Coherent Doppler Wind Lidar Data Processing Software and Wind Retrieval from the Aeolus Cal/Val Field Campaign

Observations of three-dimensional atmospheric winds are highly desired for studies of transport of pollutants, carbon, aerosol and water vapor, cloud dynamics and convection, and large-scale circulation. The atmospheric wind measurement is recommended an Explorer Priority in the 2017-2027 decadal survey for Earth science and applications from space by the National Academies of Sciences, Engineering and Medicine. An airborne Doppler aerosol wind (DAWN) lidar system using coherent detection has been developed at the NASA Langley Research Center (LaRC) to provide vertical profiles of horizontal wind in the planetary boundary layer and troposphere (Kavaya et al., 2014) and flown for several field campaigns in the past decade. The DAWN team at LaRC has been developing wind processing software for the airborne DAWN measurement and toward future space mission. In this presentation we describe the LaRC wind retrieval algorithm and its application to the DAWN data acquired during the Aeolus Cal/Val field campaign in April 2019. Aeolus is a European Space Agency's satellite wind lidar mission launched in August 22, 2018. Five Aeolus underflights with DAWN were conducted during this field campaign. The theoretical foundation of the algorithm is based on earlier works in the coherent lidar community and the algorithm has been advanced to utilize matrix/vector calculation which can facilitate complex coordinate transformation from aircraft's to earth's to obtain the laser pointing information necessary in the wind retrieval. It can also provide flexibility to include additional optical parts such as an optical refractive wedge scanner that can alter laser beam pointing and make correction for imperfect alignment of lidar system relative to the airplane's frame. Comparisons of the DAWN wind profiles retrieved using the LaRC software with 64 dropsonde measurements from the Aeolus Cal/Val field campaign show a good agreement. Reasonably good agreement is also seen in the DAWN wind profiles and the preliminary Aeolus Level 2B wind profiles from the data acquired when Aeolus was overhead.

Reference:

Kavaya et al., "The Doppler Aerosol Wind (DAWN) Airborne, Wind-Profiling Coherent-Detection Lidar System: Overview and Preliminary Flight Results", J. Atmos. Oceanic Technol., 31, 826-842, 2014.