Моделирование разливов нефти в море для планирования мероприятий по обеспечению экологической безопасности при реализации нефтегазовых проектов. Часть 2. Особенности реализации прикладных задач

In the second part of the article, peculiarities of the oil spills modeling for applied problems are marked, and some examples of simulation results are submitted. As an example of a oil spill model, which able to ensure the needs of information support of applied problems, the description of model SPILLMOD is presented in the final part of the article. Also a set of parameterizations allowing to take into account the role of hydrometeorological conditions for use skimmers and booms in oil spill response operations are described.Во второй части статьи отмечены особенности постановки задачи моделировании разливов нефти для (подготовки планов ликвидации разливов нефти в море (ПЛАРН), анализа совокупной экологической выгоды при выборе стратегий реагирования на разливы (АСЭВ) и оценки воздействия на окружающую среду (ОВОС), представлены примеры результатов моделирования. В качестве примера модели нефтяного разлива, обеспечивающей потребности информационного обеспечения ПЛАРН и АСЭВ, в заключительной части статьи приведено описание модели SPILLMOD с набором параметризаций, позволяющих учитывать роль гидрометеорологических условий при использовании в операции ЛАРН скиммеров и боновых заграждени

Estimates of Turbulence Intensity and Power Density of an Asymmetric Tidal Current under Wind Forcing Variability

International audienceA high-frequency (1.2 MHz) four-beam Acoustic Doppler Current Profiler moored on the seabed has been used for direct turbulence measurements in a tidal channel. Five tidal cycles covering calm and storm periods are selected from the measurements. The effect of the tidal cycle asymmetry and the wind forcing variability on the turbulence intensity, Reynolds stresses, and the current energy characteristics is estimated. It is shown that the power density of the tidal flow is twice as low during the storm period than during the calm period. Wave filtering in calculating Reynolds stresses made it possible to estimate the contribution of small-scale turbulence to its intensity

Effects of the particle migration on the features of their transport by tidal currents in the Region of Freshwater Influence

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Modelling distribution of flounder larvae in the eastern English Channel: sensitivity to physical forcing and biological behaviour.

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Effect of variable winds on current structure and Reynolds stresses in a tidal flow: analysis of experimental data in the eastern English Channel

Wind and wave effects on tidal current structure and turbulence throughout the water column are examined using an upward-looking acoustic Doppler current profiler (ADCP). The instrument has been deployed on the seafloor of 18-m mean depth, off the north-eastern French coast in the eastern English Channel, over 12 tidal cycles, and covered the period of the transition from mean spring to neap tide, and forcing regimes varied from calm to moderate storm conditions. During storms, we observed gusty winds with magnitudes reaching 15 m s(-1) and wave heights reaching up to 1.3 m. Analysis of velocity spectra revealed a noticeable contribution of wind-induced waves to spectral structure of velocity fluctuations within the subsurface layer. Near the surface, stormy winds and waves produced a significant intensification of velocity fluctuations, particularly when the sustained wind blew against the ebb tide flow. As during wavy periods, the variance-derived Reynolds stress estimates might include a wave-induced contamination, we applied the Variance Fit method to obtain unbiased stresses and other turbulent quantities. Over calm periods, the turbulent quantities usually decreased with height above the seabed. The stresses were found to vary regularly with the predominantly semidiurnal tidal flow. The along-shore stress being generally greater during the flood flow (similar to 2.7 Pa) than during the ebb flow (similar to -0.6 Pa). The turbulent kinetic energy production rate, P, and eddy viscosity, A(z), followed a nearly regular cycle with close to a quarter-diurnal period. As for the stresses, near the seabed, we found the maximum values of estimated quantities of P and A(z) to be 0.1 Wm(-3) and 0.5 m(2) s(-1), respectively, during the flood flow. Over the storm periods, we found the highest unbiased stress values (similar to -2.6 Pa) during ebb when tidal currents were opposite to the southwesterly winds while, during the flood, the surface stresses slightly exceeded those estimated for a calm period. A comparison of obtained results gives a good agreement with those of other researchers working on direct measurements of turbulence in tidal flows

Transport and bottom accumulation of fine river sediments under typhoon conditions and associated submarine landslides: case study of the Peinan River, Taiwan

<p class="p">A combination of a three-dimensional Eulerian ocean circulation model (Princeton ocean model, POM) and a Lagrangian particle-tracking model (Surface-Trapped River Plume Evolution, STRiPE) is used to study the fate of fine river sediments discharged by the Peinan River at the southeastern coast of the island of Taiwan. The composite model is verified against in situ measurements and applied to simulate primary sediment deposition under freshet and typhoon discharge conditions of the Peinan River. It is shown that local wind plays a crucial role in sediment transport and settling in the coastal area through its influence on the river plume dynamics and turbulent mixing in the upper layer. Wind forcing conditions generally determine the location of the sediment deposit area, while its final pattern is defined by coastal circulation as modulated by the geometry of the coast and local bathymetry. In the study, region river-borne sediments are deposited to the sea floor, mainly in the shallow shelf areas. A significant portion of discharged fine sediments is moved offshore to the deeper ocean where it is further advected and dispersed by strong coastal circulation, mainly governed by the Kuroshio Current.<br><br>The performed numerical experiments showed that sediment accumulation rate under typhoon conditions is about 2 orders of magnitude greater compared to freshet conditions. Based on the simulation results, we identified areas of continental shelf and continental slope adjacent to the Peinan River estuary which exhibit a high risk of formation of submarine landslides during and shortly after the typhoon events