The Meteorological Parameterization of Specific Attenuation in Rain Viewed at Nadir

Abstract

Polynomial expressions are presented for the parameterization of the specific attenuation in rain from 9 to 38 GHz that are applicable to a wide range of naturally occurring drop size distributions and for viewing angles close to nadir. Because the temperature T affects the specific attenuation at some frequencies, expressions for the polynomial coefficients as functions of T are also provided for ?10;deg;≤T≤30°C. The advantage of this parameterization is that even without a detailed specification of the drop size distribution, useful estimates of the specific attenuation are often possible given only two out of three parameters, namely, the rainfall rate R, the rainwater content W, or Dm (the mass-weighted mean drop diameter), particularly if the temperature is also specified.