DOI: 10.3897/jbgs.e177213

Authors: Mariyana Nikolova, Miroslav Ivanov, Xu Shengdi

Abstract: The Shared Socio-economic Pathways (SSPs) presented in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) indicate that increased variability and more frequent extremes in precipitation are expected to raise the risk of droughts and floods in South-Eastern Europe. According to climate projections, the potential increase in precipitation in the region is insignificant, while the rising temperatures and the associated increase in potential evapotranspiration may lead to a substantial intensification of drought severity in the future. This study reviews previous research on droughts in Bulgaria and the analytical methods applied, thereby justifying the selection of the proposed methodological approach based on the Standardized Precipitation Evapotranspiration Index (SPEI-12 and SPEI-48). The SPEI data were obtained from the Global SPEI Database and cover the period from 1950 to 2024. The spatial characteristics of the index for the territory of Bulgaria are represented by grid cells with a spatial resolution of 0.5 degrees. The study examines changes in drought conditions across Bulgaria over the period 1950–2024, using SPEI-48 data. Long-term fluctuations in average SPEI values reveal a pronounced negative trend since 1984. The index reached its lowest value during the period 2000–2003 (−1.6), which is classified as a severe drought. Average SPEI-48 values range between 0.8 and −0.8 across the decades from 1950 to 2024, and have remained predominantly negative over the last five decades. In this context, the study highlights the need to implement measures for climate change adaptation and to address the increasing risk of drought.

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DOI: 10.3897/jbgs.e166425

Authors: Fiorella La Matta Romero, Vanessa Arevalo-Seijas, David Valqui-Peña, Moya MacDonald, Jemma Wadham, Raul Loayza-Muro

Abstract: The retreat of tropical glaciers in the Peruvian Andes, particularly in the Cordillera Blanca, has significantly altered hydrogeological and geochemical processes in mountain water-sheds. This study investigates the influence of glacier change-driven acid rock drainage (ARD) upon benthic macroinvertebrate communities in 19 glacier-fed streams of the Santa River watershed over two consecutive dry and wet seasons (2019–2020). The findings reveal that ARD driven by glacier melt and sulphide oxidation has led to increased metal concentrations (e.g., Fe, Mn, Al, Pb) and pH reductions (of 2–3 in some sites), creating a “toxic or treat” scenario for aquatic biodiversity. Statistical analyses, including principal component analysis (PCA), principal coordinate analysis (PCoA), and canonical correspondence analysis (CCA), indicate significant correlations between physical and chemical changes and macroinvertebrate assemblages. Collector-gatherers (e.g., Chironomidae, Baetidae) were dominant in sites impacted by ARD, while sensitive functional feeding groups, such as scrapers and shredders, declined under high metal stress. Seasonal variations also affected taxonomic richness, with greater abundance observed during the dry season. These results highlight the cascading effects of climate-induced glacier loss on freshwater ecosystems and provide critical insights into the ecological consequences of ongoing environmental changes in high-altitude Andean rivers.

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DOI: 10.3897/jbgs.e169740

Authors: Hrachya Astsatryan, Rita Abrahamyan, Artur Gevorgyan, Hasmik Panyan, Furtado Kalli

Abstract: Droughts cause danger to human health and socioeconomic development worldwide. The traditional station-based analysis of droughts has limitations. The most relevant is the insufficient spatial resolution of the observations, particularly over mountain topography. This study evaluates the performance of two satellite precipitation products—the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) and the Climate Prediction Center Morphing Method (CMORPH)—for monitoring meteorological droughts in mountainous environments, using the Armenian Highlands as a case study. We focused on a drought event in June 2021, which was the hottest and driest month in Armenia in nearly nine decades. The performance of gridded global precipitation products was evaluated against in-situ observations for June 2021. Statistical evaluation using the Pearson correlation coefficient, root mean square error, mean absolute error, mean bias, and standard deviation has been analyzed. Results indicate that both products have challenges in accurately estimating the Standardized Precipitation Index (SPI) under severe drought conditions. However, IMERG’s drought detection aligned more closely with in-situ observations than CMORPH’s, which tended to underestimate drought severity. In addition to precipitation-based indices, Landsat-8 and Sentinel-2 vegetation and moisture indices (NDVI, NDMI, NDWI) were evaluated, yielding complementary data regarding the impact of drought on the environment. We found a correlation between low SPI values and stressed vegetation (low NDVI/NDMI), validating the ecological impact of the meteorological drought. Outcomes discuss the merits and disadvantages of satellite precipitation records over mountainous regions and advise operational drought monitoring and early warning systems within data-limit-ed topographically complex areas worldwide.

