Book reviews     

David Gubbins  Peter Molnar  J. G. Olliver  Petr Vanīček  Kenji Satake  Allan M. Rubin  Waclaw M. Zuberek  Janusz Niewiadomski  Leszek Czechowski  David J. Steveson  Jacek Leliwa-Kopystyński  Yu. N. Korenkov  Fred Lipschultz  Marek Jerczyński  Krzysztof E. Haman  Jerzy Radziwill  Maciej Sadowski  Maciej Sadowski 《Pure and Applied Geophysics》1990,132(3):599-637

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Radioisotopic evidence of perturbations of recent sedimentary record in lakes: a word of caution for climate studies     

Janusz Dominik  Jean-Luc Loizeau  Daniel Span 《Climate Dynamics》1992,6(3-4):145-152

The rate of climatic change estimated from the gradient of signals recorded in lake sediments may be erroneous if post-depositional perturbations are overlooked. A smear out of a pulse signal, over a variable thickness of core section, due to physical or biological mixing, is a well known phenomena. Much less attention is paid to a possible overestimation of the rate of change when a part of record is missing due to an erosion event. In this paper we show a few examples of recent lake sediment perturbations and the resulting distortions in the time scale, as documented by short-lived radionuclides.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program  相似文献   

Recognition of the zones of seismic hazard in Polish Coal mines by using a seismic method     

Józef Dubiński  Janusz Dworak 《Pure and Applied Geophysics》1989,129(3-4):609-617

In the Upper Silesian Coal Field the seismic hazard induced by mining operations in collieries is closely related to the rockburst hazard. A seismic method is used for premonitory recognition of the zones of seismic hazard. It takes advantage of the relationship between the velocity of propagation of seismic waves and the state of stress existing in the rock. It consists of the determination of the velocity field of artificially induced seismic waves in a studied fragment of the rock, and of locating the velocity anomaly. The position of the velocity anomaly zones and their intensity are the basis for estimating the seismic hazard in advance of mining works.  相似文献   

Noise-Dependent Adaption of the Wiener Filter for the GPS Position Time Series     

Klos  Anna  Bos  Machiel S.  Fernandes  Rui M. S.  Bogusz  Janusz 《Mathematical Geosciences》2019,51(1):53-73

Various methods have been used to model the time-varying curves within the global positioning system (GPS) position time series. However, very few consider the level of noise a priori before the seasonal curves are estimated. This study is the first to consider the Wiener filter (WF), already used in geodesy to denoise gravity records, to model the seasonal signals in the GPS position time series. To model the time-varying part of the signal, a first-order autoregressive process is employed. The WF is then adapted to the noise level of the data to model only those time variabilities which are significant. Synthetic and real GPS data is used to demonstrate that this variation of the WF leaves the underlying noise properties intact and provides optimal modeling of seasonal signals. This methodology is referred to as the adaptive WF (AWF) and is both easy to implement and fast, due to the use of the fast Fourier transform method.

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Influence of a method of evaluation of the curvature of flexible vegetation elements on vertical distributions of flow velocities     

Elżbieta Kubrak  Janusz Kubrak  Paweł M. Rowiński 《Acta Geophysica》2012,60(4):1098-1119

Methods of computing the deflections of flexible vegetation elements under the dynamic pressure of water were presented in the paper. Two methods, based on Euler-Bernoulli beam theory, were discussed, one designed for small deflections and the other, generalized one, also for larger deflections. The choice of the method for computations of deflections was discussed from the perspective of the computation of flow velocities above flexible vegetation. Computational results were compared with laboratory experiments and it was found that the simplified, computationally less expensive method may be used in many practical situations without deterioration of the results.  相似文献   

Experimental Investigation of Kinetic Energy and Momentum Coefficients in Regular Channels with Stiff and Flexible Elements Simulating Submerged Vegetation     

Elżbieta Kubrak  Janusz Kubrak  Adam Kiczko 《Acta Geophysica》2015,63(5):1405-1422

The paper addresses the problem of determination of the energy and momentum coefficients for flows through a partly vegetated channel. These coefficients are applied to express the fluid kinetic energy and momentum equations as functions of a mean velocity. The study is based on laboratory measurements of water velocity distributions in a straight rectangular flume with stiff and flexible stems and plastic imitations of the Canadian waterweed. The coefficients were established for the vegetation layer, surface layer and the whole flow area. The results indicate that the energy and momentum coefficients increase significantly with water depth and the number of stems per unit channel area. New regression relationships for both coefficients are given.  相似文献   

Error analysis for European IGS stations     

Anna?KlosEmail author  Janusz?Bogusz  Mariusz?Figurski  Maciej?Gruszczynski 《Studia Geophysica et Geodaetica》2016,60(1):17-34

