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101.
Toward very high horizontal resolution NWP over the alps: Influence of increasing model resolution on the flow pattern 总被引:1,自引:0,他引:1
Michał Z. Ziemiański Marcin J. Kurowski Zbigniew P. Piotrowski Bogdan Rosa Oliver Fuhrer 《Acta Geophysica》2011,59(6):1205-1235
The increasing resolution of contemporary regional numerical weather prediction (NWP) models, reaching horizontal grid sizes
of O(1 km), requires robust and reliable dynamical cores, working well beyond the approximation of quasi-horizontal flows. That
stimulates an interest in an application for NWP purposes of dynamical cores based on the anelastic, or — more generally —
sound-proof flow equations, and characterized by appropriate robustness and reliability. The paper presents results from testing
the dynamical core of EULAG, the anelastic research model for multi-scale flows, as a prospective NWP dynamical core. The
model simulates the semi-realistic frictionless and adiabatic flow over realistic steep Alpine topographies, employing horizontal
grid sizes of 2.2, 1.1, and 0.55 km. The paper demonstrates not only the numerical robustness of EULAG, but also studies the
influence of the varying horizontal resolution on the simulated flow. Results show that the increased horizontal resolution
increases orographic drag on the flow. While the general flow pattern remains the same, increased resolution influences the
flow on scales from hundreds of kilometers to meso-gamma scales. The differences are especially apparent in the near-surface
layer of 1.5 to 3 km deep, and in the distribution and amplitudes of the orographically-induced gravity waves. 相似文献
102.
In this paper, a feasibility of anelastic approach for numerical weather prediction (NWP) is examined. The study concerns
the anelastic nonhydrostatic model EULAG as a prospective candidate for the new dynamical core of a high-resolution NWP model.
Such an application requires a series of benchmark tests to be performed. The study presents the results of dry idealized
two-dimensional linear and non-linear tests. They include evolution of cold and warm density currents in neutrally stratified
atmosphere, inertia-gravity waves in short and long channels, as well as mountain gravity waves for a set of different flow
regimes. Detailed comparison of the results with the reference solutions, based mainly on the results of compressible models,
indicates a high level of conformity for all of the experiments. It verifies the anelastic approach as strongly consistent
with the compressible one for a broad class of atmospheric problems. It also corroborates the robustness of EULAG numerics,
an essential requirement of dynamical core of NWP model. 相似文献
103.
Sergey Oladyshkin Holger Class Rainer Helmig Wolfgang Nowak 《Computational Geosciences》2011,15(3):565-577
CO2 storage in geological formations is currently being discussed intensively as a technology with a high potential for mitigating
CO2 emissions. However, any large-scale application requires a thorough analysis of the potential risks. Current numerical simulation
models are too expensive for probabilistic risk analysis or stochastic approaches based on a brute-force approach of repeated
simulation. Even single deterministic simulations may require parallel high-performance computing. The multiphase flow processes
involved are too non-linear for quasi-linear error propagation and other simplified stochastic tools. As an alternative approach,
we propose a massive stochastic model reduction based on the probabilistic collocation method. The model response is projected
onto a higher-order orthogonal basis of polynomials to approximate dependence on uncertain parameters (porosity, permeability,
etc.) and design parameters (injection rate, depth, etc.). This allows for a non-linear propagation of model uncertainty affecting
the predicted risk, ensures fast computation, and provides a powerful tool for combining design variables and uncertain variables
into one approach based on an integrative response surface. Thus, the design task of finding optimal injection regimes explicitly
includes uncertainty, which leads to robust designs with a minimum failure probability. We validate our proposed stochastic
approach by Monte Carlo simulation using a common 3D benchmark problem (Class et al., Comput Geosci 13:451–467, 2009). A reasonable compromise between computational efforts and precision was reached already with second-order polynomials.
