The Stratospheric Aerosol and Gas Experiment (SAGE) is a series of instruments designed by NASA to observe stratospheric ozone, aerosols, and water vapor from space. SAGE III is the newest and most advanced addition to the SAGE family.

Over the past four decades, the SAGE family of instruments have been critical in making accurate measurements of ozone loss in Earth’s atmosphere. The data collected from SAGE II helped leaders around the world institute an international treaty banning products containing harmful chemicals that destroy stratospheric ozone. SAGE has played a key role in measuring the onset of ozone recovery resulting from the internationally-mandated 1987 Montreal Protocol regulations.

Today, the SAGE technique is still the best for the job, and NASA scientists sent the third generation of the instrument into space on February 19, 2017. Instead of flying on an un-manned satellite, SAGE III is mounted to the International Space Station (ISS) where it operates alongside experiments from all over the world in the space-based laboratory. It was robotically installed on the outside of the ISS and is now taking important measurements of gases and aerosols over 70% of the planet.

SAGE III takes measurements across the globe using a technique called occultation. Every time the sun, or moon, rises and sets, SAGE uses the light that passes through the atmosphere to measure gases and particles in that region of the atmosphere. From the ISS this happens over 30 times per day.

SAGE III is externally mounted on the International Space Station.

SAGE III is the third generation of solar occultation instruments operated by NASA. The renewal of SAGE is designed to fill an anticipated gap in ozone and aerosol observations.

SAGE III was robotically mounted on the ExPRESS Logistics Carrier on the International Space Station.

SAGE III launched on a SpaceX Falcon 9 in February 2017.

SAGE III/ISS Instrument Payload

Nadir Viewing Platform

Spatial / Temporal Coverage

  • Spatial Coverage: 70N to 70S
  • Spatial Resolution: .5km vertical
  • Temporal Coverage: 03/17/2017 – Present
  • Temporal Resolution: 1 file per event

Data Products

  • Ozone (solar and lunar)
  • Aerosol Extinction Profiles
  • Water Vapor
  • Nitrogen Dioxide (solar and lunar)
  • Nitrogen Trioxide (lunar)

Science Data Processing 

The Level 1 and 2 science products are derived from the Level 0 data by algorithms running in the SAGE III/ISS Science Computing Facility (SCF) located at NASA Langley Research Center (LaRC). External ancillary data sources needed to proceed with Level 1 and 2 processing are: observation time/location and pressure/temperature profiles of the neutral atmosphere. GPS time and ISS position/velocity are standard products provided by ISS and are incorporated into the nominal SAGE III/ISS payload data stream. At the advice of the pre-flight ROSES selected Science Utilization Team, the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) is used for temperature/pressure profiles of the neutral atmosphere. This is the same ancillary source used in creating the SAGE II V7 record. MERRA-2 is generally available three weeks after the end of the preceding month. Once the necessary ancillary information is available, processing a month of occultations is complete within a day or so.   

The mission team reviews the results to assess the overall quality and remove any obvious failures, which are rare, not flagged by automated checks of data consistency, or stressing cases that are used for product improvement. Cleared data are then posted to the LaRC Distributed Active Archive Center (DAAC) for public distribution. These steps are usually completed within the required 10 days from receipt of the necessary inputs. 

The SAGE III/ISS SCF processing system architecture consists of two Linux-based servers that act as a data storage and production pair. The complete system has two of these pairs: one performs the standard processing on a monthly cadence; the other pair is for research/development processing and supplying redundant capabilities during reprocessing campaigns, such as for the initial release of version 5.1 products. There are also three Linux-based development servers that primarily act as development servers, though they also hold a copy of the raw, level 0, and intermediate files, and can act as backup servers for production. These development servers are also used for analysis, testing, and validation of the Level 1 and Level 2 data products. All seven of these servers have been verified to produce identical results between various stages of processing. 

SAGE III/ISS Version 5.21 Release Notes

The SAGE III/ISS Team is proud to announce the second official release of SAGE III/ISS products that are suitable for use in both validation and research studies for some data products as described in the associated Data Product User’s Guide (DPUG). Starting with the events on May 31, 2022, the version number reported in the data products is incremented from 5.20 to 5.21. This change reflects an upgrade of the operating system and software compilers used to generate the products. While the Level 1 and Level 2 algorithms remain the same, the underlying upgrades introduce perturbations to the processing stream which manifest as small product differences between the two versions. These differences have been determined to occur without bias or trend, and at magnitudes smaller than reported uncertainty for the vast majority of data points. 

