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Jeudi 17 Mai - Très Grande Froideur: The lowest temperatures on Earth

Par SEMSOU Dernière modification 03/04/2018 16:46
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Ted Scambos

National Snow and Ice Data Center

University of Colorado at Boulder, Colorado, USA

 

Title: Très Grande Froideur: The lowest temperatures on Earth


Abstract: The lowest measured air temperature on Earth, in situ, is -89.2°C on 23 July, 1983 at Vostok Station in Antarctica. However, satellite data collected during the Antarctic polar night reveals a broad region of the uppermost East Antarctic Plateau that regularly reaches surface (‘skin’) temperatures of -90°C and below. The most frequent occurrence of -90°C measurements, and the locations of the lowest temperatures, are in shallow (~2m closure) topographic lows on the south side of the Dome A to Dome Fuji ice divide, at 3800 - 4050 m elevation. Roughly 100 sites in this broad area reach the lowest temperatures, -98.0 to -98.6°C. Comparison with automated weather station data in the same region indicate that the actual surface temperatures are -96 ± 2°C, and typical near-surface air temperature gradients suggest that the 2m air temperatures in the sites are likely in the range of -94°C ± 3°C. Ultra-cold conditions occur more frequently during periods when the Antarctic polar vortex is stronger. A consideration of the winter surface energy balance components suggests that the limit on the lowest temperatures is set by re-radiation from the atmosphere, controlled primarily by stratospheric clouds and water vapor in the air column. 

 

Note: Ted will be a guest scientist at LEGOS from 25/04/2018 to 25/05/2018.

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