Institute for Geological and Geochemical Research

Budapest, Hungary

Institute for Geological and Geochemical Research

Budapest, Hungary
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Kereszturi A.,Konkoly Astronomical Institute | Gyollai I.,Institute for Geological and Geochemical Research | Jozsa S.,Eötvös Loránd University | Kanuchova Z.,Slovak Academy of Sciences
Meteoritics and Planetary Science | Year: 2017

The NWA 5491 CV3 meteorite is a CVoxA subtype, and composed of two substantially different units (titled “upper” and “lower” units) in the cm size range with original accreted material and also subsequent alteration produced features. Based on the large chondrules in the “upper” unit and the small chondrules plus CAIs in the “lower” unit, they possibly accreted material from different parts of the solar nebula and/or at different times, whereas substantial changes happened in the nebula's composition. Differences are observed in the level of early fragmentation too, which was stronger in the upper units. During later alteration oxidizing fluids possibly circulated only in the upper unit, mechanical fragmentation and resorption were also stronger there. In the last phase of the geological history these two rock units came into physical contact, but impact-driven shock effects were not observed. The characteristics of this meteorite provide evidence that the same parent body might accrete substantially different material and also the later processes could differ spatially in the parent body. © The Meteoritical Society, 2017.

Hatvani I.G.,Institute for Geological and Geochemical Research | Kern Z.,Institute for Geological and Geochemical Research
Polish Polar Research | Year: 2017

It is generally accepted that ice cores archive amount-weighted water stable isotope signals. In order to achieve an improved understanding of the nature of water stable isotope signals stored in ice cores annual δ18O and δ2H averages (i.e. amount-weighted) were calculated for two Antarctic meteorological stations, Vernadsky and Hal-ley Bay, using monthly precipitation amount and monthly net accumulation as weights, respectively. These were then compared with the annual mean δ18O δ2H and records of the nearest available ice cores. In addition, at the stations, both arithmetic means (i.e. time-weighted) and amount-weighted (precipitation amount and net accumulation used as weights) annual air temperature averages were calculated and then compared to amount weighted annual mean δ18O and δ2H using correlation- and regression analyses. The main hypothesis was that amount weighted annual mean water isotope and temperature records from the stations would be able to replicate the annual water isotope signal stored in ice cores to a higher degree. Results showed that (i) amount weighting is incapable of ameliorating the signal replication between the stations and the ice cores, while arithmetic means gave the stronger linear relationships; (ii) post depositional processes may have a more determining effect on the isotopic composition of the firn than expected; and (iii) mean annual air temperature provided the closest match to ice core derived annual water isotope records. This latter conveys a similar message to that of recent findings, in as much as ambient temperature, via equilibrium isotope fractionation, is imprinted into the uppermost snow layer by vapor exchange even between precipitation events. Together, these observations imply that ice core stable water isotope records can be a more continuous archive of near-surface temperature changes than hitherto believed. © Polish Academy of Sciences 2017.

Kern Z.,Institute for Geological and Geochemical Research | Leuenberger M.,University of Bern | Leuenberger M.,Oeschger Center for Climate Change Research
Global and Planetary Change | Year: 2013

A recent study relying purely on statistical analysis of relatively short time series suggested substantial re-thinking of the traditional view about causality explaining the detected rising trend of atmospheric CO2 (atmCO2) concentrations. If these results are well-justified then they should surely compel a fundamental scientific shift in paradigms regarding both atmospheric greenhouse warming mechanism and global carbon cycle. However, the presented work suffers from serious logical deficiencies such as, 1) what could be the sink for fossil fuel CO2 emissions, if neither the atmosphere nor the ocean - as suggested by the authors - plays a role? 2) What is the alternative explanation for ocean acidification if the ocean is a net source of CO2 to the atmosphere? Probably the most provocative point of the commented study is that anthropogenic emissions have little influence on atmCO2 concentrations. The authors have obviously ignored the reconstructed and directly measured carbon isotopic trends of atmCO2 (both δ13C, and radiocarbon dilution) and the declining O2/N2 ratio, although these parameters provide solid evidence that fossil fuel combustion is the major source of atmCO2 increase throughout the Industrial Era. © 2013 Elsevier B.V.

