Jump to content

Summary of the 2023 GRACE Follow-On Science Team Meeting


Recommended Posts

  • Publishers
Posted
eo-meeting-summary-banner.png?w=1037

28 min read

Summary of the 2023 GRACE Follow-On Science Team Meeting

Felix Landerer, NASA/Jet Propulsion Laboratory, felix.w.landerer@jpl.nasa.gov

Introduction

In October 2023, the annual gathering of the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On [G-FO] Science Team took place in Boulder, CO, hosted at University Corporation for Atmospheric Research’s (UCAR) Center Green campus. The event had 70 in-person participant and an additional 52 online participants – see Photo. G-FO is a U.S.–German collaboration between NASA and the Helmholtz Centre Potsdam GeoForschungsZentrum (GFZ) [German Research Centre for Geosciences].

GRACE team photo
Photo: Pictured here are the in-person attendees of the 2023 GRACE-FO Science Team. Another 52 people participated online.
Image credit: Felix Landerer/JPL

The meeting agenda featured 15-minute presentations over three days, describing new findings from G-FO observations and the combined GRACE and GRACE-FO [G/G-FO] climate data record that now spans over 21 years (2002–2023). 

The meeting began with the customary G-FO project status session, covering programmatic mission and flight segment technical updates, future mission plans, and descriptions of the latest data released from the GRACE Science Data System (SDS) centers. Subsequent sessions featured more than 53 contributed presentations covering analyses, algorithms, and science results by Science Team members and attendees, totaling 57 oral and 5 poster presentations. Many of the presentations are posted on the GRACE website. While this summary will cover all the content on the agenda of the meeting – it does do so in an exact linear fashion. It begins with a G-FO mission status update, followed by key highlights from the contributed analysis and science presentations.

Status of GRACE Follow-On

Since their launch on May 22, 2018, the twin G-FO satellites have been tracking Earth’s water movements and global surface mass changes that arise from climatic, anthropogenic, and tectonic changes. G-FO also enables new insights into variations of ice sheet and glacier mass, land water storage, as well as changes in sea level and ocean currents. These measurements have important applications and implications for everyday life. The impact of these data is underscored by the publication of over 6000 scientific papers – an average of 5 new publications per week – that have established G/G-FO as a leading Earth Science mission.

In May 2023, G-FO successfully completed its Prime Mission phase that lasted five years after launch. G-FO was among the missions that went through the 2023 NASA Earth Science Senior Review. The NASA project team submitted its response in spring of 2023 to extend mission operations through 2026. The proposal received overall Excellent score, highlighting the unique utility the data provide for Earth Science research and societal applications. However, the G-FO project’s NASA budget will be reduced (compared to the previous baseline) by 15% in fiscal year (FY) 2024 and 24% in FY 2025 and 2026 due to the overall budget constraints that NASA is facing. The G-FO team remains confident in its ability to continue delivering high-value and high-impact science data products – prioritizing science operations management and data latency over data reprocessing campaigns. Both NASA and GFZ had already formally committed to extending their collaboration on G-FO mission operations and data processing through the end of 2026 via a Memorandum of Understanding.

As of December 2023, the G-FO project team has processed and released 62 monthly gravity fields – the most recent being for October 2023 (at the time of this writing). The primary mission objective for G-FO is to provide continuity for the monthly GRACE mass-change observations (2002–2017) via its Microwave Interferometer (MWI) intersatellite range-change observations. G-FO also demonstrated a novel technology demonstration Laser-Ranging Interferometer (LRI) for more accurate satellite-to-satellite ranging observations for future GRACE-like missions. The LRI has been successfully operated in parallel with the MWI for most of the mission, delivering excellent quality data. LRI-based monthly gravity and mass change fields covering the period from mid-2018 to mid-2023 have been made available by the SDS teams for further analysis and study by the science community. 

Programmatic, Mission, and Operations Updates

The meeting began with Frank Flechtner [GFZ–German G-FO Project Manager] and Felix Landerer [NASA/Jet Propulsion Laboratory (JPL)—U.S. G-FO Project Scientist] giving welcoming remarks, followed by detailed assessments of the G-FO mission and operations status from the core SDS centers and flight operations teams.

GRACE Follow-On Project Status

Felix Landerer gave an overview of the G-FO satellites and the science data system performance. He reported that G-FO continues to meet its goal of extending the GRACE mass-change and gravity data record at equivalent precision and spatiotemporal sampling. 

Since the previous STM in October 2022, the overall G-FO science instrument performance has been stable, and the SDS team continued to deliver a gapless monthly data record to users ahead of schedule (on average, within 43 days instead of the 60-day requirement). Improving the data calibrations of the accelerometer measurements – which are noise contaminated on one of the two G-FO spacecraft – remains a core focus of the project SDS team. To this end, an improved calibration approach that reduced data errors by 10–20% has been developed and will be operationalized by the team in the coming months. 

Landerer reported that, as forecasted, the current Solar Cycle 25 has gained in strength through 2023 and will continue to do so through 2024 before subsiding again. The resulting higher non-gravitational forces acting on the satellites need to be properly accounted for in the accelerometer data processing. 

He also noted that small thruster leaks in the satellites cold gas propulsion system have been closely monitored since 2021. To ensure stable data collection and sufficient lifetime margin to achieve continuity with the proposed successor mission GRACE-Continuity, or GRACE-C (which is the new name for the Earth System Observatory Mass Change mission scheduled for launch no earlier than 2028), the G-FO project team, in conjunction with guidance from the satellite manufacturer Airbus and the German Space Operations Center, decided to adjust the operational data collection mode of G-FO to a wide pointing mode – which means that the two spacecraft are allowed to deviate from their relative line-of-sight pointing by up to 2°, whereas the previous pointing angles were 100 times smaller. This operational change necessitates fewer thruster firings, which in turn reduces leaks and improves accelerometer calibrations – and thus leads to better overall science data quality. Due to the wide pointing, the LRI intersatellite ranging data collection has been suspended in this operational mode. However, the LRI instruments are still activated and fully functional. Landerer emphasized that reducing the leak ensures that the GRACE-FO mission will have sufficient fuel to remain operational up until GRACE-C launches.

Despite these operational challenges, Landerer said that the science data delivered by G-FO continues to provide excellent utility and insights into a rapidly changing Earth system. He briefly highlighted a few scientific and decision-support contributions and achievements of G-FO over the last year. These included: 

  • Monitoring California Groundwater. G-FO recorded the largest seasonal total water storage gains over California after the multiple atmospheric rivers made landfall during the 2022/2023 winter. Yet, peak water storage in May was below values observed 15–20 years ago – due to long-term, sustained groundwater declines. Going forward, the data will be invaluable to assess groundwater recharge rates and processes.
  • Tracking Polar Ice Mass Loss. G/G-FO measured net ice mass gains over Antarctica that began around 2021 due to snow accumulation mainly in East Antarctica, which offset the unabated mass loss of the West Antarctic ice sheet.

Subsequent science presentations presented in-depth analyses of these and other findings in the dedicated science sessions, some of which are summarized below. 

Landerer also highlighted the expanding portfolio of open science contributions that the project team is supporting: Jupyter notebooks are part of an expanding GRACE Open Science toolbox with the goal to expand this toolbox with input from the Science Team and user community in the coming years. In addition, easy-to-use browser data portals at JPL and GFZ have been key to expand the science and applications user community that increasingly use the Level-3 and higher data products in decision support contexts (e.g., for drought monitoring and water resources management).

A series of status reports on programmatic G-FO mission operations, science operations, and SDS processing followed the opening presentations. Krzysztof Snopek [GFZ] reported on the ground and mission operations at the German Space Operations Center (GSOC), which is responsible for G-FO spacecraft operations. All essential flight operations, software updates, and planned calibrations were successfully scheduled and carried out by GSOC. Himanshu Save [University of Texas, Center for Space Research (CSR)] provided the science operations assessment. He described the evolving Solar Cycle 25 and its influence on the G-FO spacecraft, the mission’s fuel budget, and adjusted operational procedures and modes (such as the already-mentioned ‘wide’ pointing mode). Christopher McCullough [JPL] reviewed the status of G/G-FO Level 1 processing at JPL, detailing additional improvements made in the accelerometer calibrations. The team is using the noisy accelerometer data on one satellite and retrieving improved science information from it.

A representative from each of the G-FO mission SDS centers – which includes JPL, GFZ, CSR, and GSFC – summarized the status of the latest gravity-field and mass change data products [RL06.X L2], including an overview of background dealiasing models and the GFZ GravIS portal, the updated JPL mascon data product, new data-processing strategies, e.g., via range acceleration [CSR], and the status of ancillary Satellite-Laser-Ranging (SLR) data processing and dedicated G/G-FO products [GSFC].

Following the project team’s status presentations, there was a 30-minute session to answer questions from the science community and discuss in more detail the mission performance, near-term operations and data processing plans, as well as to gather suggestions and feedback from the community. 

