Evaposublimation from the snow in the Mediterranean mountains of Sierra Nevada (Spain)

Abstract. In this study we quantify the evaposublimation and the energy balance of the seasonal snowpack in the Mediterranean semiarid region of Sierra Nevada, Spain (37° N). In these kinds of regions, the incidence of this return of water to the atmosphere is particularly important to the hydrology and water availability. The analysis of the evaposublimation from snow allows us to deduct the losses of water expected in the short and medium term and is critical for the efficient planning of this basic and scarce resource. To achieve this, we performed 10 field campaigns from 2009 to 2015, during which detailed measurements of mass fluxes of a controlled volume of snow were recorded using a modified version of an evaporation pan with lysimeter. Meteorological data at the site of the snow control volume were extensively monitored during the tests. With these data, a point energy balance snowmelt model was validated for the area. This model, fed with the complete meteorological data set available at the Refugio Poqueira Station (2500 m a.s.l.), let us estimate that evaposublimation losses for this site can range from 24 to 33 % of total annual ablation. This ratio is very variable throughout the year and between years, depending on the particular occurrence of snowfall and mild weather events, which is generally quite erratic in this semiarid region. Evaposublimation proceeds at maximum rates of up to 0.49 mm h⁻¹, an order of magnitude less than maximum melt rates. However, evaposublimation occurs during 60 % of the time that snow lies, while snowmelt only takes up 10 % of this time. Hence, both processes remain close in magnitude on the annual scale.