Light-Absorbing Particles and their contribution to the snow melt in the Central Andes

Abstract

This research aims to comprehensively assess the effects of Light Absorbing Particles (LAPs) on the optical properties of snow surfaces and the impacts on snow hydrology, focusing on the Central Andes. Initially, an experimental study was conducted in Sierra Nevada, Spain, to analyze the optical effects of different LAPs, like sand, ash, haze, and soot on snow covers. Findings revealed a reduction in snow albedo across the entire spectrum, with soot agglomerates showing the highest potential to reduce snow albedo. Then, investigations centered on the Central Andes near the El Yeso dam, where snow was artificially contaminated using preconditioned soil samples to simulate mineral dust (MD) deposition. Contaminated surface albedo shows reductions significant in the UV and visible range, and simulated values, from the OptiPar radiative transfer model, mostly agree with field measurements regarding some discrepancies, attributed primarily to variation in MD mineralogical composition. Finally, the Utha Energy Balance snow model was coupled with the OptiPar radiative transfer model, considering particles previously characterized, to simulate snowpack accumulation and melting from 2014-2019 at Portillo weather station located in the Juncal River Basin, Chile. Black carbon (BC) and MD were found to accelerate the snowpack depletion, inducing an early meltout of up to 3 days. BC had the most significant impact on the snowpack, due to its higher absorption capacity. This extensive research shows that LAPs play a significant role in snow albedo variations and consequently in the snowpack duration, impacts that are crucial for hydrology in regions like the Central Andes.