Decadal Predictability of the North Atlantic Eddy-Driven Jet in Winter

This paper expands on work showing that the winter North Atlantic Oscillation (NAO) is predictable on decadal timescales to quantify the skill in capturing the North Atlantic eddy-driven jet's location and speed. By focusing on decadal predictions made for years 2-9 from the sixth Coupled Model Intercomparison Project over 1960-2005 we find that there is significant skill in jet latitude and, especially, jet speed associated with the skill in the NAO. However, the skill in the NAO, jet latitude and speed indices appears to be sensitive to the period over which it is assessed. In particular, skill drops considerably when evaluating hindcasts up to the present day as models fail to capture the recent observed northern shift and strengthening of the winter eddy-driven jet, and more thus positive NAO. We suggest that the drop in atmospheric circulation skill is related to reduced skill in North Atlantic sea surface temperatures.

Automated summary

This paper explores the predictability of the winter North Atlantic Oscillation (NAO) and its relation to the location and speed of the North Atlantic eddy-driven jet. Using decadal predictions made from the sixth Coupled Model Intercomparison Project, the study finds skill in capturing the jet latitude and speed associated with the NAO. However, the skill appears to be sensitive to the evaluation period, leading to reduced skill in capturing recent observed changes in the jet and NAO.