Takacs K.,Eötvös Loránd University | Kern Z.,Institute for Geological and Geochemical Research | Kern Z.,University of Bern | Nagy B.,Eötvös Loránd University
Quaternary International | Year: 2013

Anthropogenic effects on rivers, including engineering regulation, hydropower usage, and water pollution, not only change bed morphology and/or water quality but also affect the river ice regime. The length of the ice-affected season and the relative frequency of ice appearance might alter due to anthropogenic activities. Moreover, anthropogenically induced changes may vastly exceed climatic effects. When the prevailing non-natural impact co-varies with the trend of the expected climate trigger (e.g. winter air temperature), conclusions can be biased if the anthropogenic effects were not scrutinized in depth. This paper presents examples when changes in some characteristic feature of the river ice regime are related to human activities. These simple tests could be applied for other rivers, where similar anthropogenic impacts may be suspected to affect the river ice regime. © 2012 Elsevier Ltd and INQUA.

Laszlo P.,Eötvös Loránd University | Kern Z.,Institute for Geological and Geochemical Research | Kern Z.,University of Bern | Nagy B.,Eötvös Loránd University
Quaternary International | Year: 2013

Glacial landforms are commonly found throughout the highest belt (above ∼1700 m a.s.l.) of the Romanian Carpathians. This paper presents glacial geomorphological evidence from the Zânoaga Mare, Zânoaga Iezerului and the western part of Buhâescu valley complex situated on the northern slope of the Rodna Mountains, in the Eastern Carpathians, Romania. GIS-based geomorphological mapping reveals five sets of moraines in glacial phases assigned to the Late Pleistocene. The most extensive glacier was in western Buhâescu valley and had a surface area of 5 km2 and a length of 4.2 km and reached down to an altitude of 1086 m. Several methods were tested to determine the former ELAs of the glaciers. Using size-specific AAR, the average ELA for the oldest phase was 1765 m and rose to 1865, 1960, 2001 and 2025 m. The last and youngest phase was characterised only by cirque glaciers. Comparison with previous studies shows that extents were over-estimated. © 2012 Elsevier Ltd and INQUA.

Kern Z.,University of Bern | Kern Z.,Oeschger Center for Climate Change Research | Kern Z.,Institute for Geological and Geochemical Research | Kohan B.,Eötvös Loránd University | And 2 more authors.
Atmospheric Chemistry and Physics | Year: 2014

Stable oxygen isotope composition of atmospheric precipitation (δ18Op) was scrutinized from 39 stations distributed over Switzerland and its border zone. Monthly amount-weighted δ18Op values averaged over the 1995-2000 period showed the expected strong linear altitude dependence (-0.15 to-0.22‰ per 100 m) only during the summer season (May-September). Steeper gradients (∼-0.56 to-0.60‰ per 100 m) were observed for winter months over a low elevation belt, while hardly any altitudinal difference was seen for high elevation stations. This dichotomous pattern could be explained by the characteristically shallower vertical atmospheric mixing height during winter season and provides empirical evidence for recently simulated effects of stratified atmospheric flow on orographic precipitation isotopic ratios. This helps explain "anomalous" deflected altitudinal water isotope profiles reported from many other high relief regions. Grids and isotope distribution maps of the monthly δ18Op have been calculated over the study region for 1995-1996. The adopted interpolation method took into account both the variable mixing heights and the seasonal difference in the isotopic lapse rate and combined them with residual kriging. The presented data set allows a point estimation of δ18Op with monthly resolution. According to the test calculations executed on subsets, this biannual data set can be extended back to 1992 with maintained fidelity and, with a reduced station subset, even back to 1983 at the expense of faded reliability of the derived δ18Op estimates, mainly in the eastern part of Switzerland. Before 1983, reliable results can only be expected for the Swiss Plateau since important stations representing eastern and south-western Switzerland were not yet in operation. © Author(s) 2014. CC Attribution 3.0 License.

