New Methods for Modeling Laterolog Resistivity Corrections   总被引：1，自引：1，他引：0  

Jadwiga Anna Jarzyna  Adam Cichy  Dezső Drahos  Attila Galsa  Maria Joanna Bała  Andrzej Ossowski 《Acta Geophysica》2016,64(2):417-442

The paper presents methods for laterolog response modeling. In Coulomb’s charges method, Laplace’s equation is solved for the electric field distribution in rock medium with internal boundaries between different resistivity layers. There, the boundary problem is reduced to Fred-holm integral equation of the second kind. The second method uses a finite element array to model apparent resistivity from laterolog. The task is treated as DC problem and the Laplace equation is solved numerically. The presented methods were applied to borehole data covering a typical stratigraphie section of the Fore-Sudetic Monocline in southwestern Poland. Apparent resistivity was calculated using the Coulomb’s charges method and alternatively modeled using a finite element method which gave similar results. Then, a series of linear corrections for borehole, shoulder bed, and filtration effects for apparent resistivity obtained by the Coulomb’s charges method demonstrated the feasibility of calculating true resistivity of virgin and invaded zones. The proposed methods provide a flexible solution in modeling which can be adapted to other logs.  相似文献   

Tidal wave transformations in the German Bight   总被引：2，自引：2，他引：0  

Emil V. Stanev  Rahma Al-Nadhairi  Joanna Staneva  Johannes Schulz-Stellenfleth  Arnoldo Valle-Levinson 《Ocean Dynamics》2014,64(7):951-968

Mesoscale and submesoscale dynamics associated with tidal wave transformations were addressed in the German Bight using numerical simulations. Tidal gauge and velocity observations in several locations were used to validate the numerical model. A downscaling approach included analysis of simulations with horizontal resolutions of 1, 0.4, and 0.2 km. It was shown that the modified tidal wave lost most of its energy after reflection or refraction over the eastern part of the German Bight. Energy loss resulted in a pronounced change of the wave’s spectral composition and generation of overtides. Tidal oscillations were modified by mesoscale processes associated with bathymetric channels. Semidiurnal and quarterdiurnal tides revealed very different spatial patterns. The former were aligned with the bathymetric channels, while the latter were rather “patchy” and had about half the spatial scales. In numerous areas around the bathymetric channels, the major axis of the M₄ ellipses was normal or at some angle with the major axis of the M₂ ellipses. Thus, higher harmonics developed “orthogonal” patterns that drove secondary circulations. Moreover, the ratio between spring and neap tidal amplitudes was relatively low in the Wadden Sea, showing reduced sensitivity of this very shallow area to fortnightly tidal variations. It was demonstrated that simulated hydrodynamics patterns help explain the physical mechanism shaping the median grain size distribution in the German Bight.  相似文献   

Modeling the formation of the K-Pg boundary layer     

Natalia Artemieva  Joanna Morgan 《Icarus》2009,201(2):768-181

In this paper we investigate the formation of the Cretaceous-Paleogene (K-Pg) boundary layer through numerical modeling. The K-Pg layer is widely agreed to be composed of meteoritic material and target rock from the Chicxulub impact site, that has been ejected around the globe and mixed with local material during final deposition. The observed composition and thickness of the K-Pg boundary layer changes with azimuth and distance from the impact site. We have run a suite of numerical simulations to investigate whether we can replicate the observational data, with a focus on the distal K-Pg layer and the impact glasses at proximal sites such as Beloc, Haiti. Previous models of the K-Pg ejecta have assumed an initial velocity distribution and tracked the ejecta to its final destination. Here, we attempt to model the entire process, from impact to the arrival of the ejecta around the globe. Our models replicate the observed ejecta thickness at proximal sites, and the modeled ejecta is composed of sediments and silicate basement rocks, in agreement with observational data. Models that use a 45° impact angle are able to replicate the total ejecta and iridium volume at distal sites, and the majority of the ejecta is composed of meteorite and target sediments. Sub-vertical impacts generate too little iridium, and oblique impacts of ?30 degrees generate too much. However, in contrast to observations, models that involve ballistic transport of ejecta lead to ejecta thickness decreasing with increasing distance, and are unable to transport shocked minerals (quartz and zircon) from the Chicxulub basement rocks around the globe. We suggest that much of the K-Pg ejecta is transported non-ballistically, and that the most plausible mechanism is through re-distribution from a hot, expanding atmosphere. The results are important for future investigations of the environmental effects of the Chicxulub impact.  相似文献   

