Atlantic influence on content of freshwater in upper layer of the Arctic Ocean

The interdecadal changes in layer of the Atlantic water (AW) and the fresh water content (FWC)  in the  Arctic Basin  (AB) are traced for the 1960s - 2010s  in order to assess the influence of the influx from the Atlantic on the FWC changes. The results showed that the upper boundary of the AB layer, identified on zero isotherm, everywhere rose in the 1990s - 2010s by several tens of meters relative to its position before the start of the warming in the 1970s. The lower boundary of the layer, also determined by the depth of the zero isotherm, fell. Such displacements of the layer boundaries indicate an increase in the volume of the AW in the AB. A reduction in the volume of the upper freshened layer it is necessary to maintain balance. Our calculations confirmed that in the 1990s, the FWC in the layer 0–100 m decreased to 2 m or more in the Eurasian part of the Arctic Basin west of 180 °E and increased to east of 180 °E closer to the shores of Alaska and the Canadian archipelago,. This trend intensified in the 2000s and in the 2010s. A comparison of the distributions of the FWC and the position of the upper boundary of the AB layer over different decades by the method of spatial correlation confirmed a close relationship between both distributions. The response on changes of water temperature in the tropical region of the Atlantic is traced in the Barents Sea and in the Arctic basin.  That indicates the influence of low latitude SST on changes in AW layer and serves as an indicator of tropical effect on the Arctic processes. The study is supported by the RFBR grant 18-05-60107.