Circulation Types Research Articles

Comprehensive analysis of droughts over the Middle East using IMERG data over the past two decades (2001–2020)

The Middle East is home to approximately 475 million people, most of whom face food insecurity due to severe and extreme droughts that have affected most regions over the past two decades. In this study, we analyzed the spatio-temporal characteristics of different drought intensities during the period 2001–2020 using the Integrated Multi-satellitE Retrievals for GPM (IMERG) precipitation and ERA5 temperature datasets. As a first step, we compared the consistency of the IMERG-based 1-month Standardized Precipitation Evapotranspiration Index (SPEI1) with the station-based SPEI1. The results showed good agreement between them with R2 ranging from 64% to 84%. The principal component analysis method is used to show the different modes of the monthly 3-month SPEI (SPEI3) and the associated circulation types in this region. Spatially, SPEI3 shows a homogeneous region in the first five leading modes and for SPEI3 below −0.84 there was high spatial variability and inhomogeneity within and between countries. The most significant SPEI3 trend is observed in June–August with up to −0.1 SPEI3/year in some countries. Nine circulation types (CTs) were identified for the eight most severe and extreme drought episodes. The first circulation type in the positive and negative phases could explain the drought variability up to 30.1% and are closely associated with the Arabian thermal low pressure and the Siberian high pressure systems, respectively. In a final step, the moisture transport in each episode is analyzed using the vertical integral moisture flux (VIMF) and its divergence.

Role of the dipole mode index in governing the freshwater content within the bay of bengal summer pycnocline

The Bay of Bengal (BoB) surface layer receives approximately 0.13 million m3/sec (0.13 Sv) of freshwater through a combination of precipitation and river runoff minus evaporation, which then is exported to neighboring seas. Quasi-stationary salinity is established by the import of salty water from the Arabian Sea (AS), primarily within the pycnocline as an estuarine type of circulation. The BoB pycnocline is also affected by low salinity export from the southern Andaman Sea (AndS). We use Argo observations and GODAS reanalysis products to trace the spreading of AS and AndS water within BoB pycnocline during the summer monsoon when the bulk of AS water is imported. We use relative freshwater content (RFWC), which is zero for pure AS water and 1 for pure AndS water. We find significant interannual variability of the RFWC pattern, which relates to the Indian Ocean Dipole, as defined by the Dipole Mode Index (DMI). The position of the Sri Lanka Dome (SLD) off the east coast of Sri Lanka varies with DMI: the SLD is farther east during negative DMI, which directs the AS water farther to the east in BoB; whereas during the positive DMI, the AS water is directed to the north.

On the Examination of the Relationship between Mean and Extreme Precipitation and Circulation Types over Southern Romania

The main goal of the present study is to identify the prevailing atmospheric circulation patterns (circulation types) that are associated with the occurrence of precipitation (both mean and extreme) over southern Romania. A daily circulation type calendar derived from an automatic and objective classification scheme is used in synergy with the daily precipitation time series from five weather stations in the study area for a sixty-year period (1961–2020). Both mean and extreme precipitation do not show statistically significant trends, except for the annual precipitation at Constanța, for the value with daily precipitation totals greater than the 95th percentile at Craiova and the number of days exceeding the 99th percentile at Buzău and Râmnicu -Vâlcea, where significant negative trends were noticed. Moreover, the precipitation trends were analyzed in relation to the atmospheric circulation types. Non-significant positive trends were observed for the precipitation amounts (annually, winter, spring, and autumn) corresponding to very rainy circulation types (C, Cwsw), while for summer, the equivalent trends were negative. Moreover, it became evident that during extreme precipitation events, the predominant circulation types (C, Cwsw) are associated with western or almost western atmospheric circulation and Mediterranean- or Atlantic-originated depressions.