Science Presentations

The remainder of the sessions in the meeting were open-submission science sessions, each of which centered around different thematic topics, including: G/G-FO analysis techniques and next generation gravity mission (NGGM) concept studies, and science analysis of mass-transport data in the fields of glaciology, oceanography, hydrology, and solid-Earth physics. As has been the case in previous years, the presenters underscored the value of interdisciplinary and multi-instrument analyses that utilize the unique complementary value of G/G-FO mass-change observations in combination with other remote sensing data (e.g., satellite altimetry or precipitation observations) and in situ data (e.g., surface deformation or ocean temperature profiles). Such hydrogeodetic combinations yield improved spatial and temporal resolutions that enable advances in Earth system process understanding, which increasingly advance societal applications of science results in support of NASA’s programmatic focus on Earth Science to Action, which seeks to “advance and integrate Earth science knowledge to empower humanity to create a more resilient world.”

Section A: GRACE and GRACE-FO Geodesy

The project status reports presented under the previous heading were part of the first section of the agenda (Session A1) as were two additional sessions: Analysis Techniques and Intercomparisons (Session A2) and NGGM and Bridging the Gap (Session A3), which focused on plans, concepts, and technologies being developed for future gravity missions. Highlights from each of these two sessions follow in the next two subsections. 

Analysis Techniques and Inter-comparisons

This session featured 15 presentations by the SDS centers and ST members on progress in instrument data calibrations and novel data processing algorithms and methods, including data-fusion with other observations.

Representatives from G/G-FO processing centers presented updated gravity-field time-series data, which capitalize on improved parameterizations, better instrument error characterizations (e.g., from star cameras, accelerometers, or ranging instruments) and background models (e.g., for tides) for improved monthly mass change data and uncertainty quantification. The highly accurate LRI data provides further opportunities to identify and characterize measurement system errors, which can be exploited for G-FO data processing but is also informative in the development of the future GRACE-C mission. However, it was also shown that several metrics used in identifying gravitational errors are sensitive to the estimated satellite trajectory, and consequently a sufficient understanding of the orbital trajectory is necessary to make accurate adjustments to the gravity field based on satellite observations.

The G/G-FO data products make use of ground-based geodetic observations, such as satellite laser-ranging (SLR) to a network of dedicated SLR satellites, which can be used to extend the G/G-FO interannual data record back to ~1994 – albeit at a much-reduced spatial resolution. Additionally, SLR data provide an important validation and performance assessment opportunity for G/G-FO observations. In that regard one presenter showed results indicating the recent G-FO accelerometer updates have indeed resulted in better gravity and mass change fields. Other speakers discussed the value and potential for improvement that could be achieved by combining G-FO and SLR observations more formally to exploit the data strengths of the different observation types in an optimal way. Such approaches could reduce uncertainties in global ocean and land ice mass changes. Furthermore, deployment of stable, long-term ocean bottom pressure (OBP) recorders in the Arctic Ocean in 2022 has enabled progress on G/G-FO OBP data validation. The data from these OBP recorders are entirely independent of G/G-FO observations and are thus very valuable to assess the satellite data record. An initial comparison between 1.5 years of OBP data and various G-FO OBP products suggest excellent agreement.

The data collected from G/G-FO has a native resolution of about 300 km (~186 mi). By jointly analyzing these G/G-FO data with higher-resolution surface elevation changes from a multimission synthesis of radar and laser satellite altimeters, net mass changes can be effectively downscaled (within a Bayesian framework) to less than 20 km (~12 mi) resolution, which is sufficiently high resolution to resolve individual ice streams in Antarctica that cannot be separated using G/G-FO data alone.

NGGM and Bridging the Gap 

The presenters in this session provided status-update on the GRACE-C mission, a joint project between NASA and the Deutsches Zentrum für Luft- und Raumfahrt (DLR) [German Aerospace Center], as well as on future instrument developments and mission concepts. 

The 2017 NASA Earth Science Decadal Survey Report highlighted mass-transport monitoring through gravity change as one of five designated observables (i.e., top priorities for study) in Earth observations for the next decade in collaboration with international partners. The GRACE-C project successfully passed the NASA/JPL Mission Concept Review in June 2022, and the NASA Key Decision Point B review in September 2023 and is currently in its Phase B project definition phase. GRACE-C will be a single satellite pair based on a fully redundant LRI (as demonstrated on GRACE-FO) in a polar orbit at 500 km (~311 mi) altitude. To avoid a data gap after GFO, a launch date of no later than 2028 is targeted for GRACE-C.

Similarly, GFZ has been conducting model simulation studies to determine the value of adding a second satellite pair, dubbed Next-Generation Gravity Mission (NGGM) in Europe.  The experiments reveal that advanced parameterization techniques for improved de-aliasing of short-term mass variations can significantly reduce data errors and open the possibility for higher spatial and temporal resolution data products and science applications.

The technology demonstration LRI on G-FO has surpassed its performance requirements. With a LRI expected to be the primary instrument for the GRACE-C mission as well as other future GRACE-like missions, development of a new technique is required to provide long-term laser frequency knowledge to provide a scale correction factor to the geodesy measurement. The LRI-team presented updated results of a so-called scale factor measurement technique that allows the accurate determination of the laser frequency on-orbit that can meet the stringent GRACE-C mission requirements. This was achieved with a dual frequency modulation scheme, and a prototype electronics unit has been developed and tested, demonstrating performance better than the expected mission requirements. 

There were also reports on progress in technology development of low-frequency optomechanical accelerometers for geodetic applications. These highly-sensitive, compact, portable – and cost-effective – optomechanical inertial sensors build upon recent advances in optomechanics to measure accelerations with small form factors. The development of a sensor with lower cost, size, weight, and power – yet with GRACE-like performance – is a major achievement as these could be integrated into cost-effective mission designs, spacecraft miniaturization, simplified architectures, as well as for the deployment of constellations of satellite pairs flying at lower altitudes.

Section B: Geophysics and Climate Science

There were five sessions included in this section of the agenda, which are summarized in the subsections below as follows: Hydrology (Session B4), Cryosphere (Session B2), Solid Earth Sciences (Session B1), Oceanography (Session B3), and Multidisciplinary Science (Session B5). 

Hydrology 

This session, with 12 presentations, highlighted advances in hydrology research and applications using G/G-FO data enabled by the unique value of long, uninterrupted mass change climate data record. 

The topic of terrestrial water storage variations in California came up in several presentations, focusing on the see-saw swings between very wet and very dry years and the early impacts on groundwater recharge after the record-breaking snow accumulation during the 2022/2023 winter. The process of groundwater recharge – an important objective in the 2017 Earth Science Decadal Survey – is not well understood because of the challenges in observing infiltration of new water supply into the ground and the effects of rate of input, amount of input, and various aquifer characteristics. By combining observations of precipitation, snow water equivalent, surface water storage, ground surface deformation, and groundwater storage from G/G-FO, recharge behavior can be characterized in a natural experiment where source inputs are effectively not limited, but recharge capacity is limited. Results of studies shown during the meeting reveal that only a fraction of total available potential recharge can enter the aquifer, and that G/G-FO observations allow us to measure the effective aggregated recharge capacity and how it varies with several predictors. Another paper reported that subsurface water increases in California’s Sierra Nevada by 0.6 m (~2 ft) from October 2022 to June 2023, which represents 43% of the cumulative precipitation. 

Several presenters reported on efforts to advance concepts to downscale G/G-FO data to bring the information closer to decision-making scales and expand water-related applications, as well as to fill gaps and expand the data record with multisensor observations. One presenter described a new spectral approach that employs wavelet multiresolution analysis to combine seasonal terrestrial water storage change data from G/G-FO with those from global navigation satellite system (GNSS) ground station networks to downscale the observations to smaller hydrological basins and to better separate processes over complex topographical terrain. This method can also be used by fusing G/G-FO and hydrological model data [e.g., from NASA’s Global Land Data Assimilation System (GLDAS) models at continental scales]. Importantly, the method yields trends and long-term signals that match G/G-FO observations – a strength of the observing system. Another approach used a statistical Bayesian framework to incorporate G/G-FO observations and Soil Moisture Change data from different available sources [e.g., NASA’s Soil Moisture Active Passive (SMAP) mission] to obtain nonparametric likelihood functions that allow for downscaling. A statistical technique called cyclostationary empirical orthogonal function (CSEOF) analysis – which is used to interpret space-time variability in a large dataset – allowed researchers to fill short data gaps (~1 year) in G/G-FO record (e.g., between 2017 and 2018 – the gap between GRACE and GRACE–FO) without having any additional data. With the support of physically-related data (e.g., precipitation and temperature), CSEOFs can be used to reconstruct water changes into the past or fill larger data gaps. Such datasets improve understanding of trends and natural variability and anticipate future trends in response to climatic changes. 

Another presenter described a science study that found an apparent abrupt decline in temperate (non-ice) Terrestrial Water Storage (TWS) in 2015 to a new, lower regime that appears to be unique in the past 33 years. The triggering event for this new lower TWS regime appears to be the massive drought in Brazil in 2015. Subsequent droughts around the world (e.g., Europe, the western U.S., Canada, central Africa, and southern Brazil) have helped to keep TWS values depressed. Warm global sea surface temperatures, prevalent since 2015, have decreased rain accumulation over the continents, reducing TWS.

In the European Alps region, a G/G-FO data analysis found that glacier and ice changes are the major contributors to the observed signals. Overall, glaciers here have lost ice mass at rates between 1.4 to 2.2 Gt/year since 2002. Advances in spatial downscaling and data combinations are expected to allow for improved estimates and applications, including geological hazard monitoring.

