Effects of Cloud Parameter on Brightness Temperature Computation in Microwave Band

The CRTM fast radiative transfer model is utilized to simulate channel brightness temperature of NOAA-K/AMSU-A. The research focuses on effects of cloud particles type, height and thickness on simulation of each channel brightness temperature. Results show that when there exists water cloud and rain cloud, the corresponding brightness temperature is larger; when there exists ice cloud, snow cloud, hail cloud or graupel cloud, the change of corresponding brightness temperature isn't very obvious. Effects of cloud on channel brightness temperature depend on the configuration of weighting function peaks and cloud top height. When cloud exists at multiple heights, if topmost cloud is thicker (2 km), brightness temperature value of corresponding channels depends on the highest cloud. When the cloud is relative thin, brightness temperature of channels lower or slightly higher than cloud top changes obviously. For those channels far higher than cloud top, their brightness temperatures are not sensitive to cloud thickness change.