It is impossible to organize wind energy systems without studying of wind speed regime at the surface layer of the atmosphere within a specific area and at climatic scales. Such studies are often accompanied by approximations of probabilities of wind speed performed in the form of normal law of a system of random values presented by a zonal u and a meridional which are components of a wind speed vector. It is suggested that, for the purposes of wind energy, display of a wind speed vector in polar coordinates (r,a) r – where is a module of wind speed and a – is a polar angle appears to be more preferable. The article shows a transform from a normal law of distribution of probabilities with density ф(u,v) to a normal law distribution with density ф(r,a) completed by means of functional transformation with elliptic dispersion in place. Based on a normal law of distribution ф(r,a) and through integration with respect to corresponding variables (r,a) individual distributions of probabilities ф(r) and ф(a) as well as conditional distributions of probabilities ф(r/a)and ф(a/r)were obtained in the areas of their existence. The article shows individual distributions in case of circular and elliptic dispersion of a wind speed vector. It shows that an individual distribution of a wind speed probability in case of circular
dispersion and in the absence of correlated dependence turns into the Rayleigh’s distribution and a conditional distribution of a polar angle degenerates in an even distribution. The cases of distributions with dispersions of a wind speed module having elliptic properties subject to availability of correlated connection between wind speed components were also studied. Calculation of probabilities of a polar angle being within different sections of the area 0≤α≤2π with set values of a wind speed module also took place. Numerical experiments proved the advantage of such modeling of distributions of wind speed vector.
Cold-core lows are poorly understood cyclones, but they significantly impact on the formation of weather conditions in Ukraine, especially in its central and western regions.
In the paper, the evolution of a cold-core low, which is associated with the enlargement of rain-fall areas with thunderstorms over the Western Europe and Ukraine. The low formed on July 21tst, 2014, in a deep cold trough of a Rossby wave over Atlantic Europe. During period 21-24 July the low was moving to the East and there were precipitation zones under its eastern part. Therefore, sizes of precipitation zones cannot always be explained by impact of front and thermic instability, in this paper it is tried to assess hydrodynamic instability in forming of precipitation in a cold-core low. The research method is based on the use of the linear theory of the hydrodynamic instability of the zonal flow with Rossby waves.
To investigate barotropic instability fields of meridional profiles of absolute vorticity. It is shown that flow in which the low moved was barotropic unstable. Using baroclinic instability characteristics (Phillips’s criterion) Baroclinic zones were revealed in atmospheric fronts and in northern part of area in question.
It has been shown that hydrodynamic instability, both barotropic and baroclinic, in the eastern part of the cold-core low leads to intensification of atmospheric processes on the fronts, which was revealed to strengthening of precipitation and in the enlargement of zones of their formation.
At the end of the XX century and at the beginning of the XXI century climate change was one of the major problems of international community. Today the problem is still relevant. This is dueto a significant change of living conditions of population, especially due to thermal regime change which serves as the main factor directly determining comfort of weather and heat balance of a human body.
In winter period weather comfort depends on the combination of low temperature and high wind speed. It enhances a negative impact on human beings and indicates winter severity in general. This article describes discomfort of weather conditions during winter season in Ukraine. Basic characteristics of thermal regime and wind regime reflecting general features of discomfort during this season are discussed. Estimate of discomfort also includes calculation of comfort indexes – special mathematical formulas that formalize the influence of main meteorological parameters on a human body.
Since the beginning of the XXI century there is a tendency to reduction of cold discomfort in Ukraine. Such reduction is associated with reduction of the Bodman index values. The Siple and Passel index (atmosphere cooling capacity) has the same tendency. In most regions of Ukraine the reality of such changes for both indexes constitutes 90–99 %.
