E xcursions in the carbon-14 ( 14 C) record measured in tree rings are attributed to various high... more E xcursions in the carbon-14 ( 14 C) record measured in tree rings are attributed to various high energy but short-lived cosmic effects 1-7 . Wang et al. proposed a new event at 3372-3371 BCE based on a single set of annual 14 C data measured on a floating tree rings from a buried specimen of Chinese wingnut (Pterocarya stenoptera). Here we attempt to reproduce this event in tree rings of an absolutely dated bristlecone pine specimen (Pinus longaeva) from the White Mountains, USA and a subfossil oak (Quercus sp.) from the Moselle River Valley, France. We cannot confirm the presence of a cosmic-ray event as suggested at 3372-3371 BCE and we discuss potential implications to earlier results.
Tritium has been long recognized as a useful tracer for the study of atmospheric transport, ocean... more Tritium has been long recognized as a useful tracer for the study of atmospheric transport, ocean circulation, and the global water cycle. In addition, the application of tritium measurements in various fields has grown significantly in the last few decades. Since 1963, the atmospheric test-ban treaty, bomb tritium concentrations in precipitation have significantly declined. Therefore, in the last two decades, global tritium concentration of precipitation (including anthropogenic and natural sources) has almost reached a steady-state level. The aim of this study is to estimate the temporal variation of the natural tritium concentration of precipitation during the past decades. To do this, we use a backward predicting time-series model that exploits the correlation between precipitation tritium concentration and the secondary neutron flux in the atmosphere. The measured tritium time series of 21 Northern and two Southern Hemispheric stations are used, while neutron monitor (NM) data, which are widely compared to the production rate of cosmogenic isotopes in the atmosphere, is used as an external variable for the model. Backward predicting SARIMAX statistical models are fit on the period 2001–2018 and provide estimates of the natural precipitation tritium levels for the bomb peak period 1960–2000. Evaluation of backward estimations on the 1990–2000 test period yields RMSE measures between 0.5 and 4.6 TU for four of the 23 investigated stations, pointing out locations where the neutron flux is a good predictor of the precipitation tritium concentration.
Deciduous tree leaf and grass samples were collected in Debrecen, the second largest city in Hung... more Deciduous tree leaf and grass samples were collected in Debrecen, the second largest city in Hungary. The aim of the study was to determine the rate of fossil fuel-derived carbon in urban vegetation. At the locations sampled, C3 and C4 plants close to roads were collected in September 2017. In total, 82 tree and grass leaf samples were gathered at 36 different sampling points all over the city of Debrecen. The radiocarbon ( 14 C) results of the samples were compared to the local urban background atmospheric 14 CO 2 data to determine the percentage of the fossil fuel-derived carbon in the plants. Based on our results, the average fossil carbon content in the tree and grass leaf samples were 0.9 ± 1.2% and 2.5 ± 2.5%, respectively. The highest fossil carbon content was 9.6 ± 0.6% in a grass and 4.7 ± 0.7% in a tree leaf sample. It appears that the negative fossil carbon content results obtained at urban sampling areas reflect modern carbon emission, where radiocarbon content is higher than the corresponding local background, presumably due burning of recent wood containing bomb 14 C in the suburbs as well as other possible sources such as litter decomposition or soil CO 2 emission.
A periódusos rendszer VIII. főcsoportját alkotó nemesgázok izotópjainak arányait (3He/4He; 20Ne/2... more A periódusos rendszer VIII. főcsoportját alkotó nemesgázok izotópjainak arányait (3He/4He; 20Ne/22Ne; 21Ne/22Ne; 40Ar/36Ar; 136Xe/132Xe; 134Xe/132Xe) a Föld eredeti primordiális izotópos összetétele vagy a Föld kérgében/köpenyében képződése óta lezajlott spontán hasadási folyamatok határozzák meg. Felszín közelében vagy a légkörben antropogén hatásra (atomrobbantások) vagy kozmikus sugárzás hatására is képződhetnek. Amennyiben a nemesgázok a képződési helyükön felhalmozódnak folyadékzárványokba vagy ásványokba csapdázódva, akkor izotópjaik arányainak mérése alkalmassá teszi őket a bezáró közeg képződési helyének (köpeny, kéreg, atmoszféra) azonosítására, vagy az abban lezajló folyamatok azonosítására. Különösen az elsődleges, azaz a befogadó ásvány képződésével egyidős zárványok, zárványpetrográfiai és mikrotermometriai vizsgálatokkal kiegészítve, különösen értékesek lehetnek a képződési környezet meghatározásában.
Understanding climate change and revealing its future paths on a local level is a great challenge... more Understanding climate change and revealing its future paths on a local level is a great challenge for the future. Beside the expanding sets of available climatic data, satellite images provide a valuable source of information. In our study we aimed to reveal whether satellite data are an appropriate way to identify global trends, given their shorter available time range. We used the CARPATCLIM (CC) database (1961-2010) and the MODIS NDVI images (2000-2016) and evaluated the time period covered by both (2000-2010). We performed a regression analysis between the NDVI and CC variables, and a time series analysis for the 1961-2008 and 2000-2008 periods at all data points. The results justified the belief that maximum temperature (TMAX), potential evapotranspiration and aridity all have a strong correlation with the NDVI; furthermore, the short period trend of TMAX can be described with a functional connection with its long period trend. Consequently, TMAX is an appropriate tool as an explanatory variable for NDVI spatial and temporal variance. Spatial pattern analysis revealed that with regression coefficients, macro-regions reflected topography (plains, hills and mountains), while in the case of time series regression slopes, it justified a decreasing trend from western areas (Transdanubia) to eastern ones (The Great Hungarian Plain). This is an important consideration for future agricultural and land use planning; i.e. that western areas have to allow for greater effects of climate change.
