An ERA5 global climatology of tropical cyclone size asymmetry

Abstract

The size of tropical cyclone (TC), defined as the radius of gale-force (34-kt) 10-m winds (R34) from a TC centre, is often asymmetric but received limited attention. Understanding the asymmetry of TC size is particularly essential to enhance the applicability, predictability, and preparedness for the parties in the coastal regions. In this study, the ERA5 reanalysis data are first validated by the QuikSCAT satellite data. Results demonstrate that the radius of ERA5 32-kt 10-m winds estimates best R34 in the QuikSCAT satellite data with a promising linear relationship (r =.75). A 41-year (1979–2019) homogeneous ERA5 global climatology of TC size asymmetry is hence established based on this linear regression model. Both the temporal and spatial characteristics of the TC size asymmetry are investigated and discussed. This study lays the important groundwork for future sophisticated research on TC size.