АНАЛИЗ ТЕМПЕРАТУРНОГО РЕЖИМА В РАВНИННОЙ ЗОНЕ ЮГА ЕВРОПЕЙСКОЙ ТЕРРИТОРИИ РОССИИ ЗА ПОСЛЕДНИЕ 65 ЛЕТ (перевод оригинальной публикации на английский язык)

Now the problem of climate change has become serious and pressing areas of scientific and technological activity. It has been observed in various regions of the world, and the consequences that manifest themselves at the global and especially at the regional levels

A large number of studies

The quality of meteorological parameter data (homogeneity and representativeness) is very important. Time series are considered homogeneous if the variations represented by these series are the result solely of changes in weather and climate. In this paper, hydrometeorological observation data from weather stations of the Roshydromet state observation network, provided by the North Caucasus Hydrometeorological Service, were used. The temperature series data are homogeneous, representative, and contain no gaps. Throughout the period 1961–2024 the station locations remained constant, with no changes in the station environment (no urbanization of the weather station locations).

The object of this study is temperature changes in the flat zone of the southern ETR from 1961 to 2024. The plain zone (elevation less than 200 m above sea level, m a.s.l.) occupies most of the southern ETR and extends from the Black Sea to the Caspian Sea. The study was conducted using data from seven weather stations: Izobilny (194 m above sea level), Mozdok (126 m a.s.l.), Prokhladnaya (198 m a.s.l.), Derbent (30 m a.s.l.), Izberg (21 m a.s.l.), Kizlyar (-17 m a.s.l.), and Makhachkala (173 m a.s.l.).

The study was conducted for seasonal and annual average surface air temperatures from 1961 to 2024 and subperiods (1961–2000 and 2001–2024). The time series were analyzed using statistical methods

Anomalies were calculated as the deviation of current values ​​from the climate norm (average for 1991-2020).

Minimum and maximum temperatures were selected from the averaged values ​​of seasonal and annual series from all weather stations for the periods: 1961–2024, 1961–2000, 2001–2024.

The linear trend coefficients were estimated according to standard linear regression theory (using the least squares method)

D= (1-( s2rem / s2rows)) ∙100%

s2rem — the variance of the residuals; s2rows— the variance of the original series.

To construct a temperature distribution map for the study area, the Surfer6.0 program

Table 1 shows that from 1961 to 2024, the average annual air temperature in the flat zone averaged 11.9°C, with the minimum of the average temperature series (9.8°C) occurring in 1993 and the maximum (13.8°C) occurring in 2024. In the period 2001–2024 the temperature increased to 12.7°C compared to 11.4°C (1961–2000), with the maximum average annual temperature increasing from 13.1°C to 13.8°C and the minimum average annual temperature increasing from 9.8°C to 11.5°C.

The maximum and minimum values ​​were selected from the average values ​​of the lowland zone series for studying the dynamics of temperature change. All maximum values ​​of seasonal average temperatures occurred in the modern period from 2010, and all minimum values ​​occurred from 1969 to 1993, which once again confirms the fact of a steady increase in the average surface temperature in the region.

The largest increase occurred in the average summer temperature, which rose by 1.5°C, from 22.9°C (1961–2000) to 24.4°C (2001–2024). The maximum average summer temperature increased by 1.0°C, and the minimum average winter temperature increased by 1.9°C, from -3.9°C to -2.0°C, confirming climate warming in the region.

Climate change was also assessed using correlation analysis. The slope of the linear trend, b, was used to characterize the rate of change in average annual and average seasonal temperatures, as well as their increase or decrease. In all periods and seasons under consideration, the rate of temperature increase had a positive trend, with the exception of the average autumn temperature in the period 1961–2000. During this period the rate of increase in average annual temperature was b1=0.04°C/10 years with an insignificant coefficient of determination (D=0.26%). At the beginning of the 21st century, the rate increased significantly to b2=0.59°C/10 years, with D=49.6% (Table 1, Fig. 1). Thus, since the beginning of the 21st century, the region warming clearly demonstrates a significant increase in the linear trend coefficient over the period 2000-2024.

Table 1 shows that the highest growth rate is observed for average winter and summer temperatures, as illustrated in Figure 1.

