Extinction-ice water content-effective radius algorithms for CALIPSO

Interrelationships between volume extinction coefficient (sigma), ice water content (IWC), and effective radius (r(e)), each dependent upon the particle size distribution (PSD) and temperature (T), are developed using in-situ microphysical measurements at low and mid-latitudes, remote sensing data, and model results. The ratio [(IWC)/sigma], proportional to r(e), increases with T. Lower values of [IWC/sigma] are observed near cloud top and base than within a cloud layer, although [IWC/sigma] changes more with temperature than relative height within the cloud. For equivalent radar reflectivities (Z(e)) below about -28 dB, the minimum detectable with forthcoming spaceborne cloud radar, [IWC/sigma] is a nearly constant value. IWC increases almost linearly with sigma, with a temperature-dependence noted.