Shallow-generated damage within non-planar strike-slip fault zones: role of sedimentary rocks in slip accommodation,SW Holy Cross Mountains,Poland     

Rybak-Ostrowska  Barbara  Konon  Andrzej  Domonik  Andrzej  Poszytek  Anna  Uroda  Joanna 《International Journal of Earth Sciences》2017,106(6):1863-1888

International Journal of Earth Sciences - We investigated exhumed damage zones of dextral strike-slip faults dissecting the south-western part of the Mesozoic cover of the Late Palaeozoic Holy...  相似文献   

Cautious neotectonic hypotheses for assessing the seismic hazard in northeastern Italy     

Joanna E. Papoulia  Dario Slejko 《Natural Hazards》1992,5(3):249-268

A simplified tectonic scheme for hazard purposes was recently adopted for northeastern Italy, introducing large generalized seismogenic areas containing systems of complex geometry faults. This scheme considers only major faults with documented seismic activity. In the present analysis, a different tectonic scheme, with linear elements as seismogenic sources, is presented. The assessment of the regional seismic hazard is done with the fault rupture model, its most important advantage being the recognition that the length of fault rupture during an earthquake is an important consideration in probabilistic calculations of seismic hazard. Moreover, some structures with no associated seismicity but with notable neotectonic activity are considered, and their contribution to the results investigated. Important uncertainties such as those in the maximum possible magnitude of future earthquakes, in the location of the fault, in the focal depth, and in the attenuation law are accounted for in the calculations and their influence studied. The results identify a seismic belt running from Lake Garda to Friuli and along the Yugoslav coast and are very similar to those already known for Friuli, with the largest values corresponding to the zone around Gemona. Some slight differences in the shape of the areas of equal acceleration are probably due to the delineation of the seismic sources of the proposed model. For a cautious elaboration, some neotectonic lines without present seismicity were added into the fault model. Their contribution is negligible in the areas of highest acceleration, but increases remarkably in the areas where acceleration is not expected to exceed the medium values.  相似文献   

An approach to the assessment of local trace metal pollution in the Mediterranean marine atmosphere     

R Chester  A.C Saydam  E Joanna Sharples 《Marine pollution bulletin》1981,12(12):426-431

Assessing the extent of local trace metal pollution in marine atmospheric particulates presents a number of difficulties, and one potential approach to the problem has been evaluated by reference to a series of aerosols from the lower troposphere over the Eastern Mediterranean. This region, which is less remote from the continents than open-ocean areas, has two significantly different atmospheric particulate catchments: being bordered in the north by nations having industrialized, semi-industrialized and rural economies, and in the south by the North African desert belt. The elemental chemistry of the particulates is illustrated in terms of the distributions of Fe and Pb, which are presented in the form of enrichment factor diagrams, and is shown to be essentially controlled by the dilution of a ‘European’ background material, common to ‘remote’ regions of the latitudinal belt, with crust-derived, desert components. Major local perturbations in the dilution relationship can occur when either crust-derived or pollutant components strongly dominate the total particulate population. The extent of these local perturbations can be tentatively assessed using appropriate enrichment factor diagrams, which offer a framework within which to interpret the elemental chemistry of marine atmospheric particulates providing sufficient data is available for their construction. By using such an EF diagram it is suggested that the Eastern Mediterranean atmospheric particulates have not suffered local pollution on a gross scale with respect to Pb.  相似文献   

Downscaling Landsat-8 land surface temperature maps in diverse urban landscapes using multivariate adaptive regression splines and very high resolution auxiliary data     

