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Summary of the 2023 Ocean Surface Topography Science Team Meeting

Severine Fournier, NASA/Jet Propulsion Laboratory, severine.fournier@jpl.nasa.gov
Joshua Willis, NASA/Jet Propulsion Laboratory, joshua.k.willis@jpl.nasa.gov

Introduction

The annual Ocean Surface Topography (OST) Science Team Meeting (STM) provides a forum for the international altimetry community to foster collaboration, address specific issues, and highlight scientific results and applications every year. The meeting location alternates between Europe and the U.S. The 2023 meeting was held in San Juan, Puerto Rico, from November 7–11, 2023. About 130 registrants from more than a dozen different countries attended the meeting.  

During this meeting the OST Science Team addressed specific technical issues related to the reference altimetry missions, which include the Ocean Topography Experiment (TOPEX)–Poseidon (1992–2006), Jason-1 (2001–2013), Ocean Surface Topography Mission (OSTM)/Jason-2 (2008–2019), Jason-3 (2016–present), and Sentinel-6 Michael Freilich (S6MF; 2020–present) missions. There was also discussion about the upcoming Sentinel-6B mission (scheduled for launch in 2025), which will be a successor to S6MF. The technical issues addressed included algorithm and model improvement, calibration/validation (cal/val) activities, merging TOPEX–Poseidon–Jason–S6MF data with those from other altimetric satellites, initial results from the Surface Water and Ocean Topography (SWOT) mission (2022–present), and preparation for future OST missions (e.g., Sentinel-6B).

The remainder of this article provides an overview of the meeting content, then presents an update on the status of current and planned OST missions, followed by a summary of the opening plenary and a couple of the most relevant science highlights from the splinter sessions. More details are available in the full report from the OST STM. The full OST STM program lists all of the presentations from the plenary, splinter, and poster sessions as well as links to many of the presentations and abstracts for the posters.

Meeting Overview

The meeting began with an opening plenary session, followed by an invited presentation, a series of splinter sessions, and a closing plenary session. The splinter session topics spanned a variety of algorithm improvements and measurement uncertainties, as well as sessions on coastal altimetry, the Chinese–French Oceanography Satellite (CFOSAT) mission (2019–present), and science topics ranging from climate and oceanography to hydrology and cryosphere science. A complete list of splinters is available online. Some of these are described in more detail in the sections that follow.

Status Report on Current OST Missions

This section reports on the status of several current and planned OST-related satellite missions. Each is described in its own subsection.

Sentinel-6 Michael Freilich

S6MF, launched on November 21, 2020, from Vandenberg Space Force Base, successfully completed its commissioning and subsequent entry into routine operations on schedule, one year later. S6MF succeeded Jason-3 as the Reference Mission (i.e., the mission that other altimetry missions are compared to) on April 7, 2022, at which point Jason-3 vacated the reference orbit. The first full mission reprocessing of products was released in July 2022, and another full reprocessing was completed in July 2023.

Jason-3

Jason-3, launched on January 17, 2016, continues its extended mission and is fully operational with all redundant systems available. It completed a longer than initially planned 15-month tandem phase with S6MF, which allowed for calibrations of both the primary and redundant instruments. On April 25, 2022, it began operations in an orbit that optimally interleaves ground tracks with S6MF. A second tandem phase with S6MF has been requested for early 2025. The second tandem phase aims to place an uncertainty bound on any long-term drift between the two missions.

Copernicus Copernicus Sentinel-3A and -3B

Sentinel-3A and -3B are identical satellites that were launched in February 16, 2016 and April 25, 2018, respectively. Similar to past missions in the reference orbit, a tandem phase with a separation of 30 seconds between the two satellites was performed to provide cross-calibration. Subsequently, Sentinel-3B was placed in a nominal orbit 140° out of phase with Sentinel-3A. Both missions now provide sea level measurements along high inclination tracks as part of their routine operations. A full mission reprocessing of land altimetry Level-2 (L2) products was completed in 2023.

Copernicus Sentinel-6B and 6C Missions and Beyond

Identical to S6MF, Sentinel-6B is planned as its successor. The spacecraft and instrument have been completed and is now in storage awaiting launch in 2025. Sentinel-6B will assure operational continuity through the end of 2030. An additional satellite, Sentinel-6C, is under consideration by NASA, the National Oceanic and Atmospheric Administration (NOAA), the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), the European Space Agency (ESA), and the Centre National d’Études Spatiale (CNES) [French Space Agency] to continue observations through 2035.

Surface Water Ocean Topography

SWOT launched on December 16, 2022. The primary instrument on SWOT, Ka-band radar interferometer (KaRIn), is the first space-borne, wide-swath altimetry instrument, capable of high-resolution measurements of the water height in the ocean and freshwater bodies. After commissioning and initial calibration, beta products became available to the science team in August 2023. The first images from SWOT were released, and the first results are showing great promise for the instrument capabilities (see NASA and CNES news).

Discussion of Future Missions Relevant to OST

The meeting continued with presentations on several existing and upcoming missions in various stages of development, each with applications relevant to OST. Each presentation included information on the mission’s status and development plans, as described below.

Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL)

Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) is one of six, high-priority candidate Copernicus Sentinel Expansion missions that are being studied to address the European Union’s needs, as well as to extend the current capabilities of the Copernicus space components. CRISTAL will carry a multifrequency radar altimeter and microwave radiometer to ensure continuity and improve the quality of sea ice thickness measurements compared to its predecessor, Cryosat-2, and provide the first space-based measurements of overlying snow depth.

Recommendations from the OST Science Team

After discussing these missions and other issues concerning altimetry, the OST STM adopted several recommendations to particular topics relating to these missions, which are named and described in the subsections that follow:

S6MF Extended Operations Phase Orbit.  

In light of that fact that user needs remain very high for altimetry observations complementary to the reference mission, the OST ST recommends extending operations of S6MF – assuming it remains in good health – beyond the time when Sentinel-6B has become the reference mission. Specifically, the OST ST recommends:

  • Moving S6MF to an exact repeat orbit with the same characteristics as the reference orbit – except for a phase difference of 163° along the orbit, either ahead or behind Sentinel-6B – resulting in an interleaved ground-track to the reference orbit. (For reference, Jason-3 currently flies 163° behind S6MF.)
  • Adopting the same data availability requirements as expressed in the End-User Requirements Document (EURD) (R-U- 00460/490/500/515/520/570/573/576) for the extended operations phase of S6MF, with the understanding that Sentinel-6B operations will be prioritized over S6MF.

Jason-3 Orbit Change.

The OST ST endorses the current plan to move Jason-3 to a Long Repeat Orbit (LRO) immediately after the conclusion of second tandem with S6MF. This 371-nodal-day LRO should be the same as the one occupied by Jason-2. The first two LRO cycles should be phased such that Jason-3 will interleave the two Jason-2 LRO cycles, each shifted by 2 km (1.2 mi). This will result in a systematic 2-km global grid combining Jason-2 and Jason-3 LRO data. The OST ST also recommends two additional LRO cycles that revisit the Jason-2 LRO ground tracks to fill in gaps and reduce mean sea surface errors. 

