Investigating the effect of height difference correction between reanalysis grid points and observation stations on the accuracy of ERA5 2m temperature and pressure data

Temperature and surface pressure are among the critical variables in various meteorological and climatic applications. Reanalysis products have become valuable sources of temperature and pressure data in recent years and have garnered much attention. Due to the elevation difference between reanalysis grid points and ground stations, surface pressure and 2m temperature derived from reanalysis products exhibit noticeable biases. In this study, using 10 years of measured data from 202 synoptic stations in Iran, the impact of elevation correction on the accuracy of ERA5 Land (ERA5L) pressure and 2m temperature data was investigated. Three different models were used for elevation correction. A comparison of error statistics before and after elevation correction revealed that in most stations the accuracy of ERA5L temperature and pressure data are improved after elevation correction. The results indicate that after data calibration, the average bias and Root Mean Square Error (RMSE) of surface pressure in the region improved by 96% and 66%, respectively. Compared to surface pressure, the positive impact of elevation correction on ERA5L temperature was less pronounced, with average bias and RMSE improving by 68% and 13%, respectively. Furthermore, for the elevation calibration of ERA5L pressure, the three used models were compared. A comparison of error statistics across all stations demonstrated that the performance of the three models did not show significant differences in the Iran region.