Deep Orographic Cloud Structure and Composition Derived from Comprehensive Remote Sensing Measurements

TLDR: Coordinated polarization lidar, Ku-band radar and dual-channel microwave radiometer observations of a deep orographic cloud system were collected from a mountain base site in northwestern Colorado as part of the Colorado Orographic Seeding Experiment (COSE) research effort.

Abstract: Coordinated polarization lidar, Ku-band radar and dual-channel microwave radiometer observations of a deep orographic cloud system were collected from a mountain-base site in northwestern Colorado as part of the Colorado Orographic Seeding Experiment (COSE) research effort. The remote sensing observations are presented for three distinct storm stages, corresponding to a pre-frontal altostratus cloud layer, a local orographically-induced cloud development, and a peak in storm activity accompanying the passage of a weak cold front. Supercooled liquid water in the form of thin but often dense liquid layers, and expansive, more weakly mixed-phase cloud regions were usually present even to temperatures approaching −40°C. The liquid water amounts present were often below the detection threshold of the vertically-pointing radiometer measurements, but during one brief interval a liquid water content as high as 0.5 g m−3 may have occurred. The lidar depolarization data also show the presence of a persiste...