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DOI: 10.3897/jbgs.e177296

Authors: Dmytro Kasiyanchuk, Yaroslava Atamaniuk, Mykola Deputat, Svitlana Gavdey, Pavlo Horishevskyi

Abstract: The objective of the present study is to undertake a quantitative assessment of the spa-tial impact of tourism on natural complexes in the Carpathian region. This is achieved by employing geostatistical modelling methods. The present study deviates from con-ventional buffer methodologies insofar as it employs an integrated algorithm founded upon Kernel Density Estimation (KDE), thereby amalgamating multivariate analysis with detailed land use classification (LULC). In the analysis, each of the seven factors ̶ hydro-graphic network, relief, transport accessibility, hotels, tourist routes, land use types and nature conservation areas ̶ is standardised on a scale of 1–10 and synthesised into a single model of the vulnerability of natural landscapes to tourist pressure. The spatial integration of the factors demonstrates that areas exhibiting high and very high vul-nerability encompassed a total area of more than 310 km², constituting approximately 34% of the total area under consideration. These areas are predominantly concentrated within mountain valleys and along major transport axes. The findings demonstrate the substantial analytical superiority of KDE in comparison to buffer models, owing to its capacity to accommodate continuous impact gradients and its strong alignment with actual urbanisation patterns. The proposed approach can be applied to spatial planning for sustainable tourism and environmental monitoring in mountain regions.

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DOI: 10.3897/jbgs.e153003

Authors: Tsvetan Parov

Abstract: During the 33rd Bulgarian Antarctic Expedition, field studies were conducted to examine the internal microclimate of crevasse-drainage systems of the three glaciers: Balkan Ice Field, Johnsons and Contell Glaciers. The research is focusing on the relationship between fluctuations of surface meteorology parameters, internal air glacier temperatures in the crevasses and possible connection with solar activity. The total duration of the study exceeds 60 days, making it the longest temperature monitoring of glacier crevasses in Antarctica. Measurements of air temperature, humidity, and atmospheric pressure were carried out using autonomous sensors, while ultrasonic anemometers recorded airflow direction and speed inside the crevasses. Sensors were placed at depths of up to 25 m in central zones and 10 m near the glacier edges. The study identified a distinct temperature gradient at 3-meter intervals and mapped the depth of zones with persistently negative temperatures. Increased solar activity was associated with lower internal glacier temperatures and stronger air circulation. A negative correlation was found between solar activity and both temperature and downward airflow within crevasses. A glacial cave under the Balkan Ice Field allowed access to subglacial waters and sediment sampling. For the period of one year, the ablation zone of the Balkan Ice Field had expanded, and the constant negative temperature zone had deepened by 6–7 m since the previous expedition. Contell Glacier showed greater thermal stability and resistance to change compared to the larger ice fields. The extended daylight in January (approximately 20 hours) facilitated reliable correlation with solar activity patterns.

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DOI: 10.3897/jbgs.e168308

Authors: Fiorella La Matta Romero, Todd R. Lewis, Chad Staddon

Abstract: Understanding the factors that shape household water and energy use is essential for designing targeted conservation interventions that promote both sustainability and well-being. While studies in this area often rely on traditional “frequentist” statistical methods, which can struggle to capture the complex interdependencies among demographic, behavioural, psychological, and material influences. This paper introduces Bayesian network (BN) analysis as a novel and adaptable method with useful applications in water and energy studies and a wide variety of other social sciences. The paper offers a primer on how to conduct BN analysis, including underlying logic and range of choice of software platforms, before presenting a brief worked example based on the authors’ current research into household water and energy consumption in a UK city. The paper shows how Bayesian networks can generate valuable insights from relatively small and complex datasets, capture non-linear relationships, and support scenario-based reasoning, making them well-suited for exploratory studies, “what if?” scenario-testing and policy effectiveness review. The findings contribute to a more nuanced understanding of domestic water and energy consumption and offer a practical framework that can inform the design of targeted, evidence-based interventions to encourage sustainable water and energy use in households. We argue that there is much to be gained by proliferation of this analytical approach throughout the social sciences.

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DOI: 10.3897/jbgs.e149029

Authors: Nikolai Dobrev, Plamen Ivanov, Konstantin Kostov, Emil Oynakov, Nina Nikolova, Boyko Berov, Orlin Dimitrov, Elena Koleva-Rekalova, Miroslav Krastanov, Rosen Nankin

Abstract: This article aims to present the results of an 11-year monitoring of micro-tectonic movements along dangerous cracks opening in caves at Cape Kaliakra, Northeast Bulgaria. Two 3D monitoring devices TM71, were installed in two caves, the purpose of which is to monitor the movements of the rock blocks along dangerous cracks. The obtained results of microdisplacement measurements from 2013 to 2023 show active movement along the observed cracks. This is expressed not only in linear trends but also in sudden shifts and short-term shifts followed by recovery (oscillations). The comparison with the local and regional seismicity shows a correlation between the abrupt movements and seismic events along the Batovo fault. Data from the automatic weather station in the town of Kavarna point to a possible link between some oscillation type movements and heavy rainfall in the research area. The results of the analyzes show the importance of long-term monitoring in clarifying the recent geodynamics in the research area. The results obtained provide valuable information about the dynamics of this region, and hence about the geomorphological evolution and the physical-geological hazardous phenomena. The registered movements show the connection between gravitational movements and tectonic ones. For the first time, data obtained through instrumental observations are published, proving the activity of fault structures in this part of Bulgaria. The results can also be used to predict dangerous slope destabilizations, as well as to reduce the risk of their occurrence.

