Dynamics of Daily Precipitation Characteristics in the Western Caucasus

Abstract

The practice of tracking climate fluctuations is based on the analysis of series of values of surface temperature and precipitation observed at meteorological stations. Studies of the precipitation regime in the Western Caucasus show that calculations do not reveal statistically reliable dynamics in the mean annual precipitation totals in the presence of perceptible climatic changes. The purpose of this work is to investigate current changes in the characteristics of daily precipitation totals in the Western Caucasus. Materials and methods. The basis for the calculations are observations at weather stations provided in specialised arrays of the VNIIGMI-MDC. The research method is mathematical-statistical modelling. Results and discussion. It has been found that, despite significant local differences in precipitation regime, an increase in the number of days with precipitation of different intensity, an increase in average and/or maximum values of their daily intensity in October are the general trends in the study area. In most locations, trends of an increase in the number of days with precipitation of different intensities and the average daily and maximum daily totals in March have been identified. Statistically significant downward trends in various daily intensity characteristics in the West Caucasus were found in winter, April and August. Conclusion. Despite the local peculiarities of the precipitation regime, some general trends can be noted. Firstly, an increase in the values of various characteristics of the precipitation regime in October, an increase in the number of days with precipitation of various intensities, an increase in the average and/or maximum values of their daily intensity have been found across the board. And since in the region flooding in October is a fairly frequent phenomenon, the statistically reliable trends found indicate that the probability of occurrence of hazardous natural phenomena depending on the intensity and frequency of precipitation in this month does not decrease. Secondly, an increase in the number of days with precipitation and daily characteristics in March (with the exception of Shajatmaz weather station). Thirdly, a decrease in the daily intensity of precipitation in winter, April and August. Against the background of no significant changes in annual precipitation totals, their redistribution within the year was established and statistically reliable linear trends in daily precipitation characteristics, which can affect the river flow regime in the region and the formation of dangerous hydrological phenomena on them, were revealed.