Fourier Power Spectra of Solar Noise Storms     

Marian Karlický  Ján Rybák  Christian Monstein 《Solar physics》2018,293(10):143

We analyzed three noise storms recorded on 200?–?400 MHz Trieste Callisto radio spectra on 2 July 2012, 8 July 2012, and 16 July 2012 by the Fourier method. We divided intervals of the noise storms into five-minute intervals, and in these intervals we computed the mean Fourier spectra as a function of the wave numbers in the frequency and height-scale spaces. We found that these Fourier spectra, where the spectrum from the quiet-activity interval was subtracted, are power-law spectra. The mean power-law index of these spectra in the range \(\ln(k_{z}) = [1.8, 2.9]\) (where \(k_{z}\) is the wave number in the height-scale space) is \(-1.7\pm0.14\), \(-1.6\pm0.14\), and \(-1.5 \pm0.12\) for the 2 July 2012, the 8 July 2012, and the 16 July 2012 noise storms, respectively. It appears that as the number of Type-I bursts in the studied interval increases, the power-law index becomes closer to \(-5/3\); this is known as the Kolmogorov spectral index. The power-law index of the noise storms is very similar to that of the narrowband dm-spikes found in our previous studies. Furthermore, we found a break in the power spectra at \(\ln(k_{z}) \approx2.9\), and the mean power-law index values above this break are \(-2.9\pm0.46\), \(-3.1\pm0.65\), and \(-3.4\pm0.98\), respectively.  相似文献   

High-latitude dust deposition in snow on the glaciers of James Ross Island,Antarctica     

Jan Kavan  Daniel Nývlt  Kamil Láska  Zbyněk Engel  Michaela Kňažková 《地球表面变化过程与地形》2020,45(7):1569-1578

High-latitude dust (HLD) depositions on four glaciers of James Ross Island (the Ulu Peninsula) were analysed. The deposition rate on the selected glaciers varies from 11.8 to 64.0 g m⁻², which is one order of magnitude higher compared to the glaciers in Antarctica or elsewhere in the world. A strong negative relationship between the sediment amount and altitude of a sampling site was found. This is most likely caused by the higher availability of aeolian material in the atmospheric boundary layer. General southerly and south-westerly wind directions over the Ulu Peninsula – with exceptions based on local terrain configuration – help to explain the significantly lower level of sediment deposition on San Jose Glacier and the high level on Triangular Glacier. X-ray fluorescence (XRF) spectrophotometry was used to estimate the relative proportions of the main and trace (lithophile) elements in the sediment samples. Both the sediment amount and the XRF results are analysed in a depth profile at each locality and compared among the glaciers, suggesting long-range transport of fine mineral material from outside James Ross Island. The distribution of aeolian sediment among the glaciers corresponds well with the prevailing wind direction on the Ulu Peninsula. © 2020 John Wiley & Sons, Ltd.  相似文献   

Cause of scale inconsistencies in DORIS time series     

Petr Štěpánek  Vratislav Filler 《Studia Geophysica et Geodaetica》2018,62(4):562-585

In this paper we analyze the scale of the DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) solutions with respect to DORIS extension of the International Terrestrial Reference Frame (ITRF) for Precise Orbit Determination DPOD2014. The main goal is to explain the scale inconsistencies and to find the optimal solution reaching low-biased and consistent scale time series. Our analysis profits from 4 different strategies based only on the Geodetic Observatory Pecný analysis center solution, using DORIS exchange format data 2.2. A difference in the sequence of the solutions directly corresponds to one of the changes in the solution settings: data elevation dependent weighting, application of data validity indicators and application of phase center - reference point correction. We process multi-satellite and single-satellite solutions for the time period 2011.0–2017.0. Our analysis examines scale inconsistency issues in 2011/2012 and in 2015. The scale increment in 2011/2012 is explained as a result of the concurrence of changes in satellite constellation and change in the provider data validity standards for Cryosat-2 and Jason-2 satellites. The scale increment in 2015 is explained as the effect of change in the standards for phase center - reference center corrections for Saral, Jason-2 and Cryosat-2 satellites. Moreover, comparing the solutions with and without elevation dependent data downweighting using the same elevation cutoff (10°), we found a significant reduction of scale bias and scale variation applying the data downweighting. The data downweighting improved also the station positioning repeatability. We demonstrate that the solution, which is completely free from the additional data associated with observations in DORIS exchange format 2.2 and includes the data downweighting law, eventuates in a consistent scale time series with the lowest offset with respect to DPOD2014 (version 1.0) (12.7 ± 2.3 mm for 2011.0–2017.0). The only remaining scale issue is the part of 2011/2012 increment of around 5 mm, explained by a change in the DORIS satellite constellation.  相似文献   

