Spatio-temporal evaluation of air temperature estimated by reanalysis of ERA5-land in Mato Grosso, Brazil

Climate monitoring is essential for agricultural planning and environmental management, especially in regions with a low density of meteorological stations, such as the state of Mato Grosso, Brazil. In this context, atmospheric reanalysis products, such as ERA5-Land, have emerged as alternatives to fill observational gaps. This study aimed to evaluate the performance of ERA5-Land in estimating monthly mean air temperature in the state of Mato Grosso, Brazil, using data from 14 automatic weather stations of the National Institute of Meteorology (Instituto Nacional de Meteorologia - INMET) for the period from 2010 to 2024. The root mean square error (RMSE), systematic bias error (MBE) and coefficient of determination (R 2 ) were calculated using monthly mean temperature data, in addition to principal component analysis (PCA), to identify spatial and seasonal patterns of errors. The accuracy of ERA5-Land was greater than 80% in most state, with an RMSE lower than 1.0 °C and a general trend of overestimation in the warmer months (September and October). The PCA revealed that the errors may be associated with regional differences and seasonality, with greater discrepancies during the dry season. Therefore, ERA5-Land satisfactorily reproduces the spatiotemporal variability in mean air temperature in Mato Grosso, proving to be a reliable tool for obtaining historical series and supporting regional agroclimatic studies.