Tidal-driven dynamics and mixing processes in a coastal ocean model with wetting and drying   总被引：2，自引：2，他引：0  

Suriyan Saramul  Tal Ezer 《Ocean Dynamics》2010,60(2):461-478

A three-dimensional sigma coordinate numerical model with wetting and drying (WAD) and a Mellor–Yamada turbulence closure scheme has been used in an idealized island configuration to evaluate how tidally driven dynamics and mixing are affected by inundation processes. Comprehensive sensitivity experiments evaluate the influence of various factors, including tidal amplitudes (from 1- to 9-m range), model grid size (from 2 to 16 km), stratification, wind, rotation, and the impact of WAD on the mixing. The dynamics of the system involves tidally driven basin-scale waves (propagating anticlockwise in the northern hemisphere) and coastally trapped waves propagating around the island in an opposite direction. The evolutions of the surface mixed layer (SML) and the bottom boundary layer (BBL) under different forcing have been studied. With small amplitude tides, wind-driven mixing dominates and the thickness of the SML increases with time, while with large-amplitude tides, tidal mixing dominates and the thickness of the BBL increases with time. The inclusion of WAD in the simulations increases bottom stress and impacts the velocities, the coastal waves, and the mixing. However, the impact of WAD is complex and non-linear. For example, WAD reduces near-coast currents during flood but increases currents during ebb as water drains from the island back to the sea. The impacts of WAD, forcing, and model parameters on the dynamics are summarized by an analysis of the vorticity balance for the different sensitivity experiments.  相似文献   

A three-dimensional surface wave–ocean circulation coupled model and its initial testing     

Fangli Qiao  Yeli Yuan  Tal Ezer  Changshui Xia  Yongzeng Yang  Xingang Lü  Zhenya Song 《Ocean Dynamics》2010,60(5):1339-1355

A theoretical framework to include the influences of nonbreaking surface waves in ocean general circulation models is established based on Reynolds stresses and fluxes terms derived from surface wave-induced fluctuation. An expression for the wave-induced viscosity and diffusivity as a function of the wave number spectrum is derived for infinite and finite water depths; this derivation allows the coupling of ocean circulation models with a wave number spectrum numerical model. In the case of monochromatic surface wave, the wave-induced viscosity and diffusivity are functions of the Stokes drift. The influence of the wave-induced mixing scheme on global ocean circulation models was tested with the Princeton Ocean Model, indicating significant improvement in upper ocean thermal structure and mixed layer depth compared with mixing obtained by the Mellor–Yamada scheme without the wave influence. For example, the model–observation correlation coefficient of the upper 100-m temperature along 35° N increases from 0.68 without wave influence to 0.93 with wave influence. The wave-induced Reynolds stress can reach up to about 5% of the wind stress in high latitudes, and drive 2–3 Sv transport in the global ocean in the form of mesoscale eddies with diameter of 500–1,000 km. The surface wave-induced mixing is more pronounced in middle and high latitudes during the summer in the Northern Hemisphere and in middle latitudes in the Southern Hemisphere.  相似文献   

Editorial—the 4th International Workshop on Modeling the Ocean (IWMO 2012)     

Lie-Yauw Oey  Yasumasa Miyazawa  Hidenori Aiki  Yukio Masumoto  Tal Ezer  Takuji Waseda 《Ocean Dynamics》2013,63(11-12):1345-1347

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Editorial—the 4th International Workshop on Modeling the Ocean (IWMO 2012)     

Oey  Lie-Yauw  Miyazawa  Yasumasa  Aiki  Hidenori  Masumoto  Yukio  Ezer  Tal  Waseda  Takuji 《Ocean Dynamics》2013,63(11):1345-1347

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Comparison of precipitation extremes estimation using parametric and nonparametric methods     

Jan Holešovský  Michal Fusek  Vít Blachut  Jaroslav Michálek 《水文科学杂志》2013,58(13):2376-2386

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Fluid evolution of the Hub Stock, Horní Slavkov–Krásno Sn–W ore district, Bohemian Massif, Czech Republic     

Zdeněk Dolní?ek  Milo? René  Walter Prochaska  Michal Ková? 《Mineralium Deposita》2012,47(7):821-833

