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 detennined.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, but tend to be out of phase with fluctuations at mid-latitudes.The anomalies are most closely associated withjluctuations 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 prominentat 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 Drifi Stream is modulated by 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.RSUM On analyse les donnes mensuelles de la pression du niveau moyen de la mer (SLP) de l'hmisphre Nord pour la priode de janvier 1952 dcembre 1987.On dtermine les fluctuations de ce champ dans l'Arctique sur des chelles de temps interannuelles et leur association statistique avec les fluctuations plus au sud.L'cart type de la variabilit interannuelle est plus grand que celui du cycle annuel ctier des principales masses terrestres.Les anomalies de la SLP sont gnralement en phase la grandeur du bassin Arctique, s'tendent vers le sud en Russie et au Canada, mais tendent d'tre hors phase avec desfluctuations aux latitudes moyennes.Les anomalies sont associes de trs prs aux fluctuations