity cannot be represented in 1D models. An RT model can represent the effect of tree height and horizontal heterogeneity to simulate the observed change in albedo with height, which itself spatially varies.
In contrast to a snowy study area, Ovidiu Csillik [NASA/Jet Propulsion Laboratory] and his team are developing statistical models to link GEDI relative height metrics to tropical forest characteristics traceable to inventory measurements. This dataset of forest structure variables over the Amazon will be used to initialize a demographic ecosystem model to produce projections of future potential tropical forest carbon, as demonstrated by Amazon-wide simulations using initializations from airborne lidar sampling.
Wenge Ni-Meister [Hunter College of the City University of New York] is working on improving aboveground biomass estimates using GEDI waveform measurements. Ni-Meister and her team are testing models in both domestic and international tropical and temperate forests.
Breakout Sessions—Session 2
Two more breakout sessions occurred on day two:
Sean Healey led a discussion on modes of inference for GEDI data. Inference – formally derived uncertainty for area estimates of biomass, height, or other metrics – can take different forms, each of which includes specific assumptions. In this breakout session, participants considered the strengths and limitations of different inference types (e.g., intensity of computation or the ability to use different models).
Laura Duncanson [UMD—GEDI Co-I] led a discussion about facilitation of open science, in other words, how to make GEDI data more accessible and digestible for data users. While GEDI data area free and publicly available via the LP DAAC and ORNL DAAC, gaining access to said data can be intimidating. Sharing more about existing resources and creating new ones can help remove barriers. The LP DAAC and ORNL DAAC have excellent tutorials on GitHub (a cloud-based software development platform that is primarily Python-based), and Google Earth Engine applications are available for accessing and visualizing GEDI data. Future endeavors may include more webinars, R-based tutorials, workshops, and trainings on specific topics and ways to use GEDI data. More information is available via an online compilation of GEDI-related tutorials.
Perspective: A NUVIEW of Earth’s Land Surface
For the second perspective presentation of day two, meeting attendees heard from Clint Graumann, CEO and co-founder of NUVIEW, a company whose mission is to build a commercial satellite constellation of lidar-imaging satellites that will produce 3D maps of the Earth’s entire land surface. Graumann shared NUVIEW’s intent to produce land surface maps on an annual basis and provide a variety of products and services, including digital surface models (DSMs), digital terrain models (DTMs), and a point cloud generated by laser pulses.
Competed Science Team Presentations—Session 4
Laura Duncanson began the second round of science presentations with her group’s research on global forest carbon hotspots. She discussed her 2023 paper in Nature Communications on the effectiveness of global PAs for climate change mitigation – see Figure 8, which found that the creation of PAs led to more biomass – especially in the Amazon. Within GEDI-domain terrestrial PAs, total aboveground biomass (AGB) storage was found to be 125 Pg, which is around 26% of global estimated AGB. Without the existence of PAs, 19.7 Gt of the 125 Pg would have likely been lost.
Figure 8. PAs effectively preserve additional aboveground carbon (AGC) across continents and biomes, with forest biomes dominating the global signal, particularly in South America. The additional preserved AGC (Gt) in WWF biome classes (total Gt + /− SEM*area). World base map made with Natural Earth. The full set of analyzed GEDI data are represented in this figure (n = 412,100,767). Figure credit: From a 2023 article in Nature Communications. Another unique application of GEDI data has to do with water on the Earth’s surface. Kyungtae Lee [UMD], who works with Michelle Hofton [UMD—GEDI Co-I], reported that GEDI appears to capture the monthly annual cycle of lake elevation, showing good correlation with the ground-based observations. Lee explained that even though the GEDI lake elevation estimates show systematic biases relative to the local gauges, GEDI captures lake elevation dynamics well – especially the annual cycle variations. This work has the potential to expand knowledge of hydrological significance of lakes, particularly in data-limited areas of the world. Stephen Good [Oregon State University] presented a survey of his team’s recent work integrating observations from GEDI into hydrology and hydraulics studies of how vegetation can block and intercept moving water. The team found important nonlinear relationships between inferred canopy storage and canopy biomass and were able to estimate canopy water storage capacities and map these globally.
Finally, Patrick Burns [NAU], who works with Scott Goetz, presented results using GEDI canopy structure metrics in mammal species distribution models across southeast Asia (specifically focusing on Borneo and Sumatra). The team’s early results indicate that GEDI canopy structure metrics are important in many mammal distribution models and improve model performance for another smaller subset of species. In other words, when looking at predictors like mean annual precipitation or forest structure (forest structure being a metric that GEDI data provide), the GEDI-derived structure metrics are more intuitive and help us understand distributional changes and fine-scale habitat suitability. In a region like southeast Asia, for example, which has undergone high rates of deforestation in the recent decades, forest structure may be a more relevant predictor in a species distribution model (SDM) than other metrics like climate or vegetation composition. The team will continue to produce models for additional species and expand the extent of the analysis to include mainland Asia.
DAY THREE
Competed Science Team Presentations—Session 5
Day three began with the meeting’s last round of competed ST presentations. John Armston presented the progress of GEDI L2B Plant Area Volume Density (PAVD) product validation using a global Terrestrial Laser Scanning (TLS) database and fusion of the L2B product with Landsat time-series for quantifying change in canopy structure from the Australian wildfires of 2019–2020. Participants then heard from Jim Kellner on using machine-learning algorithms for L4A aboveground biomass density (AGBD). The performance of machine-learning algorithms on a testing data set was comparable to linear regressions used for the first releases of GEDI AGBD data products on average – although there were important geographical differences associated with machine learning. One application under investigation is using machine learning to identify new potential stratifications for GEDI footprint aboveground biomass density.
Lastly, Jingyu Dai [New Mexico State University (NMSU)], who works with Niall Hanan [NMSU], presented on her analysis of the global limits to tree height. Her study shows that hydraulic limitation is the most important constraint on maximum canopy height globally. This result is mediated by plant functional type. In addition, rougher terrain promotes forest height at sub-landscape scales by enriching local niche diversity and probability of larger trees.
Perspective from the Data Side
As described in the summary of Ralph Dubayah’s introductory remarks, the LP DAAC and ORNL DAAC play essential roles in the dissemination of GEDI data and the success of the GEDI program. Representatives from each of these DAACs addressed the ST to summarize recent GEDI-related activities.
