The representation of Föhn events to the east of the Antarctic Peninsula in simulations by the Antarctic Mesoscale Prediction System (AMPS)

Kirchgaessner, Amelie ORCID: https://orcid.org/0000-0001-7483-3652; King, John ORCID: https://orcid.org/0000-0003-3315-7568; Gadian, Alan. 2020 The representation of Föhn events to the east of the Antarctic Peninsula in simulations by the Antarctic Mesoscale Prediction System (AMPS). Journal of Geophysical Research: Atmospheres, 124 (24). 13663-13679. https://doi.org/10.1029/2019JD030637

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Text (Open Access) © 2019. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Kirchgaessner_et_al-2019-Journal_of_Geophysical_Research__Atmospheres.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (20MB) | Preview

Abstract/Summary

Föhn winds are warm, strong, downslope winds on the lee side of mountains, which can last from several hours to a few days. 1995 and 2002 saw the dramatic break‐up of huge parts of the Larsen Ice Shelf (LIS) on the east of the Antarctic Peninsula (AP). It is widely accepted that hydrofracturing, the widening of crevasses due to the excess hydrostatic pressure exerted by meltwater which accumulates inside them, is the mechanism behind the break‐up of the Larsen A and Larsen B ice shelves. On the LIS, in the lee of the mountain range that runs along the spine of the AP, Föhn winds are thought to provide the atmospheric conditions for significant warming over the ice shelf, leading to the initial firn densification, and subsequently providing the melt water for hydrofracturing. Measurements provide evidence that in some cases Föhn events reach an Automatic Weather Station (AWS) on the LIS at over 100 km distance. In this paper, we examine the representation of Föhn events during 2011 as they were observed in measurements by an AWS, and in simulations with the Weather Research and Forecasting Model (WRF) as run for the Antarctic Mesoscale Prediction System (AMPS). We find that, while the model generally simulates meteorological parameters very well, and shows good skill in capturing the occurrence, frequency and duration of Föhn events, it underestimates the temperature increase and humidity decrease during the Föhn significantly, and may thus underestimate the contribution of Föhn to driving surface melt on LIS.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2019JD030637
ISSN:	2169-897X
Additional Keywords:	Föhn, Antarctic, AMPS, AWS
Date made live:	09 Dec 2019 10:47 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/522350

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