The course of average annual and seasonal temperatures with trends:

a - winter; b - summer; c - year

DOI:10.60797/IRJ.2026.167.94.2

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Another common approach to analyzing modern climate change trends is calculating average annual temperature anomalies relative to standardized values. Average annual air temperature anomalies in the lowland zone of southern ETR were calculated as deviations from average values ​​for 1991–2020.

Figure 2 shows average annual surface air temperature anomalies for the period 1961–2024 with an 11-year moving average. Variations are visible, with predominantly negative temperature deviations for 1961-2000 and predominantly positive ones for 2001–2024. Since the late 1990s, a steady increase in air temperature has been observed, as can be seen in Figure 2 (11-year moving average of temperatures). Since 2012, there have been exclusively positive anomalies in average annual temperatures, with the maximum positive anomaly observed in 2024 and amounting to +1.6°C. The largest negative anomaly occurred in 1993 and amounted to -2.4°C relative to the 1991–2020 climate norm.

Change in anomalies of average annual surface air temperature in the flat zone of southern ETR

deviations from the 1991-2020 average; the bold line shows the smoothed temperature trend (11-year moving average)

DOI:10.60797/IRJ.2026.167.94.3

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The climatic features of the flat zone of southern ETR are determined by a number of factors, including the orographic heterogeneity of the territory

[15]

. Using data from

[16]

, a distribution map of average annual temperatures in all climatic zones of ETR (Fig. 3) was constructed using Surfer 6.0

[14]

, a program for visualizing data from GRD files.

Figure 3 - Annual distribution of average temperatures in various climatic zones of the southern ETR

DOI:10.60797/IRJ.2026.167.94.4

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To detail the climate changes occurring in the study area, two subzones were identified: Caspian zone and steppe zone. The steppe zone includes the Izobilny, Mozdok, Prokhladnaya weather stations. The Derbent, Izberg, Kizlyar, and Makhachkala stations belong to the Caspian zone.

Figure 4 presents the average annual and seasonal temperatures in the identified zones for 1961-2024. The figure shows that average temperatures in all seasons are higher in the Caspian zone. The difference in average annual temperatures is 1.8°C, and 1.1°C in the summer, particularly in the winter and autumn seasons, when the difference between temperatures is more than 3.0°C. This situation is a consequence of the fact that in the arid region of the Caspian lowland, to which this area belongs, when the ground layers of air are heated, very little energy is spent on evaporation, that is, all the long-wave radiation from the heated surface is used to warm the ground layer of air.

Figure 4 - Average annual and seasonal temperatures in the steppe and Caspian zones of the southern ETR for 1961-2024

DOI:10.60797/IRJ.2026.167.94.5

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Additionally, linear trend calculations were performed for average annual and seasonal temperature changes in the zones under consideration for 1961–2024, as well as for the two subperiods 1961–2000 and 2001–2024 (Table 2).

At the beginning of the 21st century, a more intense increase in surface air temperature is observed than for 1961–2000 in the steppe and Caspian zones. For average seasonal temperatures for 2001-2024 in both zones, a general pattern was observed: the highest growth rate has been observed in the summer season in both zones and amounts to 0.8°C/10 years in the period 2001–2024 with D=40.1% in the steppe zone and 46.3% in the Caspian zone, followed by the winter season with an increase rate of 0.7°C/10 years with D=10.0% to D=12.2%.

A study analyzing temperature changes in the flat zone of southern ETR showed that the average annual temperature has increased by 1.3°C between 2001 and 2024 compared to the period 1961-2000. The largest increase occurred in the summer temperature. In all periods the annual and seasonal temperature increase rates showed a positive trend, with the exception of the autumn temperature between 1961 and 2000. Since the 21st century, the annual temperature increase rate increased statistically significantly, reaching 0.59°C/10 years, with D=49.6%. Analysis of annual temperature anomalies revealed that, since 2012, only positive annual temperature anomalies were fixed, with the maximum positive anomaly observed in 2024.

Analysis of temperature changes in the Caspian and steppe zones revealed that average temperatures in all seasons are higher than in the steppe zone. Comparing the trends between the two time periods reveals that, while negative trends were observed in the period 1961–2000, and all trends were statistically insignificant, all trends in the period 2001–2024 were positive and significant, in both zones.

Such changes in average annual and seasonal air temperatures indicate increasing warming in the flat zone of southern ETR.