Monitoring of melting refreezing cycles of snow with microwave radiometers: The Microwave Alpine Snow Melting Experiment (MASMEx 2002-2003)

A study of the melting cycle of snow was carried out by using ground-based microwave radiometers, which operated con- tinuously 24 h/day from late March to mid-May in 2002 and from mid-February to early May in 2003. The experiment took place on the eastern Italian Alps and included micrometeorological and conventional snow measurements as well. The measurements con- firmed the high sensitivity of microwave emission at 19 and 37 GHz to the melting-refreezing cycles of snow. Moreover, micrometeoro- logical data made it possible to simulate snow density, tempera- ture, and liquid water content through a hydrological snowpack model and provided additional insight into these processes. Simu- lations obtained with a two-layer electromagnetic model based on the strong fluctuation theory and driven by the output of the hy- drological snowpack model were consistent with experimental data and allowed interpretation of both variation in microwave emission during the melting and refreezing phases and in discerning the con- tributions of the upper and lower layers of snow as well as of the underlying ground surface.