In Northern Italy, accelerated groundwater loss has been detected using G/G-FO, well measurements, and vertical land motion observations. Since 2015, the groundwater loss has accelerated. Assuming a best-case scenario (conditions similar to 2007–2014), it could take 13–28 years for ground water storage to recover from recent long-term period of decline, thus setting the stage for prolonged drought conditions.

Since a pioneering study in 2014, it is well-established that G/G-FO observations of TWS are an effective means to estimate flood potential and flood risks due to water-saturated soil. Novel G/G-FO data processing schemes that exploit sub-monthly variations of total water storage enabled researchers to delineate basin-specific storage-discharge dynamics more accurately. They found that at submonthly timescales in many global basins, water storage (i.e., saturated soil) has more impact on whether a flood will occur than the amount of precipitation that falls. 

Along the Nile River, G/G-FO data were used to monitor water changes in crucial artificial reservoirs. These data indicate that water losses through underground-seepage over the geologically highly fractured region via a complex network of shear systems, faults, and fractures, are significant and could impact the delicate water balance in the region. A separate study focusing on nearby Southern Arabia found that intense tropical cyclones (wind speeds > 64 kph or ~40 mph) have doubled in the past decade compared to the preceding two, which resulted in significant recharge of the aquifers in the study area. The findings demonstrate the ability of G/G-FO to capture recharge signals and monitor aquifer systems in poorly gauged basins and highlight the significant role of tropical cyclones in recharging aquifers in arid Arabia.

Cryosphere

The five contributions in this session reported on new ice mass balance results of the Earth’s land-ice, as well as on novel data-combinations approaches that can improve the spatial resolution over G/G-FO-only data.

The Antarctica Ice Sheet contributes to the largest sea level rise potential and remains as the largest uncertainty source in the prediction of future sea levels. Data from G-FO and the Ice, Clouds and land Elevation Satellite–2 (ICESat-2) mission have been used to track ice sheet mass and height changes in Greenland and Antarctica, respectively. By combining the strengths of G-FO (gravity or mass change) and ICESat-2, (laser altimetry) data, a more accurate and less uncertain estimate of ice sheet mass changes can be achieved. This combination has led to a proposal for an enhanced iterative algorithm for deriving Antarctic mass balance, incorporating key technologies such as altimetry, gravity measurements, Global Positioning System (GPS) satellite data, and surface mass balance models. The study utilizes an effective density map derived from ICESat-2 and tests the algorithm’s sensitivity and uncertainty with synthetic data, considering realistic physical processes and variability. This approach aims to address discrepancies in estimating ice mass loss in East Antarctica and provides important guidance for optimizing future ground measurements (i.e., GPS station positions). Another presentation focused on understanding the differences in mass change recovered by the G/G-FO and IceSat-2 missions – both in terms of spatial distributions and total magnitudes – to ultimately determine a best combined estimate of ice sheet mass change leveraging the strengths of each mission. 

Temporal gravity field estimates from G/G-FO data reveal that the Antarctic ice sheet contributed approximately 6.1 mm (~0.2 in) to global sea level rise from 2002–2022, with a net loss of ~2150 GT of mass. While mass change accelerated during the GRACE era, it has decelerated during the GRACE-FO era – due to increased mass gain in East Antarctica. The deceleration is attributed to surface mass balance processes: annual precipitation and increased incidences of extreme weather events in East Antarctica, challenging predictions based on correlations with climate indices like Southern Annular Mode and El Niño Southern Oscillation.

A related study confirmed a pause in Antarctica’s mass loss, a non-accelerating mass loss in Greenland, and a steady loss from glaciers and ice caps away from the poles. The use of the LRI observations enabled novel submonthly analysis in key regions (including the Amundsen Sea Embayment of West Antarctica and the Pine Island/Thwaites basins) to gain more understanding of fast ice dynamics and their spatial extent.

While G/G-FO data span two decades, estimates of Earth’s oblateness from other satellite observations that date back to 1976 and provide a much longer data record – albeit at much coarser spatial resolution. This half-century long timeseries provides important constraints on ice mass change prior to the launch of GRACE in 2002. The data suggest that ice mass loss had already begun to accelerate by the 1990s. Recent progress in Earth system models, in conjunction with the long satellite data record, are being used to isolate trends in glacial isostatic adjustment (GIA) – which is the vertical movement of the Earth’s surface after the weight of glaciers is removed from them – and to improved estimates of ice mass loss prior to GRACE.

Solid Earth Sciences

Two presenters in this session described their efforts to evaluate signals in the G/G-FO data record associated with earthquakes. The G/G-FO data provide a unique opportunity to observe the Earth’s response to great earthquakes across diverse tectonic settings at time scales from days to decades. Using 13 earthquakes of magnitude (Mw)>8.0 over the last 20 years, it was found that elastic bulk modulus and viscosity govern large-scale coseismic and postseismic gravimetric changes, respectively. By constraining the solid Earth’s viscosity structure, improved physics-based models of long-term postseismic changes can be developed that incorporate observations from G/G-FO. The portion of the long-term gravity change signal that can be attributed to these earthquakes can then be removed from the G/G-FO data to better quantify processes related to ocean mass and hydrology changes. When physics-based models are not available, alternative statistic-based approaches can be used to remove the co- and post-seismic signature of large earthquakes (e.g., 2004 Andaman-Sumatra and 2011 Tohoku, Japan quakes) from the G/G-FO data. 

As the G/G-FO data record extends into its third decade, the long time series of Earth gravity changes requires careful consideration of the solid-Earth response to contemporary surface mass changes. To isolate the gravity signature of any surface mass signal, it is becoming evident that simple elastic loading corrections are no longer sufficient. Recent advances in mantle rheology – describing and understanding the nature of Earth’s mantle – derived in mineral laboratory experiments, tidal modeling, and seismic imaging provide unequivocal evidence of anelastic contributions to solid-Earth deformation on time-scales ranging from hours to decades. New developments in the solid-Earth capabilities of JPL’s Ice-sheet and Sea-level System Model (ISSM) in the form of viscoelastic solvers for Love numbers and sea-level change was used to implement and explore the so-called Extended Burgers Material (EBM) and so resulting viscoelastic deformations between the seismic and GIA time scales. Preliminary testing with EBM rheology shows potential for a ~15–20% increase in mass change trends for some regions.

A subdecadal variation of large-scale (i.e., spanning over continental scales) gravity signals with a period of approximately six years has attracted intense interest in the geodesy and geodynamic communities. Earth’s fluid core motions, magnetic field, Earth rotation, and crustal deformations have been invoked as causes for this signal. An analysis of G/G-FO data showed that a significant part of the approximately six-year signals is in fact due to climate-related oscillation of ocean-atmosphere coupling in the Pacific and Atlantic and variations in the land water storage over Africa.

Oceanography

In the oceanography session, five presenters reported on the combination of G/G-FO, satellite altimeters (e.g., from the joint NASA–European Sentinel-6 Michael Freilich mission), and in situ ocean floats (e.g., Argo) to investigate variations in sea level and ocean circulations – e.g., see Figure 1. Other presenters discussed improvements in data processing by reducing errors in atmospheric tides that could lead to spurious trends or double-counting a subset of ocean tides and by incorporating new dedicated ocean data grids that remove geodetic signals not related to ocean dynamics (e.g., global ocean mass; large earthquake signals).

GRACE figure 1
Figure 1. The top row of maps show estimates of individual components of the observed sea level trend in the northwestern Pacific from 2003 to 2016 including contributions from: land ice melt [top row, left], non-ice land water storage [top row, middle], and stereodynamic effects [top row right], which are estimated by directly combining in situ-based steric sea level (i.e., based on Argo ocean profiling floats) with the GRACE-derived ocean mass changes. The bottom row shows the sum of all of the components of sea level trend on the top two rows [bottom row, left], compared the same measurement using satellite-altimetry [bottom row, right]. These data clearly show the strong earthquake-related signature of ocean mass change east of Japan.
Image credit: Felix Landerer/updated from a similar figure published in Nature’s Communications Earth & Environment.

Another presenter described how ocean mass redistribution and regional sea-level rise in the North-West Pacific marginal seas (i.e., around Japan and north of the Philippines) is impacted by seafloor deformation from earthquakes, which alter the ocean bathymetry. G/G-FO data are key to isolating these deformation effects, which in turn allows better sea level projections that can be used for planning purposes.

While long-term sea level trends are of major concern, the seasonal cycle is the dominating climate signal in ocean bottom pressure variability. Accurate representation of seasonal cycle is thus key to efforts to improve observations and models of ocean bottom pressure. Examining differences between models and observations elucidates remaining uncertainty in observations and missing physics in the models (e.g., lack of intrinsic variability due to coarse resolution, no accounting of gravitational and loading effects). This allows researchers to advance the quality of ocean mass change observations and unravel underlying dynamics.

Lastly, ocean bottom pressure observations from G/G-FO have been used to monitor transport variability of deep currents associated overturning circulation in the Northern Hemisphere (the Labrador Current) and Southern Hemisphere (Weddell Sea Bottom Water). This deepwater transport provides an important pathway for the sequestration of excess atmospheric heat and carbon from locations of water mass formation. Continuous observations of deep ocean currents provide valuable insight into Earth’s climate system. However, harsh conditions and complex recirculation transport pathways make in-situ observations of these deep flowing currents challenging.