XIVth Workshop of the European Society for Isotope Research, 2017
Production rates of cosmogenic nuclei are modulated by the variation of the magnetic strength of ... more Production rates of cosmogenic nuclei are modulated by the variation of the magnetic strength of the Sun, while the atmospheric concentrations of theses isotopes are further controlled by many other factors. The atmospheric concentration of several isotopes and the change of solar activity and hence secondary neutron flux has already been proven. The temporal atmospheric variation of the most studied cosmogenic isotopes (14 C, 7 Be and 10 Be) shows a significant correlation with solar cycles. However, since the artificial tritium (radioactive hydrogen isotope, 3 H) input to the atmosphere due to nuclear weapon tests suppressed the expected variations of tritium production rate by three orders of magnitude, the natural variation of tritium in meteoric precipitation could not be detected so far. We have been analysing the tritium concentration of precipitation for more than 13 years. These results suggest a connection between the solar cycle and the tritium content of precipitation. Previous model calculations have shown that the tritium production rate has a periodic variability of 5% during a solar cycle. Due to the dilution effect of the atmospheric moisture, this effect is supposed to be further weakened in the surface precipitation. In the Danube-Carpathian region the natural tritium level in the precipitation is around 5−10 TU. These low concentrations can be accurately measured only since the last 2−3 decades. Moreover, since the 50's the atmospheric thermonuclear bomb tests increased the tritium amount of precipitation by 2-3 orders of magnitude. After its maximum intensity in the early 60's, the so-called bomb peak has already diminished to a stable level, and in the 2000's years it is close to a natural level (~10 TU). In the period of 2001−2014, we have been connuously taking water samples from each precipitation events. Our study shows how the tritium concentration of monthly precipitations depends on the magnetic activity of the Sun. It can be observed that tritium concentration is varying by about 30% around mean value during the 11 years of the solar cycle. This is in accordance with the time series of other cosmogenic isotopes like 7 Be, 10 Be in the precipitation. We found trends in tritium time series for numerous locations worldwide being similar to the variation of secondary neutron flux and sun spot numbers. These variables seem to have similar
The relationship between the atmospheric concentration of cosmogenic isotopes, the change of sola... more The relationship between the atmospheric concentration of cosmogenic isotopes, the change of solar activity and hence secondary neutron flux has already been proven. The temporal atmospheric variation of the most studied cosmogenic isotopes shows a significant anti-correlation with solar cycles. However, since artificial tritium input to the atmosphere due to nuclear-weapon tests masked the expected variations of tritium production rate by three orders of magnitude, the natural variation of tritium in meteoric precipitation has not previously been detected. For the first time, we provide clear evidence of the positive correlation between the tritium concentration of meteoric precipitation and neutron flux modulated by solar magnetic activity. We found trends in tritium time series for numerous locations worldwide which are similar to the variation of secondary neutron flux and sun spot numbers. This variability appears to have similar periodicities to that of solar cycle. Frequency analysis, cross correlation analysis, continuous and cross wavelet analysis provide mathematical evidence that the correlation between solar cycle and meteoric tritium does exist. Our results demonstrate that the response of tritium variation in precipitation to the solar cycle can be used to help us understand its role in the water cycle. Cosmic rays are composed of high-energy charged particles, mainly originating from outside the solar system (galactic cosmic rays, GCR), although there are also lower-energy solar cosmic rays (SCR). When cosmic rays reach the Earth's atmosphere, a cascade of secondary particles and nuclei are produced in numerous nuclear reactions between these secondary particles and the atmospheric nuclei. Isotopes formed in such reactions are called cosmogenic isotopes 1–3. The secondary neutrons (a part of the hadronic component) produce – for example – the well-known cosmogenic isotopes: 14 C and 3 H are produced mainly in 14 N(n,p) 14 C and 14 N(n, 3 H) 12 C reactions, while 10 Be and 7 Be are formed mainly by spallation of oxygen and nitrogen 4–6. Hence, the temporal and spatial variations of cosmogenic isotopes in the environment can be used as tracers of different atmospheric, hydrological or geochemical processes 7. Tritium production is different from 14 C: the latter is caused by capture of a thermal neutron, while the former is a threshold-like reaction requiring at least ~4 MeV energy of the neutron. Long-term changes are generally attributed to geomagnetic field effects, but short-term changes in cosmogenic isotope production rates are primarily driven by the magnetic field variation of the Sun. The Earth's geomagnetic field modulated by the solar wind allows charged cosmogenic particles to enter the atmosphere at different threshold energies from the
Urban heat island and climate change belong to two separate scientific fields within meteorology ... more Urban heat island and climate change belong to two separate scientific fields within meteorology nowadays. Climate change, however, may affect the characteristics of urban heat island as well. Various atmospheric macro-circulation conditions determine the frequency of certain weather conditions at a given area, thus they influence the frequency of the occurrence of conditions advantageous for urban heat island development. In the present research the time series data of conditions advantageous for urban heat island (AMC – Advantageous Meteorological Conditions) was determined in the case of De-brecen (Hungary) and similar patterns existing in the AMC time series were searched in those of NAO (North Atlantic Oscillation), EA (East Atlantic Oscillation), EA/WR (East Atlantic/Western Russia Pattern) and SCA (Scan-dinavian Oscillation) indices for the period between 1961 and 2010 using Gábor–Morlet wavelet transformations. Several significantly coherent oscillations were found. The occurrence frequency of advantageous meteorological conditions can be approximated from macro-circulation conditions in these periods, according to the concept of heat island. These estimations are consistent with the calculated AMC time series. This proves that there is some relationship between macro-circulation and heat island development. Based on the results, using seasonal and climate models the changes of urban heat islands at seasonal and climatic scales may become predictable.
Wind erosion susceptibility of the Hungarian soils was mapped on national level integrating three... more Wind erosion susceptibility of the Hungarian soils was mapped on national level integrating three pillars of the complex phenomenon of deflation. Results of wind tunnel experiments on erodibility of various and representative soil samples were used for the parametrization of countrywide map of soil texture compiled for the upper 5 centimeter layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5' resolution using the MISH method elaborated for the spatial interpolation of surface meteorological elements. The ratio of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm) soil as spatial co-variables. Land cover was also taken into account excluding areas which are not relevant from the aspect of wind erosion (forests, water bodies, settlements etc.) to spatially assess the risk of wind erosion. According to the resulted map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible for wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary as opposed to former works.
Meteorological conditions have a remarkable impact on urban climate similarly to other local and ... more Meteorological conditions have a remarkable impact on urban climate similarly to other local and microscale climates. Clear skies and calm weather are advantageous for the development of the urban heat island (UHI). There are numerous studies on the spatial and temporal features of the phenomenon. Much less attention is paid, however, to the meteorological conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies of advantageous and disadvantageous meteorological conditions for UHI development on the basis of a 50-year-long time series. Meteorological condition categories of UHI development have been established on the basis of wind speed values, cloudiness, and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence of condition categories of UHI development were determined first. Advantageous and moderately advantageous conditions were found to be dominant in the time series. Linear trend analysis revealed a significant increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous conditions was analyzed for the years, seasons, and months of the study period as well. Spring and summer (April and June) produced significant increasing trends of frequencies of advantageous conditions, while winter (with the exception of February) and autumn did not show significant increase of those frequencies. Change-point analyses detected a significant increase in the frequency of advantageous conditions in the time series at the turn of 1981/1982 especially in the summer and spring months. Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter significantly.
IDŐJÁRÁS / QUARTERLY JOURNAL OF THE HUNGARIAN METEOROLOGICAL SERVICE, 2015
The aim of the research presented in this study is to elaborate a multivariate linear regression ... more The aim of the research presented in this study is to elaborate a multivariate linear regression model that describes the spatial structure of the mean maximal development urban heat island (UHI) formed under favorable synoptic conditions on the basis of surface parameters. Temperature data were gathered in a small town, Beregszász, Zakarpattia, Ukraine. As a first step a one-year long UHI measurement campaign has been carried out using mobile techniques in order to obtain data for the description of the UHI in the study area. Two surface parameters (ratio of non-evaporating surfaces in the environment of the measurement sites and distance of measurement sites from the center of the settlement) have been selected first. The two surface parameters had to be quantified next. On this basis, relationships between surface parameters as independent variables and UHI intensities as dependent variables could be traced by performing a multivariate linear regression. Results have showed that the two chosen parameters have strong impact on UHI development in our study area. Spatial structure and intensity of UHI can be estimated with an accuracy of 0.4°C within the built-up area of the town using our MLR model. The high resolution surface parameter database and the UHI estimating model enable the prediction of heat load of smaller spaces and town parts. This procedure helps the reduction of heat load and the determination of the location of green areas important for urban planning as well.
