Firn cold content evolution at nine sites on the Greenland ice sheet between 1998 and 2017

B. Vandecrux, R.S. Fausto, D. van As, W. Colgan, P.L. Langen, K. Haubner, T. Ingeman-Nielsen, A. Heilig, C.M. Stevens, M. MacFerrin, M. Niwano, K. Steffen, J.E. Box

Publikation: Bidrag til tidsskriftArtikelForskningpeer review

11 Citationer (Scopus)

Abstrakt

Current sea-level rise partly stems from increased surface melting and meltwater runoff from the Greenland ice sheet. Multi-year snow, also known as firn, covers about 80% of the ice sheet and retains part of the surface meltwater. Since the firn cold content integrates its physical and thermal characteristics, it is a valuable tool for determining the meltwater-retention potential of firn. We use gap-filled climatological data from nine automatic weather stations in the ice-sheet accumulation area to drive a surface-energy-budget and firn model, validated against firn density and temperature observations, over the 1998-2017 period. Our results show a stable top 20 m firn cold content (CC20) at most sites. Only at the lower-elevation Dye-2 site did CC20 decrease, by 24% in 2012, before recovering to its original value by 2017. Heat conduction towards the surface is the main process feeding CC20 at all nine sites, while CC20 reduction occurs through low-cold-content fresh-snow addition at the surface during snowfall and latent-heat release when meltwater refreezes. Our simulations suggest that firn densification, while reducing pore space for meltwater retention, increases the firn cold content, enhances near-surface meltwater refreezing and potentially sets favourable conditions for ice-slab formation.

OriginalsprogEngelsk
Sider (fra-til)591-602
Antal sider12
TidsskriftJournal of Glaciology
Vol/bind66
Udgave nummer258
DOI
StatusUdgivet - aug. 2020

Programområde

  • Programområde 5: Natur og klima

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