Aaron Friesz [United States Geological Survey (USGS)] represented the LP DAAC and gave an update on the current archive size, distribution metrics, and outreach activities. He also discussed plans to support the growth and sustainability of the community through collaboration activities that will leverage the GitHub application; he described some of the resources that are available. Friesz then highlighted the USGS Eyes on Earth podcast and the Institute of Electrical and Electronics Engineers (IEEE) Geoscience and Remote Sensing Society (GRSS)’s Down to Earth podcast, which have featured Ralph Dubayah and Laura Duncanson, and shared plans to update the current GitHub tutorials and how-to guides in the Earthdata Cloud of GEDI V2 and V3.
Rupesh Shrestha [ORNL] represented the ORNL DAAC and shared the status of GEDI L3, L4A, and L4B datasets archived there. He gave an overview of data tools and services for the GEDI datasets, which can be found on the GEDI website and GitHub tutorials website. GEDI L3, L4A, and L4B are available on NASA’s Earthdata Cloud and various enterprise-level services, such as NASA’s WorldView, Harmony, and OpenDAP. GEDI data usage metrics, data tutorials and workshops, and outreach activities, as well as other published community and related datasets were also highlighted. GEDI L3, L4A, and L4B have been downloaded over four million times collectively.
Neha Hunka [UMD] gave the final presentation of the meeting on biomass harmonization activities. She reported that the GEDI estimates of aboveground biomass are capable of directly contributing to the United Nations Framework Convention on Climate Change Global Stocktake. Hunka and her colleagues’ research is aimed at bridging the science–policy gap to enable the use of space-based aboveground biomass estimates for policy reporting and impact – see Figure 9.
Figure 9. Forest biomass estimates in the format of Intergovernmental Panel on Climate Change (IPCC) Tier 1 values from NASA GEDI and ESA Climate Change Initiative (CCI) maps. Figure credit: Neha Hunka Conclusion
Overall, the 2023 GEDI STM showcased an exceptional array of scientific research that is highly relevant to addressing pressing global challenges and answering key questions about global forest structure, carbon balance, habitat quality, and biodiversity among other topics. As the GEDI instrument enters its second epoch, we are excited to welcome a new competed GEDI science team cohort and look forward to the release of V3 data products later this year.
Ralph Dubayah concluded the STM with a summary of hibernation period goals and a farewell to this iteration of the competed ST. He extended a heartfelt thank you and farewell to Hank Margolis [NASA Headquarters, emeritus] who has been the NASA Program Scientist for the GEDI mission since 2015. Thank you, Hank. We will miss you.
Talia Schwelling
University of Maryland, College Park
tschwell@umd.edu
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Summary of the 2023 Precipitation Measurement Mission Science Team Meeting
Andrea Portier, NASA’s Goddard Space Flight Center/Science Systems and Applications, Inc., andrea.m.portier@nasa.gov
Introduction
The annual Precipitation Measurement Mission (PMM) Science Team Meeting (STM) took place September 18–22, 2023, in Minneapolis, MN. The PMM program supports scientific research and applications, algorithm development, and ground-based validation activities for the completed Tropical Rainfall Measuring Mission (TRMM) and current Global Precipitation Measurement (GPM) mission, including the GPM Core Observatory. Participants (including 137 in person and 22 virtual attendees) joined the meeting from a variety of affiliations including NASA, the Japan Aerospace Exploration Agency (JAXA), universities, and other partner agencies—see Photo.
The meeting included 46 plenary presentations spread across 7 thematically focused sessions and 77 poster presentations split between 2 sessions, with both oral and poster sessions covering mission and program status, partner reports, GPM algorithm development, and scientific results using GPM data.
The meeting also included a series of splinter sessions for precipitation working groups. The working groups included NASA–JAXA Joint Precipitation Science Team, the Committee on Earth Observation Satellites–Precipitation Virtual Constellation, GPM Mentorship Program, and topically focused groups on Applications, Hydrology, Land Surface, Latent Heating, Multisatellite, GPM Intersatellite Calibration (XCAL), Ground Validation (GV), Particle Size Distribution (PSD), and Oceanic Areas. These working groups were a combination of invitation-only, in-person, and hybrid meetings. Owing to the distributed nature of these meetings, summaries of their proceedings are not included in this article.
This article highlights current updates on the GPM mission and summarizes scientific results conveyed during the 2023 PMM STM. The meeting agenda and full presentations can be accessed through the 2023 PMM Science Team Meeting Files. Note that this is a password protected page; readers interested in accessing these files will need to reach out via the GPM Contact Form on the website to receive the access code.
Photo. Attendees of the 2023 PMM STM in front of the McNamara Alumni Center in Minneapolis, MN. Photo credit: Chris Kidd/GSFC and University of Maryland, College Park (UMD) Status Report and Updates on PMM: Perspectives from NASA and JAXA
The PMM missions are the fruit of long partnerships between NASA and JAXA. The PMM Science Team (ST) includes more than 20 international partners. The subsections that follow highlight the status of the PMM program and related activities that were conveyed by NASA and JAXA PMM Science Program Management Teams.
NASA
Will McCarty [NASA Headquarters (HQ)—GPM Program Scientist] presented the NASA HQ perspective regarding PMMs – present and future. He explained that current missions continue to drive the focus for precipitation science, and that future missions will continue to link the thermodynamic and dynamic factors of precipitation science by targeting additional temporal information. McCarty introduced several current and upcoming missions and programs, including satellite launches [e.g., NASA’s Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS), an Earth Venture Instrument (EVI), and the Investigation of Convective Updrafts (INCUS), an Earth Venture Mission], instruments [e.g., NASA’s Polarized Submillimeter Ice-cloud Imager (POLSIR), also an EVI, which will be deployed on two CubeSats], and field campaigns [e.g., NASA’s Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) and Convective Processes Experiment Cabo Verde (CPEX-CV) experiments]. He then briefly discussed the second (2017) Earth Science Decadal Survey and provided an overview of the future Earth System Observatory (ESO), which will have interconnected core missions (e.g., the Atmosphere Observing System (AOS)). He also discussed the Planetary Boundary Layer (PBL), which the Decadal Survey classifies incubation targeted observable. McCarty concluded by noting that the future PMM ST call may be integrated by combining mission science from multiple satellites.