Journal of Chemistry and Chemical Engineering, Mar 14, 2014
The emission of CuInSe2-based spark discharge plasma at atmospheric pressure in air has been inve... more The emission of CuInSe2-based spark discharge plasma at atmospheric pressure in air has been investigated by optical emission spectroscopy method. The plasma was formed by action of the high voltage pulse generator (with nanosecond pulse) on the corresponding electrodes (CuInSe2 compound). The emission characteristics have been obtained for the spark discharge plasma at 3 mm interelectrode distance. It was established that the spark discharge plasma radiation was determined by decay products of the compound from which electrodes were made. The most suitable spectral lines for plasma diagnostics is atomic copper lines in the visible spectrum and atomic indium lines in UV (ultraviolet) and visible spectrum.
Synoptic conditions have a remarkable impact on urban climate like other local- and micro climate... more Synoptic conditions have a remarkable impact on urban climate like other local- and micro climates. Synoptic conditions with clear skies and calm weather are advantageous for the development of the thermal excess in the settlements compared their environment called Urban Heat Island (UHI). There are numerous studies on the spatial and temporal features of the phenomenon. Much less attention has been paid to the synoptic conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies
of synoptic conditions advantageous and disadvantageous for development of UHI on the base of a 50 years long
time series.
Synoptic condition categories of UHI development have been established on the base of values of wind speed,
cloudiness and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence
of condition categories of UHI development have been determined. Advantageous and moderately advantageous
conditions have been found to be dominant in the time series. Linear trend analysis has revealed a significant
increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous
conditions has been analyzed for the seasons and months of the studied period as well. Spring and summer (April
and June) have produced significant increasing trends of frequencies of advantageous conditions, while winter and
autumn have not shown significant increase of those frequencies.
Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air
conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter
significantly.
Effects of two important surface parameters (distance from the center of the settlement and exten... more Effects of two important surface parameters (distance from the center of the settlement and extent of evaporating surfaces) on development of urban heat island (UHI) are examined in the present paper. The study area is the town of Beregszász (Transcarpathia, Ukraine) with a population of 26 000. Mobile temperature measurements were carried to out in order to gain information on the characteristics of the UHI in ten day intervals in two one year long campaigns in 2005 and 2008. The main purpose was to determine the urban thermal excess in the different parts of a relatively small town, and to elaborate an empirical model equation of the development of UHI in the different parts of the town affected by horizontal surface conditions.
Urban heat island (UHI) intensities are lower in urban green spaces than in their urbanized neigh... more Urban heat island (UHI) intensities are lower in urban green spaces than in their urbanized neighborhood. The phenomenon is called Park Cool Island (PCI). PCI intensities can be determined on the base of thermal differences between city centers and parks. Characteristics of the green spaces determine the degree and temporal dynamics of the thermal differences between the green areas and the built-up surfaces in the settlements. Results of a one year long UHI and PCI measurement campaign are presented here. 32 measurements were carried out using mobile techniques under different synoptic conditions in the time of the maximal development of UHI and PCI in the town of Debrecen (population cca. 220 000) in East Hungary. Beside the UHI, existence of the park cool island has been proved in Debrecen. Characteristic maximal UHI intensities have been determined for typical built-up types. The impacts of urban green spaces on the temporal and spatial dynamics of the development of the UHI and PCI were determined. Annual and seasonal mean maximal PCI intensities were calculated for Debrecen. Impacts of synoptic conditions on the development of PCI were taken into account as well. Cooling effects of the parks was traced in their urban environment.
In: Szabó V, Fazekas I (szerk.)
Környezettudatos energiatermelés és -felhasználás III. Környezet ... more In: Szabó V, Fazekas I (szerk.) Környezettudatos energiatermelés és -felhasználás III. Környezet és Energia Konferencia. 265 p. Konferencia helye, ideje: Debrecen, Magyarország, 2014.05.08-2014.05.09. Debrecen: MTA DAB Megújuló Energetikai Munkabizottsága, 2014. pp. 178-184. (ISBN:978-963-7064-31-9)
Characterising the wind field of a city is extremely difficult because the surface is very comple... more Characterising the wind field of a city is extremely difficult because the surface is very complex due to the presence of buildings and other obstacles. Numerical methods use simplified building models to determine the average pattern of the wind field, however, such models can be used generally in the case of small parts of the city. One of the most widespread method is the CFD model, e.g. OpenFOAM, URBANWIND. For our study a dynamic model developed for city environment was applied. Models were calculated for the area of the Campus at Egyetem tér in the northern part of Debrecen using the ENVI-met model. The wind field among the buildings was drawn assuming winds of known velocity from four major directions. Results may give the basis of future air quality or energetic analyses.
For a better understanding of the causes and effects of urban heat islands (UHIs) different studi... more For a better understanding of the causes and effects of urban heat islands (UHIs) different studies took place in different cities and towns using both empirical methods and numerical models. The results indicated that the development of heat islands is determined not just by physical and morphological characteristics of the urban surface, but that weather conditions may also have a significant effect.
Some statistical and dynamical characteristics of an urban heat island are shown on the example of Debrecen. Hourly temperature data, measured on an automatic urban climate station installed in the town (on the ground of ATOMKI), and on Agrometeorological Observatory located on the outlying areas (near Kismacs) were used for the study. Using air temperature data, daily and seasonal variation of the intensity of the heat island was quantified, and connections with macrocirculation types were explored.
The daily variation of UHI intensity in Debrecen showed its stronger effects during the daylight time. The seasonal dynamics of urban heat excesses is characterized by a pronounced summer maximum both in daytime and night-time values. However, lower heat island values were observed in the winter period. Relationships were found between the UHI intensity and macrocirculation types: strong thermal excesses correspond mainly to anticyclonic calm weather, and weaker periods to cyclonic rainy weather
X. Természet-, Műszaki- és Gazdaságtudományok Alkalmazása Nemzetközi Konferencia - Az előadások ö... more X. Természet-, Műszaki- és Gazdaságtudományok Alkalmazása Nemzetközi Konferencia - Az előadások összefoglalói.. Konferencia helye, ideje: Szombathely, Magyarország, 2011.05.21 Szombathely: Nyugat-magyarországi Egyetem
E xcursions in the carbon-14 ( 14 C) record measured in tree rings are attributed to various high... more E xcursions in the carbon-14 ( 14 C) record measured in tree rings are attributed to various high energy but short-lived cosmic effects 1-7 . Wang et al. proposed a new event at 3372-3371 BCE based on a single set of annual 14 C data measured on a floating tree rings from a buried specimen of Chinese wingnut (Pterocarya stenoptera). Here we attempt to reproduce this event in tree rings of an absolutely dated bristlecone pine specimen (Pinus longaeva) from the White Mountains, USA and a subfossil oak (Quercus sp.) from the Moselle River Valley, France. We cannot confirm the presence of a cosmic-ray event as suggested at 3372-3371 BCE and we discuss potential implications to earlier results.