Climate Quality Accuracy in Future Mission 

To achieve accuracy in global and regional sea level change as detailed in the Global Climate Observing System (GCOS) requirements, the OST ST noted that it will be necessary to maintain and continue to improve the accuracy of orbital determination systems, such as those achieved using a combination of three tracking systems – Satellite Laser Ranging [SLR], Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and Global Navigation Satellite System [GNSS]). The OST ST has demonstrated that these tracking systems are necessary to achieve maximum accuracy on the determination of regional sea level trends and strongly recommends that such accuracy be maintained in the design of Sentinel-6C. The OST ST also noted that accuracy of the Climate Data Record requires continued maintenance or improvement of the terrestrial reference frame, which also relies on these tracking systems. Finally, requirements on other aspects of the altimetric measurement system must also be maintained or continue to improve. 

Synergies with Argo and GRACE 

Argo (which is an international fleet of robotic instruments that drift with the ocean currents and measure the temperature and salinity of the ocean) plays a critical role in collecting data related to numerous cross-cutting, climate-related science topics important to altimetry measurements (missions discussed earlier in this article), to gravity measurements [e.g., the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow-On missions], and to broader science communities. The recent implementation of the Deep Argo mission has rapidly expanded observations of the ocean below 2000 m (~6500 ft). Data collected at these depths has helped to resolve questions about variations of temperature and salinity over the full depth of the ocean and to close regional and global sea level budgets. The OST ST recommends substantially increasing support for the OneArgo Program (which has been part of Argo’s design plan since 2020), including adding resources to expand the array to include global implementation of Deep Argo and increase coverage by Core Argo (the fleet of shallower floats) in polar regions and marginal seas. 

Altimetry Product Evolution 

OST ST recommends that agencies study the performance of the three latency products – Near Real-Time (NRT), Short Time-Critical (STC), and Non-Time Critical (NTC) – to ensure each continues to meet user needs or determine if their performance and latencies be redefined or adjusted. This should be considered across all platforms. 

Potential Gap between CryoSat-2 and CRISTAL 

The OST ST recommends studies to address which satellites, airborne operations, or other assets might help fulfill scientific needs for high-latitude ocean and ice elevation measurements during a potential gap between CryoSat-2 and CRISTAL. The OST ST also recommends minimizing the probability of a gap by extending CryoSat-2 operations through at least 2028 and avoiding delays in the launch of CRISTAL to the extent possible. 

Integrity of the Altimetry Constellation and Instrument Function 

 In light of ongoing efforts to launch a large number of communications satellites in orbits close to the 1336 km (830 mi) altimetry constellation, the OST ST recommends that agencies take steps to determine and establish sufficient margins that will safeguard altimetry missions in both reference and polar orbits from collision, debris, and interference with their passive and active instruments.

Opening Plenary Session Highlights

Severine Fournier [NASA/Jet Propulsion Laboratory (JPL)] began with welcoming remarks on behalf of all of the project scientists, who (in addition to herself) include Josh Willis [NASA/JPL], Pascal Bonnefond [CNES], Eric Leuliette [NOAA], Remko Scharroo [EUMETSAT], and Alejandro Egido [ESA]. In particular, Fournier reminded the participants of the addition of online forums, available until the next OST STM that can be accessed after logging into the site. In addition, Fournier announced that Egido will replace Craig Donlon as the ESA Project Scientist.

Program managers gave presentations on the status of altimetry and oceanographic programs at their respective institutions including: Nadya Vinogradova-Shiffer [NASA Headquarters], Annick Sylvestre-Baron [CNES], Estelle Obligis [EUMETSAT], Eric Leuliette, and Jérôme Bouffard [ESA].

In addition, Josh Willis presented Space Stories, a think tank for U.S.-based creatives and technologists to develop new storytelling approaches to sea level rise. This initiative is organized by Garage Stories and consists of masterclasses that were held in November 2023 with 15 participants across 5 teams. The winning team will have the opportunity to present their concept at JPL in 2024.

Finally, Fernando E. Pabón [Caribbean Center for Rising Seas—Director] spoke about climate issues that impact Puerto Rico. The island has about three million inhabitants and faces several climatic issues, including devastating impacts from hurricanes (with a hurricane season stretching over six months every year), sea level rise, and droughts. While Puerto Rico has a lot of outdated infrastructures, the territory has the most advanced regulatory environment in the Caribbeans. Pabón explained the economic, social, and geographical urgency of making good decisions to help the communities facing climatic challenges with a long-term vision. One of the goals of the Caribbean Center for Rising Seas is to work with practitioners and the public to change urban development practices, update building codes, zoning, and land-use regulations and spread the knowledge and understanding of sea level rise and flooding to the public.

Science Highlights

This section provides two scientifically compelling results that were shown during the splinter sessions. Complete coverage of the results shared during these sessions can be found at the website at the start of the article.

Synergies between Argo, GRACE, and Altimetry

Human activities are increasing the concentration of greenhouse gases, which have increased global temperature since the beginning of the twentieth century. Greenhouse gases trap energy within the Earth system. The ocean absorbs much of this excess energy in the form of heat (> 90%), acting as a huge heat reservoir. Global ocean heat content (GOHC) is therefore a key component in the Earth’s energy budget. Accurate knowledge of the GOHC change allows us to assess the Earth Energy Imbalance (EEI), which refers to the difference between the amount of energy the Earth receives from the Sun and the amount of energy it radiates back into space.

Various methodologies exist to estimate EEI from the GOHC. A 2022 article in Earth System Science Data describes the space geodetic approach, which relies on satellite altimetry and gravimetry measurements. Satellite altimetry is used to measure sea level rise, which is caused by both the expansion of warming ocean waters and the addition of freshwater to the ocean from melting land ice (Greenland and Antarctic ice sheets and mountain glaciers). Gravimetric measurements are used to measure ocean mass change, which can be used to estimate the contribution to sea level rise from freshwater ice melt on land. By combining gravimetry and altimetry, it is possible to estimate the thermal expansion of the entire ocean and scale it to estimate EEI – see Figure 1. The magnitude of EEI is small (0.5–1.0 W/m2) compared to the total amount of energy entering and leaving the climate system (~340 W/m2). Therefore, a high level of precision and accuracy are required to estimate the EEI mean (2) and its time variations at decadal scales (2). In this regard, the space geodetic approach emerges as a promising candidate capable of complementing other observing system elements aimed at measuring EEI.

OST Figure 1
Figure 1. This graph shows the decadal variations of the Earth Energy Imbalance (EEI) estimated from the space geodetic method that combines altimetry and gravimetric measurements (black) and direct measurements of solar radiation at the top of the atmosphere from the Clouds and the Earth’s Radiant Energy System (CERES) instrument (blue). The grey shaded area corresponds to the space geodetic method’s uncertainty.
Image credit: Michael Ablain/Collect Localisation Services (CLS), France

Large-scale Ocean Circulation Variability and Change

The year-to-year circulation changes along the coast of the western U.S. can have significant impact on the transport of nutrients that affect fisheries. A 2021 article published in the journal Limnology and Oceanography described a study that used ocean currents derived from satellite altimetry to understand the trajectory of water masses from the southern coast of California to the Pacific Northwest. The results show that after a year, subtropical/tropical water masses can reach the Oregon coast from the Southern California Bight (30 °N), and in multiple years from even further south (~26 °N–27 °N) and west. During warmer than average years associated with El Niño Southern Oscillation (1997–1998, 2002–2003, 2004–2005, 2005–2006, 2009–2010, 2014–2015, 2015–2016, 2016–2017), these subtropical/tropical waters masses reached further north compared to other years – see Figure 2. This shift is due to the increase poleward wind stress observed in the California Current. The research team also showed that these tropical warm waters tend to transport “warm water” zooplankton species with a lower fat content. The shift in zooplankton species can impact the young salmon population, which prefer fatty cold-water zooplankton, entering the ocean off the Oregon coast.