Interdisciplinary Science

Six presenters contributed to this session. The first study revisited geodetic assumptions about measuring so-called Earth Center-of-Mass (CM) motions that can be traced to planetary-scale seasonal and long-term variations of water cycling between the land the oceans. Differences in SLR and G/G-FO estimates of CM estimates can be helpful to refining global circulation models. In a related study, G/G-FO and SLR data have been used to pin down the causes and origin of polar motion, particularly the mass component related to gravity changes. A novel hybrid SLR/GRACE time-variable gravity approach closely aligned well with the hydrological excitation in independently polar motion.

Errors in GIA corrections impact altimeter estimates of sea level and ocean mass estimates and the so-called sea level budget. Choices in modeling GIA, particularly based on paleoshoreline sites, affect Earth’s viscosity structure and GIA response, influencing global mean sea level (GMSL) budget closure. Even minor Earth model changes can have notable effects on the alignment of GMSL (altimetry), ocean mass (GRACE), and steric sea level change (Argo). Thus, future research needs to focus on accounting for the complex three-dimensional structure of the solid Earth to improve GIA corrections and more accurately isolate contemporary mass change in the G/G-FO data record.

Despite GIA uncertainties, G/G-FO, in combination with sea level measurements from altimetry, provide a unique capability to measure changes in ocean heat content. The ocean takes up nearly 90% of Earth’s current energy imbalance, signifying their important role in overall planetary heating. Two presenters reported consistent findings of ocean heat uptake rates of 0.9 W/m2 based on the indirect geodetic satellite measurements of sea level and ocean mass – a value that is entirely independent of other techniques and thus provides crucial validation – see Figure 2. In addition, the results indicated the overall heating rate over the last decade has increased, which means heat accumulation is accelerating.

GRACE figure 2
Figure 2. This graph shows different estimates of ocean heat uptake (OHU), measured with in-situ ocean floats (orange curve), from top-of-the-atmosphere radiance satellite measurements of Earth energy imbalance (EEi) (black curve), and from geodetic satellites, i.e., G/G-FO and altimeters (blue curve). The satellite measurements agree well and show an increasing energy imbalance over the last 20 years.
Image credit: Felix Landerer/originally in Geophysical Research Letters.

Summary

The hybrid 2023 G-FO STM brought together over 120 international participants and showcased a broad range of science results and applications that are supported and uniquely enabled by the satellite gravimetry-based mass change observations. The G-FO data now span nearly six years and continue to provide crucial insights into how Earth’s hydrosphere, including sea level, ocean currents, and water distribution over land, is changing. The G/G-FO data are extending important climate data records (e.g., the Greenland and Antarctic ice mass time-series, ocean mass sea level data, and TWS over land) into their third decade. The upcoming GRACE-C mission will build on and expand this mature data record, which is increasingly enabling important applications in support of water-related decision making and planning.

The G-FO project team remains focused on providing the mass-change data record at a level of performance consistent with that of GRACE. As the current Solar Cycle 25 increases towards its anticipated maximum in 2024, the team continues to improve the mission’s accelerometer data products in support of that goal. Corresponding data improvements in the monthly gravity and mass change products will be released early 2024.

The next G-FO STM will be held from October 8–10, 2024 in Potsdam, Germany, organized by GFZ. Check the GRACE website for specific details as the date gets closer.

View the full article

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By NASA
      A SpaceX Falcon 9 rocket carrying Northrop Grumman’s Cygnus XL spacecraft is launched on NASA’s Northrop Grumman Commercial Resupply Services 23 mission to the International Space Station on Sunday, Sept. 14, 2025.Credit: NASA NASA is sending more science, technology demonstrations, and crew supplies to the International Space Station following the successful launch of the agency’s Northrop Grumman Commercial Resupply Services 23 mission, or Northrop Grumman CRS-23.
      The company’s Cygnus XL spacecraft, carrying more than 11,000 pounds of cargo to the orbiting laboratory, lifted off at 6:11 p.m. EDT Sunday on a SpaceX Falcon 9 rocket from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida. This mission is the first flight of the larger, more cargo-capable version of the solar-powered spacecraft. 
      Cygnus XL is scheduled to be captured at 6:35 a.m. on Wednesday, Sept. 17, by the Canadarm2 robotic arm, which NASA astronaut Jonny Kim will operate with assistance from NASA astronaut Zena Cardman. Following capture, the spacecraft will be installed to the Unity module’s Earth-facing port for cargo unloading.
      The resupply mission is carrying dozens of research experiments that will be conducted during Expedition 73, including materials to produce semiconductor crystals in space and equipment to develop improvements for cryogenic fuel tanks. The spacecraft also will deliver a specialized UV light system to prevent the growth of microbe communities that form in water systems and supplies to produce pharmaceutical crystals that could treat cancer and other diseases.
      These are just a sample of the hundreds of scientific investigations conducted aboard the station in the areas of biology and biotechnology, Earth and space science, physical sciences, as well as technology development and demonstrations. For nearly 25 years, NASA has supported a continuous U.S. human presence aboard the orbiting laboratory, where astronauts have learned to live and work in space for extended periods of time. The space station is a springboard for developing a low Earth economy and NASA’s next great leaps in exploration, including Artemis missions to the Moon and American astronaut missions to Mars.
      NASA’s arrival, capture, and installation coverage are as follows (all times Eastern and subject to change based on real-time operations):
      Wednesday, Sept. 17
      5 a.m. – Arrival coverage begins on NASA+, Amazon Prime, and more.
      6:35 a.m. – Capture of Cygnus XL with the space station’s robotic arm.
      8 a.m. – Installation coverage begins on NASA+, Amazon Prime, and more.
      All coverage times are estimates and could be adjusted based on operations after launch. Follow the space station blog for the most up-to-date information.
      Cygnus XL is scheduled to remain at the orbiting laboratory until March 2026, before it departs and disposes of several thousand pounds of trash through its re-entry into Earth’s atmosphere, where it will harmlessly burn up. The spacecraft is named the S.S. William “Willie” C. McCool, in honor of the NASA astronaut who perished in 2003 during the space shuttle Columbia accident.
      Learn more about this NASA commercial resupply mission at:
      https://www.nasa.gov/mission/nasas-northrop-grumman-crs-23/
      -end-
      Josh Finch / Jimi Russell
      Headquarters, Washington
      202-358-1100
      joshua.a.finch@nasa.gov / james.j.russell@nasa.gov
      Steven Siceloff
      Kennedy Space Center, Fla.
      321-876-2468
      steven.p.siceloff@nasa.gov
      Sandra Jones / Joseph Zakrzewski
      Johnson Space Center, Houston
      281-483-5111
      sandra.p.jones@nasa.gov / joseph.a.zakrzewski@nasa.gov
      Share
      Details
      Last Updated Sep 14, 2025 LocationNASA Headquarters Related Terms
      International Space Station (ISS) Commercial Resupply ISS Research Johnson Space Center Northrop Grumman Commercial Resupply View the full article
    • By NASA
      Ames Science Directorate’s Stars of the Month: September 2025

