Influence of the Arctic Oscillation on the Formation of Water Circulation Regimes in the Sector of the North, Norwegian and Barents Seas

Abstract

The article studies the influence of wind forcing associated with the Arctic Oscillation on the water circulation regimes in the sector of the World Ocean (65–81.5 N, 0–70 E), which consolidates the North, Norwegian and Barents Seas. The study aims at establishing quantitative patterns of variability of the ocean level and surface geostrophic current velocities depending on the value of the Arctic Oscillation index. In general, the response of the sea level averaged over the ocean sector under consideration is in an antiphase with this index. However, there are periods of mismatch between antiphase fluctuations of the sea level and the Arctic Oscillation index. After 2009, an increase in the amplitude and a decrease in the duration of the phases of the Arctic Oscillation index are noted. The difference between the areas of positive and negative values of sea level anomalies creates a pressure gradient that causes surface geostrophic currents carrying Atlantic waters along the shelf edge eastward in a cyclonic regime (the Arctic Oscillation index is greater than 0) and westward in an anticyclonic regime (the index is less than 0). The article provides estimates of the linear regression coefficients: for the sea level they are ~ 2 cm in the shelf zone and about minus 1 cm in the deep-water part of the sector. Thus, the level difference between the shelf and the deeper part of the considered water area is ~ 3 cm per 1 unit of the Arctic Oscillation index. Estimates of the linear regression coefficients for anomalies of the geostrophic currents velocity were ~ 0.5 cm/s per 1 unit of the index. Analysis of the longterm variability of the steric component of the ocean level showed a better relationship with the interannual variability of the Arctic Oscillation index as compared to the ocean level.