NASA’s ASDC has released a collection from Stratospheric Aerosol and Gas Experiment I (SAGE I) that takes measurements of aerosol extinction, ozone and nitrogen dioxide concentration profiles from February 21st, 1979 to November 18th, 1981.
On February 18, 1979, NASA deployed the Stratospheric Aerosol and Gas Experiment I (SAGE I) instrument into space on the Applications Explorer Mission-B (AEM-B) satellite. SAGE I featured four spectral channels operating at wavelengths of 385, 450, 600, and 1000 nanometers, enabling near-global profiling of aerosol extinction as well as ozone and nitrogen dioxide concentrations. To maximize latitudinal coverage for solar occultation observations, NASA positioned the AEM-B satellite in orbit at roughly 600 kilometers altitude with a 56-degree inclination, allowing measurements spanning from 79 degrees South to 79 degrees North latitude. Data collection by SAGE I continued for nearly three years until a power subsystem failure ended the AEM-B satellite's operations.
Operating as a sun photometer, the SAGE I instrument measured how Earth's atmosphere attenuated solar radiation as it passed through Earth's atmosphere during orbital sunrise and sunset events across its four spectral bands. The SAGE I team integrated these solar radiance measurements with spacecraft positioning data and meteorological information from NOAA, then processed them through numerical inversion techniques to generate vertical profiles of aerosol extinction at 450 and 1000 nanometers, along with vertical profiles of ozone and nitrogen dioxide concentrations.
The team validated SAGE I data through comparison with various independent measurement sources: the team verified aerosol data against lidar and dustsonde in situ observations, validated ozone profiles using balloon-based ECC ozonesonde and rocket measurements, and assessed nitrogen dioxide results against climatological data.
Technical Details
- Temporal coverage: 1979-02-21 – 1981-11-18
- Spatial coverage/resolution: -80 South, 80 North, -180 West, 180 East
- File format: ZIP (includes IDL reader)/Binary
- Processing level: 2
- Version: 1
Users can access this data through:
- NASA Earthdata Search
- ASDC Direct Data Download
For questions about this data release or assistance with data access, please contact the ASDC User Services team or visit the Earthdata Forum.