George Huffman [NASA’s Goddard Space Flight Center (GSFC)—GPM Project Scientist and PMM ST Lead] provided an update on the projected lifetime for GPM. Based on fuel usage alone, GPM should continue to December 2027. However, the amount of solar activity has an impact on that calculation. The Sun is expected to be quite active over the next few years as we approach the Solar Maximum for Solar Cycle 25—which could shorten GPM’s lifetime by as much as four years. He noted that a controlled reentry of the GPM Core spacecraft is planned—and enough fuel has to be kept in reserve to allow this to happen. Huffman discussed a recently developed plan for boosting the orbit of the GPM core satellite—for more details on the plan, see the subsection, “GPM Core Observatory Boost,” later in this article. He added that NASA and JAXA have both approved the plan and deemed its implementation critical for overlap with AOS for instrument intercomparison. The boosting is currently scheduled for November 7–9, 2023.(Update: Since the meeting in September, the GPM orbit boost was executed successfully on the scheduled dates.) The impact of the boosting on radiometer algorithms (e.g., for the GPM Microwave Imager (GMI)) is expected to be less than the impact on the radar algorithms (e.g., for the GPM Dual-Frequency Precipitation Radar, (DPR)). The potential impact on the combined algorithms (i.e., algorithms used to combine data from GMI and DPR) is still being assessed.
Huffman also discussed the status of the GPM data products. He reported that all GPM core data products are using Version 7 (V07). He mentioned that V07 of the Integrated Multi-Satellite Retrievals for GPM (IMERG) Final is out, but IMERG Early and Late data products are pending other actions in the NASA Precipitation Processing System (PPS). (IMERG has 3 classifications of data products: Early (latency of 4 hours), late (latency of 12–14 hours), and final (latency of 3 months).) He noted that the GPM orbit boost requires modifications to V07 core algorithms, and this accentuates the importance of a timely release of V08 algorithms (anticipated early 2026).
Erich Stocker [GSFC—GPM Deputy Project Scientist for Data and Precipitation Processing System Project Manager] discussed the status of GPM data products. He mentioned that radar/combined/IMERG products have transitioned from V06 to V07—but all radiometer products, Level-1 to Level-3, went from V05 to V07 to ensure the version is consistent on all of the products. Stocker continued that the GPM core satellite boost in November 2023 will lead to an outage of radar products for about five months for research and 2–3 months for near real-time (NRT) data products. NRT radiometer products will continue through the boost with only 2–3 days of outage while the satellite reaches its new altitude. He concluded that the initial NRT V07 IMERG processing and V07 retroprocessing of Early and Late IMERG products will start in January 2024.
David Wolff [NASA’s Wallops Flight Facility (WFF)—GPM Deputy Project Scientist for Ground Validation and Ground Validation System Manager] provided an overview of the GPM Ground Validation program and current activities. He stated that the ground validation (GV) program has state-of-the-art ground and remote sensing instruments to acquire precipitation and microphysics data to validate GPM retrievals. He described the ground validation site at NASA’s Wallops Flight Facility (WFF), which includes several radars, disdrometers (an instrument that measures drop-size distribution), and a Precipitation Imaging Processor (PIP) package. Wolff discussed the gauge-only systems, Platforms for In situ Estimation of Rainfall Systems (PIERS), activities for Increasing Participation of Minority Serving Institutions in Earth Science Division Surface-Based Measurement Networks, and pySIMBA – the GPM GV Support Software, an Open-Source Python Package to integrate and Analyze Precipitation Datasets that is available from GitHub. Wolff also provided a brief overview of the successful GPM GV Workshop that was held at Wallops Flight Facility on March 23–25, 2023. He continued by providing GPM Ground Validation Network (VN) updates and discussing VN captures of three-dimensional (3D) polarimetric information within DPR and GMI.
Wolff also noted that the GV program includes field campaigns (e.g., IMPACTS and Marquette, a five-year mini campaign conducted in collaboration with the National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service (NWS)). He also discussed the new S-band radar network in Canada that offers access to high-quality radar data at relatively high latitudes over both land and sea. This data will be used as part of the VN for evaluation of GPM products. He concluded by discussing the Global Hydrometeorology Resource Center (GHRC) that archives past and current field campaign data and provides data quality control, metadata, campaign descriptions, and digital object identifier (DOI) assignments for each instrument/sensor.
Andrea Portier [GSFC—GPM Mission Applications Lead] and Dorian Janney [GSFC—GPM Outreach Coordinator] reflected on the 2022–2023 applications and outreach efforts and also discussed upcoming activities, including the – at the time of the meeting – upcoming tenth anniversary of the GPM Mission in February 2024. The applications team continues its focus on increasing awareness and use of GPM data and products across communities through user-engagement activities, including workshops (e.g., Applying Earth Observation Data for Research and Applications in Sustainable Development held at the 2022 Fall Meeting of the American Geophysical Union (AGU) in San Francisco, CA), trainings (e.g., 2023 GPM Mentorship Program), GPM application case studies, and GPM visualizations. A continuing and integral part of GPM outreach efforts is the numerous activities that reach hundreds of students and adults in a variety of formal and informal settings. This includes cooperative efforts with NASA’s Global Learning and Observations to Benefit the Environment (GLOBE) and hands-on activities at events (e.g., the Earth Day celebration at the Washington, DC’s Union Station). (To read more about the 2023 Earth Day celebration at Union Station, see A Pale Blue Dot in Washington: NASA’s Earth Day Celebration at Union Station, in the July–August 2023 issue of The Earth Observer [Volume 35, Issue 4, pp. 4–12].)
Many of these efforts will be highlighted and amplified during GPM’s tenth anniversary celebration. The GPM Applications and Outreach Team’s planning for the anniversary is underway. The intent is to highlight the vast capabilities of the GPM Mission and how GPM data can be used to address societal applications and improve the understanding of Earth’s water and energy cycles through a series of activities and resources starting in February 2024. These efforts include a reception at GSFC Visitor’s Center, a year-long monthly webinar series, feature articles, applications eBook, and a GPM video, among others. Details of these efforts will be posted through the GPM website.
JAXA
Takuji Kubota [JAXA—JAXA GPM Program Scientist] provided an update and a review of the PMM program status and mission objectives. He emphasized that this update included the perspectives of the Japanese PMM Science Program Management Team, including their roles in the development of DPR and its algorithms, GV, GPM data processing, and GPM data distribution systems. He also gave an update on current activities related to GPM data utilization and application across Japan and Asia. Kubota continued by describing the potential impacts on the DPR instrument because of the proposed orbit boost, noting that the instrument footprints and swath widths will increase proportionately with altitude change accompanied by a slight reduction in radar sensitivity. JAXA is preparing for these impacts with revised codes for L1 algorithms and planning for external calibrations before and after the orbit boost to examine calibrations of the DPR. Kubota also discussed the reprocessing of JAXA’s Global Satellite Mapping of Precipitation (GSMaP) data product (essentially the JAXA equivalent of IMERG) to enable a longer-term precipitation dataset, highlighting its completion in September 2023. GSMaP data is now available back to January 1998. Kubota discussed the future of Japanese precipitation measurements including: Earth Cloud, Aerosol and Radiation Explorer (EarthCARE), scheduled for launch in 2024; Global Observing SATellite for Greenhouse gases and Water cycle (OSAT-GW), planned for launch NET 2024; Advanced Microwave Scanning Radiometer (AMSR) series, which currently includes AMSR2 on the (GCOM-W) and will include AMSR3 on GOSAT-GW; and the previously discussed ESO AOS mission. He concluded with a discussion of JAXA’s plan for observing and celebrating GPM’s tenth anniversary.