Tritium has been long recognized as a useful tracer for the study of atmospheric transport, ocean... more Tritium has been long recognized as a useful tracer for the study of atmospheric transport, ocean circulation, and the global water cycle. In addition, the application of tritium measurements in various fields has grown significantly in the last few decades. Since 1963, the atmospheric test-ban treaty, bomb tritium concentrations in precipitation have significantly declined. Therefore, in the last two decades, global tritium concentration of precipitation (including anthropogenic and natural sources) has almost reached a steady-state level. The aim of this study is to estimate the temporal variation of the natural tritium concentration of precipitation during the past decades. To do this, we use a backward predicting time-series model that exploits the correlation between precipitation tritium concentration and the secondary neutron flux in the atmosphere. The measured tritium time series of 21 Northern and two Southern Hemispheric stations are used, while neutron monitor (NM) data, which are widely compared to the production rate of cosmogenic isotopes in the atmosphere, is used as an external variable for the model. Backward predicting SARIMAX statistical models are fit on the period 2001–2018 and provide estimates of the natural precipitation tritium levels for the bomb peak period 1960–2000. Evaluation of backward estimations on the 1990–2000 test period yields RMSE measures between 0.5 and 4.6 TU for four of the 23 investigated stations, pointing out locations where the neutron flux is a good predictor of the precipitation tritium concentration.
Deciduous tree leaf and grass samples were collected in Debrecen, the second largest city in Hung... more Deciduous tree leaf and grass samples were collected in Debrecen, the second largest city in Hungary. The aim of the study was to determine the rate of fossil fuel-derived carbon in urban vegetation. At the locations sampled, C3 and C4 plants close to roads were collected in September 2017. In total, 82 tree and grass leaf samples were gathered at 36 different sampling points all over the city of Debrecen. The radiocarbon ( 14 C) results of the samples were compared to the local urban background atmospheric 14 CO 2 data to determine the percentage of the fossil fuel-derived carbon in the plants. Based on our results, the average fossil carbon content in the tree and grass leaf samples were 0.9 ± 1.2% and 2.5 ± 2.5%, respectively. The highest fossil carbon content was 9.6 ± 0.6% in a grass and 4.7 ± 0.7% in a tree leaf sample. It appears that the negative fossil carbon content results obtained at urban sampling areas reflect modern carbon emission, where radiocarbon content is higher than the corresponding local background, presumably due burning of recent wood containing bomb 14 C in the suburbs as well as other possible sources such as litter decomposition or soil CO 2 emission.
A periódusos rendszer VIII. főcsoportját alkotó nemesgázok izotópjainak arányait (3He/4He; 20Ne/2... more A periódusos rendszer VIII. főcsoportját alkotó nemesgázok izotópjainak arányait (3He/4He; 20Ne/22Ne; 21Ne/22Ne; 40Ar/36Ar; 136Xe/132Xe; 134Xe/132Xe) a Föld eredeti primordiális izotópos összetétele vagy a Föld kérgében/köpenyében képződése óta lezajlott spontán hasadási folyamatok határozzák meg. Felszín közelében vagy a légkörben antropogén hatásra (atomrobbantások) vagy kozmikus sugárzás hatására is képződhetnek. Amennyiben a nemesgázok a képződési helyükön felhalmozódnak folyadékzárványokba vagy ásványokba csapdázódva, akkor izotópjaik arányainak mérése alkalmassá teszi őket a bezáró közeg képződési helyének (köpeny, kéreg, atmoszféra) azonosítására, vagy az abban lezajló folyamatok azonosítására. Különösen az elsődleges, azaz a befogadó ásvány képződésével egyidős zárványok, zárványpetrográfiai és mikrotermometriai vizsgálatokkal kiegészítve, különösen értékesek lehetnek a képződési környezet meghatározásában.
Understanding climate change and revealing its future paths on a local level is a great challenge... more Understanding climate change and revealing its future paths on a local level is a great challenge for the future. Beside the expanding sets of available climatic data, satellite images provide a valuable source of information. In our study we aimed to reveal whether satellite data are an appropriate way to identify global trends, given their shorter available time range. We used the CARPATCLIM (CC) database (1961-2010) and the MODIS NDVI images (2000-2016) and evaluated the time period covered by both (2000-2010). We performed a regression analysis between the NDVI and CC variables, and a time series analysis for the 1961-2008 and 2000-2008 periods at all data points. The results justified the belief that maximum temperature (TMAX), potential evapotranspiration and aridity all have a strong correlation with the NDVI; furthermore, the short period trend of TMAX can be described with a functional connection with its long period trend. Consequently, TMAX is an appropriate tool as an explanatory variable for NDVI spatial and temporal variance. Spatial pattern analysis revealed that with regression coefficients, macro-regions reflected topography (plains, hills and mountains), while in the case of time series regression slopes, it justified a decreasing trend from western areas (Transdanubia) to eastern ones (The Great Hungarian Plain). This is an important consideration for future agricultural and land use planning; i.e. that western areas have to allow for greater effects of climate change.
XIVth Workshop of the European Society for Isotope Research, 2017
Production rates of cosmogenic nuclei are modulated by the variation of the magnetic strength of ... more Production rates of cosmogenic nuclei are modulated by the variation of the magnetic strength of the Sun, while the atmospheric concentrations of theses isotopes are further controlled by many other factors. The atmospheric concentration of several isotopes and the change of solar activity and hence secondary neutron flux has already been proven. The temporal atmospheric variation of the most studied cosmogenic isotopes (14 C, 7 Be and 10 Be) shows a significant correlation with solar cycles. However, since the artificial tritium (radioactive hydrogen isotope, 3 H) input to the atmosphere due to nuclear weapon tests suppressed the expected variations of tritium production rate by three orders of magnitude, the natural variation of tritium in meteoric precipitation could not be detected so far. We have been analysing the tritium concentration of precipitation for more than 13 years. These results suggest a connection between the solar cycle and the tritium content of precipitation. Previous model calculations have shown that the tritium production rate has a periodic variability of 5% during a solar cycle. Due to the dilution effect of the atmospheric moisture, this effect is supposed to be further weakened in the surface precipitation. In the Danube-Carpathian region the natural tritium level in the precipitation is around 5−10 TU. These low concentrations can be accurately measured only since the last 2−3 decades. Moreover, since the 50's the atmospheric thermonuclear bomb tests increased the tritium amount of precipitation by 2-3 orders of magnitude. After its maximum intensity in the early 60's, the so-called bomb peak has already diminished to a stable level, and in the 2000's years it is close to a natural level (~10 TU). In the period of 2001−2014, we have been connuously taking water samples from each precipitation events. Our study shows how the tritium concentration of monthly precipitations depends on the magnetic activity of the Sun. It can be observed that tritium concentration is varying by about 30% around mean value during the 11 years of the solar cycle. This is in accordance with the time series of other cosmogenic isotopes like 7 Be, 10 Be in the precipitation. We found trends in tritium time series for numerous locations worldwide being similar to the variation of secondary neutron flux and sun spot numbers. These variables seem to have similar
