Variability, trends and the climatic norms of days with precipitation in Stavropol

Standard climatic norms of the number of days with precipitation were calculated for the 1991–2020 base period using observations from the Stavropol meteorological station.

The days with atmospheric precipitation and the days with traces of precipitation were taken into account. The days with ground condensation were not taken into account. Standard climatic norms of the number of days with precipitation, both overall and by individual gradations, were calculated for the year, warm and cold periods, seasons, and all months. For all listed time intervals, the maximum and minimum values for the number of days with precipitation are provided, and the main statistical characteristics are calculated. Calculations of climatic norms for days with traces of precipitation, as well as for days with daily precipitation in gradations of ≥ 0.1 mm, ≥ 1.0 mm, ≥ 5.0 mm, and ≥ 10.0 mm were performed.

Graphs of the annual variability of the average number of days with precipitation by gradation were constructed, as well as graphs of the 30-year variability of the annual and seasonal number of days with precipitation, the number of days with precipitation by season, and the annual number of days with precipitation by gradation. The analysis of daily precipitation totals for large gradations (≥ 20.0 mm, ≥ 30.0 mm, ≥ 50.0 mm) was conducted by directly examining the number of days with precipitation of the specified gradations for each year. The characteristics of extended periods without precipitation, as well as days with precipitation reaching hazardous levels, were analyzed. Trend equations were derived from the analysis of the 30-year variability of all these parameters.

The comparison of the obtained data with data for various long-term periods of the 20th century revealed a trend toward a long-term change in the frequency of days with precipitation, declining both in terms of the annual number of days and in terms of their number during cold and warm periods. However, over the past 30 years, against a backdrop of a decrease in the number of days with precipitation during the cold period and overall, a slight increase in the frequency of days with precipitation during the warm period is observed.

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