Modeling microwave emission spectra of layered snowpacks

A thermal microwave emission model of layered snowpacks (MEMLS) (Wiesmann and Matzler, 1997) was developed for the frequency range, 5 to 100 GHz. It is based on radiative transfer, using six-flux theory to describe multiple volume scattering and absorption, including radiation trapping due to internal reflection and a combination of coherent and incoherent superpositions of reflections between layer interfaces. The scattering coefficient was determined empirically from measured snow samples, whereas the absorption coefficient, the effective permittivity, refraction and reflection at layer interfaces were based on physical models and on measured ice dielectric properties. The number of layers is only limited by computer time and memory. A limitation of the empirical fits and thus of MEMLS is in the range of observed frequencies and correlation lengths (a measure of grain size). First model validation for dry winter snow was successful. MEMLS has been coded in MATLAB. It forms part of a combined land-surface-atmosphere microwave radiation model for radiometry from satellites