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Vladimír Čermák Louise Bodri Jan Šafanda Milan Krešl Petr Dědeček 《Studia Geophysica et Geodaetica》2014,58(3):403-424
Long-term observations of air, near-surface (soil) and ground temperatures, collected between 1994 and 2011, monitored in the Geothermal Climate Change Observatory at Spo?ilov, Prague (GCCO) are analyzed to better understand the relationship between these quantities and to describe the mechanism of heat transport at the land-atmosphere boundary layer. The 17 years long monitoring series provided a surprisingly small mean ground-air temperature offset of only 0.31 K with no clear annual course and with the offset value changing irregularly even on a daily scale. Such value is substantially lower than similar values (1–2 K and more) found elsewhere, but it may be well characteristic for a mild temperate zones, when all so far available information referred rather to more southern locations. As many other observed geophysical data, temperature time series consist of a systematic pattern (usually a set of identifiable components) contaminated by random noise, which makes the identification of the proper pattern difficult. To identify the existing systematic patterns (cycles) of the temperature-time series at several depth levels in the investigated depth interval 0–40 m, the observed data were processed with the help of the Fast Fourier Transform (FFT) and Recurrence Quantification Interval (RQI) analysis. The latter represents recently developed powerful technique to uncover hidden periodicities in a noisy time environment. At low frequency band the RQI may provide far finer resolution than the conventional FFT technique. The results proved considerable similarity for all investigated depth levels. In addition to the annual wave all measured series proved to have a more complex pattern including predominantly 8-year and 11 years long periodicities. The results were compared with similar analysis of the meteorological air temperature series as well as with the results of other similar studies. The potential dynamics explaining the occurrence of the 8-year wave is briefly discussed. 相似文献
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Iterative Spherical Downward Continuation Applied to Magnetic and Gravitational Data from Satellite 总被引:1,自引:0,他引:1
Josef Sebera Michal Šprlák Pavel Novák Aleš Bezděk Miloš Vaľko 《Surveys in Geophysics》2014,35(4):941-958
In the last few decades, satellites have acquired various potential data sets hundreds of kilometers above the Earth’s surface. Conventionally, these global magnetic and gravitational data sets are approximated by using spherical harmonics that allow straightforward work with both fields outside the Earth’s mass. In this article, we present an alternative approach for working with potential data in mass-free space given over a regular coordinate grid on a spherical surface. The algorithm is based on an iterative scheme and the Poisson integral equation for the sphere. With help from the Fourier transform, global potential (magnetic or gravitational) data can efficiently be continued from a mean orbital sphere down to a reference surface without using the spherical harmonics. This is illustrated both with simulated magnetic field data and with real data from the satellite gradiometry mission GOCE. In the case of simulated magnetic data and the downward continuation for 450 km, we have achieved a root mean square at the level of 0.05 nT, while it was <1 E (eotvos) for real GOCE data continued for 250 km. The crucial point is to apply the algorithm twice as a large part of noise can be removed from the input data. 相似文献
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Pavel Koten Jiří Borovička Pavel Spurný Stephen Evans Rostislav Štork Andrew Elliott 《Earth, Moon, and Planets》2008,102(1-4):151-156
We carried out double station observations of the Leonid meteor shower outburst, which occurred in the morning hours of November
19, 2006. Using image-intensified cameras we recorded approximately 100 Leonid meteors. As predicted, the outburst was rich
especially in fainter meteors. The activity profile shows that the peak of the outburst occurred at 4:40 ± 0:05 UT. The maximum
reached flux was 0.03 meteoroids km−2 hod−1 for meteors brighter than +6.5 magnitude. 相似文献
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Petr Pruner Nadja Zupan Hajna Andrej Mihevc Pavel Bosák Otakar Man Petr Schnabl Daniela Venhodová 《Studia Geophysica et Geodaetica》2010,54(1):27-48
Clastic and chemogenic cave sediments were sampled and analyzed from Račiška pečina and Pečina v Borštu caves of southwestern
Slovenia. Samples were subjected to both thermal and alternating field demagnetization; specimens belonging to the same sample
of the same layer produce identical results. Unblocking temperatures of 540 to 560°C on average suggests magnetite as the
principal carrier of magnetization. These directions also pass a reversals test indicating the demagnetization results are
free of secondary overprints and have adequately averaged out paleosecular variation. Normally magnetized clays containing
fauna belonging to the MN17 mammal biozone at a depth of ∼ 4 m in Račiška pecina cave indicate these clays were deposited
at the beginning of the Olduvai subchron (1.95 Ma). Correlation with the Geomagnetic Polarity Time Scale (GPTS) indicates
the base of the speleothems in Račiška pečina terminate in the upper part of subchron C2An.3n with numerous breaks in deposition,
lasting up to 250 ka and more. Therefore rates of speleothem growth cannot be calculated. Fold tests on dome-like stalagmites
of differing sizes and ages (Pleistocene, Pliocene) from the two caves indicate the domelike structures are primary. 相似文献
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Ulrych Jaromír Krmíček Lukáš Teschner Claudia Řanda Zdeněk Skála Roman Jonášová Šárka Fediuk Ferry Adamovič Jiří Pokorný Richard 《Mineralogy and Petrology》2017,111(5):761-775
Mineralogy and Petrology - Tachylytes from rift-related volcanic rocks were recognized as: (i) irregular veinlets in host alkaline lava flows of the Kozákov volcano, Czech Republic, (ii)... 相似文献
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