May 14, 2012: FB2-Seminar

13 c.t., lecture hall, western shore building

Abstract:

The origin of river and sea-ice derived freshwater in the Arctic Ocean halocline can be determined and quantified by a combination of salinity, stable oxygen isotopes (d¹⁸O) and nutrients.

The dataset from summer 2007 features 2 parallel sections in the Eurasian and Makarov basins across the Transpolar Drift System and thereby gives a quasi-synoptic view as well as some temporal information. Our study indicates which layers of the Arctic Ocean halocline are primarily influenced by sea-ice formation in coastal polynyas and which are primarily influenced by sea-ice formation over the open ocean. With the ongoing changes in sea-ice coverage in the Arctic Ocean it can be expected that these processes will change in the immediate future and that the relative contributions to the halocline will change accordingly.

Outside the Atlantic regime dominated by net sea-ice melting in the southern Eurasian Basin, a pronounced layer influenced by brines released during sea-ice formation is present at about 30-50 m water depth with a maximum over the Lomonosov Ridge. The geographically distinct definition of this maximum demonstrates the rapid release and transport of signals from the shelf regions in discrete pulses within the Transpolar Drift. We use the ratio of sea-ice derived brine influence and river water to link the maximum in brine influence within the Transpolar Drift with a pulse of shelf waters from the Laptev Sea likely released in summer 2005.