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Abstract

The Sierra Nevada mountain range in Spain, at 37°N, hosts the southernmost snow-covered area in Europe. The highly changeable weather conditions significantly affect the energy and mass balance of the snowpack. Up to 30% of the total annual snow ablation is due to the effect of evaposublimation, which is amplified by intense solar radiation and strong dry winds. The analysis of evaposublimation is crucial for predictions on water availability in Andalusia. However, intense snowpack monitoring in this area is not feasible given the challenges in accessing and collecting data on a continuous basis in the terrain. Thus, snow dynamics are simulated with a physically based model at watershed scale. One of the key input parameters is the roughness length (z0), which influences the latent-heat and sensible-heat transfer coefficients, and consequently evaposublimation. For simplicity, previous studies assumed a temporally and spatially constant z0, even though this parameter is known to vary in a range of several magnitudes depending on the state of snow metamorphosis, introducing a large uncertainty in modeled evaposublimation rates. To address this issue, we conduct a sensitivity analysis to evaluate the impact of temporally variable z0 on evaposublimation estimates and compare our results with measurements of evaposublimation rates and z0 at a pilot area in Sierra Nevada. Results show that evaposublimation rates change significantly with z0 at local scale. This analysis constitutes the first step of a distributed analysis at catchment scale where changes in evaposublimation estimates might have important implications for water resource management in the region.