The impact of horizontal resolution on the representation of atmospheric circulation types in Western Europe using the MPI‐ESM model

AbstractIn this study, the added value in using the sea level pressure field from the coupled higher‐resolution version of the Max Planck Institute Earth System Model (MPI‐ESM‐HR), compared to the lower‐resolution version (MPI‐ESM‐LR) for circulation typing, within the regional context of Western Europe was examined. The results show that the MPI‐ESM‐HR and the MPI‐ESM‐LR simulations can produce the classified circulation types (CTs) and their long‐term statistical characteristics as obtained from the ERA5 reanalysis. Overall, there are improvements in the composite maps, probability of occurrence and annual cycle of the simulated CTs in the MPI‐ESM‐HR compared to the MPI‐ESM‐LR. The model bias in simulating the structure of anticyclonic circulations over the Western European landmass was reduced by 14% under MPI‐ESM‐HR. Furthermore, under the shared socio‐economic pathways (SSP2‐4.5 and SSP5‐8.5) future emission scenarios, the historical CTs in the region of assessment were classified, suggesting that in Western Europe, the same historical CTs are present under future climate change scenarios. However, the frequency distribution and geographical structure of some of the CTs in Western Europe are projected to change by the MPI‐ESM model, especially under the higher future emission scenario.

Regional Scale, Fault‐Related Fluid Circulation in the Ionian Zone of the External Hellenides Fold‐And‐Thrust Belt, Western Greece: Clues for Fluid Flow in Fractured Carbonate Reservoirs

AbstractWe combined field mapping, structural and microstructural analyses, stable‐clumped isotope geochemistry, and U‐Pb dating of calcite veins and syn‐tectonic slickenfibres, to assess the regional scale fault‐related fluid flow during the evolution of the External Hellenides fold‐and‐thrust belt. We show that fluid circulation during forebulge uplift was characterized by cold meteoric water‐derived fluids, from which calcite precipitated and sealed bed‐perpendicular joints. Fluid circulation during foreland flexuring and early layer‐parallel shortening was characterized by warm fluids buffered by the carbonate host rock, which circulated through normal faults and bed‐parallel veins. Mixing with meteoric‐derived fluids also occurred at this stage of tectonic evolution. Fluid circulation during the late stage of thrust wedge accretion and post‐orogenic extension at 1.6 ± 1 Ma was characterized by increasing dominance of cold meteoric water circulating in strike‐slip and normal faults. The ingress of meteoric‐derived fluids was controlled by throughgoing fault conduits, while host rock‐buffered fluids were confined in isolated structures such as minor faults and veins. We developed a conceptual model of fault‐related fluid circulation, which invokes a transition from an open fluid system during forebulge uplift, to a semi‐closed fluid system during foreland flexuring and early layer‐parallel shortening, and to an open system during late thrust wedge accretion and post‐orogenic extension. This type of fluid circulation may have impacted fluid migration/leakage, including hydrocarbons, into or outside potential reservoirs in the highly prospective Hellenides‐Albanides fold‐and‐thrust belt, a renovated frontier for hydrocarbon exploration in the Mediterranean area.

Definition of Circulation Conditions and Groundwater Genesis of the Complex Krupaja Hydrogeological Karst System (Eastern Serbia)

The complex Krupaja karst system, located in Serbia, which consists of a strong karst spring, a thermal karst spring, and a borehole that captures sub-thermal waters, has been studied. A phenomenon which gives rise to the occurrence of karst waters of three different temperatures within a relatively short distance (about 200 m) led us to assume that these karst waters are formed within the same karst aquifer and circulate through different levels of karst channels that are zonally distributed within a vertical profile; this was confirmed by assessing the groundwater ages. Based on the development of karstification, as presented in this paper, as well as on previous investigations, explanations of four types of circulation within same karst system are provided. The results of measurements of stable isotopes (H, 18O, and 13C) and radioactive isotopes of tritium and T+He and 14C, as well as hydrochemical water analyses, speleogenetic spatial modeling, speleodiving research, etc., confirmed the assumption that these groundwaters belong to the same karst system. However, these karst waters have different residence times, i.e., from only a few days to over several decades and even up to approximately 4000 years, circulating through channels with various distributions along the depth of the karst aquifer.

