The Impact of Land-Surface Parameter Properties and Resolution on the Simulated Cloud-Topped Atmospheric Boundary Layer     

Leonhard Gantner  Vera Maurer  Norbert Kalthoff  Olga Kiseleva 《Boundary-Layer Meteorology》2017,162(3):475-502

A method to simulate characteristics of wind speed in the boundary layer of tropical cyclones in an idealized manner is developed and evaluated. The method can be used in a single-column modelling set-up with a planetary boundary-layer parametrization, or within large-eddy simulations (LES). The key step is to include terms in the horizontal velocity equations representing advection and centrifugal acceleration in tropical cyclones that occurs on scales larger than the domain size. Compared to other recently developed methods, which require two input parameters (a reference wind speed, and radius from the centre of a tropical cyclone) this new method also requires a third input parameter: the radial gradient of reference wind speed. With the new method, simulated wind profiles are similar to composite profiles from dropsonde observations; in contrast, a classic Ekman-type method tends to overpredict inflow-layer depth and magnitude, and two recently developed methods for tropical cyclone environments tend to overpredict near-surface wind speed. When used in LES, the new technique produces vertical profiles of total turbulent stress and estimated eddy viscosity that are similar to values determined from low-level aircraft flights in tropical cyclones. Temporal spectra from LES produce an inertial subrange for frequencies \(\gtrsim \)0.1 Hz, but only when the horizontal grid spacing \(\lesssim \)20 m.  相似文献   

Zinc-rich and copper-bearing amphiboles from sulfide-free ore occurrences of the Pelagonian Massif,Republic of North Macedonia     

Chukanov  Nikita V.  Zubkova  Natalia V.  Jančev  Simeon  Pekov  Igor V.  Ermolaeva  Vera N.  Varlamov  Dmitry A.  Belakovskiy  Dmitriy I.  Britvin  Sergey N. 《Mineralogy and Petrology》2020,114(2):129-140

Mineralogy and Petrology - This paper describes specific features of isomorphism of unusual amphiboles containing up to 23 wt% ZnO and up to 1.3 wt% CuO from sulfide-free...  相似文献   

Use of incipient motion data for backward erosion piping models     

Vera M. van Beek  Bryant A. Robbins  Gijs J.C.M. Hoffmans  Adam Bezuijen  Leo C. van Rijn 《国际泥沙研究》2019,34(5):401-408

Backward erosion piping involves the gradual removal of granular material under the action of water flow from the foundation of a dam or levee, whereby shallow pipes are formed that grow in the direction opposite to the flow. This pipe-forming process can ultimately lead to failure of a water-retaining structure and is considered one of the most important failure mechanisms for dikes and levees in the Netherlands and the United States. Modeling of this mechanism requires the assessment of hydraulic conditions in the pipe, which are controlled by the particle equilibrium at the pipe wall. Since the pipe's dimensions are controlled by the inflow to the pipe from the porous medium, the flow through the pipe is thought to be laminar for fine- to medium-grained sands. The literature provides data for incipient motion in laminar flow, which is reviewed here and complemented with data from backward erosion experiments. The experiments illustrate the applicability of the laminar incipient motion data to determine the erosion pipe dimensions and corresponding pipe hydraulics for fine- to medium-grained sands, for the purpose of backward erosion piping modeling.  相似文献   

Zoning of Groundwater Quality for Plain Garmsar in Iran     

Abouzar Nasiri  Shirocova  Vera A.  Zareie  Sajad 《Water Resources》2019,46(4):624-629

Water Resources - Groundwater performs an important role in the territory of the plains Garmsar. In this study, on the basis of water samples, which were obtained from the wells of the region,...  相似文献   

Efficacy of Coagulants and Ballast Compounds in Removal of Cyanobacteria (<Emphasis Type="Italic">Microcystis</Emphasis>) from Water of the Tropical Lagoon Jacarepaguá (Rio de Janeiro,Brazil)     

Leonardo de Magalhães  Natália Pessoa Noyma  Luciana Lima Furtado  Maíra Mucci  Frank van Oosterhout  Vera L. M. Huszar  Marcelo Manzi Marinho  Miquel Lürling 《Estuaries and Coasts》2017,40(1):121-133

Eutrophication is considered the most important water quality problem in freshwaters and coastal waters worldwide promoting frequent occurrence of blooms of potentially toxic cyanobacteria. Removal of cyanobacteria from the water column using a combination of coagulant and ballast is a promising technique for mitigation and an alternative to the use of algaecides. In laboratory, we tested experimentally the efficiency of two coagulants, polyaluminium chloride (PAC) and chitosan (made of shrimp shells), alone and combined with two ballasts: red soil (RS) and the own lagoon sediment, to remove natural populations of cyanobacteria, from an urban brackish coastal lagoon. PAC was a very effective coagulant when applied at low doses (≤8 mg Al L^?1) and settled the cyanobacteria, while at high doses (≥16 mg Al L^?1) large flocks aggregated in the top of test tubes. In contrast, chitosan was not able to form flocks, even in high doses (>16 mg L^?1) and did not efficiently settle down cyanobacteria when combined with ballast. The RS itself removed 33–47 % of the cyanobacteria. This removal was strongly enhanced when combined with PAC in a dose-dependent matter; 8 mg Al L^?1 was considered the best dose to be applied. The lagoon sediment alone did not promote any settling of cyanobacteria but removal was high when combined with PAC. Combined coagulant and ballast seems a very efficient, cheap, fast and safe curative measure to lessen the harmful cyanobacteria bloom nuisance in periods when particularly needed, such as around the 2016 Olympics in Jacarepaguá Lagoon.  相似文献   

