A simple model for calculating tsunami flow speed from tsunami deposits   总被引：2，自引：0，他引：2  

Bruce E. Jaffe  Guy Gelfenbuam 《Sedimentary Geology》2007,200(3-4):347-361

This paper presents a simple model for tsunami sedimentation that can be applied to calculate tsunami flow speed from the thickness and grain size of a tsunami deposit (the inverse problem). For sandy tsunami deposits where grain size and thickness vary gradually in the direction of transport, tsunami sediment transport is modeled as a steady, spatially uniform process. The amount of sediment in suspension is assumed to be in equilibrium with the steady portion of the long period, slowing varying uprush portion of the tsunami. Spatial flow deceleration is assumed to be small and not to contribute significantly to the tsunami deposit. Tsunami deposits are formed from sediment settling from the water column when flow speeds on land go to zero everywhere at the time of maximum tsunami inundation. There is little erosion of the deposit by return flow because it is a slow flow and is concentrated in topographic lows. Variations in grain size of the deposit are found to have more effect on calculated tsunami flow speed than deposit thickness. The model is tested using field data collected at Arop, Papua New Guinea soon after the 1998 tsunami. Speed estimates of 14 m/s at 200 m inland from the shoreline compare favorably with those from a 1-D inundation model and from application of Bernoulli's principle to water levels on buildings left standing after the tsunami. As evidence that the model is applicable to some sandy tsunami deposits, the model reproduces the observed normal grading and vertical variation in sorting and skewness of a deposit formed by the 1998 tsunami.  相似文献   

Advanced insights into sources of vertical velocity in the ocean     

Hervé Giordani  Louis Prieur  Guy Caniaux 《Ocean Dynamics》2006,56(5-6):513-524

Estimating vertical velocity in the oceanic upper layers is a key issue for understanding ocean dynamics and the transport of biogeochemical elements. This paper aims to identify the physical sources of vertical velocity associated with sub-mesoscale dynamics (fronts, eddies) and mixed-layer depth (MLD) structures, using (a) an ocean adaptation of the generalized Q-vector form of the ω-equation deduced from a primitive equation system which takes into account the turbulent buoyancy and momentum fluxes and (b) an application of this diagnostic method for an ocean simulation of the Programme Océan Multidisciplinaire Méso Echelle (POMME) field experiment in the North-Eastern Atlantic. The approach indicates that w-sources can play a significant role in the ocean dynamics and strongly depend on the dynamical structure (anticyclonic eddy, front, MLD, etc.). Our results stress the important contribution of the ageostrophic forcing, even under quasi-geostrophic conditions. The turbulent w-forcing was split into two components associated with the spatial variability of (a) the buoyancy and momentum (Ekman pumping) surface fluxes and (b) the MLD. Process (b) represents the trapping of the buoyancy and momentum surface energy into the MLD structure and is identified as an atmosphere/oceanic mixed-layer coupling. The momentum-trapping process is 10 to 100 times stronger than the Ekman pumping and is at least 1,000 times stronger than the buoyancy w-sources. When this decomposition is applied to a filamentary mixed-layer structure simulated during the POMME experiment, we find that the associated vertical velocity is created by trapping the surface wind-stress energy into this structure and not by Ekman pumping.  相似文献   

On the efficient calculation of ordinary and generalized spherical harmonics   总被引：1，自引：0，他引：1  

Guy Masters  & Keith Richards-Dinger 《Geophysical Journal International》1998,135(1):307-309

Algorithms for the stable computation of generalized and ordinary spherical harmonics are presented. The algorithms are fast and have the useful property that they can compute harmonics for isolated harmonic degrees. fortran and C programs implementing these algorithms are available from the authors.  相似文献   

Challenges in the Application of Existing Process-Based Models to Predict the Effect of Climate Change on C Pools in Forest Ecosystems   总被引：1，自引：0，他引：1  