OST Figure 2
Figure 2. This graph shows the density of the water mass traveling northward from the tropics and sub-tropics toward the Pacific Northwest coast during [first three panels] the average of Warm Years (1997–1998, 2002–2003, 2004–2005, 2005–2006, 2009–2010, 2014–2015, 2015–2016, 2016–2017) for January, February, and March, and [last three panels] normal, or Other Years (remaining 15 years excluded from the ‘warm year episodes’ between 1997–2020) for January, February, and March. Off the coast of Oregon, warm water masses are denser during warm years.
Image credit: Ted Strub/Oregon State University

Closing Plenary Session Highlights

The closing plenary session included discussions, notably about the key points that were addressed during the opening session and splinter sessions.

Cristina Martin-Puig [EUMETSAT] gave a presentation on the definition of the new Geophysical Data Record (GDR) standards (GDR-G) in a multimission context. There are currently 11 altimeters operating with data quality that continues to undergo improvement. While agencies have been coordinating to homogenize processing baselines across missions, a full harmonization between missions was never discussed in detail until now. All agencies are now working in full collaboration to define a set of common standards and the best data processing practices to ensure full harmony between missions.

Conclusion

During the closing session, the OST ST adopted several recommendations – see “Recommendations from the OST Science Team” above for details.

The OST STM expressed strong support for the continuation of the joint Indo–French Satellite AltiKa (SARAL) drifting period for as long as possible, with its altimeter being the most important for future improvements in mean sea surface and gravity.

The OST STM ended with acknowledgements and kudos, several of which refer to recommendations made by the OST ST. The team expressed its appreciation to NASA and CNES for the successful launch and commissioning of the SWOT mission and its revolutionary new wide-swath altimeter for ocean and surface water. Additional acknowledgements can be found in the full OST STM report link referenced in the introduction of this article.

Overall, the meeting fulfilled all of its objectives. It provided a forum for updates on the status of Jason-3, S6MF, and other relevant missions and programs. It also offered detailed analyses of mission observations by the splinter groups. The team concluded that data from the Jason-3 and S6MF altimeters continue to meet the accuracy and availability requirements of the science community.

An international altimetry meeting to celebrate the 30-year anniversary of altimetry will be held in Montpellier, France on September 2–7, 2024.

separater line

Acknowledgment: This article is based on the official meeting report, referenced in the introduction of this article and prepared in cooperation with all of the OST STM chairs: Severine Fournier [JPL]; Josh Willis [JPL]; Pascal Bonnefond [Observatoire de Paris, Laboratoire Systèmes de Référence Temps-Espace (SYRTE)/CNES]; Eric Leuliette [NOAA]; Remko Scharroo [EUMETSAT]; and Alejandro Egido [ESA].

