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Heilig B.,Geological and Geophysical Institute of Hungary | Sutcliffe P.R.,The South African National Space Agency
Geophysical Research Letters | Year: 2016

In this paper we present results of a study of Pc3 compressional waves observed at low-Earth orbit (LEO) by the Swarm satellites. The particular emphasis has been to investigate the distribution of wave coherence and phase difference as functions of magnetic latitude and local time. This is the first time that a study of this nature has been carried out using magnetic field data from multiple LEO satellites. We have also for the first time shown how our analysis technique can be used to discriminate between static spatial and simultaneous temporal wave structures observed in the ionosphere. We believe that our study provides the first observational evidence to support the prediction by the inductive thin ionosphere model that incident Alfvén mode waves are partially converted into compressional mode waves by the ionosphere. © 2016. American Geophysical Union. All Rights Reserved. Source


Heilig B.,Geological and Geophysical Institute of Hungary | Sutcliffe P.R.,South African Nation Space Agency SANSA | Ndiitwani D.C.,South African Nation Space Agency SANSA | Collier A.B.,South African Nation Space Agency SANSA | Collier A.B.,University of KwaZulu - Natal
Journal of Geophysical Research: Space Physics | Year: 2013

Studies of single events showing the signatures of Pc3 pulsation field line resonances (FLRs) observed in magnetic field data by CHAMP above the E-region ionosphere and at conjugate ground stations at L < 2 have previously been reported. Notable features of FLRs observed in these investigations were a Doppler shift in the satellite azimuthal component and a 90° rotation of the polarization ellipse between CHAMP and the ground. In this report, we extend the previous work by means of the first statistical investigation of the same features for a large number of events using CHAMP and ground magnetic field data. Our statistical study confirms the Doppler shifts to higher or lower frequencies relative to the ground FLR frequencies for equatorward or poleward passes of CHAMP over the ground station. Our statistical investigation shows the amount of rotation of the FLR polarization ellipses between the ionosphere and the ground to be ~100° on average, rather than the theoretically predicted 90°. This is explained by the polarization ellipses on the ground being oriented close to N-S irrespective of the orientation above the ionosphere, which is -13° on average. We find no evidence of ionospheric conductivity gradients associated with sunrise and sunset affecting the amount of rotation of the polarization ellipses as predicted by more recent theoretical advances. We are not able to provide conclusive evidence on the relationship between the polarization ellipse rotation and azimuthal wave number as predicted in recent numerical modeling. Key Points This is the first statistical study on field line resonances observed at LEO.Our study confirms the Doppler shifts for passes of CHAMP over a ground station.Resonant widths were estimated from the observed Doppler shifts. ©2013. American Geophysical Union. All Rights Reserved. Source


Marton E.,Geological and Geophysical Institute of Hungary | Cosovic V.,University of Zagreb | Moro A.,University of Zagreb
Tectonophysics | Year: 2014

The External Dinarides from which several conflicting tectonic models were published, are the more tectonized NE margin of autochthonous Adria. Dugi otok and Vis islands belong to this margin. From the two islands a new paleomagnetic study is presented, based on 48 geographically distributed and biostratigraphically controlled Cretaceous carbonate sediment localities. The results suggest that the two islands certainly moved in co-ordination after the mid-Albian, which was the time of resumed sedimentation after a period of emersion, although some relative movement could have occurred earlier.The new post-Aptian paleomagnetic results are in perfect agreement with recently published paleomagnetic results from stable Adria and from the more northerly Adriatic islands. This consistency suggests that all these areas moved together from the Albian on, while the coastal range of the External Dinarides seems to have moved independently. Thus, autochthonous Adria together with the Adriatic islands is established as a crustal block within the Central Mediterranean region, which rotated significantly in CCW sense in post-Cretaceous times. © 2013 Elsevier B.V. Source


Haas J.,Eotvos Lorand University | Budai T.,Geological and Geophysical Institute of Hungary | Budai T.,University of Pecs | Raucsik B.,University of Pecs
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2012

During the Triassic the Transdanubian Range was a segment of the western Neotethys margin where the climate was mostly determined by a strong global monsoonal system. As a consequence of the global climatic conditions and its geographic setting, warm to hot temperature prevailed in this area. However, there were significant changes in the precipitation pattern from dry to wet conditions in connection with the intensity of the monsoon system and the actual setting of this area within the monsoon system. The aim of our research was to interpret the palaeoclimatic conditions and their changes for the Triassic succession of the Transdanubian Range on the base of geochemical, mineralogical, sedimentological and palaeontological data, with special regard to the climate indicator facies (e.g. different types of dolomites; clay mineral assemblages). Nine evolutionary stages were distinguished. During the Early Triassic mixed siliciclastic-carbonate ramp sedimentation took place under arid climate that was interrupted by a humid pulse (Campil Pluvial Event). In the early Anisian a shallow carbonate ramp was developed under arid to semi-arid climate. The predominatly dry conditions prolonged during the middle Anisian,. The latest Anisian and the Ladinian carbonate platforms were developed under mostly semi-arid climate. The semi-humid climate of the earliest Carnian was followed by a definitely wet interval (Carnian Pluvial Event) that was characterised by an intense terrigenous input into the Julian intraplatform basins. Arid and humid conditions alternated during the final stage of basin upfilling from the latest Julian to early Tuvalian. Then a marked climatic change took place in the latest Carnian when the humid climate was changed to semi-arid conditions. From the middle to late Norian a gradual increase of humidity may have taken place that resulted in a decreasing intensity of the early dolomitisation of the carbonate sediments of the broad internal platform. At the very end of the Norian there was a marked climate change leading to enhanced humidity but with a definite seasonality. Humid climatic conditions prevailed during the Rhaetian (Kössen Event).Evaluation of the similarities and differences of the palaeoclimatic conditions for the Transdanubian Range and some selected areas in the western Neotethys (Dolomites, Northern Calcareous Alps, Mecsek), and the Peri-Tethyan Germanic Basin is also presented. © 2012 Elsevier B.V. Source


Pacheco F.A.L.,Royal University | Pacheco F.A.L.,University of Tras os Montes e Alto Douro | Landim P.M.B.,Sao Paulo State University | Szocs T.,Geological and Geophysical Institute of Hungary
Applied Geochemistry | Year: 2013

Correspondence Analysis was adopted as tool for investigating the statistical structure of hydrochemical and weathering datasets of groundwater samples, with the main purpose of identifying impacts on mineral weathering caused by anthropogenic activities, namely fertilizing of farmlands. The hydrochemical dataset comprised measured concentrations of major inorganic compounds dissolved in groundwater, namely bicarbonate, silica (usually by-products of chemical weathering), chloride, sulphate and nitrate (typically atmospheric plus anthropogenic inputs). The weathering dataset consisted of calculated mass transfers of minerals being dissolved in loess sediments of a region located in SW Hungary (Szigetvár area), namely Na-plagioclase, calcite and dolomite, and of pollution-related concentrations of sodium, magnesium and calcium. A first run of Correspondence Analysis described groundwater composition in the study area as a system of triple influence, where spots of domestic effluents-dominated chemistries are surrounded by areas with agriculture-dominated chemistries, both imprinted over large regions of weathering dominated chemistries. A second run revealed that nitrification of N-fertilizers is promoting mineral weathering by the nitric acid reaction (anthropogenic pathway), in concurrence with the retreating of weathering by carbonic acid (natural pathway). It also indicated that dolomite and calcite are being players in a dedolomitization process driven by dissolution of gypsum fertilizers and nitrification of N-fertilizers. © 2013 Elsevier Ltd. Source

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