CloudSat Product Stats - Algorithm Developer Edition
27 Jan 2015 East Coast Blizzard
The CloudSat Snow Profile product (2C-SNOW-PROFILE) provides estimates of vertical profiles of snowfall rate along with snow size distribution parameters and snow water content for radar reflectivity profiles observed by the CloudSat Cloud Profiling Radar (CPR) which, based on an evaluation of the profile and ancillary data, appear to coincide with snow at the surface. For these profiles, the product also estimates snowfall rate at the surface. Because of ground clutter, the CPR cannot reliably measure reflectivities near the surface. To overcome this limitation, the product algorithm estimates snow properties using a truncated reflectivity profile, terminated somewhat above the surface, then uses the estimated snow properties in the bottom-most portion of the profile to estimate the surface snowfall rate. For the truncated reflectivity profile, profiles of size distribution parameters are retrieved using an optimal estimation algorithm which incorporates a priori information about snow microphysical properties, radar scattering properties, and size distribution parameters. Retrievals are performed only for profiles which appear likely to contain snow at the surface, either dry snow or snow with a small melted mass fraction. The retrieved size distribution parameter profiles and the a priori information are then used to calculate profiles of snowfall rates and snow water contents. The optimal estimation method produces uncertainty estimates for the retrieved size distribution parameters, and these uncertainties are then used to estimate uncertainties for the snowfall rates and snow water contents.

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