Firn cold content evolution at nine sites on the Greenland ice sheet between 1998 and 2017
| Autor: | 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 |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Journal of Glaciology, Vol 66, Pp 591-602 (2020) |
| Druh dokumentu: | article |
| ISSN: | 0022-1430 1727-5652 65112830 |
| DOI: | 10.1017/jog.2020.30 |
| Popis: | 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. |
| Databáze: | Directory of Open Access Journals |
| Externí odkaz: |
|