The purpose of this work consists in identifying the main trends of present-day formation and distribution of ground frosts throughout Ukraine. For this purpose the analysis of a minimum air temperature field has been conducted based on observation data at 186 stations of Ukraine for the period from 1991 to 2014. It is known that extreme values of air temperature are much more informative than its average values. Therefore analyses of meteorological extreme values usually lead to more substantial and qualitative results.
In the course of the work, occurrences of frost in April, May and September have been studied separately from each other while these three months are deemed to be the most dangerous in terms of frosts’ frequency and negative impact. In order to identify trends to occurrence of this dangerous weather phenomenon a comparison of two decades of 1991-2000 and 2001-2010 has been made.
In addition, the latest observation period of 2011-2014 has been considered separately taking into account the results of comparative analysis of two preceding decades.
The results of the work indicate a decrease of number of September days having this dangerous weather phenomenon during the last few years. However, recurrence of frosts remains stably high in April while in May it appears to be high only in certain years. The obtained results also indicate the fact that the northern and northeastern territories of Ukraine appear to be the most vulnerable to frosts.
Thus it should be noted that a threat of adverse consequences caused by ground frosts is still there and remains to be quite high, especially for agriculture.
The decision about writing this article was made after familiarization with the “Brief Climatic Essay of Dnepropetrovsk City (prepared based on observations of 1886 – 1937)” written by the Head of the Dnipropetrovsk Weather Department of the Hydrometeorological Service A. N. Mikhailov.
The guide has a very interesting fate: in 1943 it was taken by the Nazis from Dnipropetrovsk and in 1948 it returned from Berlin back to the Ukrainian Hydrometeorological and Environmental Directorate of the USSR, as evidenced by a respective entry on the Essay’s second page.
Having these invaluable materials and data of long-term weather observations in Dnipro city we decided to analyze climate changes in Dnipropetrovsk region.
The article presents two 50-year periods, 1886-1937 and 1961-2015, as examples. Series of observations have a uniform and representative character because they were conducted using the same methodology and results processing.
We compared two main characteristics of climate: air temperature and precipitation.
The article describes changes of average annual temperature values and absolute temperature values. It specifies the shift of seasons’ dates and change of seasons’ duration.
We studied the changes of annual precipitation and peculiarities of their seasonable distribution. Apart from that peculiarities of monthly rainfall fluctuations and their heterogeneity were specified.
Since Dnipro city is located in the center of the region the identified tendencies mainly reflect changes of climatic conditions within the entire Dnipropetrovsk region.
In the paper it is outlined the main methodological positions and the results of the approbation of new approaches to the integrated assessment of the potential of crop yields.
There are considered the theoretical foundations of a joint assessment of the biological, ecological and anthropogenic components of the yield potential of agricultural crops which are based on the ecosystem concept and the mathematical model “Weather-Crop Yield” developed by V. P. Dmytrenko. In the considered approaches the peculiarities of the influence of various environmental factors on the formation of crop yields are determined by indicators of various potential yields – general, climatic and trend (agrotechnological). Each type of yield potential can be used for evaluation of the effectiveness of the conditions of field crop growing for each factor taken into account, as well as the optimality criterion in the agrometeorological adaptation strategies and also as a criterion for the degree of sensitivity of the yield level to the conditions of crops cultivating.
The developed approaches are tested on the example of estimation of long-term dynamics of winter wheat yield potential in Ukraine. According to the results of the evaluation of different factors of the potential of the productivity of winter wheat for the periods 1961-1990 and 1991-2010 the dominant importance of organizational and technological processes in comparison with the contribution of changes of agroclimatic conditions has been determined in both periods.