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May 31, 2024

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      Summary of the Second OMI–TROPOMI Science Team Meeting
      By NASA
      Earth Observer Earth Home Earth Observer Home Editor’s Corner Feature Articles Meeting Summaries News Science in the News Calendars In Memoriam More Archives 22 min read
      Summary of the Second OMI–TROPOMI Science Team Meeting
      Introduction
      The second joint Ozone Monitoring Instrument (OMI)–TROPOspheric Monitoring Instrument (TROPOMI) Science Team (ST) meeting was held June 3–6, 2024. The meeting used a hybrid format, with the in-person meeting hosted at the National Center for Atmospheric Research (NCAR) in Boulder, CO. This was the first OMI meeting to offer virtual participation since the COVID-19 travel restrictions. Combining the onsite and virtual attendees, the meeting drew 125 participants – see Photo.
      OMI flies on NASA’s Earth Observing System (EOS) Aura platform, launched July 15, 2004. TROPOMI flies on the European Space Agency’s (ESA)–Copernicus Sentinel-5 Precursor platform. OMI has collected nearly 20 years of data and TROPOMI now has amassed 5 years of data. 
      Meeting content was organized around the following four objectives:
      discussion of the final reprocessing of OMI data (called Collection 4) and of data preservation; discussion of OMI data continuity and enhancements using TROPOMI measurements; development of unique TROPOMI products [e.g., methane (CH4)], applications (e.g., tracking emissions – and using them as indicators of socioeconomic and military activities), and new focus regions (e.g., Africa); and leverage synergies between atmospheric composition (AC) and greenhouse gas (GHG) missions, which form the international constellation of low Earth orbit (LEO) and geostationary orbit (GEO) satellites. The remainder of this article summarizes the highlights from each day of the meeting.
      Photo. Group photo of the in-person participants at the OMI–TROPOMI Science Team meeting. Photo credit: Shaun Bush/NCAR’s Atmospheric Chemistry Observations & Modeling DAY ONE
      The topics covered on the first day of the meeting included OMI instrument performance, calibration, final Collection 4 reprocessing, and plans for data preservation.
      OMI and Data Products Update
      Pieternel Levelt [Royal Netherlands Meteorological Institute (KNMI)—OMI Principal Investigator (PI) and NCAR’s Atmospheric Chemistry Observations & Modeling (ACOM) Laboratory—Director] began her presentation by dedicating the meeting to the memory of Johan de Vries, whose untimely death came as a shock to the OMI and TROPOMI teams – see In Memoriam: Johan de Vries for a celebration of his accomplishments and contributions to the OMI-TROPOMI team. She then went on to give a status update on OMI, which is one of two currently operating instruments on EOS Aura [the other being the Microwave Limb Sounder (MLS)]. OMI is the longest operating and stable ultraviolet–visible (UV-VIS) spectrometer. It continues to “age gracefully” thanks to its design, contamination control measures undertaken after the launch, and stable optical bench temperature. Lessons learned during integration of OMI on the Aura spacecraft (e.g., provide additional charged couple device shielding) and operations (i.e., monitor partial Earth-view port blockages) guided the development and operations of the follow-on TROPOMI mission.
      Continued monitoring of OMI performance is crucial for extending science- and trend-quality OMI records to the end of the Aura mission (currently expected in 2026). Antje Ludewig [KNMI] described the new OMI Level-1B (L1B) processor (Collection 4), which is based on TROPOMI data flow and optimized calibrations. The processor has been transferred to the U.S. OMI ST, led by Joanna Joiner [NASA’s Goddard Space Flight Center (GSFC)]. Matthew Bandel [Science Systems and Applications, Inc. (SSAI)] described NASA’s new OMI monitoring tools.
      Sergey Marchenko [SSAI] discussed OMI daily spectral solar irradiance (SSI) data, which are used for monitoring solar activity and can be compared with the dedicated Total and Spectral Solar Irradiance Sensor (TSIS-1) on the International Space Station. Continuation of OMI measurements will allow comparisons with the upcoming NASA TSIS-2 mission. Antje Inness [European Centre for Medium-range Weather Forecasts (ECMWF)] described operational assimilation of OMI and TROPOMI near-real time data into the European Copernicus Atmosphere Monitoring Service (CAMS) daily analysis/forecast and re-analysis – see Figure 1.
      In Memoriam: Johan de Vries
      Johan de Vries
      June 10, 1956 – May 8, 2024 Johan de Vries [Airbus Netherlands—Senior Specialist Remote Sensing] passed away suddenly on May 8, 2024, after a distinguished career. As a member of the Ozone Monitoring Instrument (OMI)–TROPOspheric Monitoring Instrument (TROPOMI) program, Johan conceptualized the idea of using a two-dimensional (2D) charged couple detector (CCD) for the OMI imaging spectrometer. This “push-broom” design led to high-spatial resolution spectra combined with high-spatial resolution and daily global coverage capability. His pioneering design for OMI has now been repeated on several other U.S. and international atmospheric composition measuring instruments – in both low and geostationary orbits – that are either in orbit or planned for launch soon. This achievement ensures that Johan’s legacy will live on for many years to come as these push-broom Earth observing spectrometers result in unprecedented data for environmental research and applications. The OMI and TROPOMI teams express their deepest condolences to de Vries family and colleagues over this loss. 
      Figure 1. An example of TROPOMI pixel nitrogen dioxide (NO2) observations over Europe on September 8, 2018 [top] and the corresponding super observations [bottom] for a model grid of 0.5 x 0.5o. Cloudy locations are colored grey. TROPOMI super observations are tested for use in the European Centre for Medium Range Weather Forecasting (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) data assimilation framework and will also be used for combined OMI–TROPOMI gridded datasets. Figure credit: reprinted from a 2024 paper posted on EGUSphere. Updates on OMI and TROPOMI Level-2 Data Products
      The U.S. and Netherlands OMI STs continue to collaborate closely on reprocessing and improving OMI and TROPOMI L2 science products. During the meeting, one or more presenters reported on each product, which are described in the paragraphs that follow.
      Serena Di Pede [KNMI] discussed the latest algorithm updates to the Collection 4 OMI Total Column Ozone (O3) product, which is derived using differential absorption spectroscopy (DOAS). She compared results from the new algorithm with the previous Collection 3 and with both the TROPOMI and OMI NASA O3 total column (Collection 3) algorithms. Collection 4 improved on previous versions by reducing the retrieval fit error and the along-track stripes of the product.
      Juseon “Sunny” Bak and Xiong Liu [both from Smithsonian Astrophysical Observatory (SAO)] gave updates on the status of the Collection 4 O3 profile products.
      Lok Lamsal [GSFC/University of Maryland, Baltimore County (UMBC)] and Henk Eskes [KNMI] compared Collection 3 and Collection 4 of the nitrogen dioxide (NO2) products.  
      Zolal Ayzpour [SAO] discussed the status of the OMI Collection 4 formaldehyde (HCHO) product.
      Hyeong-Ahn Kwon [SAO] presented a poster that updated the Glyoxal product.
      Omar Torres [GSFC] and Changwoo Ahn [GSFC/SSAI] presented regional trend analyses using the re-processed OMI Collection 4 absorbing aerosol product – see Figure 2.
      Figure 2. Reprocessed OMI records (from Collection 4) of monthly average aerosol optical depth (AOD) at 388 nm derived from the OMI aerosol algorithm (OMAERUV) over Western North America (WNA): 30°N–50°N, 110°W–128°W) [top] and over Eastern China (EC): 25°N–43°N, 112°E–124°E) [bottom]. A repeatable annual cycle over WNA occurred with autumn minimum at around 0.1 and a spring maximum in the vicinity of 0.4 during the 2005–2016 period. After 2017 much larger AOD maxima in the late summer are associated with wildfire smoke occurrence. Over EC (bottom) the 2005–2014 AOD record depicts a large spring maxima (0.7 and larger) due to long-range transport of dust and secondary pollution aerosols followed by late autumn minima (around 0.3). A significant AOD decrease is observed starting in 2015 with reduced minimum and maximum values to about 0.2 and 0.5 respectively. The drastic change in AOD load over this region is associated with pollution control measures enacted over the last decade. Figure credit: Changwoo Ahn/GSFC/SSAI and Omar Torres/GSFC Updates on EOS Synergy Products
      Several presenters and posters during the meeting gave updates on EOS synergy products, where OMI data are combined with data from another instrument on one of the EOS flagships. These are described below.
      Brad Fisher [SSAI] presented a poster on the Joint OMI–Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products.
      Wenhan Qin [GSFC/SSAI] presented a poster on the MODIS–OMI Geometry Dependent Lambertian Equivalent Surface Reflectivity (GLER) product.
      Jerry Ziemke [GSFC and Morgan State University (MSU)] presented on the OMI–MLS Tropospheric Ozone product that showed post-COVID tropospheric O3 levels measured using this product, which are consistent with similar measurements obtained using other satellite O3 data – see Figure 3.
      Figure 3. Anomaly maps of merged tropospheric column O3 (TCO) satellite data (Dobson Units) for spring–summer 2020–2023. In this context, an anomaly is defined as deseasonalized O3 data. The anomaly maps are derived by first calculating seasonal climatology maps for 2016–2019 (i.e., pre-COVID pandemic) and then subtracting these climatology maps from the entire data record. 
      Note: The sensors used in this analysis include: the Ozone Mapping and Profiler Suite (OMPS)/ Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and Cross-track Infrared Sounder (CrIS) on the Joint Polar Satellite System (JPSS) missions, which currently include the joint NASA–NOAA Suomi National Polar-orbiting Partnership (Suomi NPP), NOAA-20, and NOAA-21; the Earth Polychromatic Imaging Camera (EPIC)/MERRA-2 on the Deep Space Climate Observatory (DSCOVR); the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS), both on EOS Aura; the Infrared Atmospheric Sounding Interferometer (IASI)/ Fast Optimal Retrievals on Layers (FORLI), IASI/SOftware for Fast Retrievals of IASI Data (SOFRID), and IASI/Global Ozone Monitoring Experiment–2 (GOME2). IASI flies on the European MetOp-A, -B, and -C missions. The OMPS/MERRA-2 and EPIC/MERRA-2 products subtract coincident MERRA-2 stratospheric column O3 from total O3 to derive tropospheric column O3. Figure credit: Jerry Ziemke/GSFC and Morgan State University (MSU)  Updates on Multisatellite Climate Data Records
      The OMI ST also discussed refining and analyzing multisatellite climate data records (CDRs) that have been processed with consistent algorithms. Several presenters reported on this work, who are mentioned below.
