Remote sensing of Clouds
Estimation of Storms Cloud Parameters from AMSU-B radiances

Georg Heygster, Gang Hong

Clouds play a major role in our climate by a effcting the earth's heat, moisture, and radiation balance. Clouds that are associated with storms and can reach or penetrate into the tropical tropopause layer (TTL, about 14-18 km), contribute to the exchange of air between the troposphere and the stratosphere, and hereby influence the physical and chemical processes occurring in the TTL and the stratosphere. However, in climate models clouds still remain a biggest source of uncertainty. Since the launch of the Special Sensor Microwave Temperature 2 (SSM/T2) onboard the Defense Meteorological Satellite Program (DMSP), the Advance Microwave Sounding Unit (AMSU)-B onboard NOAA-15, 16, and 17, and the AMSU/HSB (Humidity Sounder for Brazil) on board Aqua satellite, the radiometric signatures of clouds at frequencies of 90-190GHz are explored extensively. These frequencies are more sensitive to scattering by frozen hydrometeors. Consequently, the effects of clouds and precipitation provide possibilities to estimate cloud parameters. The goal of this work is to understand the effects of storms on microwave brightness temperatures (mainly in the frequency range of 90-190GHz) and to explore the retrieval of cloud parameters from them.

1. The canting angle of tilted  convective systems  (from aircraft  sensors mesuring at AMSU-B frequencies):For details see publication 5 and 2.
   

2. The global distribution of tropical deep convective cloud fractions, see publications 1 and 2

3. The method is explained in publications 4 and 2
   

4. The sensitivity of the observed brightness temperatures to various cloud physical parameters, e.g. cloud ice and snow, see publications 3 and 2:

1. Gang Hong, Georg Heygster, and Klaus Kunzi 2005: Intercomparison of deep convective cloud fractions from passive infrared and microwave radiance measurements,  IEEE Geoscience and Remote Sensing Letters in press (4MB).
   
2. Gang Hong 2004: Effects of storms on microwave brightness temperatures and its application to estimate cloud parameters from AMSU-B, Ph.D. Thesis, August, 2004.
3. Gang Hong, Georg Heygster, Jungang Miao, and Klaus Kunzi: Sensitivity of microwave brightness temperatures to hydrometeors in tropical deep convective cloud system at 89-190 GHz, submitted to Radio Science in July 2004.
4. Gang Hong, Georg Heygster, Jungang Miao, and Klaus Kunzi: Detection of tropical deep convective clouds from AMSU-B water vapor channels measurements, submitted to Journal of Geophysical Research - Atmospheres in April 2004 (3MB).
5. Gang Hong, Georg Heygster, Jungang Miao, and Klaus Kunzi 2005: Potential to estimate the canting angle of tilted structure in clouds from microwave radiances around 183 GHz, IEEE Geoscience and Remote Sensing Letters in press (3MB).