Evaluation of air temperature estimated by ERA5-Land reanalysis using surface data in Pernambuco, Brazil

This study aimed to analyze the average air temperature data estimated by ERA5-Land reanalysis over 10 years (01/01/2011 to 12/31/2020), based on data from 12 automatic weather stations located in different cities in the state of Pernambuco, northeast of Brazil. For more careful evaluation, the average air temperature data were stratified by mesoregions of the state. ERA5-Land reanalysis data were validated using statistical indices that evaluated the accuracy. The average air temperature estimated by ERA5-Land reanalysis agree well with weather stations in almost the entire state of Pernambuco. The highest accuracy of the average air temperature estimated by ERA5-Land occurred in the city of Ibimirim (R² = 0.98), while the lowest accuracy was measured in the city of Caruaru (R² = 0.57). Root-mean-square error (RMSE) generated by the ERA5-Land reanalysis was lower than 0.60 °C in most Pernambuco. The highest RMSE of ERA5-Land for average air temperature was calculated using data from the city of Caruaru (1.11 °C), whereas the lowest RMSE was obtained with data from the city of Recife (0.41 °C). According to mean bias errors, (MBE) the ERA5-Land underestimated the average air temperature data compared to automatic weather stations data, especially in Ouricuri, which had the highest underestimation (-0.80 °C). On the other hand, among the municipalities where ERA5-Land overestimated the temperature values, the highest overestimation was identified in Garanhuns (0.35 °C). Therefore, based on the results of this study, ERA5-Land reanalysis successfully estimated the average air temperature for the state of Pernambuco.