Pacific versus Atlantic Contributions to Multidecadal Variability in the Arctic: A Multi-Model Intercomparison

Lea Svendsen1, Yu Kosaka2, Bunmei Taguchi3 and Noel Keenlyside1, (1)Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway, (2)University of Tokyo, Research Center for Advanced Science and Technology, Bunkyo-ku, Japan, (3)University of Toyama, Faculty of Sustainable Design, Toyama, Japan
Instrumental records show multidecadal variability in Arctic winter surface temperature throughout the 20th century. This variability is thought to be caused by a combination of external forcing and internal variability, but their relative importance is not clear.In addition, there is an ongoing discussion on the importance of variability in the Atlantic and the Pacific for decadal trends in Arctic surface temperature and sea ice extent, and studies suggest that both the mechanisms and the relative strength of these links could be model-dependent. To investigate the model diversity of the role of the Pacific impact relative to the Atlantic impact on multidecadal variability of Arctic surface temperature, we compare CMIP5 and available CMIP6 preindustrial control simulations. The results suggest that the relative strength of the Pacific-Arctic link is sensitive to the mean sea ice cover and the location and strength of the climatological Aleutian Low. Model differences in inter-basin interactions between the Atlantic and the Pacific on decadal-to-multidecadal timescales may also play a role. These results have implications for understanding the present and future Arctic warming, and inter-basin teleconnection patterns between the Atlantic, the Pacific, and the Arctic.