Decadal changes of the θ−S relationship of the Eastern North Atlantic Central Water

Observations of the eastern North Atlantic mode waters spanning a 20-year period were assembled including previously unpublished observations and historical data, to investigate spatial and temporal variations. Along 42°N, the freshening of salinity on the isopycnal σθ = 27.1 is shown to persist until 1990 and to be followed by an abrupt increase in 1991 to levels not seen since the late 1970s. Some suggestions are made of mechanisms 1970s. Some suggestions are made to mechanisms that may be involved in the variability.