Evaluation of HYCOM sea surface salinity and temperature using buoy measurements

The Sea Surface Temperature and Salinity (SST/S) are influential climatic parameters that play an essential role in determining the state of the ocean and the relationship between the sea surface and the atmosphere. Access to accurate data sources with an appropriate spatial and temporal resolution of these variables is of interest to researchers in various fields, such as climatology and monitoring the growth and reproduction of different animals in the aquatic environments. This research evaluates the quality of SST/S data obtained from the Hybrid Coordinate Ocean Model (HYCOM) global reanalysis using local observations obtained from buoys. To assess the daily values of HYCOM reanalysis with a spatial resolution of 0.08 degrees, the time series of SST/S data measured in 14 buoys from 2012 to 2022 was considered as reliable values. Based on the data used in this study, there was a high correlation between HYCOM SST data and corresponding local values up to 0.99. In addition, the agreement between the HYCOM data and the buoy observations was lower for salinity than the water temperature. Statistical assessments showed that the bias of HYCOM SST values has a different sign at distinct locations, while HYCOM estimated SSS more than the corresponding buoy observation. In most stations, the absolute bias value of the HYCOM reanalysis in the SST and SSS products was less than 0.38 C and 0.5 psu, respectively. Also, the average RMSE of the differences between HYCOM reanalysis and local observations at all stations for temperature and salinity was estimated to be 0.58 Celsius and 0.57 psu.