The energy and mass balance of Peruvian glaciers

Catriona Fyffe*, Emily Potter, Stefan Fugger, Andrew Orr, Simone Fatichi, Edwin Loarte, Katy Medina, Robert A. Hellstrom, Maud Bernat, Caroline Aubry-Wake, Wolfgang Gurgiser, L. Baker Perry, Wilson Suarez, Duncan J. Quincey, Francesca Pellicciotti

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Peruvian 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 non-linearly with air temperature.
Original languageEnglish
Article numbere2021JD034911
Number of pages22
JournalJournal of Geophysical Research: Atmospheres
Volume126
Issue number23
Early online date2 Dec 2021
DOIs
Publication statusE-pub ahead of print - 2 Dec 2021

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