Increasing amounts of midwestern Tibetan Plateau vortices and their response to soil moisture distribution coupled with different synoptic systems

AbstractTibetan Plateau Vortices (TPVs) are important synoptic systems that affect precipitation over the Tibetan Plateau (TP) and downstream weather. By using daily reanalysis data provided by ECMWF and the objective identification methods, the study identified the basic spatiotemporal changes of TPVs, clustered the TPVs by different dynamic circulation types and explored the dynamic circulation background of the classified TPVs in the midwestern TP and their relationship with thermal factors, such as sensible heat and soil moisture. The results show that TPVs in the midwestern TP exhibited an increasing trend from May to August, resulting from the coupling of dynamics with thermal forcing. The related synoptic circulations were divided into four types according to the dynamic circulations: the shortwave trough, the longwave trough, the shear line and the plateau anticyclone type. Among the TPVs, the percentage of TPVs in the shortwave and longwave trough type was relatively large, accounting for 48.7% and 31.5%, respectively, both of which were dominated by the coupling of increased sensible heat and decreased soil moisture. The shear line type was less affected by thermal factors, and mainly driven by dynamic factors, whereas the soil moisture gradient was responsible for the plateau anticyclone type. The simulation experiment also proved this conclusion.

Integration degree of China’s the new development pattern of dual circulation and industrial green development

The long-standing development pattern dominated by international circulation makes China face the risk of "low-end lock-in" and "being decoupling". In addition, the current global climate change and environmental crisis are becoming increasingly severe, coupled with the COVID-19 impact. Chinese enterprises must actively build a green development system for domestic industries in a mutually reinforcing manner in the context of the domestic general circulation, in order to adapt to the new dual circulation environment as soon as possible. This paper analyzes the specific coupling and coordination relationship between the two systems based on the relevant data of China’s three major industries from 2008–2014 using Index DEA, entropy value method, gray correlation analysis and coupling coordination model. The results of the study show that: the two systems of dual circulation pattern and industrial green development have a strong correlation and basically present a coupling relationship, but within the industry, there is a problem of the collapse of the tertiary industry. In terms of the type of coupling, the domestic and international circulation in general gradually present the green development leading state, except for the primary industrial segment of the international circulation. On the whole, the coupling quality of the two systems needs to be further improved. Based on this, this paper puts forward the following suggestions: (1) coordinate the internal and external development of the industry; (2) take innovation as the driving force to promote the green transformation of industries; (3) take green sharing as the goal to strengthen the policy orientation of green development; (4) take the opportunity of mutual promotion of dual circulation to stabilize the steady state of green development coupling.

Exceptionally Cold and Warm Spring Months in Kraków Against the Background of Atmospheric Circulation (1874–2022)

In the changing climate, exceptionally warm (EWMs) and dry spring months are increasingly observed. At the same time, exceptionally cold months (ECMs) are less frequent, although their impact on a warming climate becomes significant. Due to the role that such climatic anomalies play in the environment and their effects on human activity, it is very important to explain the causes of their occurrence. For this reason, in this study, the authors have attempted to determine the circulation conditions favourable to the occurrence of extremely cold (ECM) and warm (EWM) spring months in Kraków in the years 1874–2022. The study used the average temperature of individual spring months (March–May), as well as types of atmospheric circulation and air masses from the daily Calendar of Atmospheric Circulation Types for southern Poland. A distinct increase in spring air temperature (0.181 °C/10 years) and its individual months (0.162–0.191 °C/10 years) was confirmed. It was accompanied by a significant increase in the occurrence of EWM and a decrease in ECM. It was also found that the direction of air advection and the related temperature characteristics of air masses have the greatest impact on the occurrence of exceptionally cold or warm months. A slight positive effect of zonal circulation on the temperature increase at the beginning of the spring season and the advection of air from the south in April and east in May was found. In the case of the coldest months (ECMs), low temperatures most often developed in the presence of advection from the NW-N-NE directions.

