Key to the Atlantic Gates of the Arctic

Abstract

We consider the decomposition of water temperature fields into the Empirical Orthogonal Functions (EOFs), also known as Principal Components (PCs). We use the GREP data (Global Reanalysis Ensemble Product) in this study and we examine water temperature at the horizon of 457 m for the period 1993–2019 in the area limited to 50°–80°N, 50°W–20°E. It is shown that the first two Principal Components of decomposition (PC1 and PC2) are responsible for 48% of the total variance, and all subsequent ones are smaller by an order of magnitude. The time series of PC1 and PC2 are further considered as indicators responsible for the transfer of Atlantic heat to the Arctic. Transport and heat fluxes have been calculated through the cross-section 64.5°N, which connects Iceland with Scandinavia. It is shown that PC1 characterizes transport through the cross-section, and PC2 is responsible for heat fluxes. The analysis of the spatial distribution of PC1 and PC2 loadings allowed us to introduce three new NAT, NAHT1, and NAHT2 indices determined by water temperature anomalies. The NAT index is responsible for the transport of Atlantic waters to the Arctic, and two identical indices NAT1 and NAT2 characterize the corresponding heat transfer by these waters. The time series responsible for heat transfer to the Arctic [https://doi.org/10.2205/2022ES000792-data] in text format  are available at the website of Earth Science Data Base (ESDB) repository [http://esdb.wdcb.ru/] located in Geophysical Center RAS.