Spatial–Temporal Analysis of the Air Temperature, Precipitation, and Aridity Index on the Territory of the Lake Baikal Basin

The territory of the basin of Lake Baikal is a complex mosaic of oroecosystems, in which anthropogenic and natural processes lead to significant and often difficult-to-predict changes in the structure of both individual ecosystems and the entire complex. The aim of this work was a spatiotemporal analysis of some climatic parameters as the primary link in energy and mass exchange, which sets the general trend in the development of ecosystems: average values of the air temperature, precipitation, and aridity index. For the period from 1975 to 2019, climate data were obtained on the average daily air temperature from 84 weather stations and on the amount of precipitation from 72 weather stations. The obtained climate data were divided into five-year periods and processed in ArcMap 10.7 and Qgis 3.16 GIS; statistical preparation was carried out in the Python 3.10 programming environment. The construction of precipitation and temperature distribution rasters was carried out using the Spline interpolation method. We have constructed a series of maps of the distribution of the average air temperature values, total precipitation, and the Morton aridity index, as well as a series of large-scale maps of the distribution of average air temperature values, taking into account the morphometric features of the Earth’s surface. It is noted that the most stable directional changes in annual air temperature are observed in the Russian part of the basin, and the highest rate of transformation of the temperature field in annual values is characteristic of the mountainous regions of the Mongolian part (the spurs of Khangai and Khentii). The main share of the increase in the annual air temperature values occurs during the warm period, and it is formed due to the Mongolian part of the basin. The greatest variability in the amount of precipitation during the warm period corresponds to the mountainous regions of Khangai (the southwestern part of the basin, the Zavkhan aimag, and the southwestern part of the Khuvsgol aimag), as well as the valley complex of the Orkhon–Selenga interfluve. There are strong differences in the temporal dynamics of precipitation of the cold period between the northern and southern parts of the basin. Thus, for the period 1975–2019, the increase in precipitation in the Russian part was only 4%, while in the Mongolian part, it was about 40% of the average value of precipitation during the cold period of 1975–2019. The territory is characterized by multidirectional changes in the values of the aridity index. Two large areas of increasing aridity have been identified: the southern and central parts of the Bulgan aimag, together with the eastern end of the Arkhangai aimag, represent the Mongolian area of increasing aridity, and the central part of the Republic of Buryatia is the Russian area of aridity. Details of the methodology for constructing rasters and for processing the initial data are located in the database GIS Ecosystems of the Lake Baikal Basin (available at https://mon-exp.nextgis.com/resource/12/display?panel=layers), which also presents a detailed analysis of the climate parameters considered, both on the scale of the entire basin and at the level of its individual administrative–territorial units.