Air-Truth Lidar Polarization Studies of Orographic Clouds

Abstract

The results of a field program of coordinated lidar and aircraft observations of orographically induced clouds are reported. An evaluation of polarization diversity lidar for cloud physics research applications on the basis of the air-truth measurements and earlier findings indicates that the remote sensing technique can monitor some kinds of cloud microphysical information currently measured only through in situ sampling methods. In particular, lidar polarization measurements are indicated from the observations reported here to be sensitive to the composition of mixed phase clouds, including a measure of cloud ice balance, and to permit observations of the ice particle riming process in precipitation formation. Detailed vertical cross sections of hydrometeor content are derived from height versus time displays of lidar returns in combination with the polarization analysis, revealing some interesting features of the structure of complex orographic cloud systems. As a further aid in the evaluation of lidar, the operational restrictions of typical lidars during field operations are also discussed. It is concluded that polarization diversity lidar displays the potential for important applications in cloud physics and modification research programs involving the study of particles in the ice phase.