The Sensitivity of Microwave Remote Sensing Observations of Precipitation to Ice Particle Size Distributions

Abstract

Abstract This study investigates the effect of variable size distribution and density of precipitation ice particles on microwave brightness temperatures. For this purpose, a set of self-consistent relationships among rain rate, size parameters of an exponential drop size distribution, and the radar reflectivity–rain rate relations for frozen and liquid precipitation was derived. Further, a scaling factor was introduced that is the ratio between the average melted diameter of the frozen and liquid precipitation and allows the specification of different sizes of the frozen particles. For given radar observations, this method allows size distributions of frozen and liquid precipitation to be derived, which are then used as input for a radiative transfer model. These relationships were used to perform Mie calculations for different precipitation rates and different types of hydrometeors (snow, graupel, and hail) and to investigate the dependence of their respective optical properties on rain rate as well as ...