ASSESSMENT OF THE FEATURES OF EXTREME LOW TEMPERATURES OF THE SURFACE AIR LAYER IN THE LAKE SEVAN BASIN (ARMENIA)

The study is aimed to assess the patterns of spatio-temporal distribution of the extreme low temperatures of the Lake Sevan basin, their impact on the surrounding natural landscape landscape. As the source material, observations of daily data on the extremes of the minimum temperatures of the surface air layer at seven meteorological stations of the basin for the entire period (1891-2018). The methods used are mathematical-statistical, extrapolation, analytic, correlation, cartographic. A correlation was obtained between the average annual and annual absolute minimum values, as well as between the annual absolute minimum temperatures and the height of the area above sea level. The obtained relationships can be used to assess the thermal conditions of unexplored or little studied territories. As a result, a map of the spatial distribution of the annual absolute minimum temperatures of the surface air layer in the lake Sevan basin was compiled. Main conclusions. An analysis of the trend lines of temporary changes in the absolute minimum air temperatures shows that, at all weather stations currently operating in the basin, the absolute minimum temperatures tend to increase both monthly and annual...

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VARIABILITY OF WINTER EXTREME LOW TEMPERATURES OF THE SURFACE AIR LAYER IN THE LAKE SEVAN BASIN (ARMENIA)

Sustainable Development of Mountain Territories ◽

10.21177/1998-4502-2020-12-4-523-531 ◽

2020 ◽

Vol 12 (4) ◽

pp. 523-531

Author(s):

Vardui MARGARYAN ◽

Keyword(s):

Low Temperatures ◽

Global Climate ◽

Temporal Trends ◽

Temporal Distribution ◽

Cold Air ◽

Lake Sevan ◽

Air Temperatures ◽

Long Time ◽

Spatio Temporal ◽

Surface Air Layer

The purpose of this work to study, analyze and evaluate the patterns of spatial variability of long-term fluctuations in winter extreme low temperatures of the surface layer of atmospheric air in mountainous territories of Armenia (for example, the lake Sevan basin). To achieve this goal, the results of actual observations by Armhydromet and the available literary sources have been collected, processed and analyzed. As a result of the analysis of the values of extreme low temperatures, it can be noted that the genesis of winter extreme low temperatures is different in the territories under consideration. Winter extreme low temperatures stand out for their uneven distribution – they range from -26.3 to -38.1. For the calculation of winter extreme low air temperatures of unexplored or poorly studied territories, correlations were obtained between the value of extreme low temperatures and the altitude of the area above sea level. In the study area, a tendency towards an increase in winter extreme low temperatures is mainly observed. The scientific novelty of the obtained results lies in the fact that in modern observational materials, for the first time, the regularities of the variability of the spatio-temporal distribution of winter extreme low temperatures of the surface air layer in the lake Sevan basin are estimated. Findings • The study of the patterns of variability of the spatial-temporal distribution of winter extreme low temperatures of the surface air layer under conditions of regional and global climate change is an urgent task of modern geographical science; • Winter extreme low air temperatures are mainly due to the nature of the underlying surface and the features of the relief. The smallest values are observed not in high-altitude zones, but in those places where cold air accumulates (that is, in depressions). In winter, in the hollow valleys, an inversion is mainly observed- in parallel with the height, the air temperature rises. In valleys, as a result of the accumulation of cold air, low temperature conditions can be observed for quite a long time; • The study area is distinguished by a characteristic regime and an uneven spatial distribution of winter extreme low temperatures. They range from -26.3 (Semenovka) to -38.1(Masrik). • Winter extreme low temperatures rise up to 2000-2100m with altitude, and on the contrary, they decrease at altitudes above 2000-2100m. The vertical temperature gradient is -0.5C/100m and 0.8C/100m, respectively; • On the basis of the obtained correlation between winter extreme low temperatures and terrain heights, two regions were identified: 1) heights up to 2000-2100m and 2) 2000- 2100m and higher; • Temporal trends during perennial winter extreme low temperatures are mixed. In the study area, these is a predominance of positive trends. Negative trends are characteristic for the period 1935-1966 at the Sevan, Masrik and Martuni meteorological stations; • In the study area, winter conditions become thermally milder, which should be taken into account when developing strategic programs for the future development of this area.

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ON THE THERMAL REGIME OF THE SURFACE AIR LAYER IN THE DEBED RIVER BASIN (ARMENIA)

News of the Tula state university. Sciences of Earth ◽

10.46689/2218-5194-2021-1-1-31-44 ◽

2021 ◽

Vol 1 (1) ◽

pp. 31-44

Author(s):

MARGARYAN V.G. ◽

Keyword(s):

River Basin ◽

Air Temperature ◽

Thermal Regime ◽

Time Course ◽

Temporal Distribution ◽

Thermal Conditions ◽

High Mountain ◽

Air Temperatures ◽

Using Data ◽

Surface Air Layer

The features of the thermal regime of the surface air layer in the Debed river basin are considered. A statistical analysis of the average annual and average seasonal values of air temperature from 1964 to 2018 was carried out, two periods were identified, their time course was shown. The analysis was carried out using data from six meteorological stations representing the lowland, mountain and high-mountain climatic zones of the Debed river basin. A correlation was obtained between the absolute altitude and the monthly average values of air temperature for January and July, which can be used to assess the thermal conditions of unexplored or poorly studied territories and for cartography. The time course of average values of air temperatures for the seasonal period has been studied. Analysis of trend lines of temporal changes in air temperatures shows that in all situations on the territory of the basin as a whole, there is a tendency of temperature growth. Moreover, with a range of interannual fluctuations, a break in the course of temperatures in the early to mid 1990 is clearly visible, after which their significant increase began. It turned out that a significant increase in seasonal temperatures is observed especially over the period 1993-2018, which means that the annual warming after the mid 1990 occurred primarily due to summer and spring seasons. The regular dynamics indicates that in the studied area in terms of temperatures, a tendency of softening winters, a decrease in the water content of rivers, aridization of the climate. The results obtained can be used to assess the regularities of the spatial-temporal distribution of the temperature of the study area, to clarify the thermal balance, for the rational use of heat resources, as well as in the development of strategic programs for longterm analysis.