Each of the GPS time series that describes the changes of topocentric components consists of a deterministic and a stochastic part, whose character influences the errors of the deterministic parameters. As to the uncertainties of reliable velocities of permanent satellite station systems, surveys that estimate and take into account any dependencies that may affect subsequent operational efficiency are very important. For this analysis, we used 42 stations from the IGS (International GNSS Service) network from Europe, processed at the Military University of Technology EUREF Permanent Network Local Analysis Centre (MUT LAC). The deterministic part of the GPS time series was removed using the least squares method. The seasonal periods in topocentric components were determined assuming the existence of the residual Chandler oscillation (1.67 cpy), as well as the annual tropical (1 cpy) and draconitic (1.04 cpy) oscillations with their harmonics up to 4th. We assumed the character of the residue as a combination of white and powerlaw noise. The obtained results show, that in the case of the European sub-network of IGS stations we are dealing with the coloured noise between white and flicker noise with the amplitudes between 3 to 6 mm/year^-k/4 for horizontal components and between 6 to 15 mm/year^-κ/4 for the vertical ones, where κ is a spectral index. Finally, we showed that the amplitudes and spectral indices of noise are reduced after performing a spatio-temporal filtering. All the elicited results referred to the uncertainties of velocities by estimating them before and after filtration and the simulation of their values for different lengths of the time series.  相似文献   

On the origin of seasonal variation of aerosol optical thickness in UV range over Belsk,Poland     

Janusz Jarosławski  Aleksander Pietruczuk 《Acta Geophysica》2010,58(6):1134-1146

Aerosol optical thickness (AOT) and seasonal variation of AOT over Belsk, Poland, in the UV wavelength range (310–380 nm) have been analysed using results of measurements by Brewer spectrophotometer No. 064 and Cimel sunphotometer data for the 2002–2007 period. The comparison of AOT derived from direct Sun measurements by Brewer spectrophotometer in the 310–320 nm range and retrieved from Cimel measurements at longer wavelengths shows good correlation (R = 0.96), with overestimation of retrieved values compared to the measured ones by about 6%. Basing on aerosol microphysical properties taken from almucantar retrievals and Mie theory, optical properties of aerosol in the UV range has been calculated. Analysis of seasonal variation of AOT at Belsk reveals two maxima: in April and July–August. Analysis of back-trajectories in conjunction with analysis of fire maps from Fire Information For Resource Management System shows that these seasonal maxima are connected with seasonal biomass burning in Eastern and Southern Europe.  相似文献   

Chemistry of sediments from the Dobezyce Reservoir, Poland, and the environmental implications     

Witold RECZYNSKI  Malgorzata JAKUBOWSKA  Janusz GOLAS  Andrew PARKER  Barbara KUBICA 《国际泥沙研究》2010,25(1):28-38

Sediments samples of the Dobczyce Reservoir(South Poland) were taken in three successive years(2004-06) at 17 points,analyzed for 12 elements by atomic absorption spectrometry.Substantial variations in elemental composition due to hydrological and environmental reasons were found.The use of statistical and chemometric tools enabled objective and effective analysis of the data obtained,both in case of long term observations as well as in terms of interpretation of incidental changes in metal concentrations.T...  相似文献   

Identification of stoichiometric iron-phosphorus colloids produced in a eutrophic lake     

Charles-Philippe Lienemann  Marc Monnerat  Janusz Dominik  Didier Perret 《Aquatic Sciences - Research Across Boundaries》1999,61(2):133-149

: Iron-rich colloids formed at the oxic-anoxic interface of a eutrophic lake (Lake Lugano; CH) were characterized by bulk chemical methods and analytical electron microscopy. Fractionation of raw waters showed that non-dissolved iron is particulate above the oxicline and mainly colloidal in the anoxic part of the hypolimnion, while non-dissolved ortho-phosphate is mostly colloidal through the water column. Because of these differences, filtration did not prove helpful for the determination of the role of iron-rich species in the scavenging of ortho-phosphate. On the other hand, analytical electron microscopy revealed that iron-rich nano-granules (ca. 50nm) are associated to the surface of bacterially produced fibrillar polysaccharides. Iron colloids in these complex entities contain important and constant amounts of phosphorus ([PO4]part:[Fe]part = 0.48 - 0.11, n = 1096 Fe-rich entities analyzed by electron microscopy), which suggests that phosphates are stoichiometrically incorporated into the hydrous iron oxide phase, with a tentative composition Fe2[OOH]1-x[(OH)3]x[PO4], during its genesis.  相似文献