Yukari Takayabu [University of Tokyo—JAXA GPM Project Scientist] highlighted results from recent science studies using DPR and GSMaP data products from the JAXA assembled GPM Program Science Team. She noted the use of DPR for extracting high-altitude precipitation information over Africa, capturing low-level precipitation statistics near the center of typhoons, narrowing the blind zone of the DPR to improve shallow precipitation detection in mountainous areas, validation studies of DPR, and retrieving frozen precipitation data using DPR. She concluded her presentation with highlights of GSMaP use for several applications, including the new GSMaP validation work in Japan to observe extreme rainfall, improvements to GSMaP through data-driven approaches, and data assimilation of GSMaP into the JAXA Realtime Weather Watch system.
Nobuhiro Takahashi [Nagoya University] presented an overview of significant updates to the DPM algorithm since the last PMM ST meeting, including changes in the latest V07 processing to accommodate the full-swath Ka-band operations – see Figure 1. He emphasized the impacts on the planning and development of V08 DPR algorithm with respect to the GPM orbit boost (described in George Huffman’s presentation). He noted that the major impacts to the performance of DPR include a degradation of measurement sensitivity and the “rain/no rain” classification. Takahashi concluded by saying that the release of V08 is expected in January 2026.
Figure 1. Evaluation of DPR product improvements from V06 to V07. Dual frequency product has smaller bias than KuPR product. The correlation coefficient improved from V06 to V07.Figure credit: Nobuhiro Takahashi/Nagoya University Kosuke Yamamoto [Earth Observation Research Center (EORC) and JAXA] summarized application activities initiated by the JAXA GPM Program Science Team. He discussed the use of GSMaP precipitation data to support and enhance several application areas, e.g., the operational use of GSMaP for flood and severe weather forecasting as well as the use of GSMaP in operational systems, including the JAXA Agro-meteorology Information Provision System (JASMIN), ASEAN Food Security Information System (AFSIS), and the Japanese’ Coast Guard’s Maritime Domain Awareness (MDA) initiative. Yamamoto also discussed the 2022 Japan–Australia–India–U.S. (QUAD) Joint Leaders’ Meeting Tackling Extreme Precipitation Events Workshop, an online event that took place March 1–3, 2023, and associated workshop reports focusing on the utilization of satellite observations across Pacific Islands.
GPM Algorithm Updates
Presenters during this session provided information and updates on various aspects of the five major algorithms of GPM. Full documentation and detailed updates for each algorithm are available at the Precipitation Data Directory.
Dual Frequency Radar Algorithm
The DPR algorithm team provided updates on DPR-related work, including the further refinement of the path-integrated attenuation (PIA) estimates used in the surface reference technique (SRT). They examined the effects of using the new AutoSnow algorithm – which uses satellite snowfall observations to create snowfall maps – on PIA estimations and changes in the surface type classification. Overall, the changes were small on the estimated precipitation profiles. Other algorithm refinements include the addition of a dry and wet snow category and wind speed. The team is currently examining how to recover Ka-band attenuation from the Ku-band. They stressed that results from this analysis are preliminary, and more work is needed to assess the utility of this technique. Finally, the team is discussing the implications of the GPM orbit boost on the DPR algorithm.
GPM Combined Radar–Radiometer Algorithm
The GPM Combined Radar–Radiometer Algorithm (CORRA) team discussed the changes and improvements to the CORRA V07 algorithm over the previous version. They highlighted the new AutoSnow algorithm and its impacts within CORRA V07. The team also examined the impact of the precipitation particle size distribution (PSD) initial assumptions on the estimation of snowfall as well as a machine-learning based initialization approach that improves the agreement between CORRA and NOAA’s Multi-Radar/Multi-Sensor System (MRMS) snow estimates. In addition, the team continues to examine a radiometer-only module to estimate light precipitation over oceans. This module will be included in the next version (V08) of CORRA. The team is also looking at the consequences of the GPM orbit boost.
Goddard Profiling Algorithm for GMI
The Goddard Profiling Algorithm (GPROF) team continues to work on well-known issues. The V07 update includes improvements in the a priori database to help constrain outputs from GPM constellation radiometers as well as inclusion of the radiometers on TROPICS and NASA’s Temporal Experiment for Storms and Tropical Systems–Demonstration (TEMPEST-D). The two new neural network-based implementations of GPROF in V08 are anticipated in roughly a year. The team reported that they have no issues with the GPM orbit boost.
Integrated Multi-Satellite Retrievals for GPM Algorithm
The IMERG algorithm team reported on V07, which includes a wide range of algorithm changes from V06. V07 includes retrospective reprocessing of the entire TRMM–GPM record and thus supersedes all previous versions. The team also reported that the algorithm changes improve the performance of IMERG estimates both in terms of its precipitation detection and systematic and random bias. The presenters noted improvements over frozen, orographic, and coastal surfaces. The team is now working on priority items that need completing in order to implement V08.
Convective–Stratiform Heating Algorithm
The GSFC Convective–Stratiform Heating (CSH) algorithm team provided an overview on latent heating (LH) retrievals. The presentation highlighted some of the details in updating to V07, including more accurate cloud-resolving model (CRM) simulations (using 3D domain rather than two-dimensional) and new detailed radiation retrievals. V07 is also “terrain aware,” meaning that the algorithm includes added details of radiative heating profiles and eddy transport terms. For V08, the CSH team plans to have a new 3D CRM database with a grid size of 250 m (820 ft) and look-up tables (LUTs) for non-surface raining columns for the tropical/summertime part of the algorithm as well as LUTs for terrain. These V08 improvements are still in development as of this meeting.
Science Results and Data Quality
A large component of the meeting was dedicated to presentations by NASA PMM-funded Principal Investigator (PI) teams on the science research and applications being achieved using PMM data. PI oral presentations were divided into four thematically focused topical sessions: Precipitation Microphysics, Snow and Hail, Storm Analysis, and Data Uncertainty. The subsections that follow highlight scientific results from each of these sessions. The reader is referred to the full reports online for more details.
