19 February, 2018 Paper

On 30th January 1982, a record high temperature of +19.8°C was measured at Signy Research Station – a record for any station south of 60°S.

In this paper, we examined the causes of this exceptional meteorological event. Global atmospheric analyses showed that, at the time of the event, persistent northerly winds were bringing very warm air from the subtropics towards the South Orkney Islands. During its long passage across the cold Southern Ocean, this air cooled at low levels but remained relatively warm above 1km altitude. Simulations with a high-resolution (1km grid spacing) regional atmospheric model demonstrated that as the air mass crossed the high topography of Coronation Island (just north of Signy Island), very warm air from around 1km was forced down towards sea level as a ‘föhn wind’, giving rise to the exceptional temperatures over Signy Island. Interestingly, temperatures at the nearby Orcadas station on low-lying Laurie Island remained unexceptional, highlighting the role played by the mountains of Coronation Island in driving this extreme event.

 

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

Authors
King, J. C., D. Bannister, J. S. Hosking, and S. R. Colwell (2017)

Published by
Atmospheric Science Letters, doi: 10.1002/asl.793