A spectral model for turbulence and microphysics dynamics in an ice cloud

Abstract. A one-dimensional, nine-mode spectral model for temperature, velocity, and the mixing ratios of suspended and precipitating ice-particle components is shown to be consistent with ice-cloud observations. The observations include Doppler radar time-series measurements of a single winter ice cloud and direct measurements of mean particle size vs. icewater content for a set of ice clouds. Fitting of the model to the Doppler vertical-velocity measurements allows a prediction to be made of the vertical scale and turbulent Prandtl number active in the ice-cloud vertical motions. The model is then used to explore the question of how turbulence and gravity-wave motions affect the microphysical properties of an ice cloud. The model predicts interesting dynamical effects on the mixing ratios due to these motions, but no significant effects on the time-averaged microphysical quantities.