      Jenny Stavrakou [Koninklijk Belgisch Instituut voor Ruimte-Aeronomie, Royal Belgian Institute for Space Aeronomy (BIRA–IASB)], reported on work focusing on the OMI and TROPOMI HCHO CDR and Huan Yu [BIRA–IASB)] reported harmonized OMI and TROPOMI cloud height datasets based on improved O2-O2 absorption retrieval algorithm.
      Lok Lamsal [GSFC/UMBC, Goddard Earth Sciences Technology and Research (GESTAR) II], Henk Eskes, and Pepijn Veefkind [KNMI] reported on the OMI and TROPOMI NO2 CDRs – see Figure 4. 
      Si-Wan Kim [Yonsei University, South Korea] reported on OMI and TROPOMI long-term NO2 trends.
      Figure 4. OMI nitrogen dioxide (NO2) time series bridging the first GOME mission (which flew on the European Remote Sensing Satellite–2 (ERS–2) from 1995–2011 with limited coverage after 2003) and measurements from the two currently operating missions – OMI (2004–present) and TROPOMI (2017–present) – offer consistent climate data records that allow for studying long-term changes. This example shows tropospheric NO2 column time series from three instruments over Phoenix, AZ. The overlap between the OMI and TROPOMI missions allows for intercomparison between the two, which is crucial to avoid continuity-gaps in multi-instrument time series. The ERS-2 (GOME) had a morning equator crossing time (10:30 AM), while Aura (OMI) and Metop (TROPOMI) have afternoon equator crossing times of 1:45 PM and 1:30 PM respectively. Figure credit: Lok Lamsal/GSFC/University of Maryland, Baltimore County (UMBC) Update on Aura’s Drifting Orbit
      Bryan Duncan [GSFC—Aura Project Scientist] closed out the first day with a presentation summarizing predictions of Aura’s drifting orbit. Overall, the impact of Aura’s drift is expected to be minor, and the OMI and MLS teams will be able to maintain science quality data for most data products. He thanked the OMI/TROPOMI ST and user community for expressing their strong support for continuing Aura observations until the end of the Aura mission in mid–2026.
      DAY TWO
      The second day of the meeting focused on current and upcoming LEO and GEO Atmospheric Composition (AC) missions.
      TROPOMI Mission and Data Product Updates
      Veefkind presented an update on the TROPOMI mission, which provides continuation and enhancements for all OMI products. Tobias Borssdorf [Stichting Ruimte Onderzoek Nederland (SRON), or Netherlands Institute for Space Research] explained how TROPOMI, with its innovative shortwave infrared (SWIR) spectrometer, measures CH4 and carbon monoxide (CO). This approach continues measurements that began by the Measurements of Pollution in the Troposphere (MOPITT) instrument on Terra.
      Hiren Jethva [NASA Airborne Science Program] and Torres presented new TROPOMI near-UV aerosol products, including a new aerosol layer optical centroid height product, which takes advantage of the TROPOMI extended spectral range – see Figure 5.
      Figure 5. Global gridded (0.10° x 0.10°) composite map of aerosol layer optical centroid height (AH) retrieved from TROPOMI O2-B band observations from May–September 2023. Figure credit: Hiren Jethva/NASA Airborne Science Program GEMS–TEMPO–Sentinel-4 (UVN): A Geostationary Air Quality Constellation
      TROPOMI global observations serve as a de facto calibration standard used to homogenize a new constellation of three missions that will provide AC observations for most of the Northern Hemisphere from GEO. Two of the three constellation members are already in orbit. Jhoon Kim [Yonsei University—PI] discussed the Geostationary Environmental Monitoring Spectrometer (GEMS), launched on February 19, 2020 aboard the Republic of Korea’s GEO-KOMPSAT-2B satellite. It is making GEO AC measurements over Asia. The GEMS team is working on validating measurements of NO2 diurnal variations using ground-based measurements from the PANDORA Global Network over Asia and aircraft measurements from the ASIA–AQ field campaign.
      Liu discussed NASA’s Tropospheric Emission Monitoring of Pollution (TEMPO) spectrometer, launched on April 7, 2023, aboard a commercial INTELSAT 40E satellite. From its GEO vantage point, TEMPO can observe the Continental U.S., Southern Canada, Mexico, and the coastal waters of the Northwestern Atlantic and Northeastern Pacific oceans.
      Gonzales Abad [SAO] presented the first measurements from TEMPO. He explained that TEMPO’s design is similar to GEMS, but GEMS includes an additional visible and near infrared (VNIR) spectral channel (540–740 nm) to measure tropospheric O3, O2, and water vapor (H2Ov). TEMPO can perform optimized morning scans, twilight scans, and scans with high temporal resolution (5–10 minutes) over selected regions. Abad reported that the TEMPO team released L1B spectra and the first provisional public L2 products (Version 3), including NO2, HCHO, and total column O3. Andrew Rollins [National Oceanic and Atmospheric Administration’s (NOAA) Chemical Sciences Laboratory (CSL)] reported that the TEMPO team is working on validation of provisional data using both ground-based data from PANDORA spectrometers and data collected during several different airborne campaigns completed during the summer of 2023 and compiled on the AGES+ website.
      Ben Veihelmann [ESA’s European Space Research and Technology Center—PI] explained that ESA’s Copernicus Sentinel-4 mission will be the final member of the GEO AC constellation. Veefkind summarized the Sentinel-4 mission, which is expected to launch on the Meteosat Third Generation (MTG)-Sounder 1 (MTG-S1) platform in 2025. The mission is dedicated to measuring air quality and O3 over Europe and parts of the Atlantic and North Africa. Sentinel-4 will deploy the first operational UV-Vis-NIR (UVN) imaging spectrometer on a geostationary satellite. (Airbus will build UVN, with ESA providing guidance.) Sentinel-4 includes two instruments launched in sequence on MTG-S1 and MTG-S2 platforms designed to have a combined lifetime of 15 years. The mission by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) will operate Sentinel-4, and the Deutsches Zentrum für Luft- und Raumfahrt (DLR) or German Aerospace Center will be responsible for operational L2 processing.
      These three GEO AC missions, along with the upcoming ESA/EUMETSAT/Copernicus LEO (morning orbit, 9:30 a.m.) Sentinel-5 (S5) mission, will complete a LEO–GEO satellite constellation that will enable monitoring of the most industrialized and polluted regions in the Northern Hemisphere into the 2030s. Sentinel-5 will not continue the OMI–TROPOMI data record in the early afternoon; however, it will be placed in the morning orbit and follow ESA’s Global Ozone Monitoring Experiment (GOME) and EUMETSAT GOME-2 missions. By contrast, GEO AC observations over the Southern Hemisphere are currently not available. Several presenters described ongoing projects for capacity building for LEO satellite air quality data uptake and emission monitoring in Africa and advocated for the new geostationary measurements.
      Synergy with Other Current or Upcoming Missions
      Attendees discussed the synergy between upcoming AC, GHG, and ocean color missions. Current trends in satellite AC measurements are toward increased spatial resolution and combined observations of short-lived reactive trace gases – which are important for air quality (AQ) monitoring – and long-lived GHG – which are important for climate monitoring and carbon cycle assessments. Some trace gases (e.g., O3 and CH4) are both polluters and GHG agents. Others [e.g., NO2 and sulfur dioxide (SO2 )] are aerosol [particulate matter (PM)] and O3 precursors and are used as proxies and spatial indicators for anthropogenic CO2 and CH4 emissions.
      Yasjka Meijer [ESA—Copernicus Anthropogenic Carbon Dioxide Monitoring (CO2M) Mission Scientist]) reviewed the plans for CO2M, which includes high-resolution measurements [~4 km2 (~1.5 mi2)] of CO2 , CH4 , and NO2.
      Jochen Landgraf [SRON] described ESA’s new Twin Anthropogenic Greenhouse Gas Observers (TANGO) mission, which has the objective to measure CO2 , CH4 , and NO2 at even higher spatial resolution [~300 m (~984 ft)] using two small CubeSat spectrometers flying in formation.
      Hiroshi Tanimoto [National Institute for Environmental Studies, Japan] described the Japan Aerospace Exploration Agency’s (JAXA) Global Observing SATellite for greenhouse gases and water cycle (GOSAT-GW) mission, which includes the Total Anthropogenic and Natural Emission mapping SpectrOmeter (TANSO-3) spectrometer to simultaneously measure CO2 , CH4, and NO2 with ~1–3 km (~0.6–1.8 mi) spatial resolution in focus mode. GOSAT-GW will also fly the Advanced Microwave Scanning Radiometer 3 (AMSR3).
      Joanna Joiner [GSFC—Geostationary Extended Operations (GeoXO) Project Scientist and ACX Instrument Scientist] described the plans for the next-generation U.S. geosynchronous satellite constellation, which will consist of three satellites covering the full Earth disk: GEO-East, GEO-West, and GEO-Central. (By contrast, the current Geostationary Operational Environmental Satellite (GOES) series has two satellites: GOES–East and GOES–West.) GEO-Central will carry an advanced infrared sounder (GXS) for measuring vertical profiles of many trace gases, temperature and humidity, and a new UV-VIS spectrometer (ACX), which is a follow-on to TEMPO for AQ applications. Both GXS and ACX instruments will be built by BAE Systems, which acquired Ball Aerospace and Technology, and will also build the GeoXO ocean color spectrometer (OCX).
      Andrew Sayer [UMBC] described NASA’s Plankton, Aerosols, Clouds, and ocean Ecosystem (PACE), which launched on February 8, 2024. The PACE payload includes a high-spatial resolution [~1 km (~0.6 mi) at nadir] Ocean Color Instrument (OCI), which is a UV-Vis-NIR spectrometer with discrete SWIR bands presenting additional opportunities for synergistic observations with the AC constellation. Sayer presented OCI “first light” aerosol data processed using the unified retrieval algorithm developed by Lorraine Remer [UMBC].
      The second day concluded with a joint crossover session with NASA’s Health and Air Quality Applied Sciences Team (HAQAST) followed by a poster session. Several OMI–TROPOMI STM participants presented on a variety of topics that illustrate how OMI and TROPOMI data are being used to support numerous health and AQ applications. Duncan, who is also a member of HAQAST team, presented “20 years of health and air quality applications enabled by OMI data.” He highlighted OMI contributions to AQ and health applications, including NO2 trend monitoring, inferring trends of co-emitted species [e.g., CO2, CO, some Volatile Organic Compounds (VOCs)], validation of new satellite missions (e.g., TEMPO, PACE), and burden of disease studies.
      DAY THREE
      Discussions on the third day focused on advanced retrieval algorithms, leading to new products and new applications for OMI and TROPOMI data. Several presentations described applications of TROPOMI CH4 data and synergy with small satellites.
      Advanced Retrieval Algorithms and New Data Products
      Ilse Aben [SRON] described TROPOMI global detection of CH4 super-emitters using an automated system based on Machine Learning (ML) techniques – see Figure 6. Berend Schuit [SRON] provided additional detail on these methods. He introduced the TROPOMI CH4 web site to the meeting participants. He explained how TROPOMI global CH4 measurements use “tip-and-cue” dedicated satellites with much higher spatial resolution instruments [e.g., GHGSat with ~25-m (~82-ft) resolution] to scan for individual sources and estimate emission rates. Most CH4 super-emitters are related to urban areas and/or landfills, followed by plumes from gas and oil industries and coal mines.
