NASA's Aerosol-Cloud-Ecosystems (ACE) Mission: Science Goals and Implementation

The Aerosol-Cloud-Ecosystem (ACE) mission was recommended by US National Research Council (NRC) Decadal Survey in 2007. NASA assembled a team of scientists and engineers, the ACE Science Working Group, who have worked over the past 2 years to further develop the mission concept, provide a detailed scientific rationale, and develop a traceable implementation strategy for this Tier-2 DS mission that directly addresses key climate change issues. The results of their efforts will be reported here. ACE is designed to substantially advance the state of aerosol, cloud and ocean ecology science by providing global data sets of unmatched accuracy and substantially improved information content to enable a major step forward compared to what is presently known, or possible with present capabilities. ACE will be the successor to the A-Train and EarthCare as regards aerosol, cloud and ocean ecology global data products. Driving the approach for ACE is the goal to substantially reduce the uncertainty in climate forcing associated with aerosol-cloud interactions, including precipitation, and to markedly advance knowledge of ocean ecosystem, and its CO2 uptake, though synergistic use of advanced aerosol characterization in the retrieval of ocean ecosystem parameters. To do these things, ACE is designed to take advantage of new and emerging capabilities to dramatically enhance knowledge of the contents of these components, specifically aerosol properties, cloud microphysics, and marine biosphere properties that are not presently available, especially on a global basis.

The present ACE mission implementation concept will be presented and the scientific rationale will be summarized. How these science objectives and measurement requirements translate into nominal instrument requirements will be briefly described. At present, ACE is envisioned to include a multi-angle spectral polarimeter, a multi-wavelength High Spectral Resolution Lidar (HSRL), a dual-frequency cloud radar, and a multi-band spectral radiometer. The polarimeter is primarily focused on aerosol and cloud requirements while the spectral radiometer is mostly focused on ocean ecology measurements. The lidar provides a major step forward for aerosol science and also offers new capabilities for ocean ecology. The dual-wavelength radar is essential to quantifying microphysical profiles, where the effects of aerosol-cloud interaction are most explicit, and which will provide new insights into global cloud processes. The current ACE concept also calls for radiometer measurements in the infrared, microwave and submillimeter spectral regions to quantify cloud properties at sufficient accuracy and to provide a relatively complete picture of the local components of the atmospheric hydrologic cycle, necessary to describe cloud processes and their interactions.