Abstract
AbstractPeruvian glaciers are important contributors to dry season runoff for agriculture and hydropower, but they are at risk of disappearing due to climate change. We applied a physically based, energy balance melt model at five on‐glacier sites within the Peruvian Cordilleras Blanca and Vilcanota. Net shortwave radiation dominates the energy balance, and despite this flux being higher in the dry season, melt rates are lower due to losses from net longwave radiation and the latent heat flux. The sensible heat flux is a relatively small contributor to melt energy. At three of the sites the wet season snowpack was discontinuous, forming and melting within a daily to weekly timescale, and resulting in highly variable melt rates closely related to precipitation dynamics. Cold air temperatures due to a strong La Niña year at Shallap Glacier (Cordillera Blanca) resulted in a continuous wet season snowpack, significantly reducing wet season ablation. Sublimation was most important at the highest site in the accumulation zone of the Quelccaya Ice Cap (Cordillera Vilcanota), accounting for 81% of ablation, compared to 2%–4% for the other sites. Air temperature and precipitation inputs were perturbed to investigate the climate sensitivity of the five glaciers. At the lower sites warmer air temperatures resulted in a switch from snowfall to rain, so that ablation was increased via the decrease in albedo and increase in net shortwave radiation. At the top of Quelccaya Ice Cap warming caused melting to replace sublimation so that ablation increased nonlinearly with air temperature.
Highlights
This document includes supplementary information on the Weather Research and Forecasting (WRF) climate model methodology, the derivation of snowlines, details of the meteorological stations, the meteorological data cleaning and filling steps and full details of the Tethys-Chloris model used, including the Monte-Carlo uncertainty assessment
This document includes supplementary information on the WRF climate model methodology, the derivation of snowlines, details of the meteorological stations, the meteorological data cleaning and filling steps and full details of the Tethys-Chloris model used, including the Monte-Carlo uncertainty assessment. It includes extended results, including the validation of the model and supplementary figures to support the results. It includes a table supporting the discussion of Peruvian glaciers in a South American context
The magnitude of the raw WRF data is approximately double that of the observations, and the percentage bias is very variable in the dry season
Summary
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