Challenges in modeling the energy balance and melt in the percolation zone of the Greenland ice sheet.

F. Covi*, Regine Hock, Carleen Reijmer

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Increased surface melt in the percolation zone of the Greenland ice sheet causes significant changes in the firn structure, directly affecting the amount and timing of meltwater runoff. Here we force an energy-balance model with automatic weather stations data at two sites in the percolation zone of southwest Greenland ( and 2360 m a.s.l.) between spring and fall . Extensive model validation and sensitivity analysis reveal that the skin layer formulation used to compute the surface temperature by closing the energy balance leads to a consistent overestimation of melt by more than a factor of two or three depending on the site. In contrast, model results match the observations well when the model is forced by observed surface temperatures; however, unexplained residuals in the energy balance occur. The sensible and ground heat flux differ markedly in the two simulations accounting largely for the difference in modeled melt amounts. This indicates that the energy available for melt is highly sensitive to small changes in surface temperature. Thus, regional climate models that also use the skin layer formulation may have a bias in surface temperature and melt energy in the percolation zone of the ice sheet.
Original languageEnglish
Pages (from-to)164-178
Number of pages15
JournalJournal of Glaciology
Volume69
Issue number273
Early online date19 Jul 2022
DOIs
Publication statusPublished - 19 Feb 2023

Bibliographical note

Funding Information:
This study was supported by NSF grant no. 397516-66782. Polar Field Services provided logistical support for the field campaigns. The field measurements were assisted by Å. Rennermalm, C. Miege, I. Radivojevic, J. Kingslake, J. Xiao, K. Rogers, M. MacFerrin, P. Smith, S. Leidman and S. Munsell. Special thanks to M. MacFerrin for providing SR50 data from EKT and allowing us to attach instruments to his mast at EKT. We thank scientific editor William Colgan and two reviewers for their valuable reviews.

Publisher Copyright:
Copyright © The Author(s), 2022. Published by Cambridge University Press.

Keywords

  • Energy balance
  • glacier modeling
  • melt-surface
  • polar firn

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