Requirements for the coldest place on Earth
29 May 2008
Check here for daily temperature updates at Dome A to see if the temperature drops colder than cold…
An automatic weather station (AWS, pictured right) was deployed at Dome A as part of an Australian-Chinese collaboration in January 2005. No ground-based scientific investigation had been made at this site before the arrival of the Chinese over-snow traverse team.
Dome A is one of the least-known places on the globe and may potentially be the coldest place on the surface of the Earth. Palaeo-scientists consider it suitable for collecting an ice core that will provide a record of past climate and atmospheric gas composition going back more than one million years.
The AWS at Dome A measures
- wind speed
- air temperature – with sensors mounted on mast arms at 1 m, 2 m and 4 m above the snow surface
- snow temperature at 0.1 m, 1 m, 3 m and 10 m depth
- atmospheric pressure
- wind direction
- incoming solar radiation
- relative humidity
- snow-fall rate
Wind speeds at Dome A are very low, averaging only 2.4 m/s over the two years 2005-2006, and during winter exceptionally strong surface inversions develop. It is not unusual for the air temperature one metre above the surface to be 10ºC colder than the temperature two metres above the surface. Because of this inversion the annual average air temperature for the 2005-2006 period at 2 m height was -51.7ºC, considerably warmer than the temperature at the very surface, which is what determines the temperature at depth in the snow. The monthly mean temperatures for the 2005-2006 period are shown at right.
The annual precipitation measured by the AWS was 11 cm in 2005 and 5 cm in 2006. Because of the low wind speeds, the surface snow density is very low, and this snowfall is equivalent to an annual average (over the two years) of less than 2 cm of water. Hence Dome A is a site where very old and undisturbed ice-core paleoclimate records might be obtained, possibly even older than 1 million years. It will not however be a comfortable place to work because of the extremely low temperatures and low average pressure, which averages only 574 hPa.
At 10 m depth in the snow, seasonal temperature variations are damped out. The temperature at this depth is close the annual average surface temperature. At Dome A this is -58.3ºC, 1ºC colder than the equivalent temperature at the Russian Antarctic station Vostok where, in July 1983, the temperature dropped to -89.2ºC, the coldest temperature ever recorded on the surface of the Earth.
We look forward to receiving an uninterrupted stream of AWS data, via Argos, during the International Polar Year 2007-2008 which commenced on 1 March 2007.
Ian Allison – Australian Antarctic Division and Antarctic Climate and Ecosystems CRC, Australia.
Xiao Cunde – State Key Laboratory of Cryospheric Sciences, CAREERI, CAS & Chinese Academy of Meteorological Sciences, CMA China.
Li Yuansheng – Polar Research Institute of China, China.