Data for the geoecology of solution karst dolines, with particular attention to climatic, soil and biogenic environment

In this study the changes in the nighttime heat load in Carpathian Basin cities during the 21st century were examined. To quantify the heat load, the tropical night climate index was used. The MUKLIMO_3 local scale climate model was used to describe the urban processes and the land use classes were defined by the local climate zones. The expected change was examined over three periods: the 1981–2010 was taken as reference period using the Carpatclim database and the 2021–2050 and 2071–2100 future periods using EURO-CORDEX regional model simulation data for two scenarios (RCP4.5 and RCP8.5). To combine the detailed spatial resolution and the long time series, a downscaling method was applied. Our results show that spectacular changes could be in the number of tropical nights during the 21st century and the increasing effect of the urban landform is obvious. In the near future, a slight increase can be expected in the number of tropical nights, which magnitude varies from city to city and there is no major difference between the scenarios. However, at the end of the century the results of the two scenarios differ: the values can be 15-25 nights in case of RCP4.5 and 30-50 nights in case of RCP8.5. The results show that dwellers could be exposed to high heat load in the future, as the combined effect of climate change and urban climate, thus developing various mitigation and adaptation strategies is crucial.

Projected changes in heat load in Carpathian Basin cities during the 21st century

In this study the changes in the nighttime heat load in Carpathian Basin cities during the 21st century were examined. To quantify the heat load, the tropical night climate index was used. The MUKLIMO_3 local scale climate model was used to describe the urban processes and the land use classes were defined by the local climate zones. The expected change was examined over three periods: the 1981–2010 was taken as reference period using the Carpatclim database and the 2021–2050 and 2071–2100 future periods using EURO-CORDEX regional model simulation data for two scenarios (RCP4.5 and RCP8.5). To combine the detailed spatial resolution and the long time series, a downscaling method was applied. Our results show that spectacular changes could be in the number of tropical nights during the 21st century and the increasing effect of the urban landform is obvious. In the near future, a slight increase can be expected in the number of tropical nights, which magnitude varies from city to city and there is no major difference between the scenarios. However, at the end of the century the results of the two scenarios differ: the values can be 15-25 nights in case of RCP4.5 and 30-50 nights in case of RCP8.5. The results show that dwellers could be exposed to high heat load in the future, as the combined effect of climate change and urban climate, thus developing various mitigation and adaptation strategies is crucial.

Astronomical causes of climate change. Milanković–Bacsák cycle and the last ice age

György Bacsák, a Hungarian polyhistor, was born 150 years ago and died 50 years ago. He played an important role in refining and further developing the Milanković cycle. Milanković's theory describes the effect of changes in Earth's movements on the climate. The theory came from its creator, Milutin Milanković, a Serbian geophysicist and astronomer. The Serbian scientist was imprisoned in the Austro-Hungarian Monarchy during World War I as a citizen of a hostile state. He developed his theory in the library of the Hungarian Academy of Sciences. Understanding the essence of the theory, György Bacsák enjoyed the theoretical support of Milanković in the form of regular correspondence between 1938 and 1955. In total, György Bacsák wrote 56 letters to Milutin Milanković, while the Serbian scholar wrote 10 letters, all of which can be found in the Library of the Hungarian Academy of Sciences. The language of the letters was German, since both Bacsák and Milanković spoke German fluently. Three articles from György Bacsák, from the year 1940, were published in the Magazine “Weather” and a part of his book “Earth’s history of the last 600,000 years” was published in 1944 both of them were based on this letter exchange.

Projection of present and future daily and evening urban heat load patterns

In this modeling study the recent and future daily and evening thermal climate of a Central-European city (Szeged, Hungary) was investigated in terms of heat load modification by applying MUKLIMO_3 model to project daily and evening climate indices. For surface parameterization the Local Climate Zone (LCZ) scheme was used. The investigation encompassed three climatological time periods (1981–2010, 2021–2050 and 2071–2100) and two emission scenarios for future climate (RCP4.5 and RCP8.5). Our results show that highest index values appear in the city centre and stretch to the NW direction (LCZs 2, 3 and 8) and they decrease towards to the vegetated rural surfaces (mainly LCZ D). That is, the values depend on the zone types and there are more days towards to the densely built-up LCZs. Also, a general temporal change can be detected as the index patterns show the substantial increasing tendency for both indices towards the end of this century. This temporal change suggests a two-way conclusion: first, the increasing number of hot days means a strongly deteriorating change of unfavourable thermal conditions, and second, the change in the number of the evening index provides more opportunities for regeneration and leisure-time activities outdoors in the already thermally less stressful evening hours for the urban inhabitants. This study gives very illustrative examples on the expected climate changes during this century and these examples show that there are several sides to these changes in urban environments. Furthermore, they clearly prove that global or regional scale climate predictions without urban climate interactions do not have enough detailed information.