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DOI: 10.3897/jbgs.e142535

Authors: Hristina Prodanova, Vanya Stoycheva

Abstract: Ecosystem services research in Bulgaria has been actively studying different aspects of this concept and its implementation. Although it is widely recognizable, the concept has still not been sufficiently implemented in Bulgaria’s decision-making process. Following the European and global initiatives for implementing biodiversity and ecosystem services (BES) into the decision-making process, we have identified the stakeholders’ perceptions regarding the possible initiatives for improving the uptake and the lack of sufficient education program coverage within secondary and higher education. In this short communication, we suggest practical priorities for the future development of BES activities enabling the uptake in Bulgarian education and policy.

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DOI: 10.3897/jbgs.e136806

Authors: Samy A. Anwar, Latifa Zhouri, Bilel Zerouali, Yong Jie Wong

Abstract: This study aims to reduce uncertainty in future projections of potential evapotranspiration (PET) across Egypt by utilizing the regional climate model (RegCM4) under two distinct Representative Concentration Pathways (RCP): RCP4.5 and RCP8.5. The RegCM4 was downscaled using the medium-resolution Earth System Model from the Max Planck Institute, achieving a horizontal resolution of 20 km over Egypt. Initially, the spatial distribution of simulated PET was assessed, followed by the orrection of historical PET calculations using long-term gridded data from the Climate Research Unit (CRU) through a linear regression model (LRM) at twelve locations representing diverse climate zones in Egypt. The LRM was then applied to adjust future PET projections covering the period from 2006 to 2100. Significant spatial anomalies in PET were observed, articularly during the periods 2061–2080 and 2081–2100, with more pronounced anomalies under the RCP8.5 scenario compared to RCP4.5. Across all locations, the RegCM4 effectively captured the monthly variability of PET in relation to CRU data. Furthermore, the application of the LRM substantially improved the accuracy of simulated PET, demonstrating the ffectiveness of this approach in enhancing model performance and reducing uncertainty in future projections.

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DOI: 10.3897/jbgs.e135422

Authors: Peter Nojarov

Abstract: This study examines the total evaporation and precipitation-evaporation difference in Bulgaria. Data from ERA5-Land reanalysis for the period 1979–2023 were processed using statistical methods. The results show that the main factors for evaporation in Bulgaria are air temperature and precipitation. Evaporation has a positive trend due to the rise in air temperature. This trend is significant only in mountainous regions, which are well-supplied with water. Evaporation is somewhat limited in the other parts of the country because of the water deficits in the warm part of the year. Precipitation is a possible source of water for the earth’s surface, but there has been only an insignificant increase in it in recent decades. Precipitation-evaporation difference remains relatively unchanged during the studied period, which is a favorable trend, as there is no increase in the water deficit in Bulgaria on an annual basis. In addition, most of the country has positive values in terms of the average annual values of precipitation-vaporation difference. However, there is a need to introduce monitoring of actual evaporation, because this study has shown that different calculation methods give different results, which is a significant problem in determining how much precipitation remains in a given area. The exact values of this indicator are extremely important for various sectors of the economy such as agriculture, water supply and sewage, transport, energy, etc.

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DOI: 10.3897/jbgs.e128961

Authors: Hanene Guergour, Mohammed Cheraitia, Assoule Dechaicha, Djamel Alkama

Abstract: Climate-aware urban environments pose a significant imperative to obtain thermally comfortable outdoor areas. The present study addresses the optimization of urban block morphology in Guelma City, Algeria, to enhance thermal performance in a semi-arid climate. Using in-situ measurements and simulation generated by the ENVI-met simple forcing scheme, the impact of urban morphology on the variation of outdoor comfort factors, including air temperature, relative humidity, and wind speed arameters, is identified. The conducted investigation illustrates building configuration, orientation, and street canyon geometry as key indices affecting thermal comfort. Results pointed out urban green cover’s role in mitigating heat island effects. In conclusion, the study underscored the significance of an interconnected analysis of urban patterns and heir correlated influence on urban microclimate for achieving thermally comfortable outdoor environments.

