Abstract
The Mie theory is used to determine the absorption and scattering properties of liquid hydrometeors at 27 microwave frequencies from 500 MHz (60-cm wavelength) to 60 GHz (5-mm wavelength). Based on the Marshall-Palmer distribution of drop sizes, regression equations are developed for the volume absorption coefficient of rain as a function of its temperature and content of liquid water. Measurements of the dielectric constant of water and aqueous sodium chloride by Lane and Saxton are used to form regression equations for the dielectric constant of water as a function of its temperature and salinity. These equations and the Fresnel equations for reflection are used to compute the polarized components of the thermal emission of sea water for a wide range of sea temperatures, sea salinities, microwave frequencies, and angles of viewing. From the derived regression equations for the volume absorption coefficient of rain and known expressions for that of clouds, molecular oxygen, and water vapor, the direct problem of radiative transfer is solved for 582 plane-parallel, horizontally-homogeneous, model atmospheres. The thin atmosphere approximation, in which effects of multiple scattering are ignored for both extinction and emission, is used in these calculations. The resulting fields of emission and the transmissivities are analyzed in terms of their predictability by the integrated contents of water in gaseous form, in cloud form, and in rain form. With the use of these predictors, the emission and transmissivity of the atmosphere are predictable by a set of third-degree regression equations where the multiple correlation coefficients are greater than 0.995 and the standard errors of estimate are less than 9.7%. ...
Paris, Jack Frederick (1971). Transfer of thermal microwaves in the atmosphere. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -172589.