      The NASA Ames Science Directorate recognizes the outstanding contributions of (pictured left to right) Taejin Park, Lydia Schweitzer, and Rachel Morgan. Their commitment to the NASA mission represents the entrepreneurial spirit, technical expertise, and collaborative disposition needed to explore this world and beyond.
      Earth Science Star: Taejin Park
      Taejin Park is a NASA Earth eXchange (NEX) research scientist within the Biospheric Science Branch, for the Bay Area Environmental Research Institute (BAERI). As the Project Scientist for the Wildfire, Ecosystem Resilience, & Risk Assessment (WERK) project, he has exhibited exemplary leadership and teamwork leading to this multi-year study with the California Natural Resources Agency (CNRA) and California Air Resources Board (CARB) to develop tracking tools of statewide ecological condition, disturbance, and recovery efforts related to wildfires.
      Space Science and Astrobiology Star: Lydia Schweitzer
      Lydia Schweitzer is a research scientist within the Planetary Systems Branch for the Bay Area Environmental Research Institute (BAERI) as a member of the Neutron Spectrometer System (NSS) team with broad contributions in instrumentation, robotic rovers and lunar exploration. Lydia is recognized for her leadership on a collaborative project to design and build a complex interface unit that is crucial for NSS to communicate with the Japanese Space Agency’s Lunar Polar eXploration rover mission (LUPEX). In addition, she is recognized for her role as an instrument scientist for the Volatiles Investigating Polar Exploration Rover (VIPER) and MoonRanger missions.
      Space Science and Astrobiology Star: Rachel Morgan
      Rachel Morgan is an optical scientist in the Astrophysics Branch for the SETI Institute. As AstroPIC’s lead experimentalist and the driving force behind the recently commissioned photonic testbed at NASA Ames, this month she achieved a record 92 dB on-chip suppression on a single photonic-integrated chip (PIC) output channel. This advances critical coronagraph technology and is a significant milestone relevant to the Habitable Worlds Observatory.
      View the full article
    • By NASA
      Explore This Section Earth Earth Observer Editor’s Corner Feature Articles Meeting Summaries News Science in the News Calendars In Memoriam Announcements More Archives Conference Schedules Style Guide 21 min read
      Summary of the 11th ABoVE Science Team Meeting
      Introduction
      The NASA Arctic–Boreal Vulnerability Experiment (ABoVE) is a large-scale ecological study in the northern regions of North America (Alaska and western Canada) that was developed to understand environmental changes in the region and the implications of those changes for society. Funded primarily by the NASA Terrestrial Ecology Program, this 10-year campaign has included field, airborne, and satellite remote sensing research to address its overarching scientific question of how environmental change in the Arctic and boreal region of western North America will affect vulnerable ecosystems and society.
      ABoVE deployed in three phases: 1) ecosystem dynamics (2015–2018); 2) ecosystem services (2017–2022); and 3) analysis and synthesis (2023–present). Now in the last year of the third phase, the Science Team (ST) consists of 67 active NASA-funded projects with more than 1000 individuals participating. The ABoVE ST has met yearly to discuss the progress of individual teams, plan joint field work, and discuss synthesis activities. ABoVE was featured in a 2019 The Earth Observer article, titled “Summary of the 2019 ABoVE Science Team Meeting” [July–August 2019, Volume 31, Issue 4, pp. 19–22], as well as a 2022 The Earth Observer article, titled “Summary of the Eighth ABoVE Science Team Meeting” [September–October 2022, Volume 34, Issue 5, pp. 28–33].
      Meeting Overview
      The 11th – and final – ABoVE Science Team Meeting (ASTM11) was held May 12–15, 2025, with 96 registered in-person attendees meeting at the University of Alaska, Fairbanks (UAF) and 67 registered virtual attendees – see Photo 1. The meeting included presentations from Phase 3 projects and synthesis reports from thematic working groups (WGs). ABoVE partners, including collaborators [e.g., the Department of Energy’s Next Generation Ecosystem Experiment-Arctic (NGEE-Arctic), Polar Knowledge Canada (POLAR), the Canadian Forest Service (CFS), and the Government of the Northwest Territories (GNWT)] and representatives from upcoming NASA campaigns focusing on the Arctic, shared updates on their activities. Additionally, the meeting featured sessions highlighting cross-project activities, e.g., ABoVE’s participation in regional fire workshops. The meeting also focused on collaborations with the Scotty Creek Research Station in Canada, the many types of science communication activities during ABoVE, and projects conducting collaborative research with community or regional partners.
      Photo 1.The 11th Arctic–Boreal Vulnerability Experiment Science Team (ABoVE) meeting group photo of in-person and virtual participants. Photo credit: Peter Griffith, Leane Kending, and David Stroud The meeting included additional team activities designed to encourage collaboration and understanding between team members. There were opportunities for multiple field trips for in-person attendees, including visits to the Alaska Satellite Facility (ASF) at the Geophysical Institute, the Permafrost Tunnel operated by the Cold Regions Research and Engineering Laboratory (CRREL), the Yankovich Road Fire Interpretive Trail, and the Arctic Research Open House at UAF – see ABove Field Trips section to learn more. The meeting offered early career researchers a chance to receive feedback on their posters and participate in an Early Career lunch event. The meeting even hosted an ABoVE bingo competition, which encouraged attendees to make new scientific and social connections – see Photo 2.
      Photo 2. Scott Goetz [University of Northern Arizona—ABoVE Science Team Lead] poses with ABoVE BINGO winner Wanwan Liang [University of Utah]. Photo credit: Wanwan Liang Meeting Opening
      The first day of the meeting began with a series of opening remarks from the ABoVE leadership team. Peter Griffith [NASA’s Goddard Space Flight Center (GSFC)/Science Systems and Applications, Inc. (SSAI)—Chief Scientist, Carbon Cycle and Ecosystems Office (CCEO)], Scott Goetz [Northern Arizona University (NAU)—ABoVE ST Lead], and Ryan Pavlick [NASA Headquarters (HQ)—ABoVE Program Manager] all noted the significance of this final meeting and discussed the major scientific advances of ABoVE made possible through the dedication of ST members, WG leads, planning committees, and contributors who have made ABoVE a success. Goetz reviewed the meeting goals and objectives:
      receive updates about currently funded projects; receive reports on Thematic WG advances with an emphasis on multiple WG and cross-phase synthesis activities; receive updates on research connections with partners and collaborators; discuss, reflect, and document the history of ABoVE, including major advances, lessons learned, and items to accomplish in the time remaining; and celebrate ABoVE success stories, with advice for potential future NASA large-scale coordinated campaigns. Working Group Presentations and Breakouts
      Throughout the first few days of the meeting, leads for the thematic working groups (WG) presented synthetic overviews of the research efforts of their group members, identified current gaps in planned or completed research, and discussed potential future work. Following these presentations, breakout groups convened to discuss future activities of the WGs. Short summaries of each presentation are available below. Together, these presentations demonstrate the highly interconnected nature of carbon cycles, hydrology, permafrost dynamics, and disturbance regimes in Arctic–boreal ecosystems. The presentations also showcase the substantial ongoing WG efforts to synthesize findings and identify critical knowledge gaps for future research priorities.
      Vegetation Dynamics Working Group
      WG Leads: Matthew Macander [Alaska Biological Research, Inc. (ABR)] and Paul Montesano [GSFC/ADNET Systems Inc.]
      The Vegetation Dynamics WG discussed new advances in understanding Arctic–boreal vegetation structure and function that have been made over the past 10 years through comprehensive biomass maps and multidecadal trend analyses. ABoVE research revealed a critical boreal forest biome shift with greening in nitrogen-rich northern forests and browning in drought-stressed southern forests. The group has identified key knowledge gaps in predicting post-fire vegetation recovery and detecting pervasive declines in vegetation resilience across southern boreal forests. The results suggest higher vulnerability to abrupt forest loss that could dampen the expected increase in carbon sequestration under future climate scenarios.
      Spectral Imaging Working Group
      WG Leads: Fred Huemmrich [GSFC/University of Maryland Baltimore County] and Peter Nelson [Laboratory of Ecological Spectroscopy (LECOSPEC)]
      Over the past year, the Spectral Imaging WG focused on the fundamental scale problem in Arctic ecology, which refers to the mismatch between observation scales and ecological process scales, which span spatial scales from leaf level to larger study areas and temporal scales from minutes to decades. The Airborne Visible/Infrared Imaging Spectrometer – Next Generation (AVIRIS-NG) and AVIRIS-3 datasets provide the first broad-area and high-spatial and spectral resolution coverage of high-latitude terrestrial ecosystems. The WG is now completing a scaling synthesis paper and preparing for the new era of data-rich spectral imaging with improved capabilities in data management, machine learning, and modeling applications for high-latitude research.
      Modeling Working Group
      WG Lead: Josh Fisher [Chapman University]
      The Modeling WG aims to reduce model uncertainties in simulations and projections in the Arctic–boreal region across all ABoVE ecosystem indicators. The WG had polled the ST to determine the variables most needed for their Earth system models and is now using the field, airborne, and satellite datasets to better constrain these models. This WG discussed the benefits to the modeling community of transforming the more than 100 ABoVE datasets into a common grid and projection format used by modelers.
      Carbon Dynamics Working Group
      WG Leads: Jonathan Wang [University of Utah] and Jennifer Watts [Woodwell Climate Research Center (WCRC)]
      The Carbon Dynamics WG has focused its recent work on three areas: decadal syntheses of carbon dioxide (CO2) fluxes from eddy covariance towers, machine learning approaches to upscaling wetland and lake methane (CH4) emissions, and carbon flux modeling across the Arctic–boreal zone. The research integrated atmospheric CO2 observations to improve carbon flux estimates and examined wildfire impacts on both carbon emissions and albedo changes. A significant component of the work involved comparing top-down versus bottom-up carbon flux models, with particular attention to permafrost and peatland regions.
      Hydrology-Permafrost-Wetlands Working Group
      WG Leads: Laura Bourgeau-Chavez [Michigan Technological University], David Butman [University of Washington], John Kimball [University of Montana], and Melissa Schwab [University of California, Irvine]
      The Hydrology–Permafrost–Wetlands WG focused on the processes controlling changes in permafrost distribution and properties and their impacts. There was discussion about the nature, causes, and consequences of hydrologic change (e.g. water storage, mobility, and distribution) and about ecosystem water, energy, and carbon cycle linkages. The presenters mentioned integration of ABoVE datasets with NASA satellite missions [e.g., NASA–Indian Space Research Organisation (ISRO) Synthetic Aperture Radar (NISAR) and Surface Water and Ocean Topography (SWOT) missions]. WG members discussed the connections between ABoVE research and several crosscutting initiatives, including two NASA Arctic coastlines efforts [e.g., Frontlines Of Rapidly Transforming Ecosystems Earth Venture Suborbital (FORTE EVS) campaign and NASA’s Arctic-COastal Land Ocean InteRactionS (COLORS)] and the WCRC’s Permafrost Pathways.