Precipitation Microphysics
Presenters during this session described various techniques and new methodologies to study microphysical properties of precipitation including shape and size of precipitation particles (e.g., drop size distribution (DSD)), phase identification (e.g., liquid, solid, and mixed phase/melting), scattering properties, and precipitation rate, using both radar and radiometer observations. These property measurements play a pivotal role in improving precipitation retrieval algorithms, allowing scientists and decision makers to better understand and forecast storms.
One presenter in this session discussed new methods for classifying different types of precipitation (e.g., rain, graupel, hail, and dry and wet snow) using DPR precipitation retrievals. The new technique will be implemented into the V08 DPR algorithm. The discussion also covered a technique to establish relationships between GMI brightness temperature and hydrometeor type (e.g., rain, snow, graupel, and hail), leveraging the GPM validation network to construct LUTs of hydrometeor type likelihood – see Figure 2. Another presenter introduced a model to understand how DSD changes near the surface can be used to estimate rainfall rate. The last presenter in this session discussed the development of a precipitation scattering property database—which includes scattering characteristics of about 10,000 different types of ice particles. The database includes scattering cross sections calculated in thousands of orientations for each type of particle. This database is accessible to the public, which helps support the development of physically based scattering calculations and improvement of precipitation retrieval algorithms for both radar and radiometers.
Figure 2. A technique for retrieving hydrometeor information from GMI brightness temperature. In these RGB plots, snow and rain are combined into one category (green), while the individual probabilities are retained in the lookup tables.Figure credit: Dan Cecil/NASA’s Marshall Space Flight Center (MSFC) Snow and Hail
In this session, speakers discussed a broad move toward satellite retrievals for frozen hydrometeors, not just to identify bulk effects (e.g. snow or hail accumulation at the surface), but also to gather information on physical properties of frozen hydrometeors (e.g., where hailstones reside within clouds or what shapes snowflakes take). Understanding frozen hydrometeor properties can significantly improve precipitation and latent heat estimates that are essential for numerical weather forecasting and climate model development.
One speaker applied a method that used DPR and GMI observations to estimate frozen precipitation particle properties for an Olympic Mountain Experiment (OLYMPEX) field campaign case. The results he showed indicated a significant difference in the shapes of snowflakes between land and sea. Another speaker detailed the use of a simple machine learning framework trained on measurements of the use of snowfall and cloud type observations from the CloudSat Cloud Profiling Radar (CPR) to infer surface snowfall from GMI microwave measurements. Other presenters conveyed the results of a study examining different potential indicators of hail within the GPM database. These hail indicators were mapped, and the mean vertical profiles of radar reflectivity and storm structure were contrasted. The final pair of presentations focused on detecting hail in South America and Africa. In South America, hail-producing storms were shown to be strongly linked to local topography – in contrast to hotspots of hail in the U.S. Meanwhile, in Africa, new algorithms for identifying hail in GPM data suggest hail should be common – but this outcome is at odds with ground truth observations. This test case is being used to develop new methods for retrieving hail that include analyzing horizontal profile information within the data.
Storm Analysis
Presenters in this session discussed a variety of applications and assessments of PMM products for analyzing a variety of storms, particularly their cloud, precipitation, and kinematic structures and their structural evolution. The first speaker compared precipitation events simulated in IMERG to the same event with rain gauge observations. They found that while IMERG missed many winter precipitation events in mountainous regions –which rain gauges typically can measure – IMERG also captured summer virga events – which rain gauges typically miss. Another presenter compared IMERG to river catchment and integrated watershed observations and found that IMERG overestimated small precipitation events but underestimated large events. The next presenter showed a comparison IMERG simulations to the multi-instrument MRMS dataset during the lifecycle of precipitation events. The results shown suggest that IMERG errors in precipitation intensity could be improved by inputting other variables (e.g., ice water path or vertical velocity) into the precipitation retrievals. The discussions during this session also covered other plans to use PMM products to study convection in atmospheric river events, in combination with a modeling analysis using different convection schemes. The final pair of presenters spoke about understanding convective-scale drivers of the Inter Tropical Convergence Zone ascent and widening the use of a simple prognostic model that will use PMM data for filling terms in the model. One model weakness is the decay term for the convection cloud shield, which, if determined, could reduce error in climate models, particularly with radiative processes. The final speaker used TRMM Visible and Infrared Scanner (VIRS) data to develop and test a method for identifying and classifying cloud areas (i.e., core, midrange extent, and outer bound split window testing) and determine their relationships to other environmental variables, such as sea surface temperatures and column water vapor.
Data Uncertainty
Presenters during this session discussed new methodologies to address data uncertainties and bias in precipitation retrievals to improve precipitation estimates for science and applications research. Two of the presenters delved into the details of how the GPROF algorithm has inherent precipitation biases due to different hydrometeor characteristics captured by GMI passive microwave brightness temperature – which may be related to thermodynamic environments. Another PI presented updates for improving uncertainty estimates to enhance hydrological prediction. Specifically, he discussed multiscale precipitation uncertainties in precipitation products, including a new product that combines the Space-Time Rainfall Error and Autocorrelation Model (STREAM) with single-orbit rainfall estimates from the combined GPM data product, called STREAM-Sat. He explained how the uncertainties in these products can influence hydrologic prediction. The session concluded with a discussion of machine learning methods to estimate the probability distribution of uncertainties in passive microwave precipitation retrievals at different temporal and spatial scales.
Discussion of Future Missions, Observations, and Activities Relevant to GPM
This session featured presentations on several other existing and upcoming missions in various stages of development, as well presentations covering the future of precipitation instruments and observations, each with applications relevant to GPM. Each presentation included information on plans to advance and support precipitation science in the near term and the coming decade, as described below.
TROPICS
The TROPICS Pathfinder CubeSat mission provides microwave observations of tropical cyclones with less than a 60-minute revisit time to capture better storm dynamics and improve forecasting. The Pathfinder has demonstrated all mission elements and provided new tropical cyclone imagery (12,000+ orbits and counting). The Cal/Val team hopes to release the data to the public in Fall 2023. (UPDATE: Provisional TROPICS data was released in January 2024.) The TROPICS pathfinder satellite showed that the compact TROPICS design performs comparably to the state-of-the-art sounders. Lessons learned will help the TROPICS Team as they work to improve efforts and operate the TROPICS constellation, which now holds a total of five satellites.