In our case study, the proposed approach yields a significant computational speed-up by a factor of 100 compared with the
Monte Carlo evaluation. We demonstrate that, due to the non-linearity of the flow and transport processes during CO2 injection, including uncertainty in the analysis leads to a systematic and significant shift of the predicted leakage rates
toward higher values compared with deterministic simulations, affecting both risk estimates and the design of injection scenarios. 相似文献
104.
Wojciech Zgłobicki Małgorzata Telecka Sebastian Skupiński Aneta Pasierbińska Marcin Kozieł 《Environmental Earth Sciences》2018,77(23):774
Heavy metals are constantly emitted into the environment and pose a major threat to human health, particularly in urban areas. The threat is linked to the presence of Cd, Cr, Cu, Ni, Pb, and Zn in street dust, which consists of mineral and organic particles originating from the soil, industrial emitters, motor vehicles, and fuel consumption. The study objective was to determine the level of street dust contamination with trace metals in Lublin and to indicate their potential sources of origin. The analyses were carried out with an energy-dispersive X-ray fluorescence spectrometer. The sampling sites (49) were located within the city streets characterised by varying intensity of motor traffic. The following mean content values and their variation (SD) were determined: Cd: 5.1?±?1.7 mg kg?1, Cr: 86.4?±?23.3 mg kg?1, Cu: 81.6?±?69.2 mg kg?1, Ni: 16.5?±?3.9 mg kg?1, Pb: 44.1?±?16.4 mg kg?1, and Zn: 241.1?±?94.6 mg kg?1. The level of pollution was assessed with several widely used geochemical indices (geoaccumulation index, enrichment factor, pollution index, index of ecological risk, and potential ecological risk index). For most of the indices, the mean (median) values are arranged in the following manner: Zn?>?Cu(or Cd)?>?Pb?>?Ni?>?Cr. In general, street dust in Lublin does not show pollution with Cr, Ni, and Pb. Igeo and EF indices show moderate levels for Cu, Cd, and Zn; their presence in street dust is linked with anthropogenic factors (motor traffic). A significant threat is posed by Cd, and more than half of the samples show considerable pollution with cadmium (median for the index of ecological risk: 151). The spatial pattern of indices and the results of statistical analyses (CA, PCA) indicate three groups of elements: (1) Cr and Ni: natural origin; (2) Pb: mixed origin; and (3) Cd, Cu, and Zn: anthropogenic origin (mainly motor vehicle traffic). Higher content values for metals of anthropogenic origin in street dust indicate that it is a source of pollution of soil and air in the city. 相似文献
105.
Gerardo Herrera Rosa María Mateos Juan Carlos García-Davalillo Gilles Grandjean Eleftheria Poyiadji Raluca Maftei Tatiana-Constantina Filipciuc Mateja Jemec Auflič Jernej Jež Laszlo Podolszki Alessandro Trigila Carla Iadanza Hugo Raetzo Arben Kociu Maria Przyłucka Marcin Kułak Michael Sheehy Xavier M. Pellicer Charise McKeown Graham Ryan Veronika Kopačková Michaela Frei Dirk Kuhn Reginald L. Hermanns Niki Koulermou Colby A. Smith Mats Engdahl Pere Buxó Marta Gonzalez Claire Dashwood Helen Reeves Francesca Cigna Pavel Liščák Peter Pauditš Vidas Mikulėnas Vedad Demir Margus Raha Lídia Quental Cvjetko Sandić Balazs Fusi Odd Are Jensen 《Landslides》2018,15(2):359-379
Landslides are one of the most widespread geohazards in Europe, producing significant social and economic impacts. Rapid population growth in urban areas throughout many countries in Europe and extreme climatic scenarios can considerably increase landslide risk in the near future. Variability exists between European countries in both the statutory treatment of landslide risk and the use of official assessment guidelines. This suggests that a European Landslides Directive that provides a common legal framework for dealing with landslides is necessary. With this long-term goal in mind, this work analyzes the landslide databases from the Geological Surveys of Europe focusing on their interoperability and completeness. The same landslide classification could be used for the 849,543 landslide records from the Geological Surveys, from