Submm-Wave Remote Sensing of Ice Clouds: A Climate Application

Clouds remain as a major source of uncertainty in climate models. Ice clouds, in particular, are poorly constrained and have been used as a tuning parameter in the models to balance radiation budget at the top of atmosphere and precipitation at the surface. Lack of accurate cloud ice and its microphysical property measurements has led to large uncertainty about global clouds and their processes within the atmosphere. Radiometric and polarimetric measurements from the submm-wave bands have been used to provide the needed sensitivity over a large dynamic range of cloud ice and its microphysical properties (i.e., particle size and shape). In this paper we will give a brief overview of the submm-wave remote sensing of ice clouds from spaceborne and airborne platforms. Cloud observations from Aura/MLS (Microwave Limb Sounder) and the recent polarimetric measurements from ER-2/CoSSIR (Compact Scanning Submillimeter-wave Imaging Radiometer) will be presented. In addition, the NASA/ESTO-funded SWIRP (Submm-Wave and LWIR Polarimeter) instrument development and a new Earth Venture Instrument-6 (EVI-6) PolSIR (Polarized Submillimeter Ice-cloud Radiometer) will also be discussed.