AOS
As discussed in Will McCarty’s remarks, AOS is a key component of the Earth System Observatory that was recommended in the 2017 Decadal Survey. The mission will deliver transformative observations fundamental to understanding coupled aerosol– and cloud–precipitation processes that profoundly impact weather, climate, and air quality. Two AOS projects are in the mission concept and technology development phase (Phase-A): AOS-Storm (to launch late 2020s), with a Ku Doppler radar, microwave radiometers, and backscatter lidar in a 55° inclined orbit; and AOS-Sky (to launch early 2030s) with cloud-profiling Doppler radar, backscatter lidar, microwave radiometer, polarimeter, far infrared (IR) radiometer, and aerosol and moisture limb sounders in polar orbit. (This paragraph reflects what was discussed during the meeting, however, AOS is undergoing changes that will be reflected on the website at a later date.)
GPM Microwave Radiometer Constellation in the Next Decade
The future passive microwave radiometer constellation looks robust, with multiple sensors to be launched in the next decade. Small/CubeSat constellations are becoming a reality, and a plan to incorporate them quickly into the overall precipitation constellation is needed. A point of emphasis was that a sensor in an inclined orbit is a necessity when it comes to providing a reference measurement to support this effort – see Figure 3.
Figure 3. Evaluation of passive microwave (PMW) frequencies and coverage to assess data gaps and needs for the future of precipitation constellation.Figure credit: Rachael Kroodsma/GSFC JAXA Precipitation Measuring Mission (JAXA PMM) Radar
Plans call for JAXA’s next generation of precipitation radar to be deployed as part of the agency’s future Precipitating Measuring Mission (PMM – yes, the same acronym as the Precipitation Measurement Mission). Objectives for this next-generation precipitation radar include Doppler observations, higher sensitivity measurements, and scanning capability. JAXA has collaborated with a Japanese science team and user community to explore the feasibility of a next-generation, dual-frequency precipitation radar. The discussion focused on the importance of measuring convection through Doppler velocities from spaceborne radar. The EarthCARE mission will feature the first Cloud Profiling Radar (CPR) with Doppler capability in space. JAXA has participated in NASA’s AOS Pre-Phase A activities. The synergy between the GPM DPR and PMM/KuDPR is expected to contribute to the construction of a longer-term precipitation dataset by providing overlapping observations.
Update on Cloud Services at NASA GES DISC
NASA’s Goddard Earth Sciences Data and Information Services Center (GES DISC), one of two data archive centers for GPM, is moving its data archive to the cloud – with all GES DISC data and services remaining free to all users. This will offer quick access to and subsetting capability for a large volume of data through multiple data access methods (e.g., Amazon Simple Storage Service) and cloud services. Multidisciplinary NASA data will be in one place – the Earthdata Cloud – and available for online analysis and in the cloud environment. Expanded services (e.g., access to the Common Metadata Repository–SpatioTemporal Asset Catalog (CMR-STAC), Harmony – a collective Earth Observing System Data and Information System (EOSDIS) effort to make data access more consistent and easier across all DAACs and Zarr – a data format designed to store compressed multidimensional arrays and thus well suited to cloud computing) are expected to be implemented in the near future. With the migration of GES DISC data to the cloud, some services may look different with details on the exact changes to services coming soon.
GPM Core Observatory Boost
As George Huffman discussed in his presentation, based on forecasted solar activity, the GPM Core Observatory could run out of fuel as early as October 2025 if the current orbit altitude is maintained. To prolong its operations, NASA and JAXA have decided to boost the GPM Core Observatory orbit by ~35 km (~22 mi), which places GPM at an altitude of ~435 km (~270 mi)) – placing it above the International Space Station orbital altitude. The post-boost operations of the satellite are expected to continue through the early 2030s. The boost is expected to last only 2–4 days and occur in the time window between November 2023 and March 2024 (likely November 7–9, 2023, as stated above), the boost will permanently change the sensors’ Field of Views (FOVs) and likely cause a gap of several months in DPR product delivery.
Precipitation in 2040
Sarah Ringerud [GSFC] and George Huffman led this plenary discussion that explored two questions: What comes next? and What does the cutting edge of precipitation science look like 20 years from now? CubeSats, reduced volume of low-frequency-channel observations, shorter sensor lifetimes, increased sampling, and calibration challenges are recognized as inevitable. Exciting new developments are seen in the opportunity for data fusion and interdisciplinary work. Interagency and private sector collaborations are foreseen as critical points for maintaining optimal monitoring of Earth precipitation.
Conclusion
The 2023 PMM STM brought together scientists from around the world to engage on a range of topics that advance the understanding of precipitation science, algorithms, and contributions to applications. The STM highlighted updates and activities enabled by the PMM scientific community. The closing session provided an opportunity for quick updates from precipitation working group members, who held splinter sessions. These updates were followed by an open discussion and review of PMM action items led by George Huffman. He reminded PMM STM participants of several important and noteworthy items, including updates on the orbit boost and subsequent algorithm adjustments, which will be available on the GPM website and be at the forefront for the project for the next six months; V08 of GPM data products are anticipated by early 2026; the budget reduction for the project – but not for current ROSES projects – will impact activities, including next year’s PMM STM; and the next NASA ROSES call might have a different package of opportunities, not strictly focused on PMM/GPM. He concluded by encouraging the PMM ST to share highlights and publications with the GPM Science Program Management Team as well as to continue to initiate collaborations with other colleagues to keep pushing the boundaries of science and outreach.
The next PMM STM will likely be held in September 2024. Details will be posted on the GPM website once they become available.
Acknowledgements The author would like to recognize the following individuals, all of whom made contributions to this article: Ali Behrangi [University of Arizona], Anthony Didlake [Penn State University], Gerry Heymsfield [GSFC], George Huffman [GSFC], Matthew Igel [University of California Davis], Toshio Iguchi [Osaka University], Dorian Janney [GSFC/ADNET Systems], Chuntao Liu [Texas A&M Corpus Christi], Veljko Petkovic [UMD], Courtney Schumacher [Texas A&M Corpus Christi], and Joe Turk [NASA/Jet Propulsion Laboratory].
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By NASA
(8 de noviembre de 2021) — La Estación Espacial Internacional, fotografiada desde la nave Crew Dragon Endeavour de SpaceX durante un vuelo alrededor del laboratorio orbital que tuvo lugar tras el desacoplamiento de Dragon del puerto orientado al espacio del módulo Harmony de la estación.Crédito: NASA Read this release in English here.
La NASA ofrecerá una rueda de prensa con cuatro astronautas a las 9:30 a.m. EDT (hora del este de EE.UU.) del martes 19 de marzo en la sede de la agencia en Washington. La tripulación, entre la que se encuentra el astronauta de la NASA de origen salvadoreño Frank Rubio, hablará de su reciente misión a bordo de la Estación Espacial Internacional, donde llevaron a cabo una amplia gama de experimentos científicos en beneficio de la vida en la Tierra y de la exploración con seres humanos del espacio.
