Future Satellite Observations of Coupled Convection-Aerosol Processes from the NASA Atmosphere Observing System (AOS)

Atmospheric convection plays a fundamental role in the vertical redistribution of atmospheric constituents (including aerosols), in driving atmospheric circulation, and in creating severe weather conditions that put life and property at risk. Cloud and precipitation processes in convection and their related release of latent heat are coupled to the rate of vertical air motion in convective updrafts and downdrafts, while the organization of vertical air motions in convection is intimately linked to the characteristics of the environment, including atmospheric stability, vertical wind shear, and to some extent ambient aerosols. Observations of vertical air motion in convection have generally been confined to suborbital observations of limited areas and periods of time, but understanding the global distribution of convection in relation to its ambient environment is very much needed. The Atmosphere Observing System (AOS), a NASA mission in response to the Aerosols and Clouds, Convection, and Precipitation (CCP) designated observables from the 2017 NASA Earth Science Decadal Survey, will advance understanding of convection globally by providing Doppler radar measurements over a broad spectrum of convective cloud systems in combination with a suite of sensors providing information on aerosol-cloud-precipitation interactions.

AOS plans to obtain measurements in two orbital planes. In a 55° inclined orbit, a Japan Aerospace Exploration Agency (JAXA) Ku-band Doppler radar will provide radar reflectivity and Doppler velocity measurements in moderate to strong convective systems over varying times of day, combined with Centre National d'Études Spatiales (CNES) time-differenced (over ~2-minute intervals) passive microwave brightness temperatures that will characterize the rate of change of ice water path and anvil size as well the vertical flux of ice mass. While still to be determined, the project also seeks to have in this orbit a backscatter lidar for aerosol profiling in the storm environment. The AOS science team will also make use of satellite aerosol information in the program of record such as from the set of geostationary satellites. In a polar orbiting observing system, AOS will provide a cloud-profiling Doppler radar, with the exact approach (W band or large-aperture Ka band) currently under study. This radar information will be complimented by aerosol and cloud information from a backscatter lidar, a multi-angle and multi-wavelength polarimeter, and passive microwave and far infrared imaging radiometers. Aerosol and moisture limb imagers on a separate Canadian Space Agency (CSA) spacecraft will provide information on the vertical transport of aerosols and moisture to the upper troposphere and lower stratosphere.