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DOI: 10.3897/jbgs.e126650

Authors: Tsvetan Parov

Abstract: Discovered only about 200 years ago, Antarctica is the poorest and most isolated ecosystem on Earth. Its thinner atmosphere, due to the centrifugal forces of Earth’s rotation, the ozone hole, and stronger solar radiation, creates a natural laboratory that provides information about the state and trajectory of Earth’s climate condition. This study aimed to determine the depth of heat penetration from the surface of the glacier into the crevasses in the ablation zone and establish the zone of constant temperatures in the glacier. It explored the relationship between the air temperature at the glacier surface and the temperature distribution in the crevasses, including the temperature gradient at different levels and the direction of the airflow. We used autonomous data loggers for measuring and recording temperature and relative humidity. The measured depth reached 18 m in the central part of the glacier and 9 m in the periphery. An ultrasonic anemometer was installed in the deepest crevasse in to the center of the glacier to determine the size and direction of air flows. Meteorological parameters such as air temperature, humidity, atmospheric pressure, and solar radiation were measured on-site using autonomous sensors and recording devices mounted on installations on the glacier surface and at depth using alpine techniques. The results show a temperature gradient through 3-meter layers, a relatively clear boundary of the constant temperature zone, and a significant infiltration of cold air through the crevices driven by turbulent wind processes. Additionally, a weak negative correlation was found between solar activity and temperatures in the crevasses. It appears that as solar activity increases, the temperature decreases. There are also weak but consistently positive correlations with air movement both upward and downward. The temperature becomes constant with the increase of the depth until a zone of constant temperatures is determined and the temperature variance becomes insignificant. This zone varies in different crevаsses, meaning it is influenced by the specific characteristics of each crevasse location. At shallow depths, temperature is influenced by external temperature, but with the depth increasing this influence decreases. On windy days, the zone of constant temperature expands. During higher solar activity, air circulation accelerates—both upward and downward. The relationship between solar activity and climatic processes in glacier drainage systems adds new insights to solar-terrestrial physics.

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DOI: 10.3897/jbgs.e126690

Authors: Tabaro Kabanda

Abstract: This study examines the effects of extreme temperature events, defined explicitly as the 98th percentile temperature for heat, in Tanzania from 1981 to 2023. The study utilises percentile analysis, z-score calculations, and trend mapping to highlight the prevalence of extreme temperatures. The z-score analysis examines the occurrence of extreme temperatures and their distribution in terms of frequency and space. It identified Tanzania’s mid-eastern and north-western regions as areas with a high concentration of extreme temperatures over the previous 43 years. The study analyses the length of extreme occurrences and reveals changing patterns. In 2020, the events were shorter, while in 2021 and 2022, they became longer-lasting, and there was a notable concentration of extended anomalies near the northern coastline. In 2023, the highest temperatures ever recorded were observed, with more than half of the regions seeing prolonged periods of extreme temperatures lasting for a week and significant deviations from the norm staying for four weeks or more. This was particularly notable in the southern regions of Lindi and Mtwara. The harmonic trend analysis of temperature shows an upward temperature trend noticeably in regions such as Arusha, Kilimanjaro, Kagera, Morogoro, Simiyu, and Shinyanga and is somewhat inconspicuous in most areas.

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DOI: 10.3897/jbgs.e124098

Authors: Ibrahim Olatunji Raufu

Abstract: In an era of rapid urbanization, understanding the complex relationship between vegeta-tion dynamics and land surface temperature (LST) is crucial for addressing the challeng-es posed by urban heat island (UHI) and promoting sustainable urban development. Our study aimed to explore these dynamics in a rapidly urbanizing environment by analyzing the relationships between remote sensing-based vegetation indices and LST through quantitative analysis. A cloud-free Landsat 8 OLI/TIRS level 2 satellite imagery of Ibadan region city for 2022 was obtained from the United State Geological Survey (USGS) and LST was estimated using the radiative transfer approach. Utilizing different combina-tions of spectral bands, seven vegetation indices including Normalized Difference Veg-etation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), Atmospherically Resistant Vegetation Index (ARVI), Green Normalized Difference Vegetation Index (GNDVI), Ratio Vegetation Index (RVI), Optimized Soil Adjusted Vegetation Index (OSAVI), and Green Chlorophyll Index (GCI) were analyzed. Combined with the spatial distribution of LST in Ibadan, regression analysis were performed to explore the relationship between vege-tation indices and LST. Results indicate that among the seven vegetation indices, ARVI has the strongest correlation with LST in the study area (R2 = 0.65). Additionally, urban cores experience lower vegetation density and higher LST values, which can be attribut-ed to land use intensity, anthropogenic heat release, and impervious surface cover while the peripheral areas exhibit higher vegetation indices and lower LST values. The findings of this study contribute to a deeper understanding of urban environmental dynamics and provide valuable insights for sustainable urban planning, ecosystem management, and climate adaptation strategies in rapidly urbanizing areas.