Geophysical evidence of the Eastern Marginal Fault of the Cheb Basin (Czech Republic)     

Vratislav Blecha  Tomáš Fischer  Petr Tábořík  Jan Vilhem  Radek Klanica  Jan Valenta  Petra Štěpančíková 《Studia Geophysica et Geodaetica》2018,62(4):660-680

The western part of the Bohemian Massif hosts an intersection of two regional fault zones, the SW-NE trending Oh?e/Eger Graben and the NNW-SSE trending Mariánské Lázně Fault, which has been reactivated several times in the geological history and controlled the formation of the Tertiary Cheb Basin. The broader area of the Cheb Basin is also related to permanent seismic activity of M_L 3+ earthquake swarms. The Eastern Marginal Fault of the Cheb Basin (northern segment of the Mariánské Lázně Fault) separates the basin sediments and underlying granites in the SW from the Kru?né Hory/Erzgebirge Mts. crystalline unit in the NE. We describe a detailed geophysical survey targeted to locating the Eastern Marginal Fault and determining its geometry in the depth. The survey was conducted at the Kopanina site near the Nový Kostel focal zone, which shows the strongest seismic activity of the whole Western Bohemia earthquake swarm region. Complex geophysical survey included gravimetry, electrical resistivity tomography, audiomagnetotellurics and seismic refraction. We found that the rocks within the Eastern Marginal Fault show low resistivity, low seismic velocity and density, which indicates their deep fracturing, weathering and higher water content. The dip of the fault in shallow depths is about 60° towards SW. At greater depths, the slope turns to subvertical with dip angle of about 80°. Results of geoelectrical methods show blocky fabric of the Cheb Basin and deep weathering of the granite bedrock, which is consistent with geologic models based on borehole surveys.  相似文献   

Prevailing-frequency approximation of the coupling ray theory along the SH and SV reference rays in a heterogeneous generally anisotropic medium which is approximately uniaxial     

Petr Bulant  Luděk Klimeš 《Studia Geophysica et Geodaetica》2017,61(3):513-540

The behaviour of the actual polarization of an electromagnetic wave or elastic S–wave is described by the coupling ray theory, which represents the generalization of both the zero–order isotropic and anisotropic ray theories and provides continuous transition between them. The coupling ray theory is usually applied to anisotropic common reference rays, but it is more accurate if it is applied to reference rays which are closer to the actual wave paths. In a generally anisotropic or bianisotropic medium, the actual wave paths may be approximated by the anisotropic–ray–theory rays if these rays behave reasonably. In an approximately uniaxial (approximately transversely isotropic) anisotropic medium, we can define and trace the SH (ordinary) and SV (extraordinary) reference rays, and use them as reference rays for the prevailing–frequency approximation of the coupling ray theory. In both cases, i.e. for the anisotropic–ray–theory rays or the SH and SV reference rays, we have two sets of reference rays. We thus obtain two arrivals along each reference ray of the first set and have to select the correct one. Analogously, we obtain two arrivals along each reference ray of the second set and have to select the correct one. In this paper, we suggest the way of selecting the correct arrivals. We then demonstrate the accuracy of the resulting prevailing–frequency approximation of the coupling ray theory using elastic S waves along the SH and SV reference rays in four different approximately uniaxial (approximately transversely isotropic) velocity models.  相似文献   