      Disturbance Working Group
      WG Leads: Dong Chen [University of Maryland, College Park] and Jinhyuk Kim [University of California, Irvine]
      The Disturbance WG leads presented their decade-long perspective on disturbance-related research in the ABoVE domain. The presentation incorporated artificial intelligence (AI)-generated summaries of ABoVE-affiliated research across multiple disturbance types, including boreal wildfires, tundra wildfires, and thermokarst/permafrost degradation processes. Chen and Kim acknowledged the extensive contributions from researchers and WG members while outlining future directions for disturbance research.
      Success Stories
      Four “Success Story” presentations and panels took place during ASTM11, which showcased efforts of ABoVE ST members and the leadership team to create and coordinate engagement efforts that spanned individual projects.
      Success Story 1: ABoVE Participation in Regional Fire Workshops
      A substantial portion of ABoVE research has focused on wildfire, and many members of the ST have participated in domestic and international wildfire efforts, connecting researchers with land managers across Alaska and Canada. Randi Jandt [UAF] discussed the Alaska Fire Science Consortium workshops (held in 2017 and 2022). Jenn Baltzer [Wilfred Laurier University (WLU), Canada] discussed Northwest Territories workshops (held in 2014 and 2025), both of which occurred in response to extreme fire seasons in the region. Laura Bourgeau-Chavez outlined ABoVE’s participation in all of these workshops. The workshops facilitated knowledge exchange and collaboration on critical wildfire management priorities, including fire risk assessment, real-time modeling, post-fire effects, and climate change impacts on fire regimes. Key features included small focus groups, field trips to command centers and fire-affected areas, and integration of Indigenous knowledge with new technologies to inform management practices and climate preparedness strategies.
      Success Story 2: Collaborations with Scotty Creek Research Station (SCRS)
      ASTM11 participants watched the film, “Scotty Creek Research Community – The Spirit of Collaboration,” about the SCRS, Canada’s first and only Indigenous-led research station. Following the film, station team members participated in a panel discussion. Ramona Pearson [Ramona Pearson Consulting, Canada], Maude Auclair [WLU], Mason Dominico [WLU], Michael McPhee [Sambaa K’e First Nation, Canada], and William “Bill” Quinton [WLU] discussed their decade-long collaboration with ABoVE. The partnership involved ABoVE collecting airborne hyperspectral, lidar, and radar imagery, while SCRS researchers provided field data for calibration and validation. In 2022, management of the station transitioned to Łı́ı́dlı̨ı̨ Kų́ę́ First Nation (LKFN, Canada), and ABoVE continued collaborating through knowledge exchange, including with early-career researchers and interns. When a 2022 fire destroyed the field station and surrounding area, ABoVE flew additional flights to capture airborne imagery observations to allow comparison of pre- and post-fire conditions.
      Success Story 3: Science Communication
      During the ABoVE field campaign, ST members and CCEO staff engaged in multiple strategies to communicate research results to the public. The activities included interactive engagement through airborne open houses and guest flights, ST member narratives in the “Notes from the Field” blog posts on the NASA Earth Observatory website, and professional multimedia production, including Earth Observatory content and award-winning videos. This multifaceted strategy demonstrates effective scientific communication through direct public engagement and high-quality, multimedia storytelling, making complex research accessible to diverse audiences.
      Success Story 4: Engagement Activities
      This session highlighted several examples of community engagement across the ABoVE domain. Gerald “J.J.” Frost [ABR] discussed synthesizing ecosystem responses and elder observations in western Alaska for his ABoVE project. In another example, ABoVE researchers from Michigan Tech Research Institute (MTRI) partnered with Ducks Unlimited Canada (DUC) and local organizations. Dana Redhuis [MTRI] and Rebecca Edwards [DUC] described their on-the-land camps that provide hands-on training for Northwest Territories youth in wetlands education and ecological monitoring. Kevin Turner [Brock University, Canada] showcased his work with members of the Vuntut Gwitchin First Nation in Old Crow Flats, Yukon, evaluating how climate and land cover change influence water dynamics and carbon balance. These activities demonstrate collaborative research that integrates Indigenous and Western knowledge approaches to address climate change impacts.
      ABoVE Phase 3 Project Presentations
      Project leads of the 20 NASA-funded ABoVE Phase 3 projects presented updates that were organized by scientific theme. The presentations spanned multiple days of the meeting. Table 1 below provides all the project titles, presenter names, and links to each project and presentation. Science results from four of the presentations are shown in Figures 1–4 below as indicated in the table.
      Table 1. An overview ofABoVE Phase 3 projects and presenters. The Project name includes the last name of the Principal Investigator, NASA funding program (TE for Terrestrial Ecology), the year of the NASA solicitation funding the research, and provides a hyperlink to the Project Profile. A hyperlink to each presentation is provided as either PowerPoint (PPT) file or PDF.
      Project   Carbon Presenter(s) Bloom (TE 2021): Using CO2, CH4 and land-surface constraints to resolve sign and magnitude of northern high latitude carbon-climate feedbacks [PDF] Eren Bilir [NASA/Jet Propulsion Laboratory (JPL)]; Principal Investigator (PI): Alexis (Anthony) Bloom [NASA/Jet Propulsion Laboratory (JPL)] Butman (TE 2021): Do changing terrestrial-aquatic interfaces in Arctic-boreal landscapes control the form, processing, and fluxes of carbon? [PPT] David Butman [University of Washington] – see Figure 1 Watts (TE 2021): Contributions of tundra and boreal systems to radiative forcing in North America and Russia under contemporary and future conditions [PPT] Jennifer Watts [Woodwell Climate Research Center] Miller-S (TE 2021): A synthesis and reconciliation of greenhouse gas flux estimates across the ABoVE domain [PDF] Scot Miller [Johns Hopkins University] Michalak (TE 2021): Quantifying climate sensitivities of photosynthesis and respiration in Arctic and boreal ecosystems from top-down observational constraints [PDF] Wu Sun and Jiaming Wen [both Carnegie Institution for Science, CI]; PI: Anna Michalak, [Carnegie Institution for Science] Fire Presenter(s) Bourgeau-Chavez (TE 2021): Integrating remote sensing and modeling to better understand the vulnerability of boreal-taiga ecosystems to wildfire [PPT] Laura Bourgeau-Chavez [Michigan Technological University (MTU)] Walker (TE 2021): Drivers and Impacts of Reburning in boreal forest Ecosystems (DIRE) [PDF] Jeremy Forsythe [Northern Arizona University (NAU)]; PI: Xanthe Walker [NAU] Wang (TE 2021): Quantifying disturbance and global change impacts on multi-decadal trends in aboveground biomass and land cover across Arctic-boreal North America [PPT] Jonathan Wang [University of Utah]– see Figure 2  Wildlife Presenter(s) Boelman (TE 2021): The future of the Forest-Tundra Ecotone: A synthesis that adds interactions among snow, vegetation, and wildlife to the equation [PPT] Natalie Boelman [Lamont-Doherty Earth Observatory, Columbia University] French (TE 2021): Informing wetland policy and management for waterfowl habitat and other ecosystem services using multi-frequency synthetic aperture radar [PPT] Nancy French [MTU] – see Figure 3 Hydrology / Permafrost Presenter(s) Du (TE 2021): High resolution mapping of surface soil freeze thaw status and active layer thickness for improving the understanding of permafrost dynamics and vulnerability [PPT] Jinyang Du [University of Montana] Miller (TE 2021): Enhanced methane emissions in transitional permafrost environments: An ABoVE phase 3 synthesis investigation [PPT] Charles “Chip” Miller [NASA/JPL] Tape (TE 2021): Characterizing a widespread disturbance regime in the ABoVE domain: Beaver engineering [PPT] Kenneth Tape [University of Alaska, Fairbanks] Zhuang (TE 2021): Role of linked hydrological, permafrost, ground ice, and land cover changes in regional carbon balance across boreal and Arctic landscapes [PDF] Qianlai Zhuang [Purdue University]  Vegetation Structure Presenter(s) Duncanson (TE 2021): Mapping boreal forest biomass recovery rates across gradients of vegetation structure and environmental change [PPT] Paul Montesano [GSFC/ADNET Systems Inc]; PI: Laura Duncanson [University of Maryland]—see Figure 4 Lara (TE 2021): ABoVE-Ground characterization of plant species succession in retrogressive thaw slumps using imaging spectroscopy [PPT] Mark Lara [University of Illinois, Urbana-Champaign]  Vegetation Dynamics  Presenter(s) Frost (TE 2021): Towards a warmer, less frozen future Arctic: Synthesis of drivers, ecosystem responses, and elder observations along bioclimatic gradients in western Alaska [PPT] Gerald “J.J.” Frost [ABR] Goetz (TE 2021): Mapping and modeling attributes of an Arctic-boreal biome shift: Phase-3 applications within the ABoVE domain [PPT] Scott Goetz [NAU] Liu (TE 2021): Characterizing Arctic-boreal vegetation resilience under climate change and disturbances [PPT] Yanlan Liu [The Ohio State University] Townsend (TE 2021): Functional diversity as a driver of gross primary productivity variation across the ABoVE domain [PPT] Philip Townsend [University of Wisconsin] Determining Aboveground Biomass Density Using ICESat-2 Data and Modeling
      Figure 1. Despite their relatively small coverage, surface water extent across boreal and arctic lowlands significantly impacts landscape-scale estimates of carbon emissions. The red points on the map in the figure indicates locations of available lake chemistry data derived from ABoVE-supported research, from collaborators, and from a preliminary literature search. Figure credit. David Butman Figure 2. The Arctic-boreal carbon cycle is inextricably linked to vegetation composition and demography, both of which are being altered by climate change, rising levels of atmospheric carbon dioxide, and climate-induced changes in disturbance regimes. The map in the figure shows above-ground biomass (AGB) change across Arctic-boreal North America (2022–1984) created using a machine learning model of AGB trained on from more than 45,000 field plots and 200,000 km2 of airborne lidar data. Figure credit:  Wanwan Liang Figure 3.  Wetlands provide many ecosystem services, including waterfowl habitat, carbon sequestration, and water quality. Northern wetlands Iin the ABovE study area) are threatened from both land use expansion and climate change disruptions, prompting the need for informed management strategies.  Copernicus Sentinel 1 synthetic aperture radar (SAR) data have been used to create this map of flooding (hydroperiod) in wetland areas around the Great Slave Lake in Canada  The color code on the map corresponds to the number of times the SAR imagery indicated a place was flooded (inundated). Such information is helpful for predicting within-season changes in wetland extent. Figure credit: Nancy French Figure 4. Advances have been made in mapping aboveground biomass density (AGBD). Shown here as an example is an AGBD map created using stata from the   ICESat-2 pan-Boreal 30-m (98-ft) tree height and biomass data product [left] and the ensemble mean of the standard deviation of AGBD, aggregated to modelling tiles [right]. Current research aims to expand these maps and understand regional vegetation changes.  Figure credit. Laura Duncanson/data from ORNL DAAC ASTM11 Poster Sessions
      ASTM11 featured 41 research posters across three sessions, organized by thematic area – see Table 3 and Photo 3. The Poster Session agenda details the range of topics that spanned airborne synthetic aperture radar (SAR) and satellite imagery to northern ecosystem fieldwork. Key research topics that emerged included CO2 and CH4 emissions from terrestrial and aquatic systems, ongoing permafrost thaw, fire impacts on carbon cycling, vegetation mapping and biomass estimation, and the impacts of wildlife on the landscape.