      Figure 6. Methane plume map produced by SRON shows TROPOMI large CH4 emission plumes for the week of the OMI–TROPOMI meeting (June 3–6, 2024). Figure credit: Itse Aben/Stichting Ruimte Onderzoek Nederland (SRON) Alba Lorente [Environmental Defense Fund—Methane Scientist] introduced a new MethaneSAT satellite launched in March 2024, which aims to fill the gap in understanding CH4 emissions on a regional scale [200 x 200 km2 (~77 x 77 mi2)] from at least 80% of global oil and gas production, agriculture, and urban regions. Alex Bradley [University of Colorado, Boulder] described improvements to TROPOMI CH4 retrievals that were achieved by correcting seasonal effects of changing surface albedo.
      Daniel Jacob [Harvard University] presented several topics, including the highest resolution [~30 m (~98 ft)] NO2 plume retrievals from Landsat-8 – see Figure 7 – and Sentinel-2 imagers. He also discussed using a ML technique trained with TROPOMI data to improve NO2 retrievals from GEMS and modeling NO2 diurnal cycle and emission estimates. He introduced the ratio of ammonia (NH3) to NO2 (NH3/NO2) as an indicator of particulate matter with diameters less than 2.5 µm (PM2.5) nitrate sensitivity regime. Jacob emphasized the challenges related to satellite NO2 retrievals (e.g., accounting for a free-tropospheric NO2 background and aerosols).
      Figure 7. Landsat Optical Land Imager (OLI) image, obtained on October 17, 2021 over Saudi Arabia, shows power plant exhaust, which contains nitrogen dioxide (NO2) drifting downwind from the sources (the two green circles are the stacks). The ultra-blue channel (430–450 nm) on OLI enables quantitative detection of NO2 in plumes from large point sources at 30-m (~98-ft) resolution. This provides a unique ability for monitoring point-source emissions of oxides of nitrogen (NOx). The two stacks in the image are separated by 2 km (~1.2 mi). Figure credit: Daniel Jacob – repurposed from a 2024 publication in Proceedings of the National Academies of Sciences (PNAS) Steffen Beirle [Max Planck Institute for Chemistry, Germany] explained his work to fit TROPOMI NO2 column measurements to investigate nitric oxide (NO) to NO2 processing in power plant plumes. Debra Griffin [Environment and Climate Change Canada (ECCC)] used TROPOMI NO2 observations and ML random forest technique to estimate NO2 surface concentrations. Sara Martinez-Alonso [NCAR] investigated geographical and seasonal variations in NO2 diurnal cycle using GEMS and TEMPO data.  Ziemkecombined satellite O3 data to confirm a persistent low anomaly (~5–15%) in tropospheric O3 after 2020.  Jethva presented advanced OMI and TROPOMI absorbing aerosol products. Yu described improved OMI and TROPOMI cloud datasets using the O2-O2 absorption band at 477 nm. Nicholas Parazoo [Jet Propulsion Laboratory (JPL)] described TROPOMI Fraunhofer line retrievals of red solar-induced chlorophyll fluorescence (SIF) near O2-B band (663–685 nm) to improve mapping of ocean primary productivity. Liyin He [Duke University] described using satellite terrestrial SIF data to study the effect of particulate pollution on ecosystem productivity.
      New Applications
      Zachary Fasnacht [SSAI] used OMI and TROPOMI spectra to train a neural network to gap-fill MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) ocean color data under aerosol, sun glint, and partly cloudy conditions. This ML method can also be applied to PACE OCI spectra. Anu-Maija Sundström [Finnish Meteorological Institute (FMI)] used OMI and TROPOMI SO2 and O3 data as proxies to study new particle formation events. Lindsey Anderson [University of Colorado, Boulder] described how she used TROPOMI NO2 and CO measurements to estimate the composition of wildfire emissions and their effect on forecasted air quality. Heesung Chong [SAO] applied OMI bromine oxide (BrO) retrievals to the NOAA operational Ozone Mapping and Profiling Suite Nadir Mapper (OMPS-NM) on joint NOAA–NASA Suomi-National Polar-orbiting Partnership (Suomi NPP) satellite with the possibility to continue afternoon measurements using similar OMPS-NM instruments on the four Joint Polar Satellite System missions (JPSS-1,-2,-3,-4) into the 2030s. (JPSS-1 and -2 are now in orbit and known as NOAA-20 and -21 respectively; JPSS-4 is planned for launch in 2027, with JPSS-3 currently targeted for 2032.)
      Kim demonstrated the potential for using satellite NO2 and SO2 emissions as a window into socioeconomic issues that are not apparent by other methods. For example, she showed how OMI and TROPOMI data were widely used to monitor air quality improvements in the aftermath of COVID-19 lockdowns. (Brad Fisher [SSAI] presented a poster on a similar topic.)
      Cathy Clerbaux [Center National d’Études Spatiale (CNES), or French Space Agency] showed how her team used TROPOMI NO2 data to trace the signal emitted by ships and used this information to determine how the shipping lanes through the Suez Canal changed in response to unrest in the Middle East. Iolanda Ialongo [FMI] showed a similar drop of NO2 emissions over Donetsk region due to the war in Ukraine. Levelt showed how OMI and TROPOMI NO2 data are used for capacity-building projects and for air quality reporting in Africa. She also advocated for additional geostationary AQ measurements over Africa.
      DAY FOUR
      Discussions on the final day focused on various methods of assimilating satellite data into air quality models for emission inversions and aircraft TEMPO validation campaigns. The meeting ended with Levelt giving her unique perspective on the OMI mission, as she reflected on more than two decades being involved with the development, launch, operation, and maintenance of OMI.  
      Assimilating Satellite Data into Models for Emissions
      Brian McDonald [CSL] described advance chemical data assimilation of satellite data for emission inversions and the GReenhouse gas And Air Pollutants Emissions System (GRA2PES). He showed examples of assimilations using TROPOMI and TEMPO NO2 observations to adjust a priori emissions. He also showed that when TEMPO data are assimilated, NOx emissions adjust faster and tend to perform better at the urban scale. Adrian Jost [Max Planck Institute for Chemistry] described the ESA-funded World Emission project to improve pollutant and GHG emission inventories using satellite data. He showed examples of TROPOMI SO2 emissions from large-point sources and compared the data with bottom-up and NASA SO2 emissions catalogue.
      Ivar van der Velde [SRON] presented a method to evaluate fire emissions using new satellite imagery of burned area and TROPOMI CO. Helene Peiro [SRON] described her work to combine TROPOMI CO and burned area information to compare the impact of prescribed fires versus wildfires on air quality in the U.S. She concluded that prescribed burning reduces CO pollution. Barbara Dix [University of Colorado, Boulder, Cooperative Institute for Research in Environmental Sciences] derived NOx emissions from U.S. oil and natural gas production using TROPOMI NO2 data and flux divergence method. She estimated TROPOMI CH4 emissions from Denver–Julesburg oil and natural gas production. Dix explained that the remaining challenge is to separate oil and gas emissions from other co-located CH4 sources. Ben Gaubert [NCAR, Atmospheric Chemistry Observations and Modeling] described nonlinear and non-Gaussian ensemble assimilation of MOPITT CO using the data assimilation research testbed (DART).
      Andrew (Drew) Rollings [CSL] presented first TEMPO validation results from airborne field campaigns in 2023 (AGES+ ), including NOAA CSL Atmospheric Emissions and Reactions observed from Megacities to Marine Aeras (AEROMMA) and NASA’s Synergistic TEMPO Air Quality Science (STAQS) campaigns.
      A Reflection on Twenty Years of OMI Observations
      Levelt gave a closing presentation in which she reflected on her first involvement with the OMI mission as a young scientist back in 1998. This led to a collaboration with the international ST to develop the instrument, which was included as part of Aura’s payload when it launched in July 2004. She reminisced about important highlights from 2 decades of OMI, e.g., the 10-year anniversary STM at KNMI in 2014 (see “Celebrating Ten Years of OMI Observations,” The Earth Observer, May–Jun 2014, 26:3, 23–30), and the OMI ST receiving the NASA/U.S. Geological Survey Pecora award in 2018 and the American Meteorological Society’s Special award in 2021.
      Levelt pointed out that in this combined OMI–TROPOMI meeting the movement towards using air pollution and GHG data together became apparent. She ended by saying that the OMI instrument continues to “age gracefully” and its legacy continues with the TROPOMI and LEO–GEO atmospheric composition constellation of satellites that were discussed during the meeting.
      Conclusion
      Overall, the second OMI–TROPOMI STM acknowledged OMI’s pioneering role and TROPOMI’s unique enhancements in measurements of atmospheric composition: 
      Ozone Layer Monitoring: Over the past two decades, OMI has provided invaluable data on the concentration and distribution of O3 in the Earth’s stratosphere. This data has been crucial for understanding and monitoring the recovery of the O3 layer following international agreements, such as the Montreal Protocol. Air Quality Assessment: OMI’s high-resolution measurements of air pollutants, such as NO2, SO2, and HCHO, have significantly advanced our understanding of air quality. This information has been vital for tracking pollution sources, studying their transport and transformation, and assessing their impact on human health and the environment. Climate Research: The data collected by OMI has enhanced our knowledge of the interactions between atmospheric chemistry and climate change. These insights have been instrumental in refining climate models and improving our predictions of future climate scenarios. Global Impact: The OMI instrument has provided near-daily global coverage of atmospheric data, which has been essential for scientists and policymakers worldwide. The comprehensive and reliable data from OMI has supported countless research projects and informed decisions aimed at protecting and improving our environment. OMI remains one of the most stable UV/Vis instruments over its two decades of science and trend quality data collection. The success of the OMI and TROPOMI instruments is a testament to the collaboration, expertise, and dedication of both teams.
      Nickolay Krotkov
      NASA’s Goddard Space Flight Center
      Nickolay.a.krotkov@nasa.gov
      Pieternel Levelt
      National Center for Atmospheric Research, Atmospheric Chemistry Observations & Modeling
      levelt@ucar.edu
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      Last Updated Nov 12, 2024 Related Terms
      Earth Science View the full article
    • NASA
      Station Science Top News: Nov. 8, 2024
      By NASA
      Researchers demonstrated the feasibility of 3D bioprinting a meniscus or knee cartilage tissue in microgravity. This successful result advances technology for bioprinting tissue to treat musculoskeletal injuries on long-term spaceflight or in extraterrestrial settings where resources and supply capacities are limited.

