Freshwater variability in the Arctic Ocean and subarctic North Atlantic

• Main Author: Horn, Myriel
• Format: Thesis
• Language: unknown
• Published: Staats- und Universitaetsbibliothek Bremen 2018
• Subjects: Arctic; Arctic Ocean; Nordic Seas; North Atlantic; Sea ice; Subarctic
• Online Access: https://epic.awi.de/id/eprint/49044/; https://elib.suub.uni-bremen.de/edocs/00106914-1.pdf; https://hdl.handle.net/10013/epic.1953ba5b-7776-4e18-a03c-09e272c32596

In the past decades, observations in the upper Arctic Ocean and subpolar North Atlantic have shown significant freshwater changes that were in each region mainly attributed to independent processes. Both regions are sensitive to changes in the density stratification with possible implications for the ocean–atmsophere heat exchange and the deep convection. Thus changes in the freshwater content of the Arctic Ocean and subpolar North Atlantic have the potential to impact the climate locally and globally. The objectives of the present study are to investigate the freshwater content (co)variability of the upper Arctic Ocean and subpolar North Atlantic, to identify the processes causing the observed changes in freshwater content and to analyse possible drivers of these processes. To investigate the freshwater content variability I used objectively mapped salinity fields for the subpolar North Atlantic and Nordic Seas, and objectively mapped liquid freshwater inventories and sea ice volume estimates from the Pan-Arctic Ice Ocean Modeling and Assimilation product for the upper Arctic Ocean. To explore possible links, I compared the liquid freshwater content of the subarctic North At- lantic (SANA; combination of subpolar North Atlantic and Nordic Seas) with the sum of liquid and solid freshwater content of the upper Arctic Ocean from the observational and assimilation products. I found a distinct anti-correlation of the freshwater anomalies in these two regions between 1992 and 2013 with anomalies of the same magnitude. An analysis of freshwater fluxes from the global Finite Element Sea ice Ocean Model and the Common Ocean-ice Reference Experiment version 2 atmospheric forcing data set suggested that the observed freshwater variations resulted from changing freshwater transports. Variations in the Arctic freshwater export to the North Atlantic are found to be most important for the total freshwater content variability of the upper Arctic Ocean and for the liquid freshwater content variability of the western SANA. The ...