sentences:  Later research by Robin Bell and Michael Studinger from the Lamont–Doherty Earth Observatory of Columbia University suggested that the water of the lake is continually freezing and being carried away by the motion of the Antarctic ice sheet, while being replaced by water melting from other parts of the ice sheet in these high pressure conditions.This resulted in an estimate that the entire volume of the lake is replaced every 13,300 years — its effective mean residence time.The coldest naturally occurring temperature ever observed on Earth, , was recorded at Vostok Station on 21 July 1983.