The impact of the latest reanalysis data of the ECMWF model on the surface temperature changes of the Caspian Sea

In many studies related to hydrodynamic modeling of seas and oceans, ERA-Interim data have been utilized while the use of ERA5 data has been emphasized more in recent research. Thereby, investigating the difference between the two recent reanalysis data and their impact on determining the physical parameters of the sea is of particular importance. In this research, the surface temperature changes of the Caspian Sea were investigated based on the latest reanalysis data of the European Center for Medium-Term Atmospheric Forecasts (ECMWF), using a developed three-dimensional hydrodynamic numerical model. In this model, the data of wind and atmospheric fluxes were obtained from ECMWF daily database with a spatial resolution of 0.25 and a time step of 6 hours. The model was implemented separately for the ERA-Interim and ERA5 data for a period of 10 years (2009-2018). A comparison of the surface temperatures of the Caspian Sea extracted from the model outputs and satellite images showed that the difference in temporal and spatial changes of the surface temperature was more consistent in ERA5 compared to ERA-Interim. The results showed that the difference in the temporal and spatial changes in the surface temperature of the Caspian Sea in the ERA5 and ERA-Interim was insignificant in the northern basin, relatively significant in the middle basin, and highly significant in the southern basin, so that the data of ERA5 has improved the results of the average annual temperature of the model output by about 7% in the southern basin of the Caspian Sea.