The relationship between the atmospheric concentration of cosmogenic isotopes, the change of sola... more The relationship between the atmospheric concentration of cosmogenic isotopes, the change of solar activity and hence secondary neutron flux has already been proven. The temporal atmospheric variation of the most studied cosmogenic isotopes shows a significant anti-correlation with solar cycles. However, since artificial tritium input to the atmosphere due to nuclear-weapon tests masked the expected variations of tritium production rate by three orders of magnitude, the natural variation of tritium in meteoric precipitation has not previously been detected. For the first time, we provide clear evidence of the positive correlation between the tritium concentration of meteoric precipitation and neutron flux modulated by solar magnetic activity. We found trends in tritium time series for numerous locations worldwide which are similar to the variation of secondary neutron flux and sun spot numbers. This variability appears to have similar periodicities to that of solar cycle. Frequency analysis, cross correlation analysis, continuous and cross wavelet analysis provide mathematical evidence that the correlation between solar cycle and meteoric tritium does exist. Our results demonstrate that the response of tritium variation in precipitation to the solar cycle can be used to help us understand its role in the water cycle. Cosmic rays are composed of high-energy charged particles, mainly originating from outside the solar system (galactic cosmic rays, GCR), although there are also lower-energy solar cosmic rays (SCR). When cosmic rays reach the Earth's atmosphere, a cascade of secondary particles and nuclei are produced in numerous nuclear reactions between these secondary particles and the atmospheric nuclei. Isotopes formed in such reactions are called cosmogenic isotopes 1–3. The secondary neutrons (a part of the hadronic component) produce – for example – the well-known cosmogenic isotopes: 14 C and 3 H are produced mainly in 14 N(n,p) 14 C and 14 N(n, 3 H) 12 C reactions, while 10 Be and 7 Be are formed mainly by spallation of oxygen and nitrogen 4–6. Hence, the temporal and spatial variations of cosmogenic isotopes in the environment can be used as tracers of different atmospheric, hydrological or geochemical processes 7. Tritium production is different from 14 C: the latter is caused by capture of a thermal neutron, while the former is a threshold-like reaction requiring at least ~4 MeV energy of the neutron. Long-term changes are generally attributed to geomagnetic field effects, but short-term changes in cosmogenic isotope production rates are primarily driven by the magnetic field variation of the Sun. The Earth's geomagnetic field modulated by the solar wind allows charged cosmogenic particles to enter the atmosphere at different threshold energies from the
Urban heat island and climate change belong to two separate scientific fields within meteorology ... more Urban heat island and climate change belong to two separate scientific fields within meteorology nowadays. Climate change, however, may affect the characteristics of urban heat island as well. Various atmospheric macro-circulation conditions determine the frequency of certain weather conditions at a given area, thus they influence the frequency of the occurrence of conditions advantageous for urban heat island development. In the present research the time series data of conditions advantageous for urban heat island (AMC – Advantageous Meteorological Conditions) was determined in the case of De-brecen (Hungary) and similar patterns existing in the AMC time series were searched in those of NAO (North Atlantic Oscillation), EA (East Atlantic Oscillation), EA/WR (East Atlantic/Western Russia Pattern) and SCA (Scan-dinavian Oscillation) indices for the period between 1961 and 2010 using Gábor–Morlet wavelet transformations. Several significantly coherent oscillations were found. The occurrence frequency of advantageous meteorological conditions can be approximated from macro-circulation conditions in these periods, according to the concept of heat island. These estimations are consistent with the calculated AMC time series. This proves that there is some relationship between macro-circulation and heat island development. Based on the results, using seasonal and climate models the changes of urban heat islands at seasonal and climatic scales may become predictable.
Wind erosion susceptibility of the Hungarian soils was mapped on national level integrating three... more Wind erosion susceptibility of the Hungarian soils was mapped on national level integrating three pillars of the complex phenomenon of deflation. Results of wind tunnel experiments on erodibility of various and representative soil samples were used for the parametrization of countrywide map of soil texture compiled for the upper 5 centimeter layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5' resolution using the MISH method elaborated for the spatial interpolation of surface meteorological elements. The ratio of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm) soil as spatial co-variables. Land cover was also taken into account excluding areas which are not relevant from the aspect of wind erosion (forests, water bodies, settlements etc.) to spatially assess the risk of wind erosion. According to the resulted map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible for wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary as opposed to former works.
Meteorological conditions have a remarkable impact on urban climate similarly to other local and ... more Meteorological conditions have a remarkable impact on urban climate similarly to other local and microscale climates. Clear skies and calm weather are advantageous for the development of the urban heat island (UHI). There are numerous studies on the spatial and temporal features of the phenomenon. Much less attention is paid, however, to the meteorological conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies of advantageous and disadvantageous meteorological conditions for UHI development on the basis of a 50-year-long time series. Meteorological condition categories of UHI development have been established on the basis of wind speed values, cloudiness, and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence of condition categories of UHI development were determined first. Advantageous and moderately advantageous conditions were found to be dominant in the time series. Linear trend analysis revealed a significant increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous conditions was analyzed for the years, seasons, and months of the study period as well. Spring and summer (April and June) produced significant increasing trends of frequencies of advantageous conditions, while winter (with the exception of February) and autumn did not show significant increase of those frequencies. Change-point analyses detected a significant increase in the frequency of advantageous conditions in the time series at the turn of 1981/1982 especially in the summer and spring months. Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter significantly.
IDŐJÁRÁS / QUARTERLY JOURNAL OF THE HUNGARIAN METEOROLOGICAL SERVICE, 2015
The aim of the research presented in this study is to elaborate a multivariate linear regression ... more The aim of the research presented in this study is to elaborate a multivariate linear regression model that describes the spatial structure of the mean maximal development urban heat island (UHI) formed under favorable synoptic conditions on the basis of surface parameters. Temperature data were gathered in a small town, Beregszász, Zakarpattia, Ukraine. As a first step a one-year long UHI measurement campaign has been carried out using mobile techniques in order to obtain data for the description of the UHI in the study area. Two surface parameters (ratio of non-evaporating surfaces in the environment of the measurement sites and distance of measurement sites from the center of the settlement) have been selected first. The two surface parameters had to be quantified next. On this basis, relationships between surface parameters as independent variables and UHI intensities as dependent variables could be traced by performing a multivariate linear regression. Results have showed that the two chosen parameters have strong impact on UHI development in our study area. Spatial structure and intensity of UHI can be estimated with an accuracy of 0.4°C within the built-up area of the town using our MLR model. The high resolution surface parameter database and the UHI estimating model enable the prediction of heat load of smaller spaces and town parts. This procedure helps the reduction of heat load and the determination of the location of green areas important for urban planning as well.
Journal of Chemistry and Chemical Engineering, Mar 14, 2014
The emission of CuInSe2-based spark discharge plasma at atmospheric pressure in air has been inve... more The emission of CuInSe2-based spark discharge plasma at atmospheric pressure in air has been investigated by optical emission spectroscopy method. The plasma was formed by action of the high voltage pulse generator (with nanosecond pulse) on the corresponding electrodes (CuInSe2 compound). The emission characteristics have been obtained for the spark discharge plasma at 3 mm interelectrode distance. It was established that the spark discharge plasma radiation was determined by decay products of the compound from which electrodes were made. The most suitable spectral lines for plasma diagnostics is atomic copper lines in the visible spectrum and atomic indium lines in UV (ultraviolet) and visible spectrum.
Synoptic conditions have a remarkable impact on urban climate like other local- and micro climate... more Synoptic conditions have a remarkable impact on urban climate like other local- and micro climates. Synoptic conditions with clear skies and calm weather are advantageous for the development of the thermal excess in the settlements compared their environment called Urban Heat Island (UHI). There are numerous studies on the spatial and temporal features of the phenomenon. Much less attention has been paid to the synoptic conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies
of synoptic conditions advantageous and disadvantageous for development of UHI on the base of a 50 years long
time series.