Vertical profiles of ozone, nitrogen dioxide (NO2), and water vapor (H2O) concentrations, as well as multi-wavelength aerosol extinction coefficient, are included in the solar Level 2 data product files. Three ozone profiles are available in this release of the solar products: a UV-based mesospheric product (i.e., “Ozone_Mes” in the product files) and two Chappuis-based products. One Chappius-based product uses a spectrally-focused spectral fitting retrieval (i.e., “Ozone_MLR”) while the other uses a broad-spectrum retrieval scheme that is similar to that of SAGE II (i.e., “Ozone_AO3”). Composite ozone and retrieved temperature/pressure products are not included in the V5.21 data set. Vertical profiles of ozone, nitrogen dioxide (NO2), and nitrogen trioxide (NO3) concentrations are included in the lunar Level 2 product files. Chlorine Dioxide (OClO) from lunar occultation are not included in this release. The channel wavelengths used in solar and lunar retrievals are available in the Data Product User’s Guide (DPUG).

SAGE III/ISS Data Products User’s Guide: Version 5.21, July 2022

Read more about SAGE III data:

SAGE III/ISS First Atmospheric Data Release

SAGE III/ISS Lunar Data Release

SAGE III/ISS Observes 2017 British Columbia Wildfires

SAGE III Instrument Observes Aerosol Spike from Australian Fires

SAGE III Sees California Wildfire Effects in Stratosphere

Studying Earth’s Stratospheric Water Vapor

Enhanced Stratospheric Aerosols from Fukutoku-Okanoba Eruption

SAGE III Instrument Detects Stratospheric Effects of Indonesian Volcanic Eruption

SAGE III/ISS Science Team:

Jun Wang (Team Lead) / University of Iowa, Iowa City
Peter Bernath / Old Dominion University
Mian Chin / Goddard Space Flight Center
Sean Davis / Office of Oceanic and Atmospheric Research, Boulder
Glenn Jaross / Goddard Space Flight Center
Lars Kalnajs / University of Colorado, Boulder
Travis Knepp / Langley Research Center
Katherine Emma Knowland / Universities Space Research Association, Columbia
Stanley Sander / Jet Propulsion Laboratory
Jean-Paul Vernier / National Institute of Aerospace Associates
Hsiang-Jui (Ray) Wang / Georgia Institute of Technology

SAGE III/ISS Bi-Monthly Presentations

August 23, 2022
Title: The Copernicus Atmosphere Monitoring Service (CAMS) Stratospheric Ozone
Abstract: Copernicus services have been set up by the European Union in order to monitor the state of our planet and to help policy makers make decisions. There are six Copernicus services: Atmosphere Monitoring, Marine Environment Monitoring, Land Monitoring, Climate Change, Emergency Management and Security. This talk will focus on the first one, CAMS (Copernicus Atmosphere Monitoring Service). CAMS provides global quality-controlled information related to air pollution and health, solar energy, greenhouse gases and climate forcing. This is achieved by data assimilation of operational satellite data, providing near real time analysis and forecast of tropospheric composition and stratospheric ozone. CAMS also performs reanalyses starting in 2003. This presentation will provide an overview of CAMS in general and of the stratospheric ozone products in particular. We will also describe the evaluation of CAMS products using, among others, SAGE III/ISS ozone profiles.
Speaker Bio: Dr. Quentin Errera is an expert in chemical data assimilation and stratospheric modeling. He started his career at BIRA-IASB in 1995 by analyzing balloon measurement of stratospheric aerosols. Then he obtained a PhD in 2022 by developing a chemistry data assimilation system. He has a strong involvement in the development of the Belgian Assimilation System for Chemical ObsErvations (BASCOE), and produced the BASCOE Reanalysis of Aura MLS, version 2 (BRAM2, Errera et al., ACP, 2019). He also has a long expertise in observations taken by satellite limb instruments and their use to evaluate models or data assimilation analyses. Since 2020, he is responsible for the validation of stratospheric ozone provided by the Copernicus Atmospheric and Monitoring Service (CAMS). Between 2013 and 2021, he was co-leader of the SPARC Data Assimilation Working Group. For several years, he also contributed to the definition of the ESA Earth Watch ALTIUS mission by having set up several Observing System Simulation Experiments (OSSE).

