Interannual variability of water mass properties over the transatlantic section along 60° N in the subpolar North Atlantic

The thermohaline structure of the subpolar part of the North Atlantic is described in detail on the basis of the data of four surveys over the transatlantic section in 1997-2004 along 60 degrees N. For 8 years, a two-mode structure of the Labrador Sea Water was observed in the Irminger Basin. On the basis of the data obtained in 1997, it is shown that the formation of the Labrador Sea Water (LSW) can occur not only in the Labrador Sea, but also in the southern part of the Irminger Sea. The analysis of the data of four surveys made it possible to conclude that the modified East Iceland Water permanently penetrates into the subpolar region of the Atlantic Ocean. The analysis of the interannual variability of the characteristics of the water masses made it possible to distinguish that, from the end of the 1990s to 2003, a reconstruction of the Meridional Overturning Circulation (MOC) was observed in the North Atlantic. During this period, a gradual destruction of the dense deep LSW core occurred. The newly formed LSW of relatively low density propagated in the upper layer. The influence of the flow of the Deep Denmark Strait Overflow Water and the Iceland-Scotland Overflow Water spreading from the Arctic seas through the Denmark Strait increased. The northward transport of warm and saline surface and intermediate waters of the southern origin increased. It is possible that the cooling and a decrease in the salinity of the Labrador Sea Water found in the Irminger Basin in 2004 indicates the formation of the next mode of the meridional circulation.