On the decreases in North Atlantic significant wave heights from climate projections

Consistent projected decreases in significant wave heights (H-S) over the North Atlantic sub-basin under climate change scenarios have been endorsed by recent scientific literature. Here, the underlying causes of these projected decreases are investigated, by statistically characterizing the relationship between atmospheric circulation patterns, and wind generated waves. We apply a non-hierarchical partitioning method to the historical reference ERA5 mean sea level pressure (MSLP) over the North Atlantic, defining Weather Types (WTs) at annual and seasonal scales. The H-S fields related to those WTs are then characterized. Projected changes in the WTs frequencies of occurrence and related H-S, towards the end of twenty-first century, are analyzed for the RCP4.5 and RCP8.5 scenarios using a 10-member multi-model ensemble. Results show projected increases in the occurrence of WTs dominated by high-latitude storm tracks (above 50 degrees N) and atmospheric blocking patterns, and projected decreases in the occurrence of WTs dominated by lower-latitude storm tracks and NAO- patterns, over the North Atlantic, consistent with generalized projected decreases in H-S.

Automated summary

Recent scientific literature has endorsed the consistent projected decreases in significant wave heights over the North Atlantic sub-basin under climate change scenarios. The underlying causes of these projected decreases are found to be increases in high-latitude storm tracks and atmospheric blocking patterns, and decreases in lower-latitude storm tracks and NAO- patterns.