Evaluation of the near-surface wind products from reanalyses over the North-Western Indian Ocean

The increasing availability of global and regional reanalysis products emphasises their region-specific evaluation, which helps to provide more accurate and detailed information about ocean processes. This study aims to identify the most suitable reanalysis dataset for wind fields over the North-Western Indian Ocean, thereby limiting the uncertainty related to reanalysis selection. Five reanalysis datasets – JRA3Q, IMDAA, ERA5, MERRA2, and NCEP CFSv2/CFSR - were evaluated using optimal satellite-blended wind data, validated against buoy observations as a reference. Spatially averaged wind speeds from reanalyses were compared with CCMP wind speed across the open ocean and coastal region of the North-Western Indian Ocean over ten years. The comparison employed statistical methods, including correlation, RMSE, MBE, standard deviation, and the NSE skill test.In both the statistical and skill tests regarding climatological wind speeds, ERA5 demonstrates superior performance compared to other reanalyses along most of the regions. However, JRA3Q performs best in the open Arabian Sea among the evaluated reanalyses. Seasonal analysis revealed that during DJFM, all reanalyses underestimate wind speed, with IMDAA showing the lowest bias among the evaluated datasets. While in the JJAS season, ERA5 shows a reasonable consistency. At the same time, directional accuracy with respect to buoys is higher for NBSv2. The study concludes that ERA5 performs reasonably well in accurately representing wind fields over the Northwest Indian Ocean during the JJAS. However, it also highlights that reanalyses encounter difficulties in accurately capturing wind fields during the DJFM season.