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DOI: 10.3897/jbgs.e120301

Authors: Emil Gachev, Erald Meshini, Simeon Matev, Martin Iliev, Georgi Gachev, Maria Gacheva

Abstract: Several perennial snow and ice bodies have been recently studied and monitored in three mountain massifs across the Balkan Peninsula: Prokletije (Northern Albania), Durmitor (Montenegro) and Pirin (Bulgaria), the two glacierets in the Pirin Mountains until soon considered as southernmost of their kind in Europe. In September 2022 a relatively large snow field (about 1.5 ha) was discovered and described for a first time in the glacial cirque Gryka e Kazanit in the Nëmerçka Mountains of Southern Albania. The snow accumulation lies on 1550–1650 m a.s.l. below a vertical limestone cliff with a height of almost 1000 m. The site was visited again in November 2023, when the snow field diminished its size to less than 1 ha. At the same time, multi-annual firn layers were exposed under the last year snow, with depth at least several metres, and indications were observed of ice, buried in the debris cover below. Newest findings indicate that the studied snow-firn body is a glacieret similar to those found in the Pirin Mountains. On a longer-term, nine perennial snow/firm bodies on the Balkans resemble small glaciers rather than snow and ice patches at least under current climatic conditions. Situated on 40°08′ Northern latitude, the newly discovered Nemërçka Glacieret is nominated to be the southernmost glacier in Europe.

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DOI: 10.3897/jbgs.e113695

Authors: Mohamed Brahimi, Moussadek Benabbas, Djamila Djaghrouri

Abstract: Urbanization has radically transformed natural landscapes, giving rise to complex urban environments worldwide. This transformation poses unique challenges in terms of climatic conditions. We emphasize the crucial importance of understanding urban microclimates shaped by geographical, architectural and human factors, requiring meticulous management for sustainable urban planning. These multifaceted factors interact to produce spatial variations in solar exposure, temperature and wind conditions, leading to distinct microclimatic pockets within cities. This underlines the imperative need for sustainable urban planning and design that takes account of their impact. Our field survey is located in Djelfa, Algeria, featuring a semi-arid to arid climate with continental influences. This article presents a methodology involving a detailed morphological analysis of the urban fabric, focusing on its structure, vegetation cover and spatial characteristics. It describes the use of ENVI-met, a powerful microclimate simulation tool offering a complete three-dimensional modeling system that integrates various urban elements, including buildings, streets and green spaces. Our spatial considerations guarantee model accuracy, with a rigorous geometry validation process maintaining model fidelity. The tool produces invaluable output data, including air temperature, relative humidity and thermal comfort indices. This paper emphasizes on the application of the model in Djelfa, Algeria, highlighting its potential in evaluating thermal condition in urban environments. The results of our study highlight significant temperature and humidity disparities between urbanized and green areas in the survey area, with temperature differences of up to 6°C during the day. Urbanized areas consistently have higher air temperatures and lower humidity levels, particularly during the day. Conversely, green spaces, including gardens and tree-lined areas, exhibit lower temperatures and higher humidity levels, offering valuable respite from heat stress. The use of the Physiological Equivalent Temperature (PET) index allows us to assess thermal comfort, revealing variations in heat stress levels across the urban landscape. This research highlights the crucial importance of integrating green infrastructure into urban planning to improve thermal comfort and livability in cities. Furthermore, our study reveals the value of advanced tools like ENVI-met in understanding urban microclimates and provides valuable information for sustainable urban development and climate adaptation strategies.

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DOI: 10.3897/jbgs.e114034

Authors: Tsvetan Parov

Abstract: This study focuses on the meteorological parameters of the near atmosphere, the surface of the Earth and karst areas, such as temperature of water and air, relative humidity, and wind speed. These parameters are significantly influenced by solar activity, which in turn affects the temperature distribution in karst underground cavities, specifically in the “Kolkina Dupka” cave located within the Ponor Mountain of the Western Balkan Mountains range in Bulgaria. This is the deepest and longest cave in Bulgaria with a length of more than 20 km and a calculated depth of 800 m. Meteorological data within the cave was collected using data loggers, while surface weather data was sourced from National Institute of Meteorology and Hydrology of Bulgaria. Solar activity information was obtained from the website of the Royal Observatory of Belgium. The impact of solar activity on karst regions is substantial and affects temperature, precipitation, and atmospheric circulation. Changes in solar radiation can alter heat absorption on the surface of the Earth, leading to shifts in temperature and precipitation patterns. We performed statistical analysis and modeling to understand the complex interactions between Earth's near atmosphere, the karst system of the Kolkina Dupka cave, and the role of air and water flows in regulating cave temperatures. Results showed a significant negative correlation between air temperatures in the deep underground airflows (at a depth of 130 m below the surface) and temperatures at the cave entrance (at a depth of 40 m during the winter months. Conversely, during spring and summer, an intriguing reversal occurs where higher external temperatures are linked to increased air temperatures at the cave entrance, accompanied by lower temperatures in the deeper zone. Furthermore, by employing “lagged correlations” in result analysis, investigating correlations between internal temperatures and external temperatures over the preceding and subsequent seven days, cyclic variations in heat exchange between the near-surface atmospheric layer and the underground temperatures within the karst system were observed. Specifically, a consistent temperature elevation was noted at the cave entrance three days prior to an increase in external temperatures during the spring-summer season. This temporal relationship was also observed in the solar activity data, where an increase in temperature at a depth of -40 m was registered three days prior to the escalation of solar activity within the measured range of 2800 MHz. The obtained results formed the basis for the development of new theories in solar-terrestrial physics. In summary, there is a connection between solar activity and Earth's climate, but it is not a direct and simple correlation, and it is just one piece of the larger puzzle that shapes temperature variations of the Earth. Climate science involves studying these interactions over extended periods to gain a more comprehensive understanding of the climate system of the Earth.