Attributing the driving mechanisms of the 2015–2017 drought in the Western Cape (South Africa) using self-organising maps

The Southwestern Cape (SWC) region in South Africa experienced a severe rainfall deficit between 2015–2017. The resulting drought caused the City of Cape Town to almost run out of water during the summer of 2017–2018. Using the self-organising maps approach, we identify and classify the synoptic circulation states over Southern Africa known to influence the local climate in the SWC into three groups (dry, intermediate, and wet circulation types) using large ensembles of climate model simulations with anthropogenic forcing and natural forcing. We then assessed the influence of anthropogenic climate change on the likelihood of these circulation types and associated rainfall amounts over the SWC during the drought. Our findings suggest that during the drought, the frequency of dry (wet) circulation types increases (decreases) across all models under anthropogenic forcing relative to the natural forcing. While there was no clear direction in the associated rainfall change in the dry circulation types, rainfall decreased across most models in wet nodes. All models agree that anthropogenic climate change has increased the likelihood of dry circulation types (median probability ratio (PR): 0.93–0.96) and decreased that of wet circulation types (median PR: 1.01 and 1.12), indicating a shift towards lesser (more) wet (dry) synoptic circulation states and associated rainfall during the drought. The long-term climatology also depicts similar patterns indicating the drought may result from long-term changes in the frequency of wet circulations and their associated rainfall. This study further explains the anthropogenic influence on the dynamic (synoptic circulation states) and thermodynamic (rainfall) factors that influenced the SWC 2015–2017 drought.

Reasons for shortening snow cover duration in the Western Sudetes in light of global climate change

AbstractThis article discusses the reasons for shortening snow cover duration in the Western Sudetes, considering local changes in: air temperature; amount and type of precipitation; sunshine duration and atmospheric circulation leading to changes in the number of days with snow cover and its depth; and its start and end dates. All factors were linked to the exposure and relief of the study area. The analysis was made for the winter seasons (Nov–Apr) 1961/1962–2020/2021. It was found that the primary reasons for the shortening of snow cover duration in the Western Sudetes are: a multi‐year increase in air temperature and sunshine duration; changes in precipitation patterns—a decrease in the proportion of solid precipitation, changes in atmospheric circulation—including an increase in anticyclonic circulation types with sunny weather, especially in April (snow cover disappears in most of the elevation profile of the Sudetes); and less cyclonic weather types. The above factors synergistically affect the lower snow depth, and fewer days with solid precipitation, which promotes its faster spring ablation. In the subsequent 30 years (climatological norms), there is a successive shortening in its duration. On the snow cover start dates, there are no clear trends in the direction and rate of change. On end dates, negative trends are observed, in most cases statistically significant. The rate of change for the end dates of snow cover is about twice as high as the start dates. The rate of decline in snow cover is higher at stations at similar altitudes with northern macro‐exposure than southern. The results correspond with other studies from Europe and the world on the earlier disappearance of snow cover. They confirm the successive global warming and shortening snow cover duration, especially evident in the last few decades.

Impact of Atmospheric Circulation Patterns on Ozone Changes in the Pearl River Delta from 2015 to 2020

Based on the ozone observation data and meteorological reanalysis data of the Pearl River Delta (PRD) from 2015 to 2020, the Lamb-Jenkinson weather typing method (LWTs) was used to analyze the characteristics of different circulation types and quantify their contributions to the interannual ozone variation. The results showed that there was a total of 18 weather types in PRD. Type ASW was more likely to occur with ozone pollution, and Type NE was associated with more serious ozone pollution. To better explore the ozone generation mechanism under different weather types, the 18 weather types were merged into five weather categories based on the wind direction change of the 850 hPa wind field and the different positions of the central system. The weather categories with high ozone concentration were the N-E-S directional category[(161±68) μg·m-3] and category A[(122±39) μg·m-3]. The ozone concentrations of these two categories were significantly positively correlated with the daily maximum temperature and the net amount of solar radiation. The N-E-S directional category was the dominant circulation pattern in autumn, whereas category A mostly occurred in spring, and 90% of the ozone pollution events occurring in PRD in spring were related to category A. The contribution of changes in atmospheric circulation frequency and intensity to interannual change in ozone concentration in PRD was 69%, and the contribution of changes in atmospheric circulation frequency alone was 4%. The changes in atmospheric circulation intensity and frequency on ozone-exceeding days contributed comparably to the interannual fluctuations in ozone pollution concentrations.

