CMIP5 Projected Change in Northern Hemisphere Winter Cyclones with Associated Extreme Winds

Abstract

In this study, 19 simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) have been analyzed to examine how winter cyclones producing extreme near-surface winds are projected to change. Extreme wind thresholds correspond to a top 5 or top 1 cyclone per winter month in the entire Northern Hemisphere (NH). The results show that CMIP5 models project a significant decrease in the number of such cyclones, with a 19-model mean decrease of about 17% for the entire NH toward the end of the twenty-first century, under the high-emission RCP8.5 scenario. The projected decrease is larger in the Atlantic (about 21%). Over the Pacific, apart from an overall decrease (about 13%), there is a northeastward shift in the extreme cyclone activity. Less decrease is found in the frequency of cyclones producing extreme winds at 850 hPa (about 5% hemisphere-wide), with models mainly projecting a northeastward shift in the Pacific. These results suggest that 850-hPa wind changes may not be a good proxy for near-surface wind changes. These results contrast with those for the Southern Hemisphere, in which the frequency of cyclones with extreme winds are projected to significantly increase in all four seasons.

Robustness and uncertainties in global multivariate wind-wave climate projections

“…S5), emphasizing the dominant influence of wind-wave modelling approaches. A detailed discussion on the dissimilarities between simulations is provided in Supplementary Information, supported by global pairwise comparisons of mean and variability bias in a coherent subset with common forcing-method (Supplementary Table 3 well-documented large-scale atmospheric wind circulation changes 36,37 and modes of natural climate variability 10 .…”

Future changes in the extratropical storm tracks and cyclone intensity, wind speed, and structure

“…Commonly only the most extreme cyclones in the top 10% of the intensity distribution are examined as these often provide the clearest climate change signal (Catto et al, 2010;Sinclair et al, 2020;Chang, 2018Chang, , 2017Zappa et al, 2013) and are associated with the highest impacts (Ulbrich et al, 2001, e.g.). However, it has been demonstrated in numerous studies that cyclones in the middle of the distribution can respond differently to the most extreme cyclones (Champion et al, 2011;Pfahl et al, 2015;Michaelis et al, 2017;Sinclair et al, 2020).…”

Comment on egusphere-2024-656

“…However, Colle et al (2013) found the best (highest resolution) Coupled Model Intercomparison Project (CMIP5) models projected a 5-10% increase in cyclones and 5%-40% increase in deeper cyclones (<980 hPa) by the late twenty-first century inland along the U.S. east coast, but a 15%-20% decrease in cyclones and little increase in strong cyclones over the east coast water domain. Zappa et al (2013), Chang (2014Chang ( , 2018, and Seiler and Zwiers (2016) found similar decreases in extratropical cyclone frequency in various locations within the Pacific and Atlantic basins.…”