Variation of freshwater in the western Nordic Seas

by Katrin Latarius and Ursula Schauer

Near-surface freshwater sets the density stratification in the western Nordic Seas and thereby affects their contribution to formation of deep waters. The freshwater distribution in the Nordic Seas undergoes strong variability, but neither the specific source of the freshwater nor the cause of the variability is well understood. The goal of this project is therefore to analyze the freshwater fluctuations in the western Nordic Seas and to identify the freshwater sources and to understand the mechanisms influencing the freshwater distribution.

The Nordic Seas are shaped by the strong salinity contrast arising from the northward flow of saline Atlantic Water along their eastern rim and the southward flow of very fresh Polar Water and sea ice along their western rim in the East Greenland Current. The huge import of freshwater to the Arctic Ocean from continental runoff, from the Pacific Ocean and the freshwater concentrated at the surface through sea ice formation is drained to the North Atlantic. In the Nordic Seas itself, freshwater is added to the East Greenland Current by the increasing runoff from Greenland.

The last decades showed significant changes of the freshwater yield and distribution and the convective activity in the Nordic Seas. Glider measurements from the first phase of FOR1740 and other recent studies indicate that in the Greenland Sea mostly sea ice is the source of freshwater.





Plans for the second phase of this project are:

In this project we will use the high-resolution data from two glider missions lasting over several months together with Argo data to understand the processes causing the freshwater leakage from the East Greenland Current to the Greenland Basin.

The data sets, together with atmospheric reanalysis and sea ice products will enable us to relate the small-scale frontal fluxes with the region-wide changes on time scales from seasonal to interannual.

Eventually, glider sections and Argo measurements will be used for the validation of salinity observations from SMOS and Aquarius, although the errors from these observations in high latitudes are currently large.