Abstract

Atmospheric and ocean datasets using numerical modeling allied to data assimilation are valuable tools for planning and maintaining marine activities, particularly due to their spatial coverage and resolution. However, even modern analyses and reanalyses present critical errors where cyclonic winds are often underestimated in some locations, leading to issues in wind-wave climate hindcasts and forecasts. This work aims to evaluate two of the newest datasets available regarding their ability to reproduce extratropical cyclone tracks associated with extreme waves in the Atlantic Ocean. The analysis is focused on the storm track position and cyclone intensity, two important features that control the wave climate. The datasets used are the ECMWF’s ERA5 and NCEP’s CFSv2. The cyclones are identified and compared between 2011 and 2018 using the relative vorticity at 850hPa and the intensity is measured through the 10-meters wind speed. The results show that the differences in track density exist mainly in coastal areas and they can be related to the coarser resolution of CFSv2 compared to ERA5. CFSv2 presents a higher number of cyclones associated with extreme wave events in the South and North Atlantic, corresponding to 87.1% and 89.2% of the cyclones identified, while ERA5 presents 66.6% and 59.5% respectively. The maximum intensity distribution shows that CFSv2 tends to produce more intense cyclones than ERA5, even for identical storms in the datasets. The distances of matching cyclones in the two datasets are around 0.5°.

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