Vol. 129, No. 3 * Pages 241–372 * July - September 2025

To describe and study the climate and its changes more accurately, climate databases are needed that are representative in time and spatial coverage, and that are based on sufficiently long measurement data series. In Hungary, air pressure measurements have a long history, similar to temperature and precipitation, but a homogeneous gridded database of Hungarian air pressure measurements over a century, with a daily resolution covering the whole 20th century, has not yet been produced. Therefore, the main aim of this research was to produce a homogenized gridded daily air pressure database from the beginning of the 20th century, which is currently available from 1961 only. In addition, in the period after 1961, and especially in the last few decades, station data series are used in much greater numbers than before. This will produce a more accurate interpolation, i.e., a more accurate grid point database than at present, which can be updated annually in the future, as for temperature and precipitation.
In this paper, we describe the methods used, discuss the station systems used for homogenization and interpolation of air pressure in different time periods, analyze the main verification statistics of the homogenization, and also analyze the results of the interpolation, examine the annual, seasonal, and monthly surface air pressure data series and their extremes, including the daily extremes for the period 1901–2023.

The atmospheric teleconnection presented in our former paper (Babolcsai and Hirsch, 2019) shows a particularly strong regularity between the Euro-Atlantic mean sea level pressure anomaly pattern in September and the pattern three months later, in December, in the current positive AMO (Atlantic Multidecadal Oscillation) phase lasting since 1995.
Euro-Atlantic mean sea level pressure anomaly patterns for September were divided into four clusters, whereas cases that could not be classified as any of these, were assigned to a fifth cluster.
Based on the clustering, the December macrosynoptic situation in Europe can be predicted in a significant number of cases, and hence the sign of the temperature anomaly in Central Europe.
In our paper, these regularities are described, as well as their connection to the polar vortex, which is the main factor in forming the mean sea level anomaly of the winter months of the northern hemisphere. In the last 29 years, clustering based on the mean sea level pressure anomaly for September has been able to divide significantly cold and mild December months even better than the state of the polar vortex in December (sign of the AO index).
In addition, a new phenomenon is presented, which might be a sign of climate change and has been interfering in the atmospheric processes since 2019.

It is a well-known phenomenon that sinkholes, compared to their environment, have a relatively colder microclimate, due to the topographic conditions (closed depressions). Its geomorphological characteristics favors the development of cold-air pools and can cause significant temperature anomalies. This process has been documented in several papers before, but the detailed buildup and breakup, and especially the environmental covariates that drive these processes, are not well documented yet. This paper aims to summarize a three months period measurement (spring of 2023) in Northern Hungary, on the karst plateau of the Bükk Mountains. This plateau is characterized with a complex karst surface development, having interconnected sinkhole systems. The Mohos sinkhole – the largest sinkhole of the area with several contributing smaller sinkholes – was selected for the measurement campaign. A detailed terrain and remotely sensed database were built to characterize the geomorphology and its contribution to the development of the sinkhole’s microclimatic system. A sensor system was developed and adopted to the local conditions using 10 directly measured or derived meteorological parameters (air temperature (200 cm, 40 cm), dew point, solar radiation, relative humidity, wind speed, daily evapotranspiration, vapor pressure deficit., and soil temperature), along with two comparison sites from the edge of the sinkhole and from a representative site of the Bükk Plateau, where no major microclimatic derivation factor was assumed. During this period, the Carpathian Basin was characterized by a significant variability of weather patterns, and was optimal to analyze the behavior of the sinkhole's microclimate system based on the regional weather trends and their atmospheric dynamics. Several temperature inversion events were developed and analyzed to describe the relationships between the cold-air pool development and the external meteorological affects. The events were classified into the commonly accepted categories. The results demonstrated that the time of the lowest recorded temperatures was partly independent from the general temperature regimes. The most important factors are the general geomorphological factors, favorable radiation conditions, and lack of any external physical disturbance. It was also proved that the soil temperature had the largest correlation with the temperature change (r = 0.95), followed by the dew point (r = 0.92), vapor pressure deficit (r = 0.85), wind speed (r = 0.83) and the relative humidity (r = -0.8). That was also documented, that the near-surface dynamics play an important law in the behaviors of the sinkhole microclimate system, thus the buildup and breakup of the cold-air pool.

The territory of the Mura-Drava-Danube Transboundary BiosphereReserve is large and includes natural and built-up areas that local communities and tourists use during their outdoor work-related or recreational activities. These activities are affected by the outdoor thermal conditions, especially in the age of changing climate. In this paper we investigate micrometeorological and outdoor thermal comfort conditions in different natural and built-up environments at the area of the Bačko Podunavlje Biosphere Reserve. We chose one clear and calm day every month from October 2020 to June 2021, and performed measurements simultaneously at three different locations: settlement, riverside, and lake at midday hours. The results showed that thermal conditions differ between the different built-up and natural areas, and built-up areas tend to experience up to 7% less cold stress during the colder period than the other two sites according to the physiological equivalent temperature (PET) index. On the other hand, built-up area experiences more frequent strong and extreme heat stress during the warmer months. These and more detailed results presented in the paper indicate the most comfortable periods for outdoor activities in different natural or built-up environments.

In recent years, there has been a significant uptick in the frequency of disasters stemming from the impacts of global climate change. In response, both nationally and internationally, various studies are being conducted to mitigate these effects. Classifying regions affected by climate change into similar classes based on climate parameters is crucial for applying consistent methodologies in studies conducted within these regions. This approach will help determine the most appropriate strategies for mitigating the effects of climate change in these regions. The study utilized observational records of annual precipitation from 31 stations in the Black Sea Region, sourced from the Turkish State Meteorological Service, covering the data spans the period between 1982 and 2020. Cluster analysis was conducted using the k-means algorithm. The optimal cluster among those formed was determined through the silhouette index analysis. The study suggests that the optimal number of clusters is 2.

The issue of drought is treated as an important natural phenomenon that often has a negative impact on both the livelihoods of the population and environmental protection. Many parts of the world have been affected by catastrophic droughts in the past, leading to prolonged periods of famine and disease among local populations. According to the definition provided by the Intergovernmental Panel on Climate Change in 2014 (IPCC), drought can be assessed as a potential hazard and challenge depending on the evaluation of its impact on the population and its economic activities. The aim of this study is to determine drought periods in Bosnia and Herzegovina and to highlight their consequences. For the purpose of analysis, available data on average monthly precipitation from 12 meteorological stations in Bosnia and Herzegovina from 1956 to 2022 were used. The Standardized Precipitation Index (SPI-1 and SPI-3) was used to determine meteorological drought, including its intensity, frequency, and duration. Based on the results obtained, a relatively uniform frequency of drought was observed across the seasons. On the other hand, extreme droughts were most pronounced in winter and spring months. The maximum duration of drought was recorded in Zenica from November 1989 to October 1990.