June 28, 2022
Title: A New Challenge in Stratospheric Chemistry: Wildfire Smoke
Abstract: Although pyrocumulonimbus towers have long been known to reach the stratosphere and inject particulate matter, their chemical significance has only recently been recognized.  I will summarize multiple observations of aerosol and NO2 concentrations from three independent satellite instruments that identify decreases in stratospheric NO2 concentrations following the major Australian 2019 through 2020 wildfires. The data confirm that N2O5 hydrolysis did occur on these smoke particle surfaces, with important implications for both composition and ozone depletion. However, additional and more important processes are evident in available satellite data. Those findings will be discussed, and avenues for improvements in understanding will be identified.  The results indicate that increasing wildfire activity in a warming world can be expected to slow the recovery of the ozone layer for at least the next several decades.  Possible linkages to atmospheric circulation and climate will also be discussed.
Speaker Bio: Dr. Susan Solomon is the Martin Professor of Environmental Studies at the Massachusetts Institute of Technology. She is well known for pioneering research on the Antarctic ozone hole and on the irreversibility of climate change. She received the 1999 US National Medal of Science (highest scientific award in the US), the Grande Medaille of the French Academy of Sciences, the Crafoord Prize of the Swedish Academy of Sciences, the Blue Planet Prize, and the Volvo prize. She is a member of the National Academy of Sciences, the French Academy of Sciences, the Pontifical Academy of Sciences, and the Royal Society in the UK. Time magazine named Solomon as one of the 100 most influential people in the world in 2008. A glacier in the Antarctic has been named after her.

April 26, 2022
Title: Clouds and Aerosols with the Atmospheric Chemistry Experiment (ACE) and SAGE III/ISS: Overview and Latest Results
Abstract: ACE ( [1] and SAGE III/ISS are measuring atmospheric composition by solar occultation from low Earth orbit. The primary ACE instrument is an infrared Fourier transform spectrometer (ACE-FTS) and SAGE III/ISS is a UV-Visible-NearIR spectrometer. These instruments provide complementary atmospheric observations. ACE-FTS measures infrared spectra of aerosols and clouds by removing gas phase features to leave “residual” spectra. So far, ACE-FTS has observed spectra of Polar Mesospheric Clouds (PMCs), Polar Stratospheric Clouds (PSCs), stratospheric smoke, sulfate aerosols, cirrus clouds, and volcanic ash. This presentation will focus on volcanic sulfate aerosols and stratospheric smoke particles. We have discovered a new chemistry catalyzed by smoke particles injected into the stratosphere by extreme wildfires (“Wildfire smoke destroys stratospheric ozone” [2]). Most recently we have combined ACE-FTS infrared spectra with SAGE III/ISS extinction measurements to characterize sulfate aerosols more completely.
[1] P. F. Bernath, The Atmospheric Chemistry Experiment (ACE), J. Quant. Spectrosc. Rad. Transfer 186, 3-16 (2017).
[2] P. Bernath, C. Boone and J. Crouse, Wildfire smoke destroys stratospheric ozone, Science 375, 1292-1295 (2022).
Speaker Bio: Peter Bernath received his Bachelor of Science in Chemistry from the University of Waterloo and his Ph.D. in Physical Chemistry from MIT. After a post-doctoral stint at the National Research Council of Canada, he became a faculty member at the University of Arizona, followed by positions at the University of Waterloo and University of York. He is currently at Old Dominion University in Norfolk, VA, where he is a Professor and Eminent Scholar. His research interests are in laboratory spectroscopy, molecular astronomy, and atmospheric science.

February 22, 2022
Title: The JPL Lidar Atmospheric Composition Observations for NDACC: A Review of the Multi-decadal Ozone, Temperature, Aerosol, and Water Vapor Profiles at JPL Table Mountain (CA) and Mauna Loa (HI)
Abstract: Four ground-based lidar instruments have been operated for about three decades at the Jet Propulsion Laboratory Table Mountain Facility (TMF), California, and Mauna Loa Observatory (MLO), Hawaii. These instruments contribute long-term datasets of ozone, temperature, aerosol, and water vapor to the Network for the Detection of Atmospheric Composition Change (NDACC). The measurements are regularly used in international assessments of long-term trends of atmospheric composition in the troposphere, stratosphere, and mesosphere, and represent critical reference data for the validation of space-borne and airborne instruments, including SAGE III/ISS. Several examples of science and validation results involving these lidars will be presented, including recent discoveries that appear to shape the future of ground-based observations in support of future space missions.
Speaker Bio: Dr. Thierry Leblanc is a Research Scientist at NASA’s Jet Propulsion Laboratory (JPL), Principal Investigator of three JPL atmospheric lidar programs, contributing long-term measurements of atmospheric composition to the NDACC and TOLNet networks. His research interests are centered on the observation of ozone, temperature, water vapor, and aerosols using the Raman and differential absorption lidars located at JPL Table Mountain Facility (TMF) in California and Mauna Loa Observatory in Hawaii. He is also responsible for all surface, drone-based, and balloon-borne measurements performed at TMF. Thierry received his Ph.D in Atmospheric Physics in 1995 from the Université Pierre and Marie Curie (Paris, France) on the observation and modeling of gravity wave breaking and its role on the residual circulation. He joined JPL in 1996 where he developed the suite of JPL lidar retrievals used today, and built a high-capability Raman water vapor lidar for measurements in the UT/LS. He is currently co-chair of the NDACC Lidar Working Group, a member of the International Committee for Laser Atmospheric Studies (ICLAS), and a contributor to the TOAR-II Project and to several SPARC Activities.