Synoptic condition categories of UHI development have been established on the base of values of wind speed,
cloudiness and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence
of condition categories of UHI development have been determined. Advantageous and moderately advantageous
conditions have been found to be dominant in the time series. Linear trend analysis has revealed a significant
increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous
conditions has been analyzed for the seasons and months of the studied period as well. Spring and summer (April
and June) have produced significant increasing trends of frequencies of advantageous conditions, while winter and
autumn have not shown significant increase of those frequencies.
Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air
conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter
significantly.
Effects of two important surface parameters (distance from the center of the settlement and exten... more Effects of two important surface parameters (distance from the center of the settlement and extent of evaporating surfaces) on development of urban heat island (UHI) are examined in the present paper. The study area is the town of Beregszász (Transcarpathia, Ukraine) with a population of 26 000. Mobile temperature measurements were carried to out in order to gain information on the characteristics of the UHI in ten day intervals in two one year long campaigns in 2005 and 2008. The main purpose was to determine the urban thermal excess in the different parts of a relatively small town, and to elaborate an empirical model equation of the development of UHI in the different parts of the town affected by horizontal surface conditions.
Urban heat island (UHI) intensities are lower in urban green spaces than in their urbanized neigh... more Urban heat island (UHI) intensities are lower in urban green spaces than in their urbanized neighborhood. The phenomenon is called Park Cool Island (PCI). PCI intensities can be determined on the base of thermal differences between city centers and parks. Characteristics of the green spaces determine the degree and temporal dynamics of the thermal differences between the green areas and the built-up surfaces in the settlements. Results of a one year long UHI and PCI measurement campaign are presented here. 32 measurements were carried out using mobile techniques under different synoptic conditions in the time of the maximal development of UHI and PCI in the town of Debrecen (population cca. 220 000) in East Hungary. Beside the UHI, existence of the park cool island has been proved in Debrecen. Characteristic maximal UHI intensities have been determined for typical built-up types. The impacts of urban green spaces on the temporal and spatial dynamics of the development of the UHI and PCI were determined. Annual and seasonal mean maximal PCI intensities were calculated for Debrecen. Impacts of synoptic conditions on the development of PCI were taken into account as well. Cooling effects of the parks was traced in their urban environment.
In: Szabó V, Fazekas I (szerk.)
Környezettudatos energiatermelés és -felhasználás III. Környezet ... more In: Szabó V, Fazekas I (szerk.) Környezettudatos energiatermelés és -felhasználás III. Környezet és Energia Konferencia. 265 p. Konferencia helye, ideje: Debrecen, Magyarország, 2014.05.08-2014.05.09. Debrecen: MTA DAB Megújuló Energetikai Munkabizottsága, 2014. pp. 178-184. (ISBN:978-963-7064-31-9)
Characterising the wind field of a city is extremely difficult because the surface is very comple... more Characterising the wind field of a city is extremely difficult because the surface is very complex due to the presence of buildings and other obstacles. Numerical methods use simplified building models to determine the average pattern of the wind field, however, such models can be used generally in the case of small parts of the city. One of the most widespread method is the CFD model, e.g. OpenFOAM, URBANWIND. For our study a dynamic model developed for city environment was applied. Models were calculated for the area of the Campus at Egyetem tér in the northern part of Debrecen using the ENVI-met model. The wind field among the buildings was drawn assuming winds of known velocity from four major directions. Results may give the basis of future air quality or energetic analyses.
For a better understanding of the causes and effects of urban heat islands (UHIs) different studi... more For a better understanding of the causes and effects of urban heat islands (UHIs) different studies took place in different cities and towns using both empirical methods and numerical models. The results indicated that the development of heat islands is determined not just by physical and morphological characteristics of the urban surface, but that weather conditions may also have a significant effect.
Some statistical and dynamical characteristics of an urban heat island are shown on the example of Debrecen. Hourly temperature data, measured on an automatic urban climate station installed in the town (on the ground of ATOMKI), and on Agrometeorological Observatory located on the outlying areas (near Kismacs) were used for the study. Using air temperature data, daily and seasonal variation of the intensity of the heat island was quantified, and connections with macrocirculation types were explored.
The daily variation of UHI intensity in Debrecen showed its stronger effects during the daylight time. The seasonal dynamics of urban heat excesses is characterized by a pronounced summer maximum both in daytime and night-time values. However, lower heat island values were observed in the winter period. Relationships were found between the UHI intensity and macrocirculation types: strong thermal excesses correspond mainly to anticyclonic calm weather, and weaker periods to cyclonic rainy weather
X. Természet-, Műszaki- és Gazdaságtudományok Alkalmazása Nemzetközi Konferencia - Az előadások ö... more X. Természet-, Műszaki- és Gazdaságtudományok Alkalmazása Nemzetközi Konferencia - Az előadások összefoglalói.. Konferencia helye, ideje: Szombathely, Magyarország, 2011.05.21 Szombathely: Nyugat-magyarországi Egyetem
A klíma megváltozása fontos jelzője az általános geoszférikus környezetváltozásnak, egyúttal okoz... more A klíma megváltozása fontos jelzője az általános geoszférikus környezetváltozásnak, egyúttal okozója is a különböző rész-rendszerek megváltozásának, az általános légcirkuláció és tengeráramlások megváltozásától, a növényzet átrendeződésétől, a terjedő invázív növényés állatfajokon át egészen az urbanizált környezet megváltozásáig. Ezért a klímaváltozás témaköre eleve az interdiszciplináris megközelítést igényli. Szükségessé teszi, hogy a különböző szakterületek képviselői kicseréljék tapasztalataikat, összegezzék tudásukat, és dialógus alakuljon ki a különböző társadalmi szférák és a döntéshozók között is, egy, a mainál környezettudatosabb, és a klímaváltozás kihívásaival szemben hatékonyabban reagáló társadalom létrejötte érdekében. Az interdiszciplináris megközeítés hozhat közelebb a ma még megválaszolatlan kérdések megoldásához is, ahogy ezt az alábbiakban szeretném megmutatni, egyben keretet adva a következő tanulmányokhoz is.
Due to human activities the temperature conditions in the most populated urban areas differ signi... more Due to human activities the temperature conditions in the most populated urban areas differ significantly from those in the natural environment. I chose to study urban areas because ongoing modifications influence the life of people living there. Most people living in urban areas spend most of their time in the urban roof level of the urban boundary layer between the surface and the average level of roofs therefore the conditions in this layer influence their health. Apart from feeling comfortable the forming heat excess affects energy demands which are in connection with cooling demand in warmer and the heating demand in colder periods. Moreover, it determines biodiversity and the distribution of pollutants and diseases in urban areas. This study focuses on a small and a medium sized town, Beregszász and Debrecen. Although heat islands are studied in large cities worldwide urbanisation, transformation of built-up areas and not deliberate climate modification take place in smaller towns as well. The presented research studies a meso-scale phenomenon and focuses on determining the factors forming the phenomenon in Beregszász. As a result, the first task was to quantify the parameters of the surfaces forming the heat excess found in Beregszász and to analyse their relationship with urban heat island (UHI) on the basis of the results. Apart from these, it is very important to make the spatial structure and process of the heat excess in the town estimatable using models based on empirical relationships. This could be a useful tool for urban development. In the vicinity of a measurement point located in a given local climate zone the modification of climate elements is caused primarily by modified surface parameters while the size of the heat excess is determined by the dynamic meteorological parameters. Thus to expose the relationship between heat excess developed on a local scale and the meteorological parameters controlling them was set as a goal. Based on the obtained results, my target was to prepare a criteria system with the help of which the time series of the frequency of weather conditions advantageous for the development of urban heat island could be determined.
