Surface Winds Analysis in Support of CALIPSO Algorithms

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission has been providing high quality global, vertically-resolved measurements of clouds and aerosolsfor the last 13 years. The upcoming release of the next generation of CALIPSO Lidar Level 2 data products (V4.5) will include additional algorithm enhancements to derive full column optical depths using lidar returns of the ocean surface. To accurately characterize the ocean surface return and reduce uncertainties, a reliable wind speed measurement is required. Current CALIPSO production algorithms rely on the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) for global windspeed measurements. However, in previous wind compression studies (AMSRE to MERRA2) we have observed regional bias in the reported wind speed measurements in the MERRA2 product. With the recent NASA airborne field campaignin the spring of 2019 (AeolusCalVal) that included NASA’s Doppler Aerosol WiNd (DAWN) lidar we have the opportunity to perform comparisons between the DAWN wind speed measurements and those reported in the MERRA-2 data product.

The DAWN instrument was active during five flights (April 17-30, 2019, 46 hours of flight time) over the eastern Pacific Ocean collecting vertical profiles of horizontal wind up to 12km at a 65m vertical bin resolution. This study will focus on the comparisons of co-located measurements of wind velocity retrieved from the MERRA-2 data product and those retrieve from the vertical bins that encompass the surface from the DAWN instrument.

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission has been providing high quality global, vertically-resolved measurements of clouds and aerosolsfor the last 13 years. The upcoming release of the next generation of CALIPSO Lidar Level 2 data products (V4.5) will include additional algorithm enhancements to derive full column optical depths using lidar returns of the ocean surface. To accurately characterize the ocean surface return and reduce uncertainties, a reliable wind speed measurement is required. Current CALIPSO production algorithms rely on the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) for global windspeed measurements. However, in previous wind compression studies (AMSRE to MERRA2) we have observed regional bias in the reported wind speed measurements in the MERRA2 product. With the recent NASA airborne field campaignin the spring of 2019 (AeolusCalVal) that included NASA’s Doppler Aerosol WiNd (DAWN) lidar we have the opportunity to perform comparisons between the DAWN wind speed measurements and those reported in the MERRA-2 data product.

The DAWN instrument was active during five flights (April 17-30, 2019, 46 hours of flight time) over the eastern Pacific Ocean collecting vertical profiles of horizontal wind up to 12km at a 65m vertical bin resolution. This study will focus on the comparisons of co-located measurements of wind velocity retrieved from the MERRA-2 data product and those retrieve from the vertical bins that encompass the surface from the DAWN instrument.