The Horní Slavkov–Krásno Sn–W ore district is hosted by strongly altered Variscan topaz–albite granite (Krudum granite body) on the northwestern margin of the Bohemian Massif. We studied the fluid inclusions on greisens, ore pockets, and ore veins from the Hub Stock, an apical expression of the Krudum granite. Fluid inclusions record almost continuously the post-magmatic cooling history of the granite body from ～500 to <50°C. Rarely observed highest-temperature (～500°C) highest-salinity (～30?wt.% NaCl eq.) fluid inclusions are probably the result of secondary boiling of fluids exsolved from the crystallizing magma during pressure release which followed hydraulic brecciation of the gneissic mantle above the granite cupola. The greisenization was related to near-critical low-salinity (0–7?wt.% NaCl eq.) aqueous fluids with low amount of CO₂, CH₄, and N₂ (≤10?mol% in total) at temperatures of ～350–400°C and pressures of 300–530 bar. Crush-leach data display highly variable and negatively correlated I/Cl and Br/Cl values which are incompatible with both orthomagmatic and/or metamorphic origin of the fluid phase, but can be explained by infiltration of surficial and/or sedimentary fluids. Low fluid salinity indicates a substantial portion of meteoric waters in the fluid mixture that is in accordance with previous stable isotope data. The post-greisenization fluid activity associated with vein formation and argillitization is characterized by decreasing temperature (<350 to <50°C), decreasing pressure (down to ～50–100 bar), and mostly also decreasing salinity.  相似文献   

Arsenic and antimony contamination of waters,stream sediments and soils in the vicinity of abandoned antimony mines in the Western Carpathians,Slovakia     

Edgar Hiller  Bronislava Lalinská  Martin Chovan  Ľubomír Jurkovič  Tomáš Klimko  Michal Jankulár  Róbert Hovorič  Peter Šottník  Renáta Fľaková  Zlatica Ženišová  Ivana Ondrejková 《Applied Geochemistry》2012

Environmental contamination with As and Sb caused by past mining activities at Sb mines is a significant problem in Slovakia. This study is focused on the environmental effects of the 5 abandoned Sb mines on water, stream sediment and soil since the mines are situated in the close vicinity of residential areas. Samples of mine wastes, various types of waters, stream sediments, soils, and leachates of the mine wastes, stream sediments and selected soils were analyzed for As and Sb to evaluate their geochemical dispersion from the mines. Mine wastes collected at the mine sites contained up to 5166 mg/kg As and 9861 mg/kg Sb. Arsenic in mine wastes was associated mostly with Fe oxides, whereas Sb was present frequently in the form of individual Sb, Sb(Fe) and Fe(Sb) oxides. Waters of different types such as groundwater, surface waters and mine waters, all contained elevated concentrations of As and Sb, reaching up to 2150 μg/L As and 9300 μg/L Sb, and had circum-neutral pH values because of the buffering capacity of abundant Ca- and Mg-carbonates. The concentrations of Sb in several household wells are a cause for concern, exceeding the Sb drinking water limit of 5 μg/L by as much as 25 times. Some attenuation of the As and Sb concentrations in mine and impoundment waters was expected because of the deposition of metalloids onto hydrous ferric oxides built up below adit entrances and impoundment discharges. These HFOs contained >20 wt.% As and 1.5 wt.% Sb. Stream sediments and soils have also been contaminated by As and Sb with the peak concentrations generally found near open adits and mine wastes. In addition to the discharged waters from open adits, the significant source of As and Sb contamination are waste-rock dumps and tailings impoundments. Leachates from mine wastes contained as much as 8400 μg/L As and 4060 μg/L Sb, suggesting that the mine wastes would have a great potential to contaminate the downstream environment. Moreover, the results of water leaching tests showed that Sb was released from the solids more efficiently than As under oxidizing conditions. This might partly explain the predominance of Sb over As in most water samples.  相似文献   

Modeling and observations of high-frequency flow variability and internal waves at a Caribbean reef spawning aggregation site   总被引：2，自引：2，他引：0  

Tal Ezer  William D. Heyman  Chris Houser  Björn Kjerfve 《Ocean Dynamics》2011,61(5):581-598

