[Source:CloudSat Standard Data Products Handbook, Cooperative Institute for Research in the Atmosphere, Colorado State University]
The Geometrical Profile algorithm reads a CloudSat 1B-CPR granule and the corresponding
MODIS-AUX and ECMWF-AUX granules to produce an estimate of the radar reflectivity factor
for those levels, in the vertical column, ... which contain a significant echo (Stephens et al, 2001).
This product can also be called the Cloud Mask as it provides the first product to provide a field that indicates the presence of a cloud inside a CPR bin.
The presence or absence and vertical location of cloud layers impose powerful constraints on the
radiative properties of an atmospheric column and, thereby, modulate strongly the radiative
heating rate of the column. Comprehensive information on the vertical distribution of cloud layers
have been largely missing from analyses of conventional passive-sensor satellite radiometers that
observe only the emitted and reflected radiance from the atmosphere and surface. Conventional
satellite data have only allowed us to crudely estimate the location and vertical extent of clouds.