Linear relation between convective cloud base height and updrafts and application to satellite retrievals

摘要

Measurements done by the Department of Energy/Atmospheric Radiation Measurement program, at the Southern Great Plains, the central Amazon, and on board an oceangoing ship between Honolulu and Los Angeles, show that updraft speeds measured by Doppler lidar and 95GHz cloud radar are tightly linearly correlated with cloud base height (H-b). Based on these relationships, a method of satellite retrieval of maximum (W-max) and cloud base (W-b) updraft speeds in cloud topped planetary boundary layer is proposed. H-b, as an input for updraft estimation, is obtained from satellite-retrieved cloud base temperature in combination with 2m air temperature derived from European Centre for Medium-Range Weather Forecasts reanalysis. Validation by the lidar and radar measurements shows good agreements for the satellite retrieval of W-max with RMSE (root-mean-square error)=0.38m/s and MAPE (mean absolute percentage error)=19% and W-b with RMSE=0.34m/s and MAPE=21%.