Science Team Meeting Presentations

11/4 – 11/5/2021

Day 1:

  1. Mission Updates
  2. Mission Operations Over the Past Year
  3. SAGE III/ISS Contamination Update
  4. Mesospheric Ozone: Product Status and Potential Improvements
  5. Using Measurements from the Disturbance Monitoring Package in SAGE III/ISS Data Processing
  6. SAGE III/ISS Public Outreach
  7. Combining SAGE III/ISS and ACE-FTS Sulfate Aerosol Observations
  8. Status of Limb Scatter Product Retrievals
  9. Bridging the SAGE Data Gap: Toward a Climate Data Product with Ozone and Water Vapor Data from NASA SAGE and Aura Missions and NASA Reanalyses
  10. Ground-Based Diurnal Measurements of NO2 and NO3 in Support of SAGE III/ISS Mission
  11. Intercomparison of NO2 from ACE-FTS, SAGE III/ISS and OSIRIS

Day 2:

  1. Searching for (Global) Ozone Recovery: An Update
  2. SWOOSH Updates
  3. Minimizing Sampling Biases in SAGE III/ISS and Merged Multi-Satellite Ozone Datasets
  4. Synergistically Using Observations and Models for the Analysis of Stratospheric Aerosol Events 
  5. Quantifying Particle Size Distribution Errors Derived from SAGE III/ISS Observations
  6. Interannual Variability of Aerosols in the UTLS and its Connection to the Climate Variability, Asian Summer Monsoon Strengths, and Emissions
  7. Aerosols from PyroCBs in the UTLS
  8. Definitive Trends in Lowermost Stratospheric Ozone and Tropopause Height Derived from SHADOZ Soundings (1998-2019)
  9. Ticosonde: 16 Years of Balloon-borne Ozone and Water Vapor Profiles in Costa Rica for Satellite and Model Evaluation

10/19 – 10/20/2020

Day 1:

  1. Welcome / Mission Update
  2. Mission Operations
  3. Instrument Assembly / Contamination Monitoring Package
  4. Expected Changes for V5.2
  5. Utilization of Disturbance Monitoring Package (DMP) Data
  6. Validation and Mission Planning Update
  7. Communications and Public Outreach
  8. Update on ACE: Mission Status and Recent Validation Results
  9. Sustainable Ozone and Aerosol Measurements from a 6U CubeSat: The SAGE IV Pathfinder
  10. The Impacts of the 2019/2020 Australian Mega Fires on the Stratosphere
  11. The 2019 Raikoke Eruption: Can Smoke and Sulfuric Acid Aerosol Be Separated?
  12. Aerosol Discrimination in the Asian Monsoon Region: Is it a Cloud? Depolarizing Aerosol? Non-depolarizing Aerosol?
  13. In Situ Measurements of Aerosol Size Distributions: Comparisons of Estimated Extinction with SAGE III/ISS Measurements
  14. Portable Optical Particle Spectrometer Measurements in Support of SAGE III/ISS Aerosol Retrieval

Day 2:

  1. Diurnal Cycle Modeling and Scale Factors for NO2 and O3
  2. Dynamical Diagnostics for SAGE III/ISS: Progress Report & Dynamical Coordinate Investigations
  3. Comparisons with SAGE III/ISS Ozone Profiles and Umkehr
  4. Trends in Tropical LMS Ozone from SHADOZ  V06 Profiles: Reference for SAGE-Based Satellite Products
  5. Sonde Observations from Boulder & Lauder
  6. Validation of SAGE III/ISS Solar Water Vapor Data with Correlative Satellite and Balloon-Borne Measurements
  7. Near-global Variability of Stratospheric Water Vapor Observed by SAGE III/ISS
  8. Ticosonde: Over 15 Years of Balloon-borne Water Vapor and Ozone Profiling in Costa Rica
  9. Accounting for the Photochemical Variation of NO2 in the SAGE III/ISS Retrieval
  10. Ground-based Diurnal Measurements of NO2 and NO3 in Support of SAGE III/ISS Validation

