Purpose. The purpose of the study is to determine the trends and the spatio-temporal features of interannual changes in the sea surface temperature (SST) and in the upper 1000-meter layer in the extratropical zone of the northwestern Pacific Ocean, and to analyze their possible causal relationships with the large-scale and regional processes in the ocean and atmosphere over the certain phases of the modern period of global warming.
Methods and Results. To analyze the NOAA climatic data sets, the methods of cluster, correlation and regression analysis, and also the apparatus of empirical orthogonal functions were used. The results obtained made it possible to characterize the trends in interannual dynamics of thermal characteristics of the upper, intermediate and deep layers in certain areas under various conditions of the 20-year phases of the 40-year period of modern climate changes, and to quantify their features and statistical significance.
Conclusions. In general, in the above region during both phases of the modern period of climate changes, positive statistically significant trends were observed in the annual average SST, the values of which in 1982–2000 were 1.3–1.5 times higher than those in 2000–2021. During the second period, the area of positive SST trends decreased significantly and was localized in the northwestern part of the area under study. In contrast to the SST, at the same period, positive trends of the water column temperature in the upper 1000-m layer were traced over most of the area under study. The correlations between the variations in the ocean upper layer heat content and the processes in the ocean and atmosphere are most extensively manifested through the climatic indices NPGO, PDO, WP, PTW, and the anomalies in the geopotential field ΔH500.