A three-year-long methane mole fraction and d 13 C CH4 measurement campaign was performed at the ... more A three-year-long methane mole fraction and d 13 C CH4 measurement campaign was performed at the Hungarian tall tower station, Hegyhátsál, between 2013-2016. The results were compared with that of two NOAA atmospheric monitoring sites Mace Head and Zeppelin to determine the continental methane excess and the relative isotopic shift. The data then were used for bac trajectory analyses to identify potential methane source regions in Europe coupled with d 13 C CH4 results. The Hungarian station can be separated from the coastal and polar areas based on the mole fraction results having higher maxima and seasonal amplitude, but the d 13 C CH4 results match well with the NOAA stations' results. Our study shows that although the local, regional anthropogenic and natural sources are major influences, more distant regions can also influence the measured CH 4 level and d 13 C CH4 signal in the Pannonian Basin. Powered by TCPDF (www.tcpdf.org)
In this study, we focus on the relationship between the water vapor source region and the isotopi... more In this study, we focus on the relationship between the water vapor source region and the isotopic composition of the precipitation. The change of isotope characteristics of precipitation depends on the moisture source region. Long-term stable isotope (δ 18 O, δ 2 H) measurements of precipitation were performed in Debrecen, Hungary, between 2001 and 2014. The long-term isotope time series and trajectory modeling are suitable for determining moisture source regions. Backward trajectory analysis was carried out using the Lagrangian Raptor model based on ERA5 atmospheric data. Hourly backward trajectories were calculated for Debrecen for the days with precipitation in the period between 2001-2014. Based on the study three source regions were identified. Of these, 60% represented the Carpathian Basin, which is where most of the moisture evaporated from near the surface. The remaining 40% of the northwest and southwest were represented by moisture source regions. This means that the isotopic composition of precipitation significantly determines the local and continental effects, i.e. the moisture evaporated from the continental surface contributes significantly to the spatial and temporal variation of the precipitation isotope composition.
17th Stable Isotope Network Austria (SINA) Meeting: Program and abstracts, 2019
The Hungarian rural tall tower station, Hegyhátsál is widely used in long-term atmospheric greenh... more The Hungarian rural tall tower station, Hegyhátsál is widely used in long-term atmospheric greenhouse gas monitoring measurements. As the former CO2 concentration and isotope measurements proved, it is an ideal place to collect background atmospheric air samples. Background ambient air samples were collected between 2013 and 2016, 4 bags per month at the Hungarian site for methane (CH4) mole fraction and 13CCH4 measurements. The results from the Carpathian Basin were compared with two NOAA atmospheric monitoring site, Mace Head and Zeppelin to determine the excess continental CH4 level and isotopic shift. The measurement data was used coupled with back trajectory modelling and concentration weighted trajectories (CWT) to detect potential CH4 source areas. The Hungarian station can be separated from the coastal and polar area based on the concentration results, that have higher seasonal amplitude and higher maxima (from 1876 to 2119 ppb), but the 13CCH4 results match with the NOAA stations, the mean 13C ratio is -47.55 ‰, except in a short period, when an intense negative isotopic shift was detected. The trajectory modelling reveal numerous potential source areas what influence the CH4 level and its 13C signal in the Carpathian Basin. Our study presents the first, supplementary 13CCH4 dataset in the Carpathian Basin, what shows the usefulness of the Hungarian measurement site in the greenhouse gas monitoring. The measurement and modelling campaign also illustrates that the monitoring data coupled with trajectory modelling is a powerful tool for the detection of potential source areas.
This paper describes the relation of noble gas temperature (NGT) and mean annual air (MAAT) and s... more This paper describes the relation of noble gas temperature (NGT) and mean annual air (MAAT) and soil (MAST) temperature through studying water samples and meteorological data from six Hungarian regions. Alluvial plains, hilly and mountainous regions were studied to investigate the effects of geomorphological, hydrogeological and micro-climatic conditions. Water samples were collected from springs and wells fed from different aquifers. Comparing NGTs derived from these water samples with the MAAT and MAST values of the given region, we identified differences between the sampled areas. In case of the Geresd Hills, Mezőföld, Danube-Tisza Interfluves and Nyírség, the NGTs (13.0 ± 0.9 °C, 12.1 ± 1.1 °C, 12.1 ± 0.6 °C and 12.7 ± 1.6 °C, respectively) generally reflect MAST, however in karstic Bükk Mts. (6.8 ± 0.6 °C) and Mecsek Mts. (10.7 ± 1.9 °C) they are closer to MAAT. Consequently, it can be concluded that the direct relationship between noble gas temperature and mean annual air temperature is not always as well-defined as it is often assumed. It is shown that MAAT and MAST should be distinguished, especially when using NGT as a paleoclimate proxy.
17th Stable Isotope Network Austria (SINA) Meeting: Program and abstracts, 2019
Tritium of the precipitation plays a very important role in the study of the waters of our planet... more Tritium of the precipitation plays a very important role in the study of the waters of our planet because its tracer property is suitable for a better understanding of atmospheric and hydrological processes. Since the atmospheric test-ban treaty, the bomb tritium concentrations in precipitation have significantly reduced. Therefore, in the last two decades, global tritium concentration of precipitation (including anthropogenic and natural sources) have nearly reached a steady state level. The aim of this study is to explore the variability of natural tritium in the past by using the neutron monitor time series, which represents the variability of solar activity. Many previous studies focused on the reconstruction of the bomb-tritium time series, taking into account the long tritium time series of some cities (Ottawa, Vienna, Tokyo). In our study, we primarily estimate the tritium of natural origin in the northern and southern hemispheres, which may be an important input parameter for atmospheric and hydrological modeling. Therefore, we been have developed a statistical model to estimate short and long term changes in natural tritium. This estimate is based on the relationship between the global tritium time series and the neutron flux. The statistical model provides a relatively accurate estimate for stations that are poor in technogenic sources of tritium since time series values closely follow seasonal and long-term changes. Whereas for time series that are richer in technogenic tritium, the estimation is less accurate because the tritium values of the time series do not change regularly, that is, they do not follow the natural change.
XIVth Workshop of the European Society for Isotope Research, 2017
Here we show the preliminary results of a stalagmite palaeoclimate record. The stalagmite grew in... more Here we show the preliminary results of a stalagmite palaeoclimate record. The stalagmite grew in Baradla Cave, Hungary, between 98 and 129 kyr before present, covering MIS5e and MIS5d and partly MIS5c. Since the stalagmite is found broken, the upper, and maybe the lower part can be also found in the cave, hence a wider time period can be studied. The first results show that oxygen isotope ratio is hardly changing during the interglacial/glacial transition. The cave is known for stalagmites from MIS5e. Demény et al. (2017) has just published a palaeoclimate study from another part of the cave, which is about 4 km from our site. Although, the climatic signal is expected to be the same, there are significant differences in the stable oxygen signature. Further studies have to be performed to reveal these effects.
