СЕЗОННЫЕ ВАРИАЦИИ ТЕМПЕРАТУРЫ ПОВЕРХНОСТИ ОХОТСКОГО МОРЯ И ПРИЛЕГАЮЩИХ РАЙОНОВ ПО ДАННЫМ СПУТНИКОВЫХ НАБЛЮДЕНИЙ И РЕАНАЛИЗА ERA5

Abstract

Using the method of harmonic analysis and EOF decomposition of SST data for the surface of the Sea of Okhotsk and adjacent water areas (42–60° N, 135–160° E, SakhNIRO database and ERA5 reanalysis for 1998–2020), the main features of seasonal variations in thermal conditions were determined. It was revealed that the amplitude of the annual harmonic, which plays a decisive role in the seasonal variations of SST, generally decreases in the direction from west to east throughout the study area, the lowest values are in the zones of quasi- stationary upwellings. The phase increases along the northwest-southeast axis, the total shift is 24–25° (about 3 weeks). In the spatial distribution of the first mode (all values are positive), the water area of the Sea of Japan, the NWPO, and the southwestern part of the Sea of Okhotsk are characterized by high values. Its time function is characterized by a pronounced annual cycle, with a maximum in August–September and a minimum in February–March. The spatial distribution of the second mode has a nodal line running along the Kuril Islands from the Sea of Okhotsk side. The mode values vary along the northwest–southeast axis, with maximum positive values on the northwestern shelf of the Sea of Okhotsk and negative values in the remote part of the NWPO. The time function of the second mode has a positive maximum in July–August and a negative minimum in November–December. This nature of the second mode shows that, against the background of the main SST field described by the first mode, a peculiar seasonal “heat wave” is distinguished, propagating from the northwest to the southeast and passing along this axis in about three weeks, which is an important specific feature of the thermal regime of the study area.