10/29 – 10/30/2019

Day 1:

  1. Welcome / Mission Update
  2. Mission Operations
  3. Instrument Assembly
  4. Contamination Monitoring Package
  5. Expected Changes for V5.2
  6. Disturbance Monitoring Package
  7. Validation and Mission Planning Update
  8. Communications and Public Engagement
  9. Validation of SAGE III/ISS Solar Ozone Data with Correlative Satellite and Ground-Based Measurements
  10. Validation of SAGE III/ISS Solar Products
  11. Ozone Comparisons with Ground-Based Long-Term Records
  12. Assessment of SAGE III/ISS Water Vapor
  13. Water Vapor and SAGE III/ISS
  14. Validation of SAGE III/ISS Water Vapor in the Tropics and Comparisons with MLS
  15. Update on ACE: Mission Status and Recent Validation Results
  16. Trends and Variability in Stratospheric NO2 from Merged SAGE II and OSIRIS Satellite Observations
  17. Ground-Based Diurnal Measurements of NO2 and NO3 in Support of SAGE III/ISS Validation

Day 2:

  1. SAGE III/ISS and GloSSAC V2.0
  2. Optical Particle Counter Measurements for Comparison with Satellite Measurements of Extinction
  3. The Printed Optical Particle Spectrometer
  4. Validation of SAGE III/ISS Ozone and Aerosol Profiles Using JPL Lidars at Table Mountain Facility, CA and Mauna Loa Observatory, HI
  5. Early Results from a Joint Retrieval of Stratospheric Aerosol from SAGE III/ISS Solar Occultation and OMPS Limb Scattering
  6. The 2019 Raikoke Eruption
  7. A Multi-Instrument View of Upper Atmospheric Aerosol
  8. Backscatter Coefficient Profiles from SAGE
  9. Cloud Top Heights from SAGE III/ISS
  10. Dynamical Diagnostics for SAGE III/ISS: Progress Report and OCTAV-UTLS Connections
  11. Diurnal Cycle Modeling Related to SAGE III/ISS Products
  12. The Diurnal Ozone Climatology: Applications for Satellite Comparisons
  13. SAGE III/ISS Limb Scatter Retrievals
  14. Future Algorithm Development

10/30 – 10/31/2018

Day 1:

  1. Welcome / Mission Overview
  2. Mission Operations
  3. Instrument Assembly
  4. Disturbance Monitoring Package
  5. Contamination Monitoring Package
  6. SAGE III/ISS Product Status Introduction
  7. Product Status Wavelength
  8. Product Status Ozone
  9. Product Status Aerosol Extinction Coefficient
  10. Product Status Water Vapor
  11. Product Status Nitrogen Dioxide
  12. Product Status Lunar Part 1Product Status Lunar Part 2
  13. Science Data Product Algorithm Validation
  14. SAGE III-ACE Comparisons
  15. NDAAC Update
  16. Validation of SAGE III/ISS Solar and Lunar Products Using Backward and Forward Trajectories- Ozone
  17. Ozone Profile Retrievals from OMPS Limb Profiler

Day 2:

  1. Communications and Public Engagement
  2. Validation and Mission Planning
  3. Initial Evaluations of Water Vapor Retrievals from SAGE III/ISS
  4. Assessment of SAGE III/ISS Water Vapor and Ozone
  5. Using SAGE III/ISS Measurements and Numerical Models to Investigate Aerosol, Cloud, and Water Vapor Physical Processes in the Upper Troposphere/Lower Stratosphere Region
  6. Ground-Based Measurements of Diurnal NO2 and NO3 Column Abundances in Support of SAGE III/ISS Validation
  7. Validation of SAGE III/ISS Solar and Lunar Products using Backward and Forward Trajectories- Aerosol
  8. Retrieval of Aerosol Size Distributions from In Situ Particle Counter Measurements
  9. Smoke Transport into the Stratosphere
  10. SAGE III/ISS Limb Scatter Retrievals
  11. Retrieval of Aerosol Extinction Profiles from Limb Scattering Instruments- Experience with OMPS LP
  12. Future Algorithm Development

SAGE III/ISS launched on February 19, 2017! The instrument has completed its prime mission of three years of operation onboard the International Space Station. The mission has been renewed for three additional years of world class science data collection, analysis, and public release.