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 5.2 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 data products as described in the associated Data Product User’s Guide DPUG. The nominal monthly release of new SAGE III/ISS events will be processed by the V5.2 algorithm starting with March 2021. Version 5.1 remains publicly available for events from June 2017 through February 2021.  This statement applies to SAGE III/ISS Version 5.2 Solar Level 1B, Solar Level 2, and Lunar Level 2 data products.  The SAGE III/ISS Team recommends using Version 5.2 instead of Version 5.1 because of the modifications and improvements mentioned below.

Version 5.2 improvements and bug fixes recovered 311 more solar events (increase of 1.0%) compared to v5.1; 104 more lunar events (increase of 4.3%) compared to v5.1; improvements and the number of water vapor profiles withheld by QA was reduced from 570 (v5.1) to 30 (v5.2).

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

  1. Michael Cisewski, Joseph Zawodny, Joseph Gasbarre, Richard Eckman, Nandkishore Topiwala, Otilia Rodriguez-Alvarez, Dianne Cheek, Steve Hall, “The Stratospheric Aerosol and Gas Experiment (SAGE III) on the International Space Station (ISS) Mission”, Proc. SPIE 9241, Sensors, Systems, and Next-Generation Satellites XVIII, 924107 (11 November 2014); doi: 10.1117/12.2073131
  2. Bourassa, A. E., Rieger, L. A., Zawada, D. J., Khaykin, S., Thomason, L. W., & Degenstein, D. A. ( 2019). Satellite limb observations of unprecedented forest fire aerosol in the stratosphere. Journal of Geophysical Research: Atmospheres, 124, 9510– 9519.
  3. Chen, Z., Bhartia, P. K., Loughman, R., Colarco, P., and DeLand, M.: Improvement of stratospheric aerosol extinction retrieval from OMPS/LP using a new aerosol model, Atmos. Meas. Tech., 11, 6495–6509,, 2018.
  4. Chen, Z., Bhartia, P. K., Torres, O., Jaross, G., Loughman, R., DeLand, M., Colarco, P., Damadeo, R., and Taha, G.: Evaluation of OMPS/LP Stratospheric Aerosol Extinction Product Using SAGE III/ISS Observations, Atmos. Meas. Tech. Discuss.,, in review, 2019.
  5. Kloss, C., Berthet, G., Sellitto, P., Ploeger, F., Bucci, S., Khaykin, S., Jégou, F., Taha, G., Thomason, L. W., Barret, B., Le Flochmoen, E., von Hobe, M., Bossolasco, A., Bègue, N., and Legras, B.: Transport of the 2017 Canadian wildfire plume to the tropics via the Asian monsoon circulation, Atmos. Chem. Phys., 19, 13547–13567,, 2019.
  6. McCormick, M. P., Lei, L., and Hill, M. T.: Early results and Validation of SAGE III-ISS Ozone Profile Measurements from Onboard the International Space Station, Atmos. Meas. Tech. Discuss.,, in review, 2019.
  7. Rieger, L. A., Zawada, D., J, Bourassa, A. E., & Degenstein, D. A.(2019). A multiwavelength retrieval approach for improved OSIRIS aerosol extinction retrievals, JGR: Atmospheres,124, 7286–7307.

SAGE III/ISS Science Team:

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
Jun Wang / University of Iowa, Iowa City

Science Team Meeting Presentations

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 Part 1Initial Evaluations of Water Vapor Retrievals from SAGE III/ISS Part 2
  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.