Drivers of freshwater distribution in the Arctic and Atlantic oceans

• Main Authors: Kovacs, Tamas, Horn, Myriel, Gerdes, Rüdiger
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Arctic; North Atlantic; North Atlantic oscillation
• Online Access: https://epic.awi.de/id/eprint/47590/; https://epic.awi.de/id/eprint/47590/1/FAMOS_Tamas_Kovacs_C-32.pdf; https://hdl.handle.net/10013/epic.66965e62-9943-42e4-a65b-824b64993c02

Oceanic circulation plays an important role in setting the climate of the Arctic and the Northern Atlantic regions. Currents conveying large volumes of water masses at various depths transport heat and salt to great distances, forming a global circulation system. In the Atlantic, the Meridional Overturning Circulation (MOC) is driven by exchanges of heat, freshwater and momentum with the atmosphere. Previous modeling studies suggest that the stability of the MOC is sensitive to different climate scenarios due to the sensitivity of the deepwater formation, a crucial component of the circulation to perturbations of freshwater content. Global climate models predict significant temperature rise in the future with larger trends at higher latitudes, and an enhanced hydrological cycle. Both of these trends act against the MOC, decreasing its strength by reducing meridional air temperature differences and freshening of ocean waters in key high latitude areas. The observed increase of the strength of the North Atlantic Oscillation (NAO) in recent decades, a trend that is predicted by many climate models to persist in the future, however, acts as a driver of the MOC. This duel of the evolution of fresh water fluxes and the development of the NAO is most likely going to define the strength of the MOC in the future. We examine the effects of different NAO scenarios using the Modini-system, a partially coupled spin-up that allows prescription of wind stresses for the ocean in the otherwise fully coupled Earth System Model of the Max Planck Institute. In our work we describe the processes affecting the circulation in more detail. We present our first results by investigating the role different wind stress patterns play in shaping fresh water reservoirs and exchanges between different subregions of the Arctic and the Atlantic Ocean.