Analysis of Convective Structure from APR-2 Radar and the DAWN Wind Lidar During the 2017 Convective Processes Experiment (CPEX)

During the May-June 2017 Convective Processes Experiment (CPEX), NASA DC-8-based airborne observations were collected from the JPL Ku/Ka-band Airborne Precipitation Radar (APR-2) and the 2-um Doppler Aerosol Wind (DAWN) lidar during approximately 100 flight hours. Frequent dropsonde data accompanied the DAWN observations for validation purposes, and to provide complement wind profiles in and near convection. For CPEX, the APR-2 provided vertical air motion and reflectivity in nearby regions where DAWN is unable to sense. Conversely, DAWN sampled vertical wind profiles in aerosol-rich, no-cloud regions surrounding the convection, but is unable to measure wind field structure within cloud.

In this presentation, these joint data are presented from several of the June 10-11 flight dates, including the APR-2 precipitation structure and Doppler wind fields, and adjacent wind profiles from the DAWN and dropsonde data. A separate study was carried out with the NASA Unified Weather Research and Forecasting (NU-WRF) modeling system to quantify the impact of the DAWN measurements on the analyzed variables when the DAWN observations were assimilated into the model, and how the impact depends on location and times of the instrument sampling. The impact was assessed by comparing the representation of the convective cloud structure after assimilation of the DAWN measurements and the observations of the thermodynamics, and by comparing the model cloud field structure and vertical velocity with the APR-2 observations from the same flight dates. After the assimilation, the subsequent forecast produced precipitation where there was none, and more organized precipitation and a more intense and organized cold pool structure. These particular findings highlight the importance of when and where the wind observations are taken relative to the storm evolution.