Seismic hazard assessment for Iceland in terms of macroseismic intensity using a site approach     

Vera D’Amico  Dario Albarello  Ragnar Sigbjörnsson  Rajesh Rupakhety 《Bulletin of Earthquake Engineering》2016,14(7):1797-1811

We present the results of probabilistic seismic hazard assessment for Iceland in the framework of the EU project UPStrat-MAFA using the so-called site approach implemented in the SASHA computational code. This approach estimates seismic hazard in terms of macroseismic intensity by basically relying on local information about documented effects of past seismic events in the framework of a formally coherent and complete treatment of intensity data. In the case of Iceland, due to the lack of observed intensities for past earthquakes, local seismic histories were built using indirect macroseismic estimates deduced from epicentral information through an empirical attenuation relationship in probabilistic form. Seismic hazard was computed for four exceedance probabilities for an exposure time of 50 years, equivalent to average return periods of 50, 200, 475 and 975 years. For some localities, further return periods were examined and deaggregation analysis was performed. Results appear significantly different from previous seismic hazard maps, though just a semi-qualitative comparison is possible because of the different shaking measure considered (peak ground acceleration versus intensity), and the different computational methodology and input data used in these studies.  相似文献   

Preface to the special issue “Complexity in the Oil Industry 2007”     

Vera Pancaldi  Peter King  Liacir Dos Santos Lucena 《Computational Geosciences》2009,13(2):151-154

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Assessing future risk: quantifying the effects of sea level rise on storm surge risk for the southern shores of Long Island, New York   总被引：2，自引：1，他引：1  

Christine C. Shepard  Vera N. Agostini  Ben Gilmer  Tashya Allen  Jeff Stone  William Brooks  Michael W. Beck 《Natural Hazards》2012,60(2):727-745

Sea level rise threatens to increase the impacts of future storms and hurricanes on coastal communities. However, many coastal hazard mitigation plans do not consider sea level rise when assessing storm surge risk. Here we apply a GIS-based approach to quantify potential changes in storm surge risk due to sea level rise on Long Island, New York. We demonstrate a method for combining hazard exposure and community vulnerability to spatially characterize risk for both present and future sea level conditions using commonly available national data sets. Our results show that sea level rise will likely increase risk in many coastal areas and will potentially create risk where it was not before. We find that even modest and probable sea level rise (.5 m by 2080) vastly increases the numbers of people (47% increase) and property loss (73% increase) impacted by storm surge. In addition, the resulting maps of hazard exposure and community vulnerability provide a clear and useful example of the visual representation of the spatial distribution of the components of risk that can be helpful for developing targeted hazard mitigation and climate change adaptation strategies. Our results suggest that coastal agencies tasked with managing storm surge risk must consider the effects of sea level rise if they are to ensure safe and sustainable coastal communities in the future.  相似文献   

Flow-based coarsening for multiscale simulation of transport in porous media     

Vera Louise Hauge  Knut-Andreas Lie  Jostein R. Natvig 《Computational Geosciences》2012,16(2):391-408

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Energy use, climate change and folk psychology: Does sustainability have a chance? Results from a qualitative study in five European countries     

Anke Fischer  Vera PetersJan Vávra  Mirjam NeebeBoldizsár Megyesi 《Global Environmental Change》2011,21(3):1025-1034

Citizens’ support for policies that aim to curb carbon emissions and energy use is often seen as informed by their values, attitudes and perceptions of the environmental problem in question. We argue that we also need to understand how people conceptualise policies and the governance approaches underpinning them to be able to judge the likely acceptance of policy change.In this study, we draw on qualitative interviews (n = 202) from five European countries to explore citizens’ views on governance approaches to stimulate behavioural change in the field of resource use, including regulations, price changes, collective action, technological change and education.We found that many of our interviewees referred to generalised characteristics of humankind and contemporary society to back up their arguments for or against specific governance approaches. In particular, many interviewees concurred that people in general were so self-centred, driven by habit and money- and consumption-oriented that only strict regulations, drastic price changes and technological innovation could possibly achieve widespread behavioural change. As a consequence, such ‘folk psychologies’ can have substantial impact not only on public acceptance, but also on the success of policy measures that aim to reduce citizens’ resource use.  相似文献