      Table 2. A breakdown of ASTM11 poster presentations by science theme.
      Poster Theme Poster Count Carbon Dynamics 5 Crosscutting, Modeling, or Other 6 Fire Disturbance 5 Permafrost, Hydrology, and Wetlands 13 Vegetation Dynamics and Distribution 7 Vegetation Structure and Function 4 Wildlife and Ecosystem Services 1 Photo 3. Poster presentations and sessions during ASTM11 offered opportunities for presenters to share their latest research findings with meeting participants. Photo credit: Elizabeth Hoy ABoVE Field Trips
      ASTM11 offered multiple field trip options across the Fairbanks region of Alaska. The fieldtrips provided ST members an opportunity to interact with the research community – see Photo 4.
      Trip to Alaska Satellite Facility (ASF) and Geophysical Institute
      ASF is a data archive for many SAR datasets from a variety of sensors and has multiple ground station facilities. During the tour, participants visited the ASF operations room and ASF rooftop antenna. The Geophysical Institute tour also featured the Alaska Earthquake Center, Wilson Alaska Technical Center, and Alaska Center for Unmanned Aircraft Systems Integration.
      Trip to Cold Regions Research and Engineering Laboratory (CRREL) Permafrost Tunnel
      The U.S. Army Core of Engineers CRREL Permafrost Tunnel is located in Fox, AK – about 15 km (9 mi) north of Fairbanks. Over 300 m (984 ft) of tunnel have been excavated, exposing Pleistocene ice and carbon-rich yedoma permafrost that ranges in age from 18,000 to 43,000 years old. The tunnel exposes mammoth and bison bones and a variety of permafrost soils. Ongoing projects in the tunnel cover a range of topics, including engineering and geophysical work, Mars analog studies, and biogeochemistry and microbiology of permafrost soils.
      Wildfire Walk: Yankovich Road Fire Interpretive Trail
      On July 11, 2021, a wildfire burned 3.5 acres (14,164 m2) of UAF land. In 2024, the UAF Alaska Fire Science Consortium, Bureau of Land Management Alaska Fire Service, and local artist Klara Maisch collaborated with others to develop the Wildfire Walk at the site. The interpretive trail is an outdoor learning experience with interpretive wayside markers that describe the fire incident, the relationship between wildfire and the boreal forest, fire science and environmental change, and wildfire prevention – see Figure 1.
      UAF Arctic Research Open House
      The UAF Arctic Research Open House was an opportunity for ST members and the public to explore the wide range of research happening at UAF and meet other scientists. ABoVE hosted an information table at the event.
      Photo 4: Collage of images collected during a series of field trips, including [top] the Wildfire Walk along the Alaska Fire Science Consortium, [middle] the Permafrost Tunnel with Tom Douglas [Cold Regions Research and Engineering Laboratory], [bottom left] UAF Arctic Open House ABoVE Table with Margaret “Maggie” Wooton [NASA’s Goddard Space Flight Center (GSFC)/Science System and Applications, Inc. (GSFC/SSAI)], Elizabeth Hoy [GSFC/Global Science & Technology Inc.], and Qiang Zhou [GSFC/SSAI], talking with Logan Berner [Northern Arizona University], [bottom right] the Alaska Satellite Facility ground receiving antenna. Photo credit: Elizabeth Hoy Research Connections
      The success of ABoVE as a large-scale research study over the Arctic and boreal regions within and outside the United States depended on collaboration with multiple organizations. Many of the ABoVE collaborators were able to present at ASTM11.
      Andrew Applejohn [Polar Knowledge Canada (POLAR)] provided details about the scope, mandate, and facilities available through POLAR, a Canadian government agency that has partnered with the ABoVE ST for the duration of the campaign.
      Ryan Connon [Government of the Northwest Territories (GNWT)] discussed the decade-long collaboration between ABoVE and the GNWT, including knowledge sharing of wildlife collar data, field-data ground measurements, and remote sensing analyses.
      Gabrielle Gascon [Canadian Forest Service (CFS), Natural Resources Canada] explained the scope of Canada’s National Forest Inventory and the current CFS focus on wildfire and the CFS’s other areas of research related to the northern regions. Another presentation featured information about various vegetation mapping initiatives where Matthew Macander discussed an Alaska-based effort called AKVEG Map, a vegetation plot database, and Logan Berner [NAU] detailed a pan-Arctic plant aboveground biomass synthesis dataset.
      Brendan Rogers [WCRC] showcased research from Permafrost Pathways, designed to bring together permafrost-related science experts with local communities to inform Arctic policy and develop adaptation and mitigation strategies to address permafrost thaw. NGEE-Arctic is another U.S. government effort that partnered specifically with ABoVE for the duration of the two efforts, and Bob Bolton [Oak Ridge National Laboratory (ORNL)] provided updates on the project.
      Tomoko Tanabe [Japan’s National Institute of Polar Research (JNIPR)] gave a presentation about NIPR to better inform ABoVE scientists about other international Arctic efforts, including a new Japanese Arctic research initiative called the Arctic Challenge for Sustainability III (ArCS III), designed to address social issues related to environmental and social changes in the Arctic.
      Additional Presentations
      An additional presentation aimed to keep the ABoVE ST informed of future NASA Arctic research efforts. Kelsey Bisson [NASA HQ—Program Scientist for the Ocean Biology and Biogeochemistry Program] discussed NASA Arctic-COLORS and Maria Tzortziou [City University of New York/Columbia University, LDEO] discussed the FORTE EVS campaign. The proposed Arctic-COLORS field campaign would quantify the biogeochemical and ecological response of Arctic nearshore systems to rapid changes in terrestrial fluxes and ice conditions. The NASA FORTE EVS campaign will fill a critical gap in understanding Alaska’s northernmost ecosystems by investigating eroding coastlines, rivers, deltas, and estuaries that connect land and sea systems, using airborne platforms.
      Scott Goetz continued with a presentation on U.S. efforts to plan the International Polar Year, scheduled for 2032–2033. Ryan Pavlick provided details on the NISAR mission, which launched after the meeting on July 30, 2025, and discussed other possible future NASA missions.
      A Career Trajectory panel featured Jennifer Watts, Jonathan Wang, Brendan Rogers, and Xiaoran “Seamore” Zhu [Boston University]. The panelists discussed opportunities for researchers from different academic backgrounds and at different career stages, and they provided details about how ABoVE has impacted their careers. They also discussed how NASA campaigns offer opportunities for early career scientists to join a team of peers to grow their abilities throughout the duration of the decade-long research.
      Klara Maisch, a local artist, discussed her work creating science-informed artwork through interdisciplinary collaborations with scientists and other creators – see Figure 5. Maisch described the benefits of partnering with artists to share science with a broad audience and showcased artwork she has created.
      Figure 5. Lower Tanana Homelands – 2022 Yankovich Fire – Plot Painting [left], with original plot reference photograph [right]. Image Credit: Klara Maisch Overarching Presentations
      A series of presentations on the overall structure and outcomes of ABoVE were held during ASTM11. Charles “Chip” Miller [NASA/JPL—Deputy ABoVE ST Lead, ABoVE Airborne Lead] provided details about SAR, hyperspectral, and lidar airborne measurements collected between 2017 and 2024 for the ABoVE Airborne Campaign.
      ABoVE Logistics Office members Daniel Hodkinson [GSFC/SSAI], Sarah Dutton [GSFC/SSAI], and Leanne Kendig [GSFC/Global Science & Technology, Inc. (GST, Inc.)] discussed the many field teams and activities supported during ABoVE. Overall, more than 50 teams were trained in field safety topics, with more than 1,200 training certificates awarded. Elizabeth Hoy [NASA GSFC/GST, Inc.] and Debjani Singh [ORNL] discussed the more than 250 data products developed during the ABoVE program and how to access them through NASA Earthdata. Example visualizations of ABoVE data products can be found in Figure 6.
      Figure 6. ABoVE logo created with different data products from the campaign used to compose each letter.A: Active Layer Thickness from Remote Sensing Permafrost Model, Alaska, 2001-2015;. Tree (inside A): Normalized Difference Vegetation Index (NDVI) Trends across Alaska and Canada from Landsat, 1984-2012;. B: Landsat-derived Annual Dominant Land Cover Across ABoVE Core Domain, 1984-2014;; O: Wildfire Carbon Emissions and Burned Plot Characteristics, NWT, CA, 2014-2016;; V: AVHRR-Derived Forest Fire Burned Area-Hot Spots, Alaska and Canada, 1989-2000;; E: Lake Bathymetry Maps derived from Landsat and Random Forest Modeling, North Slope, AK; and Underline (under O): Plot lines from the ABoVE Planning Tool visualizer. Figure credit: Caitlin LaNeve The Collaborations and Engagement WG held a plenary discussion to highlight the many activities that ABoVE researchers have been involved in over the past decade. The discussion highlighted the need for individual projects and campaign leadership to work together to ensure participation and understanding of planned research at local and regional levels.
      A highlight of the meeting was the “Legacy of ABoVE” panel discussion moderated by Nancy French [MTU]. Panelists included Eric Kasischke [MTU], Scott Goetz, Chip Miller, Peter Griffith, Libby Larson [NASA GSFC/SSAI], and Elizabeth Hoy. Each panelist reflected on their journey to develop ABoVE, which included an initial scoping study developed more than 15 years ago. Members of the panel – all a part of the ABoVE leadership team – joined the campaign at different stages of their career. Each panelist arrived with different backgrounds, bringing their unique perspective to the group that helped to frame the overall campaign development. Following the panel, all ST members who have been a part of ABoVE since its start over a decade ago came to the front for a group photo – see Photo 5.
      Following the panel, the ABoVE ST leads presented their overall thoughts on the meeting and facilitated a discussion with all participants at the meeting. Participants noted the important scientific discoveries made during ABoVE and enjoyed the collegial atmosphere during ASTM11.
      Photo 5. A group photo of participants who have been with ABoVE since its inception: [left to right] Ryan Pavlick, Chip Miller, Elizabeth Hoy, Libby Larson, Peter Griffith, Fred Huemmrich, Nancy French, Scott Goetz, Laura Bourgeau-Chavez, Eric Kasischke, and Larry Hinzman. Photo credit: Peter Griffith Conclusion 
      Overall, ASTM11 brought together an interdisciplinary team for a final team meeting that showcased the many accomplishments made over the past decade. The group outlined current gaps and needs in Arctic and boreal research and discussed possibilities for future NASA terrestrial ecology campaigns. The synthesis science presentations at ASTM11 highlighted the advances ABoVE has made in understanding carbon and ecosystem dynamics in Arctic and boreal regions. It also highlighted the need for further study of cold season and subsurface processes. While this was the last meeting of this ST, research for some projects will continue into 2026, and more publications and data products are expected from ST members in the near term.
      Elizabeth Hoy
      NASA’s Goddard Space Flight Center/Global Science & Technology Inc. (GSFC/GST,Inc.)
      elizabeth.hoy@nasa.gov
      Libby Larson
      NASA’s Goddard Space Flight Center/Science System and Applications, Inc. (GSFC/SSAI)
      libby.larson@nasa.gov
      Annabelle Sokolowski
      NASA GSFC Office of STEM Engagement (OSTEM) Intern
      Caitlin LaNeve
      NASA GSFC Office of STEM Engagement (OSTEM) Intern
      Share