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DOI: 10.3897/jbgs.e108747

Authors: Peter Nojarov, Vladimir Vlaskov, Yoana Vatova

Abstract: The study aims to reveal spatial distribution of precipitation in the area of Sofia city during the decade 2013 - 2022 and the influence of atmospheric circulation. Statistical methods and cartographic approach are the main tools in this research. The spatial distribution of precipitation is characterized by low amounts (560 mm) in the northern and northeastern parts of Sofia depression and high amounts (760 mm) in the southern part. The main factor for this spatial distribution of precipitation is atmospheric circulation. The relief has a significant modifying effect and affects precipitation through several mechanisms. The most important is the location of mountain slope relative to the main direction of transport of air masses. Leeward slopes receive less precipitation and windward slopes receive more. The second mechanism of influence is anthropogenic relief (high buildings), which is a positive relief form compared to the surrounding plane having respective windward and leeward slopes. This study revealed a third mechanism of relief influence on spatial distribution of precipitation. The large difference in the height of the mountains located south of Sofia creates a significant difference in the air temperature in Sofia depression during a transport of air masses from south and southwest. This is due to the stronger foehn effect of the higher mountain (Vitosha) compared to the foehn effect of the lower mountains (Lyulin, Lozenska Planina), which creates a tongue of higher air temperature northeast of Vitosha, which reaches the southern and southwestern slopes of Stara Planina. The higher temperatures in this tongue create stronger upward air movements, which in turn increase the amount of precipitation. Secondary, but still important factors that affect the spatial distribution of precipitation in Sofia region are the urban heat island and the increased content of aerosols in the air in and over the city.

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DOI: 10.3897/jbgs.e105178

Authors: Patrick Sunday Asa, Idris Shehu Umar, Ambrose Audu Zemba

Abstract: The paper presents the results of studying the spatial and seasonal atmospheric temperature characteristics of Jalingo metropolis, Nigeria, with the aim of assessing seasonal temperature variations for thermal comfort planning. Temperature data for this study was collected across the local climate zones, otherwise known as thermal climate zones (TCZ), following the TZC classification of the area. Temperature data was collected for 30 days continuously and simultaneously across the TCZ. The collection of temperature data was done in the months of April and August 2021, and January 2022 – representing the dry season, the rainy season and the Harmattan period respectively. A Thermochron Ibutton sensor by Maxim Incorporation was used to collect temperature data, while the specific series used was DS1921. An improvised automated weather station was constructed to house the sensor. The result of the study indicates that air temperature varies considerably within Jalingo metropolis, as well as throughout the seasons, thus affecting human thermal comfort in the study area, as temperature is found to correlate well with both human morbidity and mortality, especially regarding cardiovascular diseases. The paper recommends increasing ventilation and nature-based solution to reduce high temperatures through tree planting in order to improve human thermal comfort in Jalingo metropolis area.

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DOI: 10.3897/jbgs.e101301

Authors: Petar Stefanov, Hristina Prodanova, Dilyana Stefanova, Vanya Stoycheva, Gergana Petkova

Abstract: Karst is a widely spread natural phenomenon which provides essential benefits to human society, such as drinking water. The water cycle in the karst geosystems is the main factor for their formation and at the same time one of the main drivers for ecosystem services (ES) provision. The monitoring of the water cycle can provide valuable information regarding its functioning and ensure data for ES assessment. This paper aims to present an overview of the monitoring of the water cycle in the karst geosystems and the opportunities to integrate the monitoring data into the water regulation ES assessment. The monitoring of the water cycle is based on the methodological framework ProKARSTerra. It is applied in model karst geosystems, which are representative of the main karst types in Bulgaria. One of them is the Brestnitsa karst geosystem, which is the case study of this work. The monitoring ensures data for analyses of the water cycle which can be used in the assessment of water-related ecosystem services. The results from the analyses of the data requirements and availability show that some services such as water flow regulation and regulation of chemical condition of freshwaters can be easily provided through data for quantification, while for others further studies are needed. The results of the long-term integrated monitoring in Brestnitsa karst geosystem provide the foundation for important conclusions and models for the karst genesis and function under global changes and active anthropogenic pressure. Their integration into the assessment framework and mapping of ecosystem services is an essential step towards the development of models for sustainable use of natural resources in the karst areas.

