Экологическая безопасность прибрежной и шельфовой зон моря (Mar 2023)
Interannual Variability of Water Circulation Regimes in the Arctic Ocean
Abstract
The article studies the interannual variability of the Arctic Ocean water circulation regimes according to altimetry data for the area from 65°N to 89.75°N including the ice-covered area of the ocean. The purpose of the work is to study the variability of the ocean level and the velocities of surface geostrophic currents depending on the value of the Arctic oscillation index, and to establish quantitative patterns between them. In addition, the paper considers the influence of different ocean circulation regimes and the value of the Arctic oscillation index on the steric level variability as an indicator of freshening/salinization processes in the polar region north of 81.5○N. The steric component of level was calculated as the difference between the dynamic topography from altimetry data and the GRACE data of the manometric level component. On an interannual time scale, the sea level response averaged over the Arctic Ocean is in antiphase with the Arctic Oscillation Index. Based on the method of multiple regression, quantitative estimates of the dependence of the sea level and geostrophic velocity components on the value of the Arctic oscillation index were obtained. The level difference between the shelf and the deeper part of the ocean was ~4 cm per unit of the Arctic oscillation index. The difference between the areas of positive and negative values of the sea level anomalies creates a pressure gradient, which leads to an increase in the anomalies of surface geostrophic velocities and enhances the inflow of Atlantic waters along the shelf edge in an easterly direction during the cyclonic regime (Arctic Oscillation Index is greater than 0). Under the anticyclonic regime of atmospheric circulation (the index is less than 0), the effect becomes opposite. This agrees with the estimates of the linear regression coefficients for the velocity anomalies of geostrophic currents, which amounted to ~0.5 cm/s per 1 index unit. On the basis of the obtained results, a conceptual scheme of the regimes of circulation and distribution of desalinated waters depending on the phase of the Arctic oscillation is proposed.
