In warm temperate mountain regions where water is often scarce vapor losses from the snow-surface can substantially limit snowmelt. Therefore, understanding the key snow dynamic processes that affect water availability in these mountains is essential. We studied the snowpack energy and mass balance in Mt. Hermon, Israel using a comprehensive field campaign during 2010/11. We analyzed the snowpack energy and mass balance during the winter of 2010/11 in a Deep Snow Patch (DSP), and in the Bulan valley experiment area (BVEA), where both windswept locations and lee-side (deep snowpack) locations were examined. We applied for this analysis an energy and mass balance snow model that was forced by input from two meteorological stations. The calibration of the model for the DSP and BVEA was based on surveyed snow water equivalent data, and melting cycles that were measured with time-lapse cameras, respectively. Using a step function to describe wind speed over the DSP we showed that the turbulent fluxes were influenced by changes in snowpack height. The turbulent fluxes were found as the dominant energy fluxes at the snow-surface. During winter, vapor losses varied between 46% and 82% of the total ablation. Consequently, latent heat flux consumed much of the available energy at the snow-surface, greatly limiting melting rate to 1 mm day(-1). During spring, vapor flux was positive which enhanced condensation, resulting in an average melting flux of 86 mm day(-1). The spatial variation in the vapor flux at the BVEA due to terrain orientation yield variation in space of the available water at the bottom of the snowpack. (C) 2014 Elsevier B.V. All rights reserved.

Snow surface temperature (SST) is a key component in the calculation of snow-surface energy balance. Common snow models have adapted a specific linearized SST equation that accounts for the energy fluxes at the snow-atmosphere interface. An inspection of this widely used equation reveals that the areal units for three of the energy fluxes disregard the effect of sloped terrain and as a result presents a unit inconsistency in the equation. The objectives of this paper are to: (1) introduce a corrected SST equation; (2) discuss the role of the SST in snow models; and (3) assess the impact of this unit inconsistency on the simulation of snow variables in various climatic conditions. Meteorological observations were used to compare results that were obtained by implementation of the original and the corrected SST equations in a point energy and mass balance snow model. The calculated SST values in the original equation tend to be higher than the calculated value in the corrected equation. As a result when the original equation is used the SST-dependent energy fluxes (i.e. sensible heat, latent heat and net long-wave radiation) into the snow are lower, which yield lower melting rates. In conclusion, while the original SST equation might be applicable in snow models for gentle terrain, it introduces substantial biases in steep terrain. Therefore, it is conservatively recommended to consider the implementation of the corrected SST equation for snow model applications in mountainous terrain that are steeper than 15 degrees. (C) 2011 Elsevier B.V. All rights reserved.