      BFF Meniscus-2 evaluated using the BioFabrication Facility to 3D print knee cartilage tissue using bioinks and cells. The meniscus is the first engineered tissue of an anatomically relevant shape printed on the station. Manufactured human tissues have potential as alternatives to donor organs, which are in short supply. Bioprinting in microgravity overcomes some of the challenges present in Earth’s gravity, such as deformation or collapse of tissue structures.
      A human knee meniscus 3D bioprinted in space using the International Space Station’s BioFabrication Facility.Redwire Complex cultures of central nervous system cells known as brain organoids can be maintained in microgravity for long periods of time and show faster development of neurons than cultures on Earth. These findings could help researchers develop treatments for neurodegenerative diseases on Earth and address potential adverse neurological effects of spaceflight.

      Cosmic Brain Organoids examined growth and gene expression in 3D organoids created with neural stem cells from individuals with primary progressive multiple sclerosis and Parkinson’s disease. Results could improve understanding of these neurological diseases and support development of new treatments. Researchers plan additional studies on the underlying causes of the accelerated neuron maturation.
      Neural growth in brain organoids that spent more than a month in space. Jeanne Frances Loring, National Stem Cell Foundation Researchers demonstrated that induced pluripotent stem cells (iPSCs) can be processed in microgravity using off the-shelf cell culture materials. Using standard laboratory equipment and protocols could reduce costs and make space-based biomedical research accessible to a broader range of scientists and institutions.

