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

• Published in: Atmospheric Science Letters
• Main Authors: King, J. C., Bannister, D., Hosking, J. S., Colwell, S. R.
• Other Authors: British Antarctic Survey, Natural Environment Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: Antarctic; Coronation Island; Signy Island; South Orkney Islands; Southern Ocean; The Antarctic; Antarc*
• Online Access: http://dx.doi.org/10.1002/asl.793; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fasl.793; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/asl.793

Abstract 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.