Microwave emission from alpine snow: Experimental data and electromagnetic models

In this paper, we study the effect of layered snow in alpine regions on microwave emission at Ku and Ka bands, using both experimental data and model simulations. A recent implementation of the multi-layer dense-medium radiative transfer model (DMRT) under the quasi-crystalline approximation (ML-QCA) was used to account for the effects of snow layers on the emission from dry snow covers. Model simulation have been compared with radiometric measurements, collected with ground based instruments during several long-term experiment carried out over three winter seasons between 2007 and 2011 in the Eastern part of Italian Alps. This comparison has the twofold purpose of validating the model and interpreting some particular aspects of snow microwave emission. The measured brightness temperatures at Ku and Ka bands were compared with those simulated through the ML-QCA model, by using the observed snow parameters as inputs. A direct comparison of measured and simulated data showed that the slope of correlation ranged between 0.7 and 1.0, with determination coefficients between 0.51 and 0.75 and Root Mean Square Error (RMSE) between 11 K and 15 K.