Garamszegi B.,Eötvös Loránd University | Kern Z.,Institute for Geological and Geochemical Research
Dendrobiology | Year: 2014

Future of beech (Fagus sylvatica L.) in a changing climate is one of the greatest debates in Europe among the studies dealing with the climate change generated xeric limit shifting. We investigated a submontane beech stand’s growth response to climate change in Northern Hungary during the past 60 years following dendrochronological methods. Tree-ring width data were processed using three alternatives of standardization. To recover the basic climate-growth relationships for beech we analyzed the correlation between the tree-ring width indices and monthly precipitation and temperature data, furthermore two drought indices were employed. Late spring-early summer precipitation was the primary climatic factor governing the beech growth at the study site since the early 1950s, while summer heat played a secondary obstructive role documented by the significant negative correlation. A 30-years running window correlation was used to identify whether the climate-growth connections changed due to the unfavorable climatic trends. The results indicated no evidence of a distinct decline in radial increment, however, a significant increase in climatic impact on growth has been detected including probable changes and shifts in the vegetation period. © 2014 Polska Akademia Nauk. All rights reserved.

Hatvani I.G.,Institute for Geological and Geochemical Research | Horvath J.,University of Szeged
Open Geosciences | Year: 2016

The present paper aims to introduce the current problems of geomathematics along with giving on overview on the papers published in the special issue covering the Croatian-Hungarian Geomathematical Congress of 2015 in Hungary. © 2016 I. G. Hatvani and J. Horváth, published by De Gruyter Open. 2016.

Sen A.K.,Indiana University | Kern Z.,Institute for Geological and Geochemical Research
Open Geosciences | Year: 2016

This study investigates the low-frequency (interannual and longer period) variability in three hydroclimatic records from east Central Europe. Two of these records consist of climate proxies derived from oak-tree rings in Bakta forest, and Balaton Highlands in Hungary, for the time interval 1783-2003. The third record consists of homogenized instrumental precipitation data from Budapest, Hungary, from 1842 to 2003. Using wavelet analysis, the three time series are analyzed and compared with one another. It is found that all three time series exhibit strong interannual variability at the 2-4 years timescales, and these variations occur intermittently throughout the length of each record. Significant variability is also observed in all the records at decadal timescales, but these variations persist for only two to three cycles. Wavelet coherence among the various time series is used to explore their time-varying correlation. The results reveal significant coherence at the 2-4 years band. At these timescales, the climatic variations are correlated to the tree-ring signal over different time intervals with changing phase. Increased (decreased) contribution of large-scale stratiform precipitation offers a potential explanation for enhanced (faded) coherence at the interannual timescale. Strong coherence was also observed occasionally at decadal timescales, however these coherences did not appear uniformly. These results reinforce the earlier assertion that neither the strength nor the rank of the similarity of the local hydroclimate signals is stable throughout the past two centuries. © 2016 A. K. Sen and Z. Kern, published by De Gruyter Open.

Ruszkiczay-Rudiger Z.,Institute for Geological and Geochemical Research | Kern Z.,Institute for Geological and Geochemical Research
Quaternary International | Year: 2015

Our critical revision of the sedimentological characteristics and genetic interpretation of relict periglacial soil deformation features (cryoturbations and sand wedges) suggests that the continuous permafrost zone did not necessarily reached the lowland areas of the Pannonian Basin, as suggested by previous studies. The discontinuous permafrost zone most probably penetrated the north-western part of the study area for a certain period, but most of the lowlands might have been affected only by sporadic/isolated permafrost and/or deep seasonal frost. The re-evaluated climate conditions implied by the periglacial soil structures and other proxies for a periglacial environment of the area do not constrain such a narrow zone of extremely low mean annual air temperature (MAAT) and mean annual precipitation (MAP). The compilation of the climate thresholds suggested by the observed and revised interpretation cryoturbation features and thermal contraction cracks with other paleoclimate proxies converge on 0±2°C MAAT and 300-490mm MAP on the lowland areas of the Pannonian Basin during the coldest phase of the last glacial. These values indicate a temperature drop of ≅10±2C° and a precipitation decrease of 30-50% relative to modern conditions. © 2015 Elsevier Ltd and INQUA.

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