Sandstone Turning by Abrasive Waterjet     

Petr Hlaváček  Ján Cárach  Sergej Hloch  Karol Vasilko  Dagmar Klichová  Jiří Klich  Dominika Lehocká 《Rock Mechanics and Rock Engineering》2015,48(6):2489-2493

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Assess hydrological responses to a warming climate at the Lysina Critical Zone Observatory in Central Europe     

Wenjuan Zheng  Anna Lamačová  Xuan Yu  Pavel Krám  Jakub Hruška  Pavel Zahradníček  Petr Štěpánek  Aleš Farda 《水文研究》2021,35(9):e14281

Climate warming is having profound effects on the hydrological cycle by increasing atmospheric demand, changing water availability, and snow seasonality. Europe suffered three distinct heat waves in 2019, and 11 of the 12 hottest years ever recorded took place in the past two decades, which will potentially change seasonal streamflow patterns and long-term trends. Central Europe exhibited six dry years in a row since 2014. This study uses data from a well-documented headwater catchment in Central Europe (Lysina) to explore hydrological responses to a warming climate. We applied a lumped parameter hydrologic model Brook90 and a distributed model Penn State Integrated Hydrologic Model (PIHM) to simulate long-term hydrological change under future climate scenarios. Both models performed well on historic streamflow and in agreement with each other according to the catchment water budget. In addition, PIHM was able to simulate lateral groundwater redistribution within the catchment validated by the groundwater table dynamics. The long-term trends in runoff and low flow were captured by PIHM only. We applied different EURO-CORDEX models with two emission scenarios (Representative Concentration Pathways RCP 4.5, 8.5) and found significant impacts on runoff and evapotranspiration (ET) for the period of 2071–2100. Results from both models suggested reduced runoff and increased ET, while the monthly distribution of runoff was different. We used this catchment study to understand the importance of subsurface processes in projection of hydrologic response to a warming climate.  相似文献   

Palynological and geochemical response to environmental changes in the Lower Cretaceous in the Outer Western Carpathians; a record from the Silesian unit, Czech Republic     

Petr Skupien  Alexandra Smar?ová 《Cretaceous Research》2011,32(4):538-551

Rich dinoflagellate cyst assemblages recorded from the Vendryne Formation, Tesin Limestone, and Hradiste Formation of the Silesian unit, Czech Republic are presented. The results of a qualitative and quantitative study of dinoflagellate cysts are presented and discussed. Age-assessment of the sediments based on 86 species suggests a Late Tithonian to Early Berriasian age for the Vendryne Formation and a Late Berriasian (Otopeta Ammonite Zone) to the basal part of the Late Valanginian (Verrucosum Ammonite Zone) age for the Tesin Limestone. Pelitic flyschoid sediments of the Hradiste Formation belong to the Late Valanginian - Early Hauterivian age. Quantitative palynological study and carbon isotope analysis were applied to understand the change from the grey clays to dark grey clays sedimentation. The dinoflagellate cyst assemblages show deposition in a shallow-sea environment. An increasing amount of sporomorphs towards the overlying layers (they are the most abundant in the Hradiste Formation) shows a growing supply of terrestrial material at the same time. The values of δ¹³C increased significantly from a level of 0.43 or 0.75-1.81‰ in the Late Valanginian. This change probably indicates an increase in organic matter storage and perturbation of the carbon cycle connected with the dark grey clays sedimentation.  相似文献   

Reply to the comments on “Magmatic history and geophysical signature of a post-collisional intrusive center emplaced near a crustal-scale shear zone: the Plechý granite pluton (Moldanubian batholith,Bohemian Massif)”     

Kryštof Verner  Jiří Žák  Jaroslava Pertoldová  Jakub Trubač  Patricie Týcová 《International Journal of Earth Sciences》2011,100(4):893-894

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Geochemical and petrological constraints on mantle composition of the Ohře(Eger) rift,Bohemian Massif: peridotite xenoliths from the České Středohoří Volcanic complex and northern Bohemia     

Lukáš Ackerman  Gordon Medaris Jr.  Petr Špaček  Jaromír Ulrych 《International Journal of Earth Sciences》2015,104(8):1957-1979

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