The characteristics and forcing mechanisms of high-frequency flow variations (periods of minutes to days) were investigated near Gladden Spit, a reef promontory off the coast of Belize. Direct field observations and a high-resolution (50-m grid size) numerical ocean model are used to describe the flow variations that impact the initial dispersion of eggs and larvae from this site, which serves as a spawning aggregation site for many species of reef fishes. Idealized sensitivity model experiments isolate the role of various processes, such as internal waves, wind, tides, and large-scale flow variations. The acute horizontal curvature and steep topography of the reef intensify the flow, create small-scale convergence and divergence zones, and excite high-frequency oscillations and internal waves. Although the tides in this area are relatively small (∼10-cm amplitude), the model simulations show that tides can excite significant high-frequency flow variations near the reef, which suggests that the preference of fish to aggregate and spawn in the days following the time of full moon may not be coincidental. Even small variations in remote flows (2–5 cm s⁻¹) due to say, meso-scale eddies, are enough to excite near-reef oscillations. Model simulations and the observations further suggest that the spawning site at the tip of the reef provides initial strong dispersion for eggs, but then the combined influence of the along-isobath flow and the westward wind will transport the eggs and larvae downstream of Gladden Spit toward less turbulent region, which may contribute to enhanced larval survival.  相似文献   

Dynamic morphology of small south‐eastern Mediterranean river mouths: a conceptual model     

Michal Lichter  Micha Klein  Dov Zviely 《地球表面变化过程与地形》2011,36(4):547-562

River mouths along the Israeli Mediterranean coast are characterized by a dynamic morphology as their channels migrate hundreds of meters along the coast. This study examines the dynamic morphology of seven such river mouths. It offers a conceptual model aimed at generalizing and describing their spatial and temporal morphological patterns, and the environmental factors influencing them. The study methodology comprised a detailed monitoring and mapping by GIS techniques, with quantitative data derived from historic aerial photographs, river discharge records, wave measurements, and a digital elevation model. These data were incorporated into a homogenous database and subsequently applied in the investigation of the morphological patterns of these mouths, and the analysis of their influencing factors. River mouths in this study occur in two distinctive topographic settings. In one setting (here termed barrier topography) the river mouth is deflected alongshore by a sandy barrier. In the second setting (termed funnel topography) the river mouth is confined to a funnel‐shaped topographic depression perpendicular to the coast. The behavior of river mouths in these two settings is quite distinctive. Barrier mouths usually migrate over larger distances, as they tend to deflect along a sand barrier and establish semi‐permanent channels along the dune toe. This enables the wide range migration of semi‐permanent channels over decades. Funnel topography mouths deflect over shorter distances and they rapidly migrate within the funnel boundaries. This study concludes that the topographic setting of the beach, a constant element in the temporal scale of this study, is the primary influencing factor on the morphology of the mouths studied. The influence of other factors on the morphology of these mouths differs in space and time and depends on the topographic settings.  相似文献   

Determination of ecological significance based on geostatistical assessment: a case study from the Slovak Natura 2000 protected area     

Michal Klaučo  Bohuslava Gregorová  Uglješa Stankov  Vladimir Marković  Polina Lemenkova 《Central European Journal of Geosciences》2013,5(1):28-42

The Sitno Natura 2000 Site covers an area of 935,56 hectares. The Sitno region is significant due to the number of rare and endangered species of plants, and as a result is considered a location of great importance to the maintenance of floral gene pools. The study area suffers human impacts in the form of tourism. The main purpose of this study is to the measure landscape elements, determine the ecological significance of habitats within the Sitno area, and from this data, organize the study area into conservation zones. The results of this landscape quantification are numerical values that can be used to interpret the quality of ongoing ecological processes within individual landscape types. Interpretation of this quantified data can be used to determine the ecological significance of landscapes in other study areas. This research examines the habitats of Natura 2000 Sites by a set of landscape metrics for habitat area, size, density, and shape, such as Number of patches (NP), Patch density (PD), Mean patch size (MPS), Patch size standard deviation (PSSD) and Mean shape index (MSI). The classification of land cover patches is based on the Annex Code system.  相似文献