Ice cores drilled at Vostok, with a portion of the station behind

The lowest reliably measured temperature on Earth of −89.2 °C (−128.6 °F) was measured here on July 21, 1983 (although since the temperature decreases with height, it is virtually certain that lower temperatures occurred higher up towards the summit of the ice sheet). During the long winter, temperatures average about −65 °C (−85 °F); in the brief summer, about −30 °C (−25 °F). The place is known as the Southern Pole of Cold. The coldest recent day at the station occurred August 8, 2005, when the high temperature reached just −78 °C (−108 °F) and the low fell to −85.4 °C (−121.7 °F). The warmest recorded temperature at Vostok is −12.2 °C (10.4 °F), which occurred on January 11, 2002, and during the month of July 1987 the temperature never rose above −72.2 °C (−98 °F). The minimum monthly mean surface temperature was occurred in August 1987 with -75.4 °C.

In addition to the cold temperatures, other factors make Vostok one of the most difficult places on Earth for human habitation:

• An almost complete lack of moisture in the air.
• An average windspeed of 5 m/s (11 mph), sometimes rising to as high as 27 m/s (60 mph).
• An acute lack of oxygen because of the high 3,488-meter (11,444 ft) altitude. Accounting for the fact that oxygen density gets lower as one approaches the poles, it is estimated that the oxygen density at Vostok is equivalent to that of a mountain over 5,000 meters (16,400 ft) tall at more temperate latitudes.
• A higher ionization of the air.
• A partial pressure of gases that is different from that which most humans are used to.
• A lack of carbon dioxide in the air, which leads to irregularities in a person's breathing mechanism.
• A polar night that lasts three months of the year.

Acclimatization to such conditions can take from a week to two months and is accompanied by headaches, eye twitches, ear pains, nose bleeds, perceived suffocation, sudden rises in blood pressure, loss of sleep, reduced appetite, vomiting, joint and muscle pain, and weight loss of 3-5 kg (7-11 lb) (sometimes as high as 12 kg (26 lb)).

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Ice core drilling

420,000 years of ice core data from Vostok, Antarctica research station. Current period is at left.From bottom to top: Solar variation at 65°N due to Milankovitch cycles (connected to ¹⁸O). ¹⁸O isotope of oxygen. Levels of methane (CH4). Relative temperature. Levels of carbon dioxide (CO₂).

In the 1970s The Soviet Union drilled a set of cores 500–952 m deep. These have been used to study the oxygen isotope composition of the ice, which showed that ice of the last glacial period was present below about 400 m depth, Then three more holes were drilled: in 1984, Hole 3G reached a final depth of 2202 m; in 1990, Hole 4G reached a final depth of 2546 m; and in 1993 Hole 5G reached a depth of 2755 m; after a brief closure drilling continued during the winter of 1995. In 1996 it was stopped at depth 3623 m, by the request of the Scientific Committee on Antarctic Research that expressed worries about possible contamination of Lake Vostok. This ice core, drilled collaboratively with the French, produced a record of past environmental conditions stretching back 420,000 years and covering four previous glacial periods. For a long time it was the only core to cover several glacial cycles; but it has recently (2004) been exceeded by the EPICA core, which whilst shallower, covers a longer time span.^[3] In 2003 drilling was permitted to continue, but was halted at the estimated distance to the lake of only 130 m.

Although the Vostok core reached a depth of 3623 m the usable climatic information does not extend down this far. The very bottom of the core is ice refrozen from the waters of Lake Vostok and contains no climate information. The usual data sources give proxy information down to a depth of 3310 m or 414,000 years.^[4] Below this there is evidence of ice deformation. It has been suggested that the Vostok record may be extended down to 3345 m or 436,000 years, to include more of the interesting MIS11 period, by inverting a section of the record.^[5] This then produces a record in agreement with the newer longer EPICA record, although it provides no new information.

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See also

• List of research stations in Antarctica
• Lake Vostok
• Soviet Antarctic Expedition
• Vostok traverse

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References

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External links

• Russian Antarctic Expedition, Vostok page
• Vostok average temperature data
• Vostok current met data
• Antarctic Connection article on Vostok Station

Coordinates: 78°28′S, 106°52′E