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DOI: 10.3897/jbgs.e97974

Authors: Ianko Gerdjikov, Zornitsa Dotseva, Eli Pavlova-Traykova, Dian Vangelov

Abstract: One of the biggest rivers in the southern part of the Balkan peninsula – the Mesta River is wellknown for frequent flash floods, especially in the upper river course. As a result of severe storms and related heavy rain in mid-July 2019, the Cherna Mesta River flooded, and this resulted in heavy damage to the road infrastructure and water-supply systems. All data indicate that this was not a usual water flood, instead at peak flow, the river carried a huge amount of gravel. Our mapping of erosional and depositional features related to the 2019 event, as well as geomorphological analysis, allows for distinguishing distinct sectors along the river valley. Most hazards are defined in the lower reaches of the Cherna Mesta River, where the processes of channel aggradation and lateral erosion are pronounced. The field analysis of the flood-related deposits indicates the operation of debris flood and hyperconcentrated and water flood processes.

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DOI: 10.3897/jbgs.e98660

Authors: Petko Bozhkov, Borislav Grigorov, Alexandar Sarafov

Abstract: The present study deals with the investigation of soil organic carbon in two water catchments in Northern Rila, Western Bulgaria. Field research, combined with analysis, provided sufficient data. Six key sites were selected and sampled in order to estimate and compare the amount of organic and inorganic carbon in the topsoil. The applied criteria for the choice of sites included: vegetation cover, predominant soil group, level of anthropogenization and transport accessibility. A total number of 13 samples from both catchments were collected and analyzed in the Central laboratory of the Institute of Soil Science, Agrotechnologies and Plant Protection (ISSAPP) “N. Pushkarov“. The results concern the amount and composition of soil organic matter in different soils – Cambisols (Albic, Humic, Dystric), Fluvisols and Umbrosols. The total carbon content of all samples varies between 1.23 and 9.69%. The amount of organic carbon ranges between 0.45 and 3.73%. The results of the study prove once again that the preservation of natural vegetation and current condition of the soil is of great importance for carbon sequestration and climate change mitigation.

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DOI: 10.3897/jbgs.e85567

Authors: Eugenia Sarafova

Abstract: Bulgaria, located in the Balkans, is subject to a number of natural disasters including floods, earthquakes, landslides, forest fires, strong winds, droughts, heavy snowfall and extreme temperatures. In addition to natural disasters, the country is at risk for man-made events like industrial and nuclear accidents, transport accidents, and infectious diseases. Disaster planning and prevention is a complex process that requires multiple data sources. At the same time, spatial data are often not available on-line, so the country's GIS specialists may find existing spatial data to be a great challenge. This research analyses the application of the health sector data provided by the Copernicus Climate Change Service to support the development, implementation and evaluation of disaster risk management plans in Bulgaria. The climate data visualizations provided by the service enable scientists and other stakeholders to view climate change data in a format that is simple to use, visually understandable, and usable for decision makers in government, business, and non-governmental organizations. Many of these visualizations are interdisciplinary and may be critical for gathering and applying information needed to develop disaster risk reduction plans.

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DOI: 10.3897/jbgs.e78709

Authors: Mariyana Nikolova, Peter Nojarov, Stoyan Nedkov

Abstract: The area of the Seven Rila Lakes is situated in the North-West part of the Rila Mountain at an altitude between 2100 and 2500 m a.s.l. within the borders of Rila National Park. There are 140 glacial lakes in Rila Mountain but the area of the Seven Rila Lakes is the most visited and famous with its natural beauty and sacred significance. It is a valuable part of the national natural heritage. The popularity of this area grows constantly with the number of visitors from the country and abroad. This process leads to the deterioration of the natural conditions in the site. At the same time, it is not clear what is the effect of climate change on the environment in the lake’s area. There are many factors that contribute to the degradation of ecosystems in the protected area of the Seven Rila Lakes and pose risk to this valuable natural heritage. These factors are natural (mainly climate change-related), anthropogenic (associated with the excessive tourist pressures on the ecosystems in the protected area), and management (stemming from the ongoing conservation policy over the years). This study explores to what extent climate change may put at risk the ecosystems of Seven Rila Lakes. Mean monthly data from The European Center for Medium-Range Weather Forecasts (ECMWF) ERA5-Land reanalysis were used in this study. The resolution of these data is 0.1 x 0.1 (9 x 9 km) and their period is 1981-2020. Reanalysis data include air temperature, precipitation, evaporation, snow depth, etc. Based on data from various sources such as reanalysis data, in situ measurements, and statistical modeling, a scenario, based on current trends in different climatic elements, has been developed in order to project future changes and their impact on lake ecosystems. The results of the modelling of climate change show that in the coming decades an increase in temperature is expected in the high mountain regions of South-western Bulgaria and in particular in the Seven Rila Lakes area. This, combined with the ever-increasing flow of tourists, and high demand for the provided cultural ecosystem services, and insufficient management practices, put at risk the state of the lakes and their capacity to provide the same quality of cultural ecosystem services in the future, which attracts tourists in the area now. Recommendations have been made for the optimization of the management of the protected area in accordance with the observed trends.