which 36% are slides, 10% are falls, 20% are flows, 11% are complex slides, and 24% either remain unclassified or correspond to another typology. Most of them are mapped with the same symbol at a scale of 1:25,000 or greater, providing the necessary information to elaborate European-scale susceptibility maps for each landslide type. A landslide density map was produced for the available records from the Geological Surveys (LANDEN map) showing, for the first time, 210,544 km2 landslide-prone areas and 23,681 administrative areas where the Geological Surveys from Europe have recorded landslides. The comparison of this map with the European landslide susceptibility map (ELSUS 1000 v1) is successful for most of the territory (69.7%) showing certain variability between countries. This comparison also permitted the identification of 0.98 Mkm2 (28.9%) of landslide-susceptible areas without records from the Geological Surveys, which have been used to evaluate the landslide database completeness. The estimated completeness of the landslide databases (LDBs) from the Geological Surveys is 17%, varying between 1 and 55%. This variability is due to the different landslide strategies adopted by each country. In some of them, landslide mapping is systematic; others only record damaging landslides, whereas in others, landslide maps are only available for certain regions or local areas. Moreover, in most of the countries, LDBs from the Geological Surveys co-exist with others owned by a variety of public institutions producing LDBs at variable scales and formats. Hence, a greater coordination effort should be made by all the institutions working in landslide mapping to increase data integration and harmonization. 相似文献
106.
Artificial Neural Networks in Proglacial Discharge Simulation: Application and Efficiency Analysis in Comparison to the Multivariate Regression; A Case Study of Waldemar River (Svalbard)
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Artificial neural networks were applied to simulate runoff from the glacierized part of the Waldemar River catchment (Svalbard) based on hydrometeorological data collected in the summer seasons of 2010, 2011 and 2012. Continuous discharge monitoring was performed at about 1 km from the glacier snout, in the place where the river leaves the marginal zone. Averaged daily values of discharge and selected meteorological variables in a number of combinations were used to create several models based on the feed‐forward multilayer perceptron architecture. Due to specific conditions of melt water storing and releasing, two groups of models were established: the first is based on meteorological inputs only, while second includes the preceding day's mean discharge. Analysis of the multilayer perceptron simulation performance was done in comparison to the other black‐box model type, a multivariate regression method based on the following efficiency criteria: coefficient of determination (R2) and its adjusted form (adj. R2), weighted coefficient of determination (wR2), Nash–Sutcliffe coefficient of efficiency, mean absolute error, and error analysis. Moreover, the predictors' importance analysis for both multilayer perceptron and multivariate regression models was done. The performed study showed that the nonlinear estimation realized by the multilayer perceptron gives more accurate results than the multivariate regression approach in both groups of models. 相似文献
107.
Pressure of natural gas in its rock reservoir determines the final radon concentration in this gas after its decompression to normal conditions. In this investigation, radon contents of 62 natural gas samples were measured and a simple physical model of the gas reservoir was applied. The model takes into account an additional dependence of radon concentration on the natural gas pressure and on the porosity of the rock reservoir. The influence of the gas pressure on the value of the radon emanating power is discussed. The mean
226
Ra content in the source rock needed for generation of
222
Rn concentrations observed in gas is also calculated. The calculations are made with the help of regression analysis. 相似文献
108.