Synoptic Weather Patterns and Atmospheric Circulation Types of PM2.5 Pollution Periods in the Beijing-Tianjin-Hebei Region

The variation of PM2.5 concentration in the atmosphere is closely related to the variation in weather patterns. The change in weather pattern is accompanied by the corresponding change in atmospheric circulation characteristics. It is necessary to explore the relationship between PM2.5 concentration changes and atmospheric circulation characteristics during pollution periods. In this paper, Lamb-Jenkinson objective classification method is applied to classify daily atmospheric circulation. The pollution periods are calculated and the atmospheric circulation variation rule is obtained. Combined with the physical parameter field (humidity, potential temperature, and potential height), a typical pollution period is analyzed. Additionally, the influence of atmospheric circulation type variation on PM2.5 concentration and transport channel during the pollution period was obtained. The results show that atmospheric circulation types in the study period are dominated by A-type (anticyclonic), N-type (north), and NE-type (northeast), indicating obvious seasonal differences, and the proportion of C-type (cyclonic) circulation was increased significantly in summer. During the pollution period analysis from 2 to 4 January 2019, atmospheric circulation type changed from N-type to NE-type (northeast), the wind direction changed from southeast wind, and the change of pressure gradient was consistent with the trend of the wind field. Moreover, the physical parameter field assisted in verifying the process of the pollution period from the conducive to the accumulation of PM2.5 to conducive to the deposition of pollutants and external transport. The research results would provide theoretical support for PM2.5 prediction during the pollution period and also supply a theoretical and technical basis for the establishment of ecological compensation standards for air pollution and atmospheric environmental control.

Classification of daily heavy precipitation patterns and associated synoptic types in the Campania Region (southern Italy)

Using a 20-year (2002−2021) dataset of daily precipitation collected by 107 rain gauges in the period from October to May, this study introduces a classification of the main heavy precipitation spatial patterns for the Campania Region (southern Italy). To pursue this aim, we apply a cluster analysis on the most relevant principal modes extracted from a principal component analysis of the between-day correlation matrix. The characteristics of the identified patterns, as well as their interannual and monthly distribution, are presented and discussed. Moreover, using global and regional reanalysis products, we have determined the large-scale and mesoscale atmospheric circulation types associated with heavy precipitation patterns.The heavy precipitation episodes are generally triggered by an upper level trough approaching the southern Italy from west and promoting a very moist southwesterly flow. They have been clustered into six different patterns. The first four exhibit a rainfall amount distribution strongly connected with the orography of the investigated region. In such scenarios, the orographic lifting, the low-level wind convergence induced by the orography and the transport of moisture from local sources (the western and the southern Mediterranean) and from distant regions (the Atlantic and the Africa tropical areas) can be regarded as the primary forcing of heavy rainfall. In the other two patterns, the highest precipitation is generally observed in the coastal areas (Gulfs of Naples and Salerno) and in the northwestern side of the region (Caserta district), respectively. In such circumstances, the abundant precipitation is closely linked to convective activity over the Tyrrhenian Sea, which is sustained by a low-level convergence and, in the sixth pattern, by a moisture plume coming from the tropics.The results of this study provide new insights about the links between torrential precipitation spatial distribution and atmospheric circulation schemes in the southern Italy and promise to add a useful contribution for civil protection activities related to the management of environmental risks.

Efficiency of hyperbaric oxygenation in complex rehabilitation of soldiers with traumatic brain injury: prospective study

