Analysis of Atlantic extratropical storm tracks characteristics in 41 years of ERA5 and CFSR/CFSv2 databases

摘要

This work aims to analyze and compare ERA5 and CFSR/CFSv2 data from 1979 to 2019 with 1-hourly outputs, regarding their ability to reproduce storm tracks and the main characteristics of cyclones at middle and high latitudes in the North Atlantic (NA) and South Atlantic (SA) Oceans. The cyclone tracking was based on relative vorticity at 850 hPa and the intensity is measured using the maximum 10-m wind speed. The climatology produced for both datasets shows the main characteristics of the NA and SA storm tracks, such as seasonal variability and genesis regions. The use of 1-hourly fields improves tracking in areas with complex terrains, such as the lee of Andes (SA) and Greenland (NA). The differences in number of cyclones and their characteristics between datasets are small. 92.7% and 93.1% of ERA5 cyclones have an identical correspondent storm in CFSR/CFSv2, in the NA and SA respectively. Genesis and lifetime statistics show that CFSR/CFSv2 may present inconsistency between forecast and analysis sequential time-steps. Large differences remain in the intensity distributions, in which the CFSR/CFSv2 presents stronger cyclones than ERAS. Divergences between the datasets decrease when the comparison is made using only CFSv2, particularly in the South Atlantic.