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Causes of the Antarctic region record high temperature at Signy Island, 30 January 1982

King, John C.; Bannister, Daniel ORCID: https://orcid.org/0000-0002-2982-3751; Hosking, J. Scott ORCID: https://orcid.org/0000-0002-3646-3504; Colwell, Steve R.. 2017 Causes of the Antarctic region record high temperature at Signy Island, 30 January 1982. Atmospheric Science Letters, 18 (12). 491-496. https://doi.org/10.1002/asl.793

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Abstract/Summary

On 30th January 1982, the research station on Signy Island (South Orkney Islands) reported a daily maximum temperature of 19.8 °C. This is a record maximum for any station south of 60°S. We use surface observations, atmospheric reanalyses and high-resolution atmospheric model simulations to investigate the drivers of this extreme event. At the time of the record temperature exceptionally warm air was being advected southwards towards the South Orkney Islands from the subtropical South Atlantic. This air mass cooled significantly at levels below 1 km during its long track over the cold Southern Ocean but remained relatively warm above this level. Atmospheric model simulations show that warm air from upper levels was brought down towards the surface over Signy Island in a föhn wind generated by northerly flow over Coronation Island, a mountainous island just to the north of Signy Island. Modelled temperatures over Signy Island are in good agreement with observations and thus support the hypothesis that the record temperature was caused by a combination of exceptional warm advection with conditions suitable for the generation of föhn. Since conditions conducive to föhn occur relatively frequently, föhn warming may have a significant influence on the local climate and ecology of Signy Island.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1002/asl.793
Programmes: BAS Programmes > BAS Programmes 2015 > Atmosphere, Ice and Climate
ISSN: 1530261X
Date made live: 13 Dec 2017 13:49 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/517295

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