OBJECTIVE: Evaluate the effect of hyperbaric oxygenation course on indicators of central hemodynamics, heart-rate variability and ability to concentrate and switch attention in soldiers with traumatic brain injury. MATERIALS AND METHODS: The main group contained 50 patients with combat traumatic brain injury, aged 25-45, whose comprehensive treatment course included hyperbaric oxygenation. The control group consisted of 20 patients, treated with medical therapy under the clinical protocol. Hyperbaric oxygenation treatment was carried out in BLKS-303 MK pressure apparatuses in the 0.3–0.7 ati mode with an isopression exposure of 40 min. The course of hyperbaric oxygenation included 10±2 sessions per day. The indicators of heart-rate variability and central hemodynamics were measured. Bourdon proofreading sample was used to assess alertness and ability to switch attention. Statistics. Statistical analysis of data was performed using “Statistica for Windows 6.5” program. Comparisons are shown as median values (Me) and quartile range (LQ÷UQ) (25% and 75% percentile). Criteria of significance was considered p<0,05. the Mann-Whitney test was used to compare quantitative indicators in the main and control groups, the Wilcoxon T test was applied when studying the dynamics of change in indicators in the study groups. RESULTS: Including hyperbaric oxygenation in the complex therapy of patients with combat traumatic brain injury led to significant reduction in indicators of sympathetic activity - mode amplitude - up to 35,7 % (29,5÷48,0), decrease of tension index up to 116,5 %/с2 (99,0÷122,0) and recovery of vegetative equilibrium indicator LF/HF up to 2,8 (2,5÷4,3). Patients with hyperkinetic type of blood circulation in the main group, compared to the control group experienced significant reduction in stroke volume index to 41,8 (40,7÷54,8) ml/m2 cardiac index up to 4,6 (4,4÷5,2) kg*m/min/m2 , decreased energy expenditure for blood moving to 12,3 (12,3÷12,7) Wh/l. improve coordination is observed in 54 % of the main group in comparison with 34 % of the control group, reduced pathological reflexes - in 50 % of the main group, compared to 22 % of the control group, decrease in the severity of deep reflection disorders - in 55 % of the main group versus 28 % of the control group. Conducting Bourdon proofreading sample test after HBO course in the main group, compared to the control group showed significant error reduction from 12,7 (10,2÷14,6) to 4,2 (3,7÷5,2) (р<0,001); reliable error reduction from 11,8 (9,6÷12,8) to 8,4 (6,5÷10,2) (р<0,05) was noted in the control group. DISCUSSION: Early application of hyperbaric oxygenation in the complex therapy of patients with combat traumatic brain injury contributes to rapid normalization of central hemodynamics, decrease in the severity of impact on the sympathetic part of the autonomic nervous system, reduction in the degree of cardiac rhythm management centralization. Reliable regression of focal symptoms in the main group was accompanied by significant improvement in concentration and stability of attention, ability to switch it, compared to the control group. CONCLUTION: Including hyperbaric oxygenation in the complex treatment of traumatic brain injury can significantly increase therapy efficiency, resulting in faster restoration of impaired brain functions, memory and attention activation, normalizing the indicators of heart-rate variability and central hemodynamics, and promotes transition to a more economical operating mode according to the new level of oxygenation.

ПОРІВНЯЛЬНА ХАРАКТЕРИСТИКА ФУНКЦІОНАЛЬНОГО СТАНУ ОРГАНІЗМУ СТУДЕНТОК ПЕРШОГО РОКУ НАВЧАННЯ ІЗ РІЗНИМ ТИПОМ ГЕМОДИНАМІКИ

Differences in the regulatory effects of cardiovascular mechanisms and heart rate variability in female students of the first year of study are considered in this article. A lot of changes occur in the social sphere and in the psychophysiological state of the students' bodies after admission to the higher educational school. Adaptive processes are multi-level and are accompanied by stress on body systems. The most striking functional changes in the body are manifested in changes in the state and functions of the cardiovascular system. The circulatory system is one of the first to be involved in the formation of adaptive reactions under the reflex-regulatory control of the ANS. Individuals with different types of blood circulation are characterized by different adaptation possibilities and different degrees of resistance to the action of extreme influences. The conditions of educational activity in the specialty at the university will be an extreme factor for students of the first year.
 In order to evaluate central hemodynamic parameters, height and body weight indicators, heart rate (HR), systolic blood pressure (BPs), diastolic blood pressure (BPd) were obtained at rest. Based on them, the following are calculated: pulse blood pressure (BP), systolic blood volume (SBV), minute blood volume (MBV), body surface area (S), cardiac index (CI). The regulatory effects of ANS were determined by heart rate indicators. Cardio intervals were registered and recorded for 5 minutes. Indicators of vegetative homeostasis were calculated according to the formulas of Baevsky R.M.
 According to CI indicators, the subject contingent was divided into groups according to the type of hemodynamics: eukinetic (n=70) and hyperkinetic (n=53).
 The obtained results showed the absence of significant differences in body weight and growth indicators between groups (p ≥ 0.05).
 The differences between groups were in indicators of central hemodynamics and heart rhythm. It was established that in students with a eukinetic type of central hemodynamics, adaptation to the conditions of a higher educational institution was ensured by optimal adaptive mechanisms - low HR, SBV, MBV and HVR. This indicates the economy in the work of the circulatory system and the predominance of parasympathetic regulation. In students with a hyperkinetic type high HR and SBV, MBV, HVR were recorded (p ≤ 0.05), which indicated an increase in the work of the circulatory system and the activity of the sympathetic branch of the ANS.
 These indicators in both groups were within the normal range, but in the group with the hyperkinetic type they approached the upper limit (p ≤ 0.05). This indicated an increase in the stress on the regulatory mechanisms in maintaining vegetative homeostasis and the stress on the body's functional reserves of students of this group.

