In order to understand the current climatic changes we investigate the impact of sea-ice formation and the composition of water masses in the Transpolardrift system. Based on stable oxygen isotopes (δ18O) and salinity the fractions of the different freshwater components (river water and sea-ice melting or formation) can be quantified (fact sheet: methods).We can thus detect the changes in sea-ice formation and its impact on arctic water masses and specifically the Arctic Halocline. Such information is necessary to estimate further climatic and ecological consequences of the considerable changes seen in the last years in the arctic ice cover.
The sea-ice signal formed in the Laptev Sea will be compared with the import and export of water masses in the upper layers as well as with the deeper water masses flowing in and out of the arctic through Fram Strait. In combination with measurements of the neodym isotopes and the rare earth fingerprints (see TP 1A) further information can be retrieved on origin of freshwater sources quantified within this subproject. The Laptev Sea and the Fram Strait are key regions of our projects that will contribute to these urgent questions: What are the changes in the formation of the sea-ice signal and the water masses on the Siberian shelves? What are the consequences of these changes on the Arctic Halocline? And how are these changes reflected in the export of water masses in Fram Strait? And are there changes in the composition of inflowing Atlantic water masses into the Arctic?
A first study on the variability of river water budgets was published: Interannual variations in river water content and distribution over the Laptev Sea between 2007 and 2011: The Arctic Dipole connection (Thibodeau et al., 2014 see also AGU poster). The variability of the budget of sea-ice formation is a further focus of our work (Thibodeau and Bauch, submitted)
