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The small valleys above the Antarctic Ice Sheet reach temperatures of almost -100 degrees Celsius, according to a new study published in the journal Geophysical Research Letters.
After badyzing data from several Earth observation satellites, scientists announced in 2013 that they had found surface temperatures of -93 degrees Celsius (-135 degrees Fahrenheit) at several points on the eastern Antarctic Plateau, a snow-covered plateau in central Antarctica spanning the South Pole.
This preliminary study has now been revised with new data showing that colder sites actually reach -98 degrees Celsius (-144 degrees Fahrenheit). These temperatures are observed during the night of the South Pole, mainly in July and August
When the researchers announced for the first time that they had found the coldest temperatures on Earth five years ago, they determined that he needed heavens and persistent winds. The new study adds that not only clear skies are needed, but that the air must also be extremely dry because water vapor blocks surface heat loss.
Small depressions on the icy surface
The researchers observed the lowest temperatures recorded in small depressions or shallow troughs in the Antarctic Ice Sheet, where the températures dépr,,,,,,,,,,,,,,,,,,,,,,, dense and descending cold air, it accumulates on the surface and can remain there for several days
. The air and air above will cool down even more, until clear, calm and dry conditions decompose and the air mixes with warmer air in the air. # 39; s atmosphere.
"In this area we see periods of air," says Ted Scambos, principal investigator and lead author of the study, in a statement.
According to researchers, the record of -98 degrees Celsius indicates the coldest temperature that can be reached on the Earth's surface.To keep the temperature so low, the clear sky and dry air must persist for several days. more if these conditions last for several weeks, but this is very unlikely, adds Scambos.
Searching for the coldest place
The Great Elevation of the Antarctic Plateau L 'East and its proximity to the South Pole are those that give this region the coldest climate of all regions of the Earth.
The lowest air temperature ever measured by a weather station, -89 degrees Celsius (-128 degrees Fahrenheit), a was recorded at the Russian Vostok station in July 1983.
But weather stations can not measure temperatures everywhere. Thus, in 2013, Scambos and his colleagues decided to badyze data from several Earth observation satellites to see if they could find temperatures in the Antarctic plateau even lower than those recorded at Vostok.
In the new study, they badyzed the data The satellites collected during the winter of the Southern Hemisphere between 2004 and 2016 used data from the MODIS instrument (Resolution Imaging Spectroradiometer) moderate) aboard NASA's Terra and Aqua satellites, as well as instrumental data on operational polar environmental satellites. The National Oceanic and Atmospheric Administration (NOAA).
Researchers observed that snow surface temperatures fell steadily below -90 degrees Celsius (-130 degrees Fahrenheit) almost every winter in a vast area of the plateau, at more than 3,500 meters above sea level. ;altitude. Within this vast region, they found that dozens of sites had much colder temperatures. In addition, they used the difference between the satellite measurements of the lowest snow temperatures of Vostok and three automatic stations, and the air temperatures at the same place and at the same time, and they deduced that the air temperatures in the coldest places (where the seasons do not exist) are probably around -94 degrees Celsius, or around -137 degrees Fahrenheit, well below the observed record in Vostok.
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