Atmospheric Circulation

Abstract

In the late 19^th century scientists undertook attempts to construct various schemes of atmospheric circulation in the Arctic on the basis of theoretical considerations. Ferrel (1882, 1889) argued that the mid-latitude westerlies circulate around a large low pressure system occurring in the Arctic with its centre above the Pole. His idea was preserved until the publication of the meteorological observations from the “Fram” drift (Mohn 1905), and according to Hobbs (1926) even until 1920. Mohn, analysing data from “Fram”, confirms an opposite conception to that which had been presented by Ferrel, and earlier by Helmholtz (1888), of the predominance of high pressure and anticyclonic circulation in the Arctic. This concept, further developed by Hobbs (1910, 1926) in his “glacial anticyclone theory”, was generally accepted by the majority of meteorologists and climatologists, and was very popular in the 1920s and 1930s (e.g. Brown 1927; Shaw 1927, 1928; Bergeron 1928; Clay­ton 1928; Baur 1929; Schwerdtfeger 1931; Sverdrup 1935; Vangengeim 1937). It was known as the “permanent Arctic anticyclone” hypothesis. Even Sverdrup (1935), having strong evidence from the “Maud” expedition that deep cyclones also enter the Arctic Ocean in winter, did not challenge this opinion. The supporters of the Arctic anticyclone hypothesis argued that, on average, the atmospheric pressure at sea level in the central Arctic was higher than at temperate latitudes, and the pressure maximum coincided with the temperature minimum. Nothing changed until the publication of the meteorological and aerological observations carried out on the Soviet drifting station NP-1 (Dzerdzeevskii 1941–1945), which confirmed and significantly supplemented the observations of the “Maud” expedition. The observations provided extensive evidence of the absence of a permanent anticyclone in the Arctic. Dzerdzeevskii (1941–1945) showed that both in winter and summer various types of isobaric systems occur in the Arctic, including intense cyclones. In addition, he calculated that the number of days with cyclones in summer was equal to, or exceeded, the number of days with anticyclones. This and other strong evidence presented in his work eventually led to the rejection of the erroneous hypothesis that a stable polar anticyclone occurs in the Arctic. The delay in reaching this conclusion was caused, among others, by the ideas and assertions of Hobbs (1926), which were highlighted again in two papers published in 1945 (Dorsey 1945 and Hobbs 1945). Even up to 1950, Hobbs (1948) maintained that a semi-peiivanent Arctic high in the Arctic should be present (Jones 1987). The most comprehensive review is presented in Dzerdzeevskii's work and in its English translation (Dzerdzeevskii 1954).