The Atlantic Gateway to the Arctic in the Mirror of the Kola Transect.

In situ temperature measurements along the Kola Transect for 1993–2019 are compared to climate indices for the North Atlantic, developed by the authors in earlier works. Five climate indices are considered: PC1, PC2, NAT, NAT1, and NAT2. It is shown that the temperature time series along the Kola Transect correlate well with climate indices PC2, as well as NAT1 and NAT2, which are responsible for warming processes in the cold North European Basin and cooling processes in the warm region south of Iceland. The correlation coefficients reach 0.80. At the same time, there is a low correlation between the temperature along the Kola Transect and the PC1 and NAT indices, which represent the volume flux of water entering the North European Basin from the Atlantic. This implies that the thermal state of the Atlantic waters entering the Barents Sea and the water temperature along the Kola Meridian are determined by the thermal state of the waters rather than the volume flux of Atlantic waters. A high consistency is found between the in situ measurements along the Kola Transect and the corresponding data from the GLORYS12V1 global ocean reanalysis. It is shown that the northern boundary of the Coastal Branch of the Murmansk Current can reach 71.5°–72° N. [ABSTRACT FROM AUTHOR]