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A fault plane model and a finite element hydrodynamic model are applied to the simulation of the Hokkaido Nansei-Oki tsunami of July 12, 1993. The joint performance of the models is assessed based on the overall ability to reproduce observed tsunami waveforms and to preserve mass and energy during tsunami propagation. While a number of observed characteristics of the waveforms are satisfactorily reproduced (in particular, amplitudes and arrival times at tidal gauges relatively close to the source, and general patterns of energy concentration), others are only marginally so (notably, wave periods at the same gauges, and wave heights along Okushiri); differences between observations and simulations are traceable to both the fault plane and the hydrodynamic models. Nonnegligible losses of energy occur throughout the simulated tsunami propagation. These losses seem to be due to a combination of factors, including numerical damping and possible deficiencies of the shallow water equations in preserving energy. 相似文献
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D. A. Jay R. J. Uncles J. Largeir W. R. Geyer J. Vallino W. R. Boynton 《Estuaries and Coasts》1997,20(2):262-280
The purpose of this contribution is to review recent developments in calculation of estuarine scalar fluxes, to suggest avenues for future improvement, and to place the idea of flux calculation in a broader physical and biogeochemical context. A scalar flux through an estuarine cross section is the product of normal velocity and scalar concentration, sectionally integrated and tidally averaged. These may vary on interannual, reasonal, tidal monthly, and event time scales. Formulation of scalar fluxes in terms of an integral scalar conservation expression shows that they may be determined either through “direct” means (measurement of velocity and concentration) or by “indirect” inference (from changes in scalar, inventory and source/sink terms). Direct determination of net flux at a cross section has a long and generally discouraging history in estuarine oceanography. It has proven difficult to extract statistically significant net (tidally averaged) fluxes from much larger flood and ebb transports, and the best mathematical representation of flux mechanisms is unclear. Observations further suggest that both lateral and vertical variations in scalar transport through estuarine cross sections are large, while estuarine circulation theory has focused on two-dimensional analyses that treatment either vertical or lateral variations but not both. Indirect estimates of net fluxes by determination of the other relevant terms in an integral scalar conservation balance may be the best means of determining scalar import-export in systems with residence times long relative to periods of tidal monthly fluctuations. But this method offers, little insight into the interaction of circulation modes and scalar fluxes, little help in verifying predictive models, and may also be difficult to apply in some circumstances. Thus, the need to understand, measure, and predict anthropogenic influences on transport or carbon, nutrient, suspended matter, trace metals, and other substances across the land-margin brings a renewed urgency to the issue of how to best carry out estuarine scalar flux determination. An interdisciplinary experiment is suggested to test present understanding, available instrument, and numerical models. 相似文献
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Analysis of Factors Influencing Simulations of the 1993 Hokkaido Nansei-Oki and 1964 Alaska Tsunamis 总被引：3，自引：0，他引：3
The purpose of this paper is to examine factorsinfluencing numerical simulations of tsunamis, andtheir implications for hazard mitigation. We focus ona specific finite element hydrodynamic model, chosenfor its role in the systematic development ofinundation maps for regions threatened primarily byCascadia Subduction Zone (CSZ) tsunamis. However, inpart for generality and in part because of poorhistorical records for CSZ events, we discuss here theperformance of the model in the context of betterdocumented past events with epicenters locatedelsewhere: the July 12, 1993 Hokkaido Nansei-Oki andthe March 28, 1964 Alaska tsunamis. Our analysisincludes the influence of grid refinement,interactions between tides and tsunamis, artificialenergy loss, and numerical parameterization. We showthat while the ability exists to reproduce pastevents, limitations remain in the modeling processthat should be accounted for in translating modelingresults into information for tsunami mitigation andresponse. 相似文献
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