Quantitative Climate Indicators Applied to the Assessment of Hydrothermal Conditions in the Republic of Kalmykia
N. A. Shumova
Abstract
The study assesses the reliability of the description of hydrothermal conditions in the territory of Kalmykia with the use of quantitative climate indicators based on air-temperature and precipitation data that are available in databases and are widely used in climate models. The present study considers the use of the Selyaninov hydrothermal coefficient, the precipitation-evaporation coefficient, the Thornthwaite aridity index, the Köppen method, and the Holdridge scheme. Quantitative climate indicators were estimated for 1966–2017 based on data on the average monthly air temperature and total monthly precipitation at Yashkul’ weather station located in the Chernye Zemli strict nature reserve, which is the most arid part of the Republic. The estimated values of Selyaninov hydrothermal coefficient for the considered period corresponded to natural zones of deserts in two cases, semideserts in 19, and steppes in 31. With the precipitation-evaporation coefficient, the climate conditions corresponded to semidesert in 45 cases and steppe in seven. The values obtained with Thornthwaite aridity index were inherent for deserts and hyperarid regions. According to the Holdridge scheme, the hydrothermal conditions matched steppe zones in 25 cases and deserts in 27. The reliability is highest for climate assessments produced with the involvement of Selyaninov hydrothermal coefficient, which indicate humid warming in Kalmykia and are supported by material collected via the observation of plant communities that form on the ameliorated lands of Priergeninskaya Plain. The presence of humid warming is also supported by estimates based on the Köppen method, the Holdridge scheme, and, to a lesser degree, the precipitation-evaporation coefficient. The assessment involving the Thornthwaite aridity index points to an intensified climate aridization, which is not in line with the modern dynamics of climate conditions in Kalmykia and is thus not reliable.