Evaluation of meteorological reanalysis data over the tropical Western Indian Ocean based on buoy observations in 2022

The Indian Ocean is the least observed of the three oceans, and a large amount of reanalysis data has to be used to study the Indian Ocean. Observations of sea surface winds, temperature, and sea level pressure, measured from Bailong real-time buoy system deployed in the western Indian Ocean, are being used to assess the capabilities of major high-frequency atmospheric reanalysis products in the western Indian Ocean region. During the study period, the atmospheric reanalysis data can accurately reproduce the temperature and sea level pressure fields, but the surface wind fields, especially for the meridional winds, are poorly described. ERA5 provides a better description of temperature and sea level pressure among all datasets. For the surface wind field, the reanalysis dataset overestimate/underestimate the intensity of the zonal/meridional winds, respectively, while the R-2 presents a worse description. Apart from the comparison of raw data, the diurnal variation of the three variables was also evaluated, and the results indicate a significant gap between the observation and reanalysis data. This study suggests that the current high-frequency reanalysis data still have shortcomings in describing atmospheric parameters in the tropical western Indian Ocean region.