The effect of atypical arterial vascularization of the liver on computed tomography signs of hemangiomas

Introduction. The article describes the role of computed tomography in the diagnosis of hemangiomas in various types of hepatic arterial circulation. Aim. To determine the features of contrast enhancement of hemangiomas in multislice computed tomography with multiphase contrast enhancement in patients with abnormalities of the arterial supplement of the liver. Materials and methods. The results of 60 computed tomographic angiographies of patients with hemangiomas of various sizes (mean age of patients 59.2±12.3 years, the study included 34 (57 %) men, 26 (43 %) women) were analyzed. Results. The most common anatomical variants of the vasculature, concomitant anomalies of the arterial supply of other abdominal organs, as well as features of contrast enhancement of hemangiomas depending on their size are described. The analysis of vascular architectonics revealed that the first type of arterial supply according to Mitchels (p <0.05) ) is prevailed, however, 3 (3.3 %), 5 (3.3 %), 6 (6.6 %) types were also determined. Thus, a correlation analysis using Fisher’s exact test was not detected a significant correlation between the presence of hemangiomas in the liver parenchyma and the presence of aberrant (r=0.11, p=0.36) or replacement arterial vessels (r=0.14, p=0.35). At the same time, when visually assessing the contrast enhancement of hemangiomas in different phases of contrast enhancement, both in the presence of aberrant and replacing vessels and without them, the main radiation patterns of changing hemangiomas density remained unchanged. Conclusion. Based on the obtained data on the liver arterial system, the absence of a significant correlation between the type of arterial blood supply, the presence of an additional or replacement vessel, and the type of contrast enhancement of hemangiomas during multiphase computed tomography of the abdominal organs was demonstrated.

ASSESSMENT OF THE DEPENDENCE OF WINTER WHEAT YIELD IN THE CENTRAL BLACK EARTH ECONOMIC REGION ON THE NATURE OF LARGE-SCALE CIRCULATION STRUCTURES OF THE ATMOSPHERE OF THE NORTHERN HEMISPHERE

The relationship between the average values of winter wheat yields in five regions that are part of the Central Black Earth Economic Region and the nature of global atmospheric circulation was analyzed using the typification of elementary circulation mechanisms of the northern hemisphere of the Earth, compiled by B.L. Dzerdzeevsky. The assessment was made for the spring-summer vegetation period of the crop in question, based on data from 1961 to 2020. Also, based on the results obtained, a correlation and regression analysis of the dependence of winter wheat yield on the total repeatability of days with one or another type of global atmospheric circulation for the spring-summer and spring periods of vegetation was carried out. It is noted that the decrease in the yield of winter wheat in relation to the previous year in the regions under consideration is characteristic of the long-term predominance of one type of global atmospheric circulation in the Northern Hemisphere of the Earth. The increase is observed when, in total, during the spring-summer and spring parts of the vegetation period, there is a predominance of two different types of atmospheric circulation.

