The new air temperature absolute minimum


A.B. Budretsky. Information Bulletin of Soviet Antarctic Expedition. 105. Leningrad, Hydrometeoizdat, 1984

During 23 years Vostok station air temperature was not registered below -88.3 (August 1960). 21 July 1983 at the station there was registered the new absolute minimum - minus 89.2C. It is known, that according to the theoretical calculations the possible temperature decrease in this area is up to -90C and below, but it is necessary, that progressive radiative cooling to be not compensated by advective heat influx.

Circulation conditions, preceding the new temperature minimum, were favorable. Since 15 July the area with pressure 614 hPa was located over Vostok station, with cloudless weather, weak wind and air temperature -75C. During following days the air temperature dropped on 2.5 per day in average, achieving -89.2C on 21 July at 5 hours 45 min by Moscow time. It was registered by remote thermometric device, composed from balanced bridge and platinum resistance thermometer enclosed in psychrometric box. This event was registered in documents.

Thermometric device is graduated up to -90C, has linear sensitivity in the range from -40 to -90 . Device readings are verified monthly. Technical condition of this device was verified 22 July 1983.

After the air temperature minimum was reached the wind changed direction from northern to north-western, wind speed began to increase quickly, and the air temperature started to rise abruptly. To 16 hours on July 21 the air temperature increased up to -85.30C. On July 23 the wind speed was 12-16 m/sec, the snow-storm was started, and the air temperature rose up to -66.70C.

Later the weather behaviour at Vostok station corresponded to averaged mean characteristics for corresponded season.

Received 2 November 1983.