We study aridity in Buryatia (Russia) during the summer periods from 1979 to 2019. Selyaninov's hydrothermal coefficient (HTC) was used as a aridity criterion. The HTC was calculated on the basis of precipitation and 2 m temperature data from two datasets: meteorological stations that are freely available [meteo.ru] and the ECMWF ERA5 project [Hersbach, H. et al. The ERA5 Global Reanalysis QJRMS 2020. doi:10.1002/qj.3803]. Comparison of HTC calculations for these two data sets was performed. The ERA5 data show underestimated HTC values ​​compared to the station data. The worst data fit is typical for June, as well as for stations in western Buryatia (Eastern Sayan and Tunka Valley) in all summer months. The good agreement of HTC is typical for central and southern stations. The inconsistencies found are mainly related to the underestimation of the precipitation amount in the ERA5 project compared to the observational data.

The study was financially supported by the Ministry of Science and Higher Education of the Russian Federation (Subsidy no.075-GZ/C3569/278) and the grant No. 075-15-2020-787 for implementation of Major scientific projects on priority areas of scientific and technological development (the project «Fundamentals, methods and technologies for digital monitoring and forecasting of the environmental situation on the Baikal natural territory»).