Joanna Zawadzka  Ron Corstanje  Jim Harris  Ian Truckell 《International Journal of Digital Earth》2020,13(8):899-914

ABSTRACT

We propose a method for spatial downscaling of Landsat 8-derived LST maps from 100(30?m) resolution down to 2–4?m with the use of the Multiple Adaptive Regression Splines (MARS) models coupled with very high resolution auxiliary data derived from hyperspectral aerial imagery and large-scale topographic maps. We applied the method to four Landsat 8 scenes, two collected in summer and two in winter, for three British towns collectively representing a variety of urban form. We used several spectral indices as well as fractional coverage of water and paved surfaces as LST predictors, and applied a novel method for the correction of temporal mismatch between spectral indices derived from aerial and satellite imagery captured at different dates, allowing for the application of the downscaling method for multiple dates without the need for repeating the aerial survey. Our results suggest that the method performed well for the summer dates, achieving RMSE of 1.40–1.83?K prior to and 0.76–1.21?K after correction for residuals. We conclude that the MARS models, by addressing the non-linear relationship of LST at coarse and fine spatial resolutions, can be successfully applied to produce high resolution LST maps suitable for studies of urban thermal environment at local scales.  相似文献   

First application of MC2-AQ to multiscale air quality modelling over Europe     

Jacek W Kaminski  David A Plummer  Lori Neary  John C McConnell  Joanna Struzewska  Lech Lobocki 《Physics and Chemistry of the Earth》2002,27(35):1517-1524

A three-dimensional air quality model (MC2-AQ) developed for studying oxidant chemistry on regional to urban scales over North America was adapted and implemented for European conditions. The modelling system is based on the Canadian Mesoscale Compressible Community (MC2) Model, a non-hydrostatic meteorological model, to which modules permitting on-line calculations of chemical transformations, anthropogenic and biogenic emissions, and deposition were added. The transport of chemical species is done on the same grid and with the same advection, convection, and diffusion schemes as are used for the meteorological fields. The developed model is highly flexible and was adapted to different scales by allowing for self-nesting. In this paper we present model results for a high-ozone episode, June 18–26, 2000, over Europe. The modelling system was able to reproduce general characteristics (growth, extent, and dissipation) of the pollution episode. Accumulation of ozone precursors during weak wind and high-temperature synoptic conditions was essential for episode formation. Subsequent episode development and advancement across Europe was driven by frontal systems. A stationary front associated with a low-pressure system over Ukraine prevented the further eastward transport of the polluted air mass. The episode was terminated after the passage of a cold front advecting relatively clean Atlantic air mass.  相似文献   

Azide as a tool to evaluate sediment trap behaviour     

Ulrich Lundgreen  Joanna Waniek  Detlef E. Schulz-Bull  Jan C. Duinker 《Ocean Dynamics》1997,49(1):57-69

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Dune mobility and vegetation cover in the Southwest Kalahari desert   总被引：1，自引：0，他引：1  

Giles F. S. Wiggs  David S. G. Thomas  Joanna E. Bullard  Ian Livingstone 《地球表面变化过程与地形》1995,20(6):515-529

As part of a wider project investigating the palaeoenvironmental significance of partially vegetated linear dunes in the southwest Kalahari, data collected in the latter part of 1992 concerning dune movement and vegetation cover suggest that sediment transport is occurring on some dune surfaces, and that the majority of surface activity occurs on the crests and upper slopes of the dunes. The data suggest that the limiting variables on surface sediment movement vary on different parts of a dune. On interdunes and lower dune slopes the primary limiting variable is available wind energy, while on dune crests and upper slopes it is vegetation cover. Ground cover by litter has much greater importance in protecting the surface sediment from erosion than rooted vegetation. From individual data points, no evidence is found to support a threshold vegetation cover below which sediment movement occurs. Rather, a gradient of activity is suggested whereby a reduction in vegetation cover increases the potential for sediment movement and surface change. However, dunes with differing amounts of mean vegetation cover display differing degrees of surface activity, and at this scale, a vegetation cover threshold in the region of 14 per cent may be recognized.  相似文献