Remote Sensing of Cloud Side of Deep Convective Clouds

Abstract

Insights into the microphysics of clouds, the formation of droplets, and their vertical profile are crucial to understand the onset of precipitation or aerosol effects. 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 initially ground-based or from airborne perspective and eventually from a satellite platform. We present some result that confirm the capabilities of this concept with respect to deep convection including liquid, ice and mixed phase cloud regions. Cloud microphysical information from a 3D cloud resolving model, the Goddard Cumulus Ensemble model, is used as input into a 3D Monte Carlo radiative transfer model, the MYSTIC code, which then simulates sensor observations in three notional channels in the visible, near-infrared, and infrared spectral region. A Bayesian retrieval algorithm is used to derive a profile of cloud phase and effective particle size accounting for uncertainty due to 3D radiative effects and the variability of the cloud particle population. Results of the retrieval are then compared to the cloud model “reality”.