Evaluation of ERA5 reanalysis temperature data over the Qilian Mountains of China

Air temperature is an important indicator to analyze climate change in mountainous areas. ERA5 reanalysis air temperature data are important products that were widely used to analyze temperature change in mountainous areas. However, the reliability of ERA5 reanalysis air temperature over the Qilian Mountains(QLM) is unclear. In this study, we evaluated the reliability of ERA5 monthly averaged reanalysis 2 m air temperature data using the observations at 17 meteorological stations in the QLM from 1979 to 2017. The results showed that: ERA5 reanalysis monthly averaged air temperature data have a good applicability in the QLM in general(R2=0.99). ERA5 reanalysis temperature data overestimated the observed temperature in the QLM in general. Root mean square error(RMSE) increases with the increasing of elevation range, showing that the reliability of ERA5 reanalysis temperature data is worse in higher elevation than that in lower altitude. ERA5 reanalysis temperature can capture observational warming rates well. All the smallest warming rates of observational temperature and ERA5 reanalysis temperature are found in winter, with the warming rates of 0.393°C/10a and 0.360°C/10a, respectively. This study will provide a reference for the application of ERA5 reanalysis monthly averaged air temperature data at different elevation ranges in the Qilian Mountains.