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DOI: 10.3897/jbgs.e77102

Authors: Hristo Popov, Jelena Svetozarevich

Abstract: The Republic of Serbia is а continental country located in the western part of the Balkan Peninsula, in Southeast Europe. In terms of physical characteristics, Serbia is divided into two parts: Pannonian part and mountainous part. The northern part of the country is located in the valley of the Middle Danube, the Sava River valley and the Tisza River valley. In the middle part of the country, the river valleys of the Drina, the Kolubara and the Morava are located. For the purposes of this research, the authors have used the annual precipitation data from 15 meteorological stations distributed throughout the Republic of Serbia. The data from these meteorological stations for the period between 1991 and 2019 has been provided by The Serbian Institute of Meteorology and Hydrology. This data has been used to calculate the annual amount of precipitation, and the trends in annual precipitation.

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DOI: 10.3897/jbgs.e73825

Authors: Peter Nojarov, Todor Arsov, Ivo Kalapov, Hristo Angelov

Abstract: This study reveals the effect of aerosols and water vapor on downward longwave radiation in the high mountain region of Musala peak, Bulgaria. The investigated period is 01/01/2017 (Jan. 1st 2017) – 30/09/2019 (Sep. 30th 2019). Statistical methods are the main tool for discovering the relationships between the different elements. The results indicate that air temperature is the leading factor for downward longwave radiation, specific humidity, and amount of aerosols in the air. That is why, in order to reveal the pure relationship between downward longwave radiation, specific humidity and amount of aerosols in the atmosphere, the air temperature was cleared from the data series. After this procedure, the results show that specific humidity has a significant influence on the downward longwave radiation flux, and an increase of 1% of the specific humidity results in an increase of about 12-15% in the values of the downward longwave radiation. At air temperatures around 0ºC the influence of water vapor on the downward longwave flux is highest, which is due to the phase transitions of the water – a process during which release/absorption of radiation in the longwave spectrum occurs. The amount of aerosols in the atmosphere also has a significant effect on this type of radiation, and an increase of 1% of the amount of aerosols in the air at air temperatures above –5.5°C results in an increase of the downward longwave radiation of about 2-4%. The findings of this study show that coarser and opaque aerosol particles have a stronger effect on downward longwave radiation. In the area of Musala peak, as the air temperature rises, there is an increase in the amount of aerosols in the air, a decrease in their size, and a transition from transparent to opaque aerosols. The combination of these different tendencies causes the influence of aerosols on downward longwave radiation to be strongest in the middle temperature interval – air temperatures between –5.5°C and +5.5°C. Due to the increased total amount of aerosols and increased amount of opaque aerosols, their influence on downward longwave radiation is significant also at air temperatures above 5.5°C.

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DOI: 10.3897/jbgs.2019.41.2

Authors: Stoyan Kyurkchiev

Abstract: Chelevchinitsa Cave is formed in the southwestern part of the Dobrostan karst region, Western Rhodopes. It has been subjected to microclimatic monitoring since April 2016. Air temperature, cave water and sediments are periodically measured at eight points, and thus the air humidity is determined. A micro-climatic zoning of the cave was being done on the basis of the analysis of the data on the temperature regimes for the period 2016–2018. A link has been sought between cave microclimate and global climate change using available data for the period 1979–2017 . The issue of the influence of the anthropogenic load on the speleomicroclimate as well as the impact of the cave enviorment on the health and safety of the tourists is also discussed. Particular attention is paid to the role of cave ventilation on the gas composition of the cave atmosphere, and especially on the regime of carbon dioxide (CO2 ) and radon (222Rn).

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DOI: 10.3897/jbgs.2019.40.5

Authors: Galin Petrov, Hristina Prodanova

Abstract: The names of geographical objects on a particular area are peculiar store for conservation of historical-geographical information. Typical versatility of the toponymic system gives possibility for usage of different approaches for analysis of it, including spatial analysis. Information for state of natural environments and their changes is coded in the toponymic system. Historical localization of landscapes with coniferous vegetation on the northern slopes of Shipchenska Mountain (Balkan Mountains, Bulgaria) on toponymic basis is presented in the article. Some conclusions about probability for existence of coniferous belt in the past are formulated. The study is an initial attempt to build a link between toponymy and onomastics on the one hand and historical geography of landscapes on the other. The used approach has some weaknesses and could be used successfully in combination with the results of other studies such as paleobotanical, paleoecological, etc.

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