Remote Sensing Microphysical Processes From Space: A Feasibility Study

Abstract:

The theoretical treatment of cloud and precipitation microphysics in models is becoming increasingly sophisticated as computing power increases. As grid resolutions reduce in size to a few kilometers and less, the explicit parameterization of microphysical processes are being found to cause the greatest uncertainty in simulations where clouds and precipitation are predominant. Constraining these processes with remote sensing data is highly desirous in order to improve parameterizations. However, because these processes typically involve two hydrometeor species interacting in a particular volume, remotely sensing their interactions range from challenging to impossible. Using in situ data collected during various field programs we seek to determine what sets of radar measurables at which frequencies and resolutions provide the most information regarding the processes of riming and aggregation in convective and stratiform clouds. We accomplish this by applying standard parameterizations of particle collection microphysics to particle size distributions measured by probes from aircraft flying in situ. From this we calculate radar observables (reflectivity and Doppler velocity) at a number of standard frequencies at varying resolutions. The information content regarding the microphysical processes present within various combinations of radar measurables at variable resolution is then quantified. Our objective is to show 1) whether diagnosis of certain microphysical processes is possible with radar remote sensing and 2) if so, which combinations of measurements at which resolutions are optimal.