Simultaneous Observation of Fine Structure of Layer Clouds at Upper- and Middle-levels by a Laser Radar and a 8.6mm Radar

Abstract

The fine structure of layer clouds at upper and middle-levels was observed by a laser radar and a vertically pointing radar of 8.6mm wavelength. Firstly we examined the possibility of identifying whether cloud-composing particles are water droplets or ice particles by measuring the depolarization ratio using the laser radar. Secondly we studied the growth processes of falling ice particles in middle-level clouds.
A case study was made for layer clouds situated near a warm front and it was revealed that the layer of supercooled water droplets existed at middle-levels and ice particles generated in upper-level cells were falling through this layer. Ice particles in some streaks grew rapidly in the layer of supercooled water droplets. There was a difference in the growth rate of ice particles in the layer and the growth rate was dependent upon the amount of supercooled water droplets. The growth processes of ice particles were discussed.