Asymmetry Analysis of ERA5 Reanalysis Data in the Context of Tropical Cyclones

A detailed analysis of temperature and relative humidity biases in the ERA5 reanalysis under tropical cyclone (TC) conditions is conducted using a composite analysis approach. This study incorporates the influences of TC movement and vertical wind shear (VWS). The results show that the temperature bias in the ERA5 data is more pronounced in the core region of TCs than in the outer regions. A similar pattern is observed for relative humidity, but it is most evident in the middle and upper troposphere. Additionally, the temperature bias exhibits a strong asymmetry, particularly in the core region of the TC, where larger errors are observed on the right-front side in the direction of motion and on the front side of the VWS at higher altitudes. This asymmetry is likely associated with more intense convection in these two directions.