| P. Minnis Atmospheric Sciences Division NASA Langley Research Center Hampton, VA 23681 804-864-5671 p.minnis@larc.nasa.gov |
D.F. Young Lockheed Engineering and Sciences Company Hampton, VA 23666 804-766-9673 |
| J.P. Taylor Meteorological Research Flight DRA Farnborough Hampshire, United Kingdom, GU14 6TD 44-252-24461 |
H. Gerber Gerber Scientific, Inc. Reston, VA 22090 703-742-9844 |
Cloud microphysics play an important role in the atmospheric energy balance.
Variations in effective, droplet size in a cloud alter the radiative flux
exchange with the atmosphere and space. They also affect precipitation
processes. Satellite-based techniques are needed to derive the global
distribution of effective, droplet size for liquid water clouds. Various
measurements taken during the Atlantic Stratocumulus Transition Experiment
(ASTEX) in June 1992 are compared to aid the development of satellite
retrievals of effective cloud droplet radius. Visible wavelength radiances
from Meteosat are combined with satellite microwave radiometer observations of
cloud liquid water path to derive mean droplet sizes. A multispectral infrared
technique using Advanced Very High Resolution Radiometer data is also used to
derive the same parameter. In situ measurements from the U.K.-C130 and
University of Washington C-131 provide a ground truth set. All data were taken
over or in marine boundary layer clouds. The intercomparisons of the different
datasets may lead to better under-standing of both effective droplet sizes and
cloud liquid water.