ON THE INTERANNUAL VARIABILITY OF ARCTIC SEA-LEVEL PRESSURE AND SEA-ICE

Monthly mean sea-level pressure (SLP) data from the Northern Hemisphere for the period January 1952-December 1987 are analysed. Fluctuations in this field over the Arctic on interannual time-scales and their statistical association with fluctuations farther south are determined. The standard deviation of the interannual variability is largest compared with that of the annual cycle along the seaboards of the major land masses. The SLP anomalies are generally in phase over the entire Arctic Basin and extend south over the northern Russia and Canada, hut tend to be out of phase with fluctuations at mid-latitudes. The anomalies are most closely associated with fluctuations over the North Atlantic and Europe except near the Chukchi Sea to the north of Bering Strait. The associations with the North Pacific fluctuations become increasingly more prominent at most Arctic sites (e. g. the Canadian Arctic Archipelago) as the time-scale increases. Associations between the SLP fluctuations and atmospheric indices that represent processes affecting sea-ice drift (wind stress and wind stress curl) are determined. In every case local associations dominate, but some remote ones are also evident. For example, changes in the magnitude of the wind stress curl over the Beaufort Sea are increased if the atmospheric circulation over the North Pacific is intensified; wind stress over the region where sea ice is exchanged between the Beaufort Gyre and the Transpolar Drift Stream is modulated hy both the Southern and North Atlantic Oscillations. Severe sea-ice conditions in the Greenland Sea (as measured by the Koch Ice Index) coincide with a weakened atmospheric circulation over the North Atlantic.