Andreas Bechtold Gerhard Paar Filippo Garolla Rebecca Nowak Laura Fritz Christoph Traxler Oliver Sidla Christian Koeberl 《Meteoritics & planetary science》2023,58(9):1274-1286
Past, present, and forthcoming planetary rover missions to Mars and other planetary bodies are equipped with a large number of scientific cameras. The very large number of images resulting from this, combined with tight time constraints for navigation, measurements, and analyses, pose a major challenge for the mission teams in terms of scientific target evaluation. Shatter cones are the only macroscopic evidence for impact-induced shock metamorphism and therefore impact craters on Earth. The typical features of shatter cones, such as striations and horsetail structures, are particularly suitable for machine learning methods. The necessary training images do not exist for such a case; therefore, we pursued the approach of producing them artificially. Using PRo3D, a viewer developed for the interactive exploration and geologic analysis of high-resolution planetary surface reconstructions, we virtually placed shatter cones in 3-D background scenes processed from true Mars rover imagery. We use PRo3D-rendered images of such scenes as training data for machine learning architectures. Terrestrial analog studies in Ethiopia supported our lab work and were used to test the resulting neural network of this feasibility study. The result showed that our approach with shatter cones in artificial Mars rover scenes is suitable to train neural networks for automatic detection of shatter cones. In addition, we have identified several aspects that can be used to improve the training of the neural network and increase the recognition rate. For example, using background data with a higher resolution in order to have equal resolution of object (shatter cone) and Martian background and increase the number of objects that can be placed in the training data set. Also using better lighting reconstructions and a better radiometric adaption between object and Martian background would further improve the results. 相似文献
109.
Marcelo Sanchez Alvis Atique Sewon Kim Enrique Romero Marcin Zielinski 《Acta Geotechnica》2013,8(6):583-596
The study of desiccation cracks in soils has been a subject of increasing attention in recent research. This paper presents the use of a 2D profile laser that is coupled with a motion controller (that allows scanning the overall surface of a drying soil) and electronic balance (to measure the water loss). The aim is to accurately track the three most relevant variables associated with the behavior of soils during desiccation: volume change, water loss and evolving crack network’s morphology. The paper presents the methodology to obtain a digital model of the soil using the experimental setup described above. The main results of a natural soil subjected to drying are presented and discussed, including evolution of cracks aperture; evolution of cracks depth, surface contour levels (at different times); and evolution of volume change. It is shown that the proposed methodology provides very useful information for studying the behavior of soils subjected to desiccation. 相似文献
110.
Mariusz Pełechaty Andrzej Pukacz Karina Apolinarska Aleksandra Pełechata Marcin Siepak 《Sedimentology》2013,60(4):1017-1035
A significant portion of calcium carbonate is deposited in lake sediments as a result of biological processes related to the photosynthetic activity of phytoplankton in the pelagic realm and, in addition, macrophytes in the littoral zone. Lake Wigry, one of the largest lakes in Poland (north‐east Poland), is characterized by: (i) carbonate sediments with a CaCO3 content exceeding 80% within the littoral zone; and (ii) large areas of submerged vegetation dominated by charophytes (macroscopic green algae, Characeae family). It is claimed that charophytes are highly effective in utilizing HCO3? and forming thick CaCO3 encrustations. Thus, this study was aimed at evaluating the CaCO3 production by dense Chara stands overgrowing the lake bottom reaching a depth of 4 m. In late July 2009, the fresh and dry mass of plants, the percentage contribution of calcium carbonate and the production of CaCO3 per 1 m2 were investigated along three transects at three depths (1 m, 2 m and 3 m, with each sample area equal to 0·0625 m2) per transect. The composition and structure of phytoplankton and the physico‐chemical properties of the water analysed in both the littoral and pelagic zones served as the environmental background and demonstrated moderately low fertility in the lake. The greatest dry plant mass exceeded 1000 g m?2 and CaCO3 encrustations constituted from 59% to over 76% of the charophyte dry weight. Thus, the maximum and average values of carbonates precipitated by charophytes were 685·5 and 438 g m?2, respectively, which exceeded previously reported results. A correlation of carbonate production with the depth of Chara stands was detected, and intermediate depths offered the most favourable conditions for carbonate precipitation (589 g m?2 on average). As precipitated carbonates are ultimately stored in bottom deposits, the results highlight the significance of charophytes in lacustrine CaCO3 sedimentation. 相似文献