ESTIMATION OF TENDENCIES IN THE HEIGHT OF THE SNOW COVERAT WEATHER STATIONS IN THE NORTHERN CAUCASUS

Introduction. Against the background of global warming observed in recent decades, changes in all climatic characteristics are taking place. In the era of global warming, as the air temperature rises, the moisture content of the air masses also increases, therefore, the amount of snow falling increases in cold regions. This indicates a high sensitivity of the snow cover to any changes in the composition of the atmosphere and its circulation. Snow cover is an important component of the natural environment during the winter. In this work, the assessment of trends in the height of snow cover at three meteorological stations in the North Caucasus, located in different climatic zones, is carried out. For the analysis, data from observations of snow cover for the period 1961- 2018 were used. Materials and research methods: To obtain the results of changes in the snow cover regime from 1960/1961 to 2017/2018. On the territory of the Caucasus region, the averaged series of snow cover characteristics were studied according to data from 3 meteorological stations: Prokhladnaya, Nalchik and Teberda. Using the statistical software package SPSS 13.0, the following statistics were calculated: mean (standard error), standard deviation, minimum, maximum, range, skewness coefficient, kurtosis coefficient, extreme values, climatic norm, Kolmogorov-Smirnov test for normal distribution curve, T- test for comparing the equality of the mean with the climatic norm. Linear trends, the rate of change of the meteorological parameter were obtained, the stability of climatic changes was assessed, and anomalies were identiied for each series under study. Research results and their discussion: To assess the change in the characteristics of the snow cover, data from the series of the snow cover depth in the cold seasons of 1961-2018 were used (from October to April for 1960/612017/18). Seasons from October to April 1960/1961, 1961/1962, ... , 2017/2018 hereinafter, for brevity, they are written as 1961, 1962, 2018. When analyzing the average ten-day snow cover, for example, in 1961, data from October, November, December 1960 and January, February, March and April 1961 were used. In the course of the study, the sustainability of climatic changes was assessed. As its integral characteristic, the Hurst exponent (H) was used, which showed the trend stability and a stable tendency to increase the height of the snow cover at the studied m/stations. The standard deviation а was used as a measure of the typical variability of snow cover (SC) over the period 1960/61-2017/18. For each row of meteorological parameters, the minimum and maximum values of the SC altitude were calculated. To identify anomalies, deviations of the current values from the long-term average for the period 1961-1990 were investigated (climatic norm). The analysis of changes in the height of snow cover for the entire period of the study (1961-2018) and during the period of global warming (from 1976 to 2018) was carried out. Studies have shown that for the period from 1961 to 2018 at all m/stations, there was an increase in the growth rate of the average 10-day snow cover, with its subsequent increase in the period from 1976. The extreme values are revealed for all studied series. The analysis of the average 10-day SC altitude by months (October-April) was carried out in order to identify the medium-snow and little-snow months. Conclusions. Analysis of changes in the growth rate of the average ten-day snow cover showed that there was an increase, both in the baseline (19612018) and in the period 1976-2018. For all the studied series of mean ten-day snow cover, the Hurst exponent demonstrates a high trend resistance of the series. It was revealed that for the entire period of research there are fewer positive anomalies than negative ones. Over the entire observation period at the considered m/stations, 9 extreme values of the height of the snow cover were identified. In the modern period, there has been an increase in the number of extreme values of the average ten-day snow cover by 3.5 times (7: 2) compared to the base period.

meteorological station, average ten-day snow cover, linear trend, Hurst exponent, extrema, anomalies

1. Доклад об особенностях климата на территории Российской Федерации за 2020 год. Росгидромет. Москва, 2021. 104 с.

2. Кренке, А. Н., Китаев, Л. М., Турков, Д. В. Климатическая роль изменений снежного покрова в период потепления // Известие РАН. Сер. геогр. 2001. №4. С. 44-52.

3. Булыгина, О. Н., Коршунова, Н. Н., Разуваев, В. Н. Критерии экстремальности климатических явлений в температурном режиме и режиме осадков на территории России // ТРУДЫ ГУ «ВНИИГМИ-МЦД», 2008. № 173. С. 120-125.

4. Булыгина О. Н., Коршунова Н. Н., Разуваев В. Н. Изменение характеристик снежного покрова на территории России в последние десятилетия // Труды ВНИИГМИ-МЦД, 2007. № 173. С. 54-62.

5. Ашабоков Б.А., Ташилова А.А., Кешева Л.А. «Климатические характеристики снежного покрова Северного Кавказа и их изменения в период глобального потепления», Материалы Международной научно-практической конференции «Глобальные вызовы современности и проблемы устойчивости развития Юга России», Россия, КБР, г Нальчик, КБНЦ РАН, 2015. С. 258-264.

6. Ашабоков Б.А., Ташилова А. А., Кешева Л.А. «Сравнительный анализ динамики количества экстремальных характеристик снежного покрова на юге России», Материалы Всероссийской конференции с Международным участием «Устойчивое развитие; проблемы, концепции, модели», Россия, КБР, г. Нальчик, КБНЦ РАН, 2017. С. 118-121.

7. Hurst H. E., Black R. P., Simaika Y. M. Long-termstorage: An experimental study. L.: Constable, 1965. 145 с.

8. Кроновер Р. М. Фракталы и хаос в динамических системах. Основы теории. Москва: Постмаркет, 2000. 352 с.

9. Федер Е. Фракталы / Е. Федер: пер. с англ. М.: Мир, 1991. 254 с.

10. Глоссарий терминов. МГЭИК, 2001. Специальный доклад Рабочей группы III МГЭИК [под редакцией Б. Метца, O. Р. Дэвидсона и др. ]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 466 с.

11. Ашабоков Б. А., Ташилова А. А., Кешева Л. А. Сравнительный анализ динамики количества экстремальных характеристик снежного покрова на юге России // Устойчивое развитие; проблемы, концепции, модели: Материалы Всероссийской конференции с Международным участием. Нальчик, 2017. С. 118-121.