Leading modes of the sea surface temperature large-scale variability in the Atlantic sector of the Arctic.

The study presents an analysis of the large-scale spatiotemporal variability of sea surface temperature (SST) in the Atlantic sector of the Arctic, a key region for the transformation of Atlantic waters and heat exchange between the North Atlantic and the Arctic Ocean. To achieve this, the Empirical Orthogonal Function (EOF) decomposition method was applied to the original monthly mean SST anomalies from the ERA5 reanalysis over the period 1950–2024. Three leading modes have been identified, collectively accounting for 55,8 % of the total SST variance. The first mode (25 % of the variance) exhibits a spatial dipole structure, separating the study area into western and eastern parts. It reflects the mechanism of intensified advection of Atlantic waters northward and eastward, correlating with the heat flux through Fram Strait ( R = 0.42) and the Arctic Dipole index ( R = 0.27). The second mode (16,4 % of the variance) is characterized by a latitude-oriented dipole structure. Its temporal evolution and significant correlation ( R = 0.58) with the Atlantic Meridional Overturning Circulation (AMOC) index reflect the influence of low-frequency oceanic variability. The third mode (14,4 % of the variance) exhibits a complex structure with a positive anomaly in the western and central parts of the basin. It is interpreted by the authors as an indicator of deep convection intensity in the Greenland Sea, a finding supported by its correlation with temperature in the 500–1750 m layer ( R = –0.48). It is established that the spatial structures identified are formed under the combined influence of advective heat transport by Atlantic waters, multi-decadal variability in the intensity of the AMOC, and atmospheric circulation patterns associated with the Arctic Dipole and the Arctic Oscillation. The results obtained quantitatively determine the contribution of the leading modes to the total SST variability in the Atlantic sector of the Arctic, which is essential for understanding the regional climate response to global changes and for refining the mechanisms of Arctic amplification.