Synergistic Opportunities for the Air Quality Satellite Constellation: Status of the CEOS Activity
Al-Saadi, Jay1; Zehner, Claus2; Veihelmann, Ben3; Kim, Jhoon4; Chance, Kelly5; Edwards, David6

This talk will summarize activities of the Committee on Earth Observation Satellites (CEOS) Atmospheric Composition Constellation (ACC) to collaboratively advance the next generation of air quality monitoring from space. CEOS ACC developed a position paper describing the benefits to be derived from such collaboration and recommending steps to achieve the vision. The ACC recommendations were endorsed by CEOS in May 2011 and much progress is now being made toward implementation.

Three countries and space agencies are currently funding geostationary Earth orbit (GEO) missions expected to launch in 2017-2019 to obtain atmospheric composition measurements for characterizing anthropogenic and natural distributions of tropospheric ozone, aerosols, and their precursors. These missions include Europe's ESA Sentinel-4 with EUMETSAT IRS, Korea's ME/MEST/KARI GEMS, and the United States' NASA TEMPO. GEO observations offer a quantum advance in air quality monitoring from space by providing measurements many times per day. However, a single GEO satellite views only a portion of the globe. These satellites, positioned to view Europe, East Asia, and North America, will collectively provide hourly coverage of the industrialized Northern Hemisphere at similar spatial resolutions. Planned low Earth orbit (LEO) missions will provide complementary daily global observations. Observations from a single LEO satellite will overlap those from each GEO satellite once per day, providing a means for combining the GEO observations and a necessary perspective for interpreting global impacts of smaller scale processes. The EUMETSAT Metop series, NOAA/NASA JPSS series, and ESA Sentinel-5 Precursor and Sentinel-5 missions will each provide such daily overlap with the GEO missions.

The development of common data products, data distribution protocols, and calibration strategies will enable critically needed understanding of the interactions between regional and global air quality. Common air quality products from these missions will be tropospheric column O3, NO2, HCHO, SO2, and aerosol nominally at 8 km spatial resolution and 1 hour temporal frequency. Synergetic use of the expected data is being explored through Observation System Simulation Experiments to quantify the value of a GEO constellation for improved knowledge of pollutant emissions and for assessing the impact of long-range transport. Such activities directly address societal benefit areas of the Global Earth Observation System of Systems (GEOSS), including Health, Energy, Climate, Disasters, and Ecosystems, and are responsive to the requirements of each mission to provide advanced user services and societal benefits in their own regions.