New Retrieval Techniques Using the NASA CATS Lidar and GEOS AGCM: Applications for Extinction and PM2.5

From February 2015 – October 2017, the NASA Cloud-Aerosol Transport System (CATS) backscatter lidar operated on the International Space Station (ISS) as a technology demonstration for future Earth Science Missions, providing vertical measurements of cloud and aerosols properties. Owing to its location on the ISS, CATS was able to acquire, process, and disseminate near-real time (NRT) data within 6 hours of observation time. This capability served as motivation to develop a new 1-D ensemble-based (1-D EnsVar) retrieval technique that incorporates vertical profiles of total attenuated backscatter to produce vertically resolved estimates of speciated aerosol extinction, concentration and surface PM2.5, among other parameters. Ensemble perturbations and prior information are derived from NASA Goddard Earth Observing System (GEOS) atmospheric general circulation model and assimilation system which currently assimilates AOT from a number of passive sensors. The applications of this methodology are multiple, providing a path forward to inform air quality forecasting models, improve estimates of surface PM2.5 concentrations from passive sensors, and develop lidar data assimilation techniques for use by future spaceborne lidars. Here, we present results and an evaluation of our 1-D EnsVar retrieval approach using independent observations from both space and ground-based platforms.