The NASA Geostationary Coastal and Air Pollution Events (GEO-CAPE) Mission

The GEO-CAPE mission was recommended by the National Research Council's Earth Science Decadal Survey to measure tropospheric trace gases, aerosols, and coastal ocean water quality and biogeochemistry from geostationary Earth orbit (GEO), providing multiple observations per day over a portion of the Western Hemisphere. Similar satellite observations have been made for approximately 20 years from low-earth orbit (LEO), viewing any point on the planet once per day at best. The GEO-CAPE mission will take advantage of this revolutionary advance in temporal frequency for both atmospheric composition and ocean color disciplines. GEO-CAPE Atmosphere and Ocean Science Working Groups have used input drawn from several community workshops to develop science and application objectives representing the research and operational needs of both disciplines.

Multiple observations per day of ozone, ozone precursors, aerosols, carbon monoxide, and other trace gases are required to better understand and monitor the physical, chemical, and dynamical processes that determine tropospheric composition and air quality over spatial scales ranging from urban to continental, and over temporal scales ranging from diurnal to seasonal. These observations are critical for improved air quality forecasts and assessments including the key aspects of emissions inventories, impacts of long-range transport and episodic events, and the interrelation of air quality and climate.

The oceans component of GEO-CAPE focuses on coastal ecosystem dynamics and would provide repeated measurements of water-leaving radiances, which will be used to derive upper ocean chlorophyll, primary productivity, particulate and dissolved organic carbon, particulate inorganic carbon, turbidity, sediment fluxes, land-ocean carbon fluxes, and phytoplankton community structure. Understanding the dynamic processes occurring in the coastal ocean is critical for managing ecosystem services and for addressing problems arising from anthropogenic disturbances such as harmful algal blooms, hypoxia, sediment transport and marine pollution.

These observations are to be achieved from a vantage point near 95 degrees West to view much of North America and its adjacent oceans several times per day. Some viewing of South America may also be possible. Planned LEO missions will continue to make daily global observations that are necessary complements to these observations, providing a means for inter-calibrating and combining GEO-CAPE observations with the similar GEO observations now being developed in Europe and Asia.

A dedicated GEO-CAPE satellite will launch no earlier than 2021 based on current budget profiles. However the mission working groups have recently endorsed a phased implementation concept to reduce mission risk and cost. With this concept, each GEO-CAPE instrument could be flown separately as secondary “hosted” payloads on commercial or government-owned geostationary satellites, potentially allowing GEO-CAPE to join the global constellation of atmospheric chemistry and coastal ocean color sensors planned to be in orbit before 2020. NASA is also making investments in advanced instrumentation technology and in field campaigns that demonstrate the uses of GEO-CAPE data. These activities are already stimulating US interagency efforts to coordinate integrated observing systems for air and water quality by the end of this decade.