Radar and radiation properties of ice clouds

The authors derive relations of the equivalent radar reflectivity, Z_e and extinction coefficient α of ice clouds and confirm the theory by in situ aircraft observations. Equivalent radar reflectivity, Z_e is a function of ice water content W and a moment of the size distribution such as the median volume diameter D₀. Stratification of the data by D₀ provides a set of W-Z_e relations from which one may deduce the dependence of particle density on size. This relation is close to that of Brown and Francis and provides confidence in the methodology of estimating particle size and mass. The authors find that with the exception of temperatures less than -40°C, temperature cannot be used to reliably parameterize the particle size as has been previously suggested. A sizable fraction of radiatively significant clouds would be missed at a radar threshold of -30 dBZ, the value proposed for a spaceborne cloud-profiling radar. -from Authors