Article in question investigates indicators of the moisture-temperature regime for the period of 1986 – 2005 (base period) and compares them to their expected changes calculated for different scenarios of climate change GFDL-30 %, A1B, A2, RCP4,5 and RCP8,5 for the period of 2021 – 2050 on the territory of Ukraine. Calculations reviled that most abrupt changes in moisturetemperature indicators in different soil-climatic zones of Ukraine can be expected in case of scenarios GFDL-30 %, А1В and А2. In case of scenarios of climate change RСР4,5, RСР8,5 thermal indicators are expected to be at the level of multilevel averages in all natural and climatic zones of Ukraine, except for Southern Steppe, where they are expected to grow. The greatest changes in all areas are expected under scenario GFDL-30 %, and they will increase from north to south. Under scenario А1В the greatest difference between calculated values and average multi-year values will be observed in the Forest-Steppe zone and in the Southern Steppe. Under scenarios RCP4,5 и RCP8,5 significant changes in the temperature regime are predicted only for the south and east of Ukraine. At the same time, according to the scenario of RCP4.5, a significant increase in seasonal winter air temperatures is forecasted.
Analysis of the results of calculations for different climatic scenarios of water availability indicators for different natural and climatic zones of Ukraine for the period from 2021 to 2050 reviled that the most drastic changes in the climatic parameters of humidification are expected in the case of the scenarios GFDL-30 %, A1B and A2. In case of climate change scenarios RCP4.5, RCP8.5, no quick changes in the distribution of precipitation over the territory of Ukraine should be expected. The greatest amount of precipitation for the year and in average for the seasons of the year is projected for the western regions of the country, the least one – for the southern regions. At the same time, for most regions the trend to increase the amount of precipitation is most likely in the case of the development of the GFDL-30 %, A1B and A2 scenarios. However, according to the scenarios RCP4.5 and RCP8.5, rainfall is expected to decline for the year as a whole and especially in the summer season in comparison with the actual for 1986 – 2005.
Climate change is one of the major global issues. Climate is one of the most significant factors
determining the level of crop yields, including sunflower crops. Currently the sunflower planting
acreage in Ukraine has already reached its maximum value. Therefore the potential for increasing sunflower production should be aimed at increasing its yield.
To assess the impact of climate change on sunflower productivity the article considers modern scenarios of RCP (Representative Concentration Pathways) such as RCP 4.5 and RCP 8.5. They belong to the scenarios of medium and high levels of greenhouse gas emissions. The RCP 4.5 and RCP 8.5 scenarios cover the climatic period from 2021 to 2050. In order to conduct a comparative analysis of scenario meteorological values with previous data from the Agroclimatic Reference Book of Ukraine, the period from 1986 to 2005 was taken. It serves as a basic period for calculations.
Calculations were made for the following natural and climatic zones of Ukraine: East Forest-Steppe, Northern and Southern Steppe.
The article studies the influence of agroclimatic conditions on sunflower cultivation as per two interphase periods: shoots – blooming and blooming – picking maturity.
Study of sunflower productivity formation was carried out using a mathematical model of the water-heat regime and sunflower productivity. The model is based on the system of equations of radiation, heat and water balances and biomass balance in vegetation cover.
According to calculations a lowered temperature regime and sufficient moisture in the first half of sunflower vegetation season will favor the formation of leaves way more than during the basic period within the entire area under study. However, expected arid conditions in the second half of vegetation period will cause a very low sunflower moisture availability during this period which would lead to reduction of sunflower seeds’ crop-producing power. Analysis of agroclimatic conditions during vegetation season from sunflower shoots to its picking maturity showed that implementation of both scenarios would ensure expected weather conditions to be more favorable for sunflower growing in the eastern forest-steppe zone of Ukraine. The greatest risk of sunflower crops shortfall in certain years is expected in the southern steppe zone of Ukraine and significant losses should be expected in case of scenario RCP4.5 implementation.