Nancy Luckai  Guy R. Larocque 《Climatic change》2002,55(1-2):39-60

Process-based models used to investigate forest ecosystem response to climate change were not necessarily developed to include the effect of carbon dioxide (CO₂) and temperature increases on physiological processes. Simulation of the impacts of climate change with such models may lead to questionable predictions. It is generally believed that significant shifts in the performance of black spruce (Picea mariana [Mill] B.S.P.) will occur under climate change. This species, which accounts for 64% of Ontario's coniferous growing stock and 80% of the annual allowable cut, represents important economic activity throughout the boreal forest region. Forest management planning requires relatively accurate productivity estimates. Thus, it is imperative to ensure that process-based models realistically predict the effect of climate change. In this study, CENTURY and FOREST-BGC models were calibrated for a productive, upland black spruce stand in northwestern Ontario. Even though both models predicted similar relative outcomes after 100 years of climate change, they disagreed on the impacts of temperature in combination with an increase in CO₂. Also, absolute amounts of carbon sequestered varied with climate change scenarios. Comparison of both models indicated that the representation of critical processes in these two forest ecosystem models is incomplete. For instance, the interactive effects of CO₂ and temperature increases on physiological processes at stand and soil levels are not well documented nor are they easily identifiable in the models. Their incorporation into models is therefore problematic. Practitioners must consequently be wary of assumptions about the inclusion of critical processes in models.  相似文献   

A new X-ray investigation of maximum microcline crystalline solutions     

Guy L. Hovis  Eric Peckins 《Contributions to Mineralogy and Petrology》1978,66(4):345-349

Refined unit-cell dimensions and molar volumes of a mircocline-low albite ion-exchange series previously studied by Waldbaum and Robie (1971) have been redetermined. Members in the sodic half of the series were found to have significantly larger b dimensions than those previously reported, resolving the major difference between the above study and that of Orville (1967). W _v, the Margules parameter related to the volume of mixing, is significantly lower (0.078 cal/bar mol) than those determined in either of the investigations above. However, it is close to values of W _v determined for several alkali feldspar series with topochemically monoclinic Al-Si distributions. Thus, the dependence of K-Na volume of mixing properties on Al-Si distribution in alkali feldspars is doubtful.  相似文献   

The flux of ²²⁶Ra from estuarine and continental shelf sediments     

Yuan-Hui Li  Guy Mathieu  Pierre Biscaye  H. James Simpson 《Earth and Planetary Science Letters》1977,37(2):237-241

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Agpaicity revisited: pattern recognition in the chemistry of nepheline syenite rocks     

Michel Dagbert  Raymond Pertsowsky  Michel David  Guy Perrault 《Geochimica et cosmochimica acta》1975,39(11):1499-1504

An attempt is made to describe global variations in the geochemistry of major and minor elements within a population of nepheline syenite samples defined by mineralogical criteria.Using correspondence analysis, a new pattern recognition procedure, it is possible to define a few trends of common behaviour which reflect most of the initial dispersion.As Al and Na participate in the scattering along the two main trends, agpaicity is recorded by them. However, the traditional form of the coefficient which measures it is proved to be unsatisfactory as variations of K are not significant.  相似文献   

Impact of Amoco Cadiz oil spill on intertidal and sublittoral meiofauna     

Guy Boucher 《Marine pollution bulletin》1980,11(4):95-101

Changes of meiofauna densities (nematodes and harpacticoid copepods) were studied in intertidal and sublittoral fine sand heavily polluted by the Amoco Cadiz oil spill. A general decrease in the nematode abundance was obvious in intertidal sand seven months after the pollution in spite of the occurrence of the natural spring bloom. No changes in the nematode and copepod densities could be detected in sublittoral sand. Comparisons with the pre-pollution data show, however, a significant decrease in the nematode diversity, mainly due to the increase of some limited dominant species after pollution.  相似文献   

Une méthode simple de sous-échantillonnage pour les prélèvements de macroinvertébrés dérivants     

Par Guy Chavanon  Michel Bournaud 《Aquatic Sciences - Research Across Boundaries》1980,42(2):322-330

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Mesures isotopiques du rubidium et du strontium et essais de mesure de l'age de la mineralisation de l'uranium du reacteur naturel fossile d'Oklo     

Robert Hagemann  Monique Lucas  Guy Nief  Etienne Roth 《Earth and Planetary Science Letters》1974,23(2):170-176

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