Remote sensing of cloud sides of deep convective clouds

Abstract

The formation of droplets starting from cloud condensation nuclei through the liquid phase mechanisms to the formation of ice crystals is reflected in the vertical profile of cloud properties. Insights into these microphysics are crucial to understand the onset of precipitation or any aerosol effect. In-situ measurements are limited in their temporal and spatial extent and applied mainly to shallow types of clouds. Satellite measurements from passive sensors are concentrating on cloud tops while vertical profiles of precipitation size drops are retrieved from radar measurements by CloudSat. These data still leave a gap, especially in our understanding of the development of deep convection where in-situ data is sparse and remote measurements difficult to interpret. The CLAIM-3D (cloud aerosol interaction mission in 3-D) passive cloud side viewing sensor concept is planned to become a new means of measuring the vertical profile of cloud microphysical properties. We present results that confirm the capabilities of this concept with respect to deep convection including liquid, ice and mixed phase cloud regions. 3D cloud microphysical information from the Goddard Cumulus Ensemble model is used as input into a 3D Monte Carlo radiative transfer model. Sensor observations in four notional channels in the visible, near-infrared, and infrared spectral region are simulated. It is demonstrated that this data set of simulated radiances and given cloud microphysics presents the basis for a Bayesian retrieval algorithm to derive a profile of cloud phase and effective particle size.