The article includes the data of long-term monitoring observations taken from 60 meteorological stations located at 450-3200 m above the sea level. It presents the results of study of time of occurrence, duration and spatial variability of bioclimatic rhythms of main ecotypes of agricultural crops under the conditions of high altitudes of the Republic of Armenia. It was found out that vertical gradients of the average periods of main phases of grow of winter wheat, potatoes, grapes and livestock pasturage within highland pastures fluctuate within 3-5 days / 100 m. Agro-ecological conditions for bioclimatic rhythms along high-altitude zones are estimated. The high-altitude regularities are determined and correlation dependence curves of time of occurrence of bioclimatic rhythms from absolute altitude are identified with specification of ways for optimizing heat and moisture availability and productivity of these crops. The probability of crop damage from drought, frosts in different periods of vegetation is calculated. Agro-climatic parameters of critical periods of growth and development of crops under study within high-altitude zones are determined which makes it possible to ensure production of stable and high yields. It became clear that the highest altitude for obtaining two crops a year after harvesting early spring grains, vegetables, potatoes is 1400 m above the sea level – in arid regions and 1200 m – in wet regions. It is proposed to develop a natural conveyor for fresh vegetables, potatoes, maize, fruit, dairy and other products using the vertical zonality of crops ripening and livestock pasturage within the summer pasture zone.
For more than 40 years estimated characteristics of rivers’ maximum runoff for rain and spring floods in Ukraine have been determined using the regulatory document SNiP 2.01.14-83. This regulatory document is based on use of reduction formulas and maximum intensity formulas .
Use of reduction structure for rain and spring floods of different reduction have no relevant grounds since in both cases we deal with calculation of maximum water discharge forming the part of unimodular hydrographs. In addition, a calculated parameter of “friendliness” is determined for spring floods by use of hydrological analogues, which, by the way, are assigned rather provi-sionally. Regarding rain floods the impact in the form of coefficients of analogy is replaced by the runoff module taken for a provisional catchment area. In methodological terms, in contrast to the “friendliness” coefficient of the spring flood determined by the method of hydrological analogy, module (for rain floods) is represented by a map of isolines. More remarks can be voiced with regard to the methodological base of determination of maximum mod-ules of rain floods runoff within small catchment areas. The main drawback relating to the use of maximum intensity formula consists in the fact that natural process of transformation of rain floods “precipitation – slope inflow – river channel runoff” is replaced by the operator of “precipitation – river channel runoff”.
The authors of this article offer a universal approach to substantiation of the structure of the formula to determine the characteristics of maximum runoff of rain and spring floods.
The original theoretical model for hydrographs of rain and spring floods is accepted as unimodular non-linear triangles.
For the first time all the components of calculation equations of modules of maximum runoff of rain and spring floods are described by the same equations and differ only in numerical values of the parameters. The proposed scientific and methodological base for determination of modules of maximum runoff of rain and spring floods underwent practical test and is recommended for use when preparing a new Ukrainian regulatory document replacing SNiP 2.01.14-83.
Introduction. Climate changes occurring in recent decades determine the relevance of the problem of forecasting such changes in future both globally and regionally. After all, knowledge of climate’s behavior in future is very important when carrying out an analysis of trends of hydrological characteristics change. Significant increase of the global surface air temperature observed since the end of the 20th century is mainly caused by increase of concentration of greenhouse gases generated as a result of industrial activity. Thus, climate changes could not but affect the continental water resources and in particular the processes taking place in rivers.
Purpose. Assessment of change of surface air layer during the winter period within the Southern Buh Basin and assessment of change of the hydrological regime of the basin’s rivers following the changes of air temperature.
Methods of research. This study is based on the data for the winter period obtained from 24 hydrological station and 15 meteorological stations within the Southern Buh River Basin. With as-sistance of scientists of the Ukrainian Hydrometeorological Institute and using the regional climate model REMO for A1B scenario forecast values of air temperature were calculated.
Results of research. The main regularities of studied characteristics change for the period of 2031-2050 were determined on the basis of prepared calculation dependences of the characteristics of ice and thermal regimes of the studied basin’s rivers and obtained forecast values of air temperature. According to the climatologists’ calculations there is a tendency of air temperature increase during the forecast period, and, respectively, increase of water temperature and decrease of ice period duration of the rivers within the Southern Buh Basin.