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Papers by Elemér László
of synoptic conditions advantageous and disadvantageous for development of UHI on the base of a 50 years long
time series.
Synoptic condition categories of UHI development have been established on the base of values of wind speed,
cloudiness and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence
of condition categories of UHI development have been determined. Advantageous and moderately advantageous
conditions have been found to be dominant in the time series. Linear trend analysis has revealed a significant
increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous
conditions has been analyzed for the seasons and months of the studied period as well. Spring and summer (April
and June) have produced significant increasing trends of frequencies of advantageous conditions, while winter and
autumn have not shown significant increase of those frequencies.
Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air
conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter
significantly.
Környezettudatos energiatermelés és -felhasználás III. Környezet és Energia Konferencia. 265 p.
Konferencia helye, ideje: Debrecen, Magyarország, 2014.05.08-2014.05.09. Debrecen: MTA DAB Megújuló Energetikai Munkabizottsága, 2014. pp. 178-184.
(ISBN:978-963-7064-31-9)
Some statistical and dynamical characteristics of an urban heat island are shown on the example of Debrecen. Hourly temperature data, measured on an automatic urban climate station installed in the town (on the ground of ATOMKI), and on Agrometeorological Observatory located on the outlying areas (near Kismacs) were used for the study. Using air temperature data, daily and seasonal variation of the intensity of the heat island was quantified, and connections with macrocirculation types were explored.
The daily variation of UHI intensity in Debrecen showed its stronger effects during the daylight time. The seasonal dynamics of urban heat excesses is characterized by a pronounced summer maximum both in daytime and night-time values. However, lower heat island values were observed in the winter period. Relationships were found between the UHI intensity and macrocirculation types: strong thermal excesses correspond mainly to anticyclonic calm weather, and weaker periods to cyclonic rainy weather
of synoptic conditions advantageous and disadvantageous for development of UHI on the base of a 50 years long
time series.
Synoptic condition categories of UHI development have been established on the base of values of wind speed,
cloudiness and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence
of condition categories of UHI development have been determined. Advantageous and moderately advantageous
conditions have been found to be dominant in the time series. Linear trend analysis has revealed a significant
increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous
conditions has been analyzed for the seasons and months of the studied period as well. Spring and summer (April
and June) have produced significant increasing trends of frequencies of advantageous conditions, while winter and
autumn have not shown significant increase of those frequencies.
Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air
conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter
significantly.
Környezettudatos energiatermelés és -felhasználás III. Környezet és Energia Konferencia. 265 p.
Konferencia helye, ideje: Debrecen, Magyarország, 2014.05.08-2014.05.09. Debrecen: MTA DAB Megújuló Energetikai Munkabizottsága, 2014. pp. 178-184.
(ISBN:978-963-7064-31-9)
Some statistical and dynamical characteristics of an urban heat island are shown on the example of Debrecen. Hourly temperature data, measured on an automatic urban climate station installed in the town (on the ground of ATOMKI), and on Agrometeorological Observatory located on the outlying areas (near Kismacs) were used for the study. Using air temperature data, daily and seasonal variation of the intensity of the heat island was quantified, and connections with macrocirculation types were explored.
The daily variation of UHI intensity in Debrecen showed its stronger effects during the daylight time. The seasonal dynamics of urban heat excesses is characterized by a pronounced summer maximum both in daytime and night-time values. However, lower heat island values were observed in the winter period. Relationships were found between the UHI intensity and macrocirculation types: strong thermal excesses correspond mainly to anticyclonic calm weather, and weaker periods to cyclonic rainy weather
This study focuses on a small and a medium sized town, Beregszász and Debrecen. Although heat islands are studied in large cities worldwide urbanisation, transformation of built-up areas and not deliberate climate modification take place in smaller towns as well. The presented research studies a meso-scale phenomenon and focuses on determining the factors forming the phenomenon in Beregszász. As a result, the first task was to quantify the parameters of the surfaces forming the heat excess found in Beregszász and to analyse their relationship with urban heat island (UHI) on the basis of the results. Apart from these, it is very important to make the spatial structure and process of the heat excess in the town estimatable using models based on empirical relationships. This could be a useful tool for urban development.
In the vicinity of a measurement point located in a given local climate zone the modification of climate elements is caused primarily by modified surface parameters while the size of the heat excess is determined by the dynamic meteorological parameters. Thus to expose the relationship between heat excess developed on a local scale and the meteorological parameters controlling them was set as a goal. Based on the obtained results, my target was to prepare a criteria system with the help of which the time series of the frequency of weather conditions advantageous for the development of urban heat island could be determined.
Background ambient air samples were collected between 2013 and 2016, 4 bags per month at the Hungarian site for methane (CH4) mole fraction and 13CCH4 measurements. The results from the Carpathian Basin were compared with two NOAA atmospheric monitoring site, Mace Head and Zeppelin to determine the excess continental CH4 level and isotopic shift. The measurement data was used coupled with back trajectory modelling and concentration weighted trajectories (CWT) to
detect potential CH4 source areas. The Hungarian station can be separated from the coastal and polar area based on the concentration results, that have higher seasonal amplitude and higher maxima
(from 1876 to 2119 ppb), but the 13CCH4 results match with the NOAA stations, the mean 13C ratio is -47.55 ‰, except in a short period, when an intense negative isotopic shift was detected. The trajectory modelling reveal numerous potential source areas what influence the CH4 level and its 13C signal in the Carpathian Basin. Our study presents the first, supplementary 13CCH4 dataset in the Carpathian Basin, what shows the usefulness of the Hungarian measurement site in the greenhouse
gas monitoring. The measurement and modelling campaign also illustrates that the monitoring data coupled with trajectory modelling is a powerful tool for the detection of potential source areas.
generally reflect MAST, however in karstic Bükk Mts. (6.8 ± 0.6 °C) and Mecsek Mts. (10.7 ± 1.9 °C) they are closer to MAAT. Consequently, it can be concluded that the direct relationship between noble gas temperature and mean annual air temperature is not always as well-defined as it is often assumed. It is shown that MAAT and MAST should be distinguished, especially when using NGT as a paleoclimate proxy.
The aim of this study is to explore the variability of natural tritium in the past by using the neutron monitor time series, which represents the variability of solar activity. Many previous studies focused on the reconstruction of the bomb-tritium time series, taking into account the long tritium time series of some cities (Ottawa, Vienna, Tokyo). In our study, we primarily estimate the tritium of natural origin in the northern and southern hemispheres, which may be an important input parameter for atmospheric and hydrological modeling. Therefore, we been
have developed a statistical model to estimate short and long term changes in natural tritium. This estimate is based on the relationship between the global tritium time series and the neutron flux. The statistical model provides a relatively accurate estimate for stations that are poor in technogenic sources of tritium since time series values closely follow seasonal and long-term changes. Whereas for time series that are richer in technogenic tritium, the estimation is less accurate because the tritium values of the time series do not change regularly, that is, they do not follow the natural change.