      Details
      Last Updated Sep 10, 2025 Related Terms
      Earth Science View the full article
    • By NASA
      Science Launching on Northrop Grumman's 23rd Cargo Resupply Mission to the Space Station
    • By NASA
      Deputy Project Manager for Resources – Goddard Space Flight Center
      Katie Bisci, photographed here with a model of NASA’s Nancy Grace Roman Space Telescope, Credit: NASA/Jolearra Tshiteya How are you helping set the stage for the Roman mission?
      I’m a deputy project manager for resources on the Nancy Grace Roman Space Telescope team, sharing the role with Kris Steeley. Together, we oversee the business team, finance, outreach, scheduling, and more. I focus more on the “down and in” of the day-to-day team — helping the financial team, resource utilization across the project, and support service contracts management — while Kris handles more of the “up and out” external work with center management and NASA Headquarters. Kris and I collaborate on many things as well. The two of us have been together on Roman for many years, and we have definitely become one brain in many aspects of the role. The main goal in the job is programmatics: We need to understand and help along the technical parts of the mission, while also supporting cost and schedule control since Roman is a cost-capped mission. I try to make sure that I partner with our engineers to understand the technical part of Roman as much as possible. I find that I can’t do my job well on the programmatic side without working together closely with our engineers to understand the hardware and testing.
      What drew you to NASA? Did you always intend to work here?
      I think I always knew I wanted to go into the business and finance side of things, but I thought I’d end up at a big investment bank. I interned at one during college, but it just didn’t feel right for me. After graduating, I worked on corporate events for defense contractors in New York City. Then my husband got a job in Annapolis, Maryland, and I took a leap and applied for a resource analyst job at NASA, where some college friends were working. Looking back, as an oldest daughter it probably should have been obvious that project management would be a good fit! Once I got to NASA, I was really drawn in by the missions and work we do. It was so different from the corporate world. Being able to work on some of the coolest missions with some of the most brilliant minds out there is a gift. Almost 15 years later, I’m still here.
      How did your career grow from there?
      After serving as a resource analyst in the Safety and Mission Assurance Directorate at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, I moved into the center’s Astrophysics Projects Division, where I began working on Roman in 2012, back when it was just a small study called WFIRST (Wide Field Infrared Survey Telescope). I could never have imagined at the time what that small study would turn into. People at NASA often say they “grew up” on the James Webb Space Telescope, and for me I definitely “grew up” on Roman. I became the mission business manager, then financial manager, and now a deputy project manager for resources. I feel lucky that most of my career has been spent on Roman. Adding it up, I’ve been on this project for over a decade. I’ve worked with so many amazing people, not just at NASA Goddard, but across the United States. It’s hard to believe we are so close to launching.
      What’s been the highlight of your career so far?
      Becoming part of the management team on Roman, for sure. Working with the leadership team has been incredible. The best part about Roman is the people. It still cracks me up to look at the plethora of people we have in the same room for our weekly senior staff meeting, from the programmatic and finance types like myself, to engineers leading super complicated integration and test programs, Ph.D.s, and some of the most brilliant science minds I will probably ever know. The Roman team is amazing, and those relationships are what keep me excited to come to work every day.
      Has your work influenced your understanding or appreciation of astronomy?
      Absolutely. I’ve learned so much just by being around brilliant people like our project scientist Julie McEnery. I even recently gave a talk about Roman at my daughter’s school! Being able to stand up in front of a group of children and talk about what Roman science is going to do is something I never would have been able to do prior to working here. I’ve learned about how the Hubble Space Telescope, Webb, and Roman all build on each other during my time on this project. And it’s really incredible science. I’ve also developed a deep admiration for the engineers who have built Roman. As a business focused person, our engineering team has really helped me understand the different facets of what our engineering team does on Roman. They are so patient with me! It’s really fulfilling to be a small part of something so big.
      What advice do you have for others who are interested in doing similar work?
      If you’re in finance, don’t just learn the numbers — learn the work behind them. Understand the mission, the tech, the people. That’s what helps you move from analyst to leader. People can tell when you really get what they’re doing, and that’s how you become a better partner and manager.
      What’s life like outside NASA?
      I have three kids — ages 9, 5, and 3 — so life is busy! When I’m not working, I’m usually at their sports games or chauffeuring them around to one event or another. It’s a little bit of a rat race, but this season of life is also really fun. Recently, my family and I have gotten back into traveling now that my kids are a little bit older. We took a spring break trip to Europe, which was fantastic.  Spending time with my family and friends is everything. Whether it’s going to the beach, spending time at the pool, or hanging out on the sideline of a lacrosse game, just like at work it’s being with my people that I thrive on. And maybe one day I will have time for more hobbies again!
      By Ashley Balzer
      NASA’s Goddard Space Flight Center, Greenbelt, Md.
      Share
      Details
      Last Updated Aug 26, 2025 EditorAshley BalzerLocationGoddard Space Flight Center Related Terms
      Goddard Space Flight Center Nancy Grace Roman Space Telescope People of Goddard View the full article
  • Check out these Videos

×
×
  • Create New...