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REGULARITIES OF THE SPATIO-TEMPORAL DISTRIBUTION OF WINTER MINIMUM TEN-DAY RUNOFF IN RIVERS OF LAKE SEVAN BASIN

News of the Tula state university. Sciences of Earth ◽

10.46689/2218-5194-2020-1-1-92-108 ◽

2020 ◽

Vol 1 (1) ◽

pp. 92-108

Author(s):

V. Margaryan ◽

◽

G. Avetisyan ◽

A.V. Polyakov ◽

◽

...

Keyword(s):

Temporal Distribution ◽

Lake Sevan ◽

Spatio Temporal

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About the features of the time course of the average annual air temperature in the territory of the Debed river basin (Armenia)

E3S Web of Conferences ◽

10.1051/e3sconf/202022303009 ◽

2020 ◽

Vol 223 ◽

pp. 03009

Author(s):

Varduhi Margaryan ◽

Gennady Tsibulskii ◽

Ksenia Raevich

Keyword(s):

River Basin ◽

Air Temperature ◽

Time Course ◽

Data Series ◽

Observation Data ◽

Air Temperatures ◽

Daily Data ◽

Long Term Observation ◽

Surface Air Layer

The article examines the features of the time course of the average annual air temperature in the Debed river basin in Armenia. As a starting material, we used daily data of actual observations of the temperature of the surface air layer for a year in the Debed river basin. The study was carried out at 6 meteorological stations in the Debed river basin based on long-term observation data series from 1930 to the present (2018). Analysis of the trend lines of temporal changes in air temperatures shows that at all meteorological stations currently operating on the territory of the basin, there is mainly a tendency for an increase in temperatures of annual values.

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Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia

Brazilian Journal of Biology ◽

10.1590/1519-6984.247073 ◽

2022 ◽

Vol 82 ◽

Author(s):

S. Boulaaba ◽

S. Zrelli ◽

A. Hedfi ◽

M. Ben Ali ◽

M. Boumaiza ◽

...

Keyword(s):

Linear Models ◽

Environmental Gradients ◽

Abiotic Factors ◽

Temporal Distribution ◽

Thermal Conditions ◽

Sodium Concentration ◽

Dominant Group ◽

Water Conductivity ◽

Northern Tunisia ◽

Spatio Temporal

Abstract In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models’ procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

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Zonal Patterns of Meteorological Drought on the Yunnan-Guizhou Plateau, China

Frontiers in Environmental Science ◽

10.3389/fenvs.2021.722285 ◽

2021 ◽

Vol 9 ◽

Author(s):

Hang Yu ◽

Long Wang ◽

Maoling Yang

Keyword(s):

Correlation Coefficient ◽

Sunshine Duration ◽

Temporal Distribution ◽

Natural Phenomenon ◽

Linear Regression Method ◽

Absolute Value ◽

Drought Characteristics ◽

The Absolute ◽

Spatio Temporal ◽

Guizhou Plateau

Drought is a natural phenomenon caused by a shortage of water resources and has a great impact on agriculture, the economy, and the environment. To study the Spatio-temporal distribution and explore the zonal patterns of drought, this paper took the Yunnan-Guizhou Plateau (YGP) as the research region, selected the air temperature, relative humidity, sunshine duration, wind speed, and precipitation data from 47 meteorological stations on the YGP. First, the standardized precipitation evapotranspiration index (SPEI) was calculated, and then the Spatio-temporal distribution of YGP drought was analyzed with the SPEI, Mann–Kendall test, and principal component analysis (PCA). Finally, the correlations between the average SPEI, drought characteristics extracted from the SPEI, and longitude/elevation/latitude were analyzed with the linear regression method, and then the zonal patterns of the YGP drought were obtained. The results revealed that the annual and seasonal SPEI values mainly decreased. Because the first component of the SPEI (the largest eigenvalue makes it the most important component) in annual and winter had a poor relationship with longitude/elevation, its correlation was weak, while the average SPEI values in other seasons were significantly correlated with longitude/elevation (α = 0.001), and the absolute value of the correlation coefficient was between 0.6879–0.9453. Except for PC1 in annual and winter, PC1 and PC2 were significantly correlated with longitude/elevation (α = 0.001), and the absolute value of the correlation coefficient was between 0.5087–0.9501. The duration, severity, intensity, frequency of drought were significantly correlated with longitude/elevation (α = 0.001) in most situations. The average SPEI values and drought characteristics showed a good multivariate linear correlation with longitude, latitude, and elevation, indicating that drought exhibited strong zonal patterns. This study will provide new ideas for drought research and technical support for regional industrial layouts, planting structure adjustments, and drought and disaster reduction.

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