      Stellar Stem Cells Ax-2 evaluated how microgravity affects methods used to generate and grow stem cells into a variety of tissue types on the ground. iPSCs can give rise to any type of cell or tissue in the human body, and insight into processing in space could support their use in regenerative medicine and future large-scale biomanufacturing of cellular therapeutics in space.
      NASA astronaut Peggy Whitson, an Axiom Mission 2 crew member, works on stem cell research on a previous mission. NASA/Shane KimbroughView the full article
    • NASA
      Powerful New US-Indian Satellite Will Track Earth’s Changing Surface
      By NASA
      6 min read
      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      The NISAR mission will help researchers get a better understanding of how Earth’s surface changes over time, including in the lead-up to volcanic eruptions like the one pictured, at Mount Redoubt in southern Alaska in April 2009.R.G. McGimsey/AVO/USGS Data from NISAR will improve our understanding of such phenomena as earthquakes, volcanoes, and landslides, as well as damage to infrastructure.
      We don’t always notice it, but much of Earth’s surface is in constant motion. Scientists have used satellites and ground-based instruments to track land movement associated with volcanoes, earthquakes, landslides, and other phenomena. But a new satellite from NASA and the Indian Space Research Organisation (ISRO) aims to improve what we know and, potentially, help us prepare for and recover from natural and human-caused disasters.
      The NISAR (NASA-ISRO Synthetic Aperture Radar) mission will measure the motion of nearly all of the planet’s land and ice-covered surfaces twice every 12 days. The pace of NISAR’s data collection will give researchers a fuller picture of how Earth’s surface changes over time. “This kind of regular observation allows us to look at how Earth’s surface moves across nearly the entire planet,” said Cathleen Jones, NISAR applications lead at NASA’s Jet Propulsion Laboratory in Southern California.
      Together with complementary measurements from other satellites and instruments, NISAR’s data will provide a more complete picture of how Earth’s surface moves horizontally and vertically. The information will be crucial to better understanding everything from the mechanics of Earth’s crust to which parts of the world are prone to earthquakes and volcanic eruptions. It could even help resolve whether sections of a levee are damaged or if a hillside is starting to move in a landslide.
      The NISAR mission will measure the motion of Earth’s surface — data that can be used to  monitor critical infrastructure such as airport runways, dams, and levees. NASA/JPL-Caltech What Lies Beneath
      Targeting an early 2025 launch from India, the mission will be able to detect surface motions down to fractions of an inch. In addition to monitoring changes to Earth’s surface, the satellite will be able to track the motion of ice sheets, glaciers, and sea ice, and map changes to vegetation.
      The source of that remarkable detail is a pair of radar instruments that operate at long wavelengths: an L-band system built by JPL and an S-band system built by ISRO. The NISAR satellite is the first to carry both. Each instrument can collect measurements day and night and see through clouds that can obstruct the view of optical instruments. The L-band instrument will also be able to penetrate dense vegetation to measure ground motion. This capability will be especially useful in areas surrounding volcanoes or faults that are obscured by vegetation.
      “The NISAR satellite won’t tell us when earthquakes will happen. Instead, it will help us better understand which areas of the world are most susceptible to significant earthquakes,” said Mark Simons, the U.S. solid Earth science lead for the mission at Caltech in Pasadena, California.
      Data from the satellite will give researchers insight into which parts of a fault slowly move without producing earthquakes and which sections are locked together and might suddenly slip. In relatively well-monitored areas like California, researchers can use NISAR to focus on specific regions that could produce an earthquake. But in parts of the world that aren’t as well monitored, NISAR measurements could reveal new earthquake-prone areas. And when earthquakes do occur, data from the satellite will help researchers understand what happened on the faults that ruptured.
      “From the ISRO perspective, we are particularly interested in the Himalayan plate boundary,” said Sreejith K M, the ISRO solid Earth science lead for NISAR at the Space Applications Center in Ahmedabad, India. “The area has produced great magnitude earthquakes in the past, and NISAR will give us unprecedented information on the seismic hazards of the Himalaya.”
      Surface motion is also important for volcano researchers, who need data collected regularly over time to detect land movements that may be precursors to an eruption. As magma shifts below Earth’s surface, the land can bulge or sink. The NISAR satellite will help provide a fuller picture for why a volcano deforms and whether that movement signals an eruption.
      Finding Normal
      When it comes to infrastructure such as levees, aqueducts, and dams, NISAR’s ability to provide continuous measurements over years will help to establish the usual state of the structures and surrounding land. Then, if something changes, resource managers may be able to pinpoint specific areas to examine. “Instead of going out and surveying an entire aqueduct every five years, you can target your surveys to problem areas,” said Jones.
      The data could be equally valuable for showing that a dam hasn’t changed after a disaster like an earthquake. For instance, if a large earthquake struck San Francisco, liquefaction — where loosely packed or waterlogged sediment loses its stability after severe ground shaking — could pose a problem for dams and levees along the Sacramento-San Joaquin River Delta.
      “There’s over a thousand miles of levees,” said Jones. “You’d need an army to go out and look at them all.” The NISAR mission would help authorities survey them from space and identify damaged areas. “Then you can save your time and only go out to inspect areas that have changed. That could save a lot of money on repairs after a disaster.”
      More About NISAR
      The NISAR mission is an equal collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on hardware development for an Earth-observing mission. Managed for the agency by Caltech, JPL leads the U.S. component of the project and is providing the mission’s L-band SAR. NASA is also providing the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem. The U R Rao Satellite Centre in Bengaluru, India, which leads the ISRO component of the mission, is providing the spacecraft bus, the launch vehicle, and associated launch services and satellite mission operations. The ISRO Space Applications Centre in Ahmedabad is providing the S-band SAR electronics.
      To learn more about NISAR, visit:
      https://nisar.jpl.nasa.gov
      News Media Contacts
      Jane J. Lee / Andrew Wang
      Jet Propulsion Laboratory, Pasadena, Calif.
      818-354-0307 / 626-379-6874
      jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
      2024-155
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      Details
      Last Updated Nov 08, 2024 Related Terms
      NISAR (NASA-ISRO Synthetic Aperture Radar) Earth Science Earthquakes Jet Propulsion Laboratory Natural Disasters Volcanoes Explore More
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