Studying the growth characteristics of urban trees using an example from Szeged, Hungary

The spatial expansion of urbanised areas and the steady increase in the urban population, as well as climate change trends, are increasing the need for the development of adequate urban green infrastructure. The social demand for combating climate change is accompanied by the revaluation of green spaces, and in this context woody vegetation plays a key role. In a changing climatic context and under intense anthropogenic stress, the challenge of developing a tree population that is climate-friendly and resistant to disturbance is a major one. In our research, we investigate all growth parameters of the newly planted trees from the start of a street reconstruction involving a complete tree replacement (Gutenberg Street, Szeged). The structural analysis of the revealed not only the growth rate over the 8 years since planting, but also the significant differences between the two sides of the street. In order to find a possible reason for this, we examined (using SAGA GIS software) potential incoming solar radiation of the street, which could explain the significant difference in growth rate. The data collected also provided an opportunity to analyse the allometric relationships. This will partly allow the prediction of the growth rate and can provide baseline data for planning and decision-making processes in the dilemma of whether to retain older trees or plant new stocks.

Model development for the estimation of urban air temperature based on surface temperature and NDVI

Predictive models for urban air temperature (Tair) were developed by using urban land surface temperature (LST) retrieved from Landsat-8 and MODIS data, NDVI retrieved from Landsat-8 data and Tair measured by 24 climatological stations in Szeged. The investigation focused on summer period (June−September) during 2016−2019 in Szeged. The relationship between Tair and LST was analyzed by calculating Pearson correlation coefficient, root-mean-square error and mean-absolute error using the data of 2017−2019, then unary (LST) and binary (LST and NDVI) linear regression models were developed for estimating Tair. The data in 2016 were used to validate the accuracy of the models. Correlation analysis indicated that there were strong correlations during the nighttime and relatively weaker ones during the daytime. The errors between Tair and LSTMODIS-Night was the smallest, followed by LSTMODIS-Day and LSTLandsat-8 respectively. The validation results showed that all models could perform well, especially during nighttime with an error of less than 1.5o. However, the addition of NDVI into the linear regression models did not significantly improve the accuracy of the models, and even had a negative effect. Finally, the influencing factors and temporal and spatial variability of the correlation between Tair and LST were analyzed. LSTLandsat-8 had a larger original error with Tair, but the regression model based on Landsat-8 had a stronger ability to reduce errors.

Urban heat island studies in Szeged, Hungary

The overview summarizes briefly the contents and results of the papers published in journals dealing with urban heat island investigations in Szeged, Hungary between 1980 and 2020. The thermal data they used came from urban station networks, mobile measurements, local-scale simulations as well as aerial and satellite images.

Adaptation of UFORE-Hydro model for Szeged and the southern region of the Great Hungarian Plainbased on local meteorological database

Urban environments are very different from natural ones in many cases. The geometry of the buildings and the various artificial surface elements can significantly influence the microclimatic and hydrological processes. In urban areas, the surface is mostly artificial and it is hard to find natural, undisturbed surfaces, in addition, the vast majority of soil surfaces are generally under strong anthropogenic influence. Models can provide a comprehensive view of the hydrological processes in the city and can help to investigate the different impacts of them. In this study, our aim is to introduce the preparation of a widely applicable model (UFORE-Hydro) for Hungarian pilot areas. Thus, we intend to introduce the procedure of preparing the weather and evaporation files and their local databases which we used for the model.

Modeling options for rainwater harvesting developments in a public institution as part of sustainable urban water management solutions

The water cycle of cities is very different from that of natural areas, and it is characterized by rtificial energy flow processes and materials. Due to the high concentration of population, weather extremes in urban areas can cause greater personal and economic damage than in rural areas. Besides extreme amounts of precipitation, which is only one type of extreme weather events, it is important to be prepared for drought and dry periods (which are typical in Szeged and the southern region of the Great Hungarian Plain). During these periods, urban vegetation requires additional irrigation due to the urban artificial environment and the special species composition. This irrigation water basically means potable water resources. It is not a sustainable way to protect potable water resources, therefore any solution that can alleviate this situation is a major improvement. In our study, we modeled a rainwater harvesting system which is established in an elementary school in Szeged. We paid special attention to the quantitative and time distribution properties of the potential precipitation available for the rainwater harvesting system.