李玉成  崔丽芳  于洋  滕斌 《中国海洋工程》1999,(4)

Nelson pointed out that the wave breaking criterion(H/d)_b for gentle slopes(i<1/100),inwhich H is the wave height and d is the water depth at the breaking point,is smaller than that for beachslopes of i>1/100),i.e.,the value of(H/d)_b for gentle slopes may be smaller than 0.6.Goda indicatedthat the wave breaking criterion given by himself is a result based on theoretical study,so it should be alsocorrect and can be used for gentle beaches,i.e.,the value of(H/d)_b for gentle slopes may be still largerthan 0.7.By use of high order nonlinear wave theory,this problem is analyzed in this study and the reasonwhy there is a large difference between different studies is explained.Moreover,the bottom energy loss dur-ing wave propagation is considered and the critical slope for the absence of wave breaking is also analyzed.  相似文献   

    

V. N. Eremeev  S. K. Konovalov  A. S. Romanov 《Physical Oceanography》1998,9(4):259-272

Regularities of oxygen and hydrogen sulfide are examined, using the method of spatial isopycnic analysis. The contribution that ventilation of winter-time surface waters over the domes of cyclonic gyres makes to the transfer of O₂ towards the upper boundary of the constant pycnocline and to the oxicline layer is demonstrated. The paper provides spatial scales of this phenomenon and indicates the areas where the upper boundary of the anoxic layer in the Black Sea, relative to the conventional density, is located much higher compared with the rest of the sea. The suboxic zone is shown to be a specific feature of the O₂/H₂S distribution in the Black Sea waters, typical, at least, of the northern part of the basin. Analysis of the suboxic spatial variability in the vertical has been conducted. Translated by Vladimir A. Puchkin.  相似文献   

    

Harilaos Loukos  Bruce Frost  D.E. Harrison  James W. Murray 《Deep Sea Research Part II: Topical Studies in Oceanography》1997,44(