Summary (conclusions and author’s recommendations). The results of the carried out research indicate the fact that the trend of increase of surface air layer temperature and change of main characteristics of ice and thermal regimes of the basin’s rivers formed at the end of 20th – the beginning of the 21th century will develop in future.
Underwater bucket channels connecting the Danube with sluices were built perpendicular to river’s main stream. Water supply tract consists of an supply bucket channel, connecting the Danube with a sluice facility, a transporting channel – from a sluice to the mouth, i.e. to an output of a channel into a lake, and a mouth section of a channel. Throughout the whole period of operation of these facilities silt accumulation has been observed within supply bucket channels, in a lesser degree – within transport channels, and emergence in a mouth section of transport channels of sandbars having considerable dimensions. Throughout the whole period of operation of facilities and channels plenty of money has been spent for cleaning facilities and channels off sediments, so there is a need for deeper examination of the nature of silting phenomenon and minimization of water supply tract siltation through its simple reconstruction.
The aim of this research consists in substantiation of proposals to eliminate or to reduce effects of silting of supply and transport channels under existing conditions and substantiation of proposed necessary structural measures on the basis of proposed mathematical modelling and methods of analytical studies. Therefore methods of analytical studies including probable and statistical approaches used when analyzing processes with constant change of environment were proposed. These studies found that boundaries of supply of inlet channels in an open river’s channel depend on distribution of flow velocities throughout a river’s stream and conditions of stream distribution and flow pattern in the middle of the supply channel depends on shape of an inlet, particularly on shape of its lower side.
These suggestions and studies give us an opportunity to recommend means of controlling a hydraulic regime in the middle of a supply channel. Fighting against deposition of bottom sediments at supply channels may be won after choosing a place for water intake and a type of bucket, as well as after specification of appropriate structural forms and sizes of their inlet components. Therefore the article provides suggestions on research of regime of interaction between the river and a supply channel, dynamics of water exchange in supply channels, forces of
stream masses developing during mixing, hydraulic regime and regime of deposition of supply and transport channels in order to determine the major requirements regarding size of water area of a supply channel.
Assessments of changes in the intra-annual spatio-temporal variability of the hydrological characteristics of the Kuialnytskyi Lyman lagoon under various runoff volumes of the Velykyi Kuialnyk River were obtained from the results of calculations, using the predictive three dimensional hydrothermodynamic model Delft3D-FLOW.
Scenarios of increasing the river runoff inflow up to 25% and 75% of the monthly natural river runoff under conditions of 2015 were modelled, as well as under different by hydraulicity typical years of the modern climatic period of the 21st century (1990-2030), determined according to the most appropriate for the Kuialnytskyi Lyman lagoon region climatic scenario from the ENSEMBLES database, which corresponds to the global A1B scenario, calculated by the MPI-REMO model. Monthly values of the natural runoff of the Velykyi Kuialnyk River, calculated with the use of “climate-runoff” model, were used during the simulation.
Implementation of water management within the catchment area of the Velykyi Kuialnyk River and realization of various engineering and technical measures aimed at the increase of river inflow to the Kuialnytskyi Lyman lagoon, are identified to significantly affect the hydroecological regime of the lagoon only in case of supplying at least 75% of the natural river runoff volume into the lagoon.
The increase of the natural runoff of the Velykyi Kuialnyk River is incapable to provide the stabilization of the hydroecological regime of the Kuialnytskyi Lyman lagoon independently, without periodical replenishment of the lagoon with seawater from the Odessa Gulf.
Under the absence of replenishment of the lagoon with sea water and deficiency in the runoff of other small water streams flowing into the lagoon, the increase of the runoff of the Velykyi Kuialnyk River even up to 75% of the volume of its natural runoff could provide the stabilization of the annual cycle of water level and salinity variability in the lagoon only during the high-water years.