Effect of regional baric systems on the occurrence of bi- oclimatic conditions in Poland

The present study concerns the determination of the characteristics of bioclimatic conditions, as well as the synoptic situations related to the occurrence of thermal stress conditions, in Poland. The study was based on daily data obtained from the Institute of Meteorology and Water Management – National Research Institute from the period 1966–2020 for 37 synoptic stations in Poland. Based on the obtained data, values of the Universal Thermal Climate Index (UTCI) were calculated. The occurrence of heat stress increases from the north to the south, corresponding with the variability of influx of solar radiation, and is modified by factors at a smaller spatial scale. The results of this paper evidently point to the cooling effect of the waters of the Baltic Sea. In circulation conditions favouring strong and very strong heat stress, e.g. in two of the designated circulation types (T1 and T2), the occurrence of an expansive high-pressure ridge in the Atlantic-European area is typical, stretching from the region of the Azores High towards the north- east, with a secondary high developed within its boundaries. In the third of the designated circulation types (T3), the high-pressure area extends from the Azores eastwards, reaching the Black Sea. Each of the three circulation patterns associated with the unfavourable biometeorological conditions of very strong and extreme cold stress in Poland is characterised by strong pressure centres formed in the Euroatlantic region, triggering the airflow from the northern (T4) or eastern (T5, T6) sector.

Analysis of natural circulation types' effect on source term during PWR severe accident

مکانیزم شکست ناشی از خزش در طی حادثه شدید یک رآکتور‌ آبی‌تحت‌فشار به‌جهت انتقال مواد رادیواکتیو به محیط‌زیست از اهمیت ویژه‌ای برخوردار است. به دنبال یک حادثه شدید، حرارت واپاشی منتقل‌شده به سایر قسمت‌های سیستم‌خنک‌کننده رآکتور می‌تواند منجر به گرم‌شدن سازه‌های سیستم خنک‌کننده رآکتور (RCS) و خرابی نواحی تحت‌فشار آسیب‌پذیر شود. حادثه قطع‌کامل‌برق (SBO) بدون اقدامات اپراتور (توالی TMLB) یکی از محتمل‌ترین سناریوهایی است که ممکن است یکپارچگی RCS تحت‌فشار را تهدید کند. در این توالی، محل شکست RCS به نوع پدیده گردش‌طبیعی سیال مدار اولیه رآکتور بستگی دارد. در این تحقیق، علاوه بر مدل­سازی کامل نیروگاه، تجزیه‌و‌تحلیل حساسیت شکست‌ناشی از خزش لوله‌های‌مولدبخار (SGTR) و خط‌لوله‌اصلی‌گرم خنک‌کننده رآکتور به نوع پدیده گردش‌طبیعی، یعنی جریان‌‌همسو و غیرهمسو، با استفاده از کد MELCOR بررسی شده است. نتایج حاصل از دو مدل جریان‌گردش‌طبیعی ‌همسو و غیرهمسو نشان می‌دهد هنگامی که پدیده گردش‌طبیعی‌غیرهمسو غالب است، شکست‌ناشی از خزش خط‌لوله‌اصلی‌گرم خنک‌کننده رآکتور زودتر از دسته‌لوله‌های مولدبخار رخ می‌دهد. در ‌صورتی‌که در اثر ‌گردش‌طبیعی همسو لوله‌های‌مولدبخار زودتر از سایر بخش‌های خطوط‌‌اصلی سیستم‌خنک‌کننده رآکتور دچار شکست‌ناشی از خزش می‌شود. علاوه بر این، مقدار مواد رادیواکتیو منتشر‌شده به قسمت‌های مختلف نیروگاه و محیط‌زیست برای هر دو مدل برآورد شده است. نتایج نشان می‌دهد که براساس شکست، برای مدل‌های گردش‌طبیعی‌همسو و غیرهمسو به‌ترتیب 18کیلوگرم و 76/145 کیلوگرم مواد رادیواکتیو به‌صورت‌ آئروسل و بخار ‌محصولات شکافت به محفظه‌ایمنی‌رآکتور تخلیه می‌شود. از طرف‌دیگر، در گردش‌طبیعی‌همسو، حدود 33/136 کیلوگرم مواد رادیواکتیو به صورت بخار و آئروسل، از طریق شیر‌ایمنی خط‌اصلی‌بخار به محیط‌زیست منتشر می‌شود.