Rubio, así como sus compañeros astronautas de la NASA Stephen Bowen y Woody Hoburg, y el astronauta de los EAU (Emiratos Árabes Unidos) Sultan Alneyadi, formaron parte de la Expedición 69 de la estación espacial y participarán en la conferencia de prensa.
Durante su primera misión espacial, Rubio completó aproximadamente un viaje de más de 157 millones de millas y 5.936 órbitas a la Tierra, lo que equivale a 328 viajes de ida y vuelta a la Luna. La misión extendida de Rubio brindó a los investigadores la oportunidad de observar los efectos de los vuelos espaciales de larga duración en el ser humano, ya que la agencia planea volver a la Luna a través de la campaña Artemis y prepararse para explorar Marte. Rubio regresó a la Tierra en septiembre de 2023 a bordo de la nave espacial Soyuz de Roscosmos tras pasar 371 días en el espacio, un récord para Estados Unidos.
Como parte de la misión SpaceX Crew-6 de la NASA, Bowen, Hoburg y Alneyadi regresaron a la Tierra en septiembre de 2023 a bordo de una nave espacial Dragon tras pasar 186 días a bordo del laboratorio en microgravedad. Como parte de la misión SpaceX Crew-6 de la NASA, Bowen, Hoburg y Alneyadi regresaron a la Tierra en septiembre de 2023 a bordo de una nave espacial Dragon tras pasar 186 días a bordo del laboratorio en microgravedad. Durante su misión, Bowen y Hoburg llevaron a cabo dos caminatas espaciales, y Alneyadi se convirtió en el primer astronauta de los EAU en realizar una caminata espacial. Con 10 caminatas espaciales realizadas durante sus varias misiones, Bowen está empatado con otros cuatro astronautas por el récord de mayor número de caminatas completadas por un astronauta estadounidense. Ocupa el tercer puesto en la lista de mayor número de horas acumuladas en caminatas espaciales.
Además de sus investigaciones, los miembros de la tripulación también realizaron demostraciones tecnológicas y actividades de mantenimiento de la estación espacial. Bowen, Hoburg y Alneyadi recorrieron 78.875.292 millas durante su misión y completaron 2.976 órbitas alrededor de la Tierra. La misión Crew-6 fue el primer vuelo espacial para Hoburg, Alneyadi y Fedyaev. Bowen ha pasado en total 227 días en el espacio, acumulados en cuatro misiones.
Los medios de comunicación interesados en participar deben confirmar su asistencia antes de las 5 pm EDT del lunes 18 de marzo a Joshua Finch (joshua.a.finch@nasa.gov) y María José Viñas (maria-jose.vinasgarcia@nasa.gov). La política de acreditación de medios de comunicación de la NASA está disponible en línea.
El encuentro con los medios de comunicación tendrá lugar en el Auditorio Webb de la sede central de la NASA, en el edificio Mary W. Jackson, 300 E. Street SW, en Washington.
Aprende más sobre la Estación Espacial Internacional:
https://www.nasa.gov/international-space-station/ (inglés)
https://go.nasa.gov/3wUF46G (español)
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Joshua Finch
Sede, Washington
202-358-1100
joshua.a.finch@nasa.gov
María José Viñas
Sede, Washington
240-458-0248
maria-jose.vinasgarcia@nasa.gov
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NASA en español Astronauts Expedition 69 Frank Rubio Humans in Space International Space Station (ISS) ISS Research NASA Headquarters Stephen G. Bowen View the full article
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By NASA
Read the article in English here.
La Estación Espacial Internacional (EEI) es un laboratorio de investigación en microgravedad que alberga innovadoras demostraciones de tecnología e investigaciones científicas. Las más de 3.700 investigaciones llevadas a cabo hasta la fecha han producido alrededor de 500 artículos publicados en revistas científicas. En 2023, este laboratorio orbital albergó más de 500 investigaciones.
Conoce más logros y hallazgos de las investigaciones en la estación espacial en la publicación Resultados anuales sobresalientes de la Estación Espacial Internacional (en inglés), y lee a continuación sobre los aspectos más destacados de los resultados publicados entre octubre de 2022 y octubre de 2023:
Nueva perspectiva sobre los púlsares
Vista del telescopio NICER, sujeto a la plataforma externa de alojamiento de carga útil de la estación espacial.NASA Las estrellas de neutrones, la materia ultradensa que queda cuando las estrellas masivas explotan como supernovas, también son llamadas púlsares porque giran y emiten radiaciones de rayos X en forma de haces que barren el cielo como faros. El Explorador de la Composición Interior de las Estrellas de Neutrones (NICER, por sus siglas en inglés) recoge esta radiación para estudiar la estructura, la dinámica y la energía de los púlsares. Los investigadores utilizaron los datos de NICER para calcular la rotación de seis púlsares y actualizar los modelos matemáticos de las propiedades de su rotación. Las mediciones precisas mejoran nuestra comprensión de los púlsares, incluyendo su producción de ondas gravitacionales, y ayudan a abordar preguntas fundamentales acerca de la materia y la gravedad.
Aprender acerca de los relámpagos
El brazo robótico de la estación espacial maniobra el Monitor de Interacciones Atmósfera-Espacio, el cual se observa en la parte superior de esta imagen, para llevar a cabo pruebas con la luz.NASA El Monitor de Interacciones Atmósfera-Espacio (ASIM, por sus siglas en inglés) estudia de qué modo la atmósfera y el clima de la Tierra afectan las descargas eléctricas de la atmósfera superior que son producidas por tormentas eléctricas severas. Estos fenómenos ocurren muy por encima de las altitudes normales de los relámpagos y las nubes de tormenta. Utilizando los datos de ASIM, los investigadores realizaron las primeras observaciones detalladas del desarrollo de un líder negativo, o el inicio de un destello, a partir de un relámpago en una nube. Comprender de qué modo las tormentas eléctricas perturban la atmósfera a gran altitud podría mejorar los modelos atmosféricos y las predicciones climáticas y meteorológicas.
Regeneración de tejidos en el espacio
La investigación Regeneración de tejidos – Defectos óseos (Investigación en Roedores 4, Centro para el Avance de la Ciencia en el Espacio, o CASIS), patrocinada por el Laboratorio Nacional de la EEI, examinó los mecanismos de cicatrización de las heridas en microgravedad. Los investigadores descubrieron que la microgravedad afectaba a los componentes fibrosos y celulares del tejido cutáneo. Las estructuras fibrosas en el tejido conectivo proporcionan estructura y protección a los órganos del cuerpo. Este hallazgo es un paso inicial en la utilización de la regeneración del tejido conectivo para el tratamiento de enfermedades y lesiones en los futuros exploradores espaciales.
Músculos poderosos en microgravedad
Instalación de la Unidad de Hábitat de Ratones en el Centro Experimental de Biología Celular de la estación.NASA/JAXA La JAXA (Agencia Japonesa de Exploración Aeroespacial) desarrolló el Sistema Múltiple de Investigación de Gravedad Artificial (MARS, por sus siglas en inglés), el cual genera gravedad artificial en el espacio. Tres investigaciones de la JAXA, MHU-1, MHU-4 y MHU-5, emplearon el sistema de gravedad artificial para examinar el efecto en los músculos esqueléticos que producen diferentes cargas gravitatorias: microgravedad, gravedad lunar (1/6 g) y gravedad terrestre (1 g). Los resultados muestran que la gravedad lunar protege contra la pérdida de algunas fibras musculares, pero no de otras. Es posible que se necesiten diferentes niveles gravitacionales para sustentar la adaptación muscular en las misiones futuras.
Mejores imágenes de ultrasonido
El astronauta de la JAXA Akihiko Hoshide utiliza el dispositivo de ultrasonido de la estación para obtener imágenes de la arteria femoral de su pierna derecha.NASA Eco vascular, una investigación de la CSA (Agencia Espacial Canadiense), examinó los cambios que se producen en los vasos sanguíneos y el corazón durante y después de los vuelos espaciales, utilizando ultrasonido y otros métodos de obtención de medidas. Los investigadores compararon la tecnología de ultrasonido 2D con un ultrasonido 3D motorizado, y descubrieron que el 3D es más preciso. Mejores mediciones podrían ayudar a mantener saludable a la tripulación en el espacio y la calidad de vida de la gente en la Tierra.
Este es tu cerebro en el espacio
El astronauta de la ESA Thomas Pesquet con un escáner cerebral previo al vuelo para la investigación Brain-DTI.ESA/NASA La investigación Brain-DTI de la ESA (Agencia Espacial Europea) llevó a cabo pruebas para saber si el cerebro se adapta a la ingravidez mediante el uso de conexiones entre neuronas previamente desaprovechadas. Las resonancias magnéticas de los miembros de la tripulación antes y después de los vuelos espaciales demuestran cambios funcionales en regiones específicas del cerebro, lo que confirma la adaptabilidad y plasticidad del cerebro en condiciones extremas. Esta información sustenta el desarrollo de formas de monitorear las adaptaciones cerebrales y de las contramedidas para promover un funcionamiento cerebral saludable en el espacio y para las personas con trastornos relacionados con el cerebro en la Tierra.
Mejores materiales para energía solar
La plataforma MISSE-FF es utilizada en la realización de pruebas para saber de qué manera la exposición al espacio afecta a los materiales, incluyendo los utilizados para la producción de energía solar en el espacio.NASA Los materiales de perovskita de haluro metálico (PHM) convierten la luz solar en energía eléctrica y son prometedores para su uso en células solares de película delgada en el espacio debido a su bajo costo, alto rendimiento, idoneidad para la fabricación en el espacio y su tolerancia a defectos y radiación. Para el Experimento 13 de Materiales de la Estación Espacial Internacional de la NASA (MISSE-13-NASA), el cual continúa una serie de investigaciones sobre cómo el espacio afecta a diversos materiales, los investigadores expusieron películas delgadas de perovskita al espacio durante diez meses. Los resultados confirmaron su durabilidad y estabilidad en este entorno. Este hallazgo podría conducir a mejoras en los materiales y dispositivos de PHM para aplicaciones en el espacio tales como paneles solares.
Comprender las burbujas de las espumas
Un colector de muestras para la investigación FOAM a bordo de la estación espacial.NASA Las espumas húmedas son dispersiones de burbujas de gas en una base líquida. Una investigación llamada Dinámica de la Materia Blanda del Laboratorio de Ciencia de Fluidos, o FSL (FOAM, por sus siglas en inglés) de la ESA examina el engrosamiento, o agrandamiento, del grano, un proceso termodinámico en el cual las burbujas grandes crecen a expensas de las más pequeñas. Los investigadores determinaron las tasas de agrandamiento para diversos tipos de espumas y encontraron una estrecha concordancia con las predicciones teóricas. Una mejor comprensión de las propiedades de las espumas podría ayudar a los científicos a mejorar estas sustancias para una diversidad de usos, incluyendo el combate de incendios y el tratamiento del agua en el espacio, y la fabricación de detergentes, alimentos y medicamentos en la Tierra.
Respuesta a preguntas candentes
Una muestra de tela compuesta de algodón y fibra de vidrio se quema durante el experimento Saffire-IV.NASA El fuego es una preocupación constante en el espacio. La serie de experimentos Saffire estudia las condiciones de las llamas en microgravedad utilizando la nave espacial de reabastecimiento Cygnus desocupada, que se ha desacoplado de la estación espacial. El Experimento Contra Incendios en Naves Espaciales IV (Saffire-IV, por sus siglas en inglés) examinó el desarrollo del fuego con diferentes materiales y condiciones, y mostró que una técnica llamada pirometría del color puede determinar la temperatura de una llama que se propaga. Este hallazgo ayuda a validar los modelos numéricos acerca de las propiedades de las llamas en microgravedad y proporciona información sobre la seguridad contra incendios en misiones futuras.
El salto de robot
Un robot Astrobee realiza una maniobra de autolanzamiento en la estación espacial.NASA La campaña de experimentos Astrobatics lleva a cabo a pruebas sobre el movimiento robótico mediante maniobras de salto o autolanzamiento de los robots Astrobee en la estación. En condiciones de baja gravedad, los robots podrían desplazarse más rápido, usar menos combustible y cubrir terrenos que de otro modo serían intransitables con estas maniobras, ampliando sus capacidades orbitales y planetarias. Los resultados verificaron la viabilidad de este método de locomoción y demostraron que proporciona un mayor rango de distancia. Este trabajo es un avance hacia la obtención de ayudantes robóticos autónomos en el espacio y en otros cuerpos celestes, lo que podría reducir la necesidad de exponer a los astronautas a entornos de riesgo.
Melissa Gaskill
Oficina de Investigaciones del Programa de la Estación Espacial Internacional
Centro Espacial Johnson
Busca en esta base de datos de experimentos científicos (en inglés) para obtener más información sobre los experimentos mencionados en este artículo.
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