Purpose. Wind speed accuracy in diverse storm systems is crucial for weather prediction, climate studies and marine applications. This study aims to evaluate the performance of the European Centre for Medium-Range Weather Forecasts (ECMWF) fifth-generation atmospheric reanalysis (ERA5) for wind speeds in extratropical cyclones (ETCs), polar lows (PLs) and tropical cyclones (TCs), as well as to propose a correction function for potential biases.

Methods and Results. We compared the ERA5 wind speeds with the data from the Advanced Microwave Scanning Radiometer-2 (AMSR-2) satellite for various storm events. Statistical metrics, including bias, root mean squared error (RMSE) and correlation coefficient (R), were calculated to quantify discrepancies between the two datasets. Based on the observed biases, a simple exponential correction function was proposed to adjust the ERA5 wind speeds. The effectiveness of the correction function was evaluated through visual comparisons and quantitative analyses. The analysis revealed that the ERA5 systematically underestimated wind speeds across large areas within ETCs, PLs and TCs compared to the AMSR-2 observations. The proposed correction function successfully improved the agreement between ERA5 and AMSR-2 wind speeds in ETCs and PLs. However, applying the same function to TCs revealed significant structural discrepancies between the ERA5 and the AMSR-2 wind fields within these systems.

Conclusions. This study demonstrates effectiveness of the proposed correction function in enhancing wind speed accuracy for ETCs and PLs, bringing them closer to AMSR-2 observations. However, further research is necessary to develop approaches for addressing wind speed biases in TCs, considering the unique characteristics and limitations of existing reanalysis data. This research contributes to improving our understanding and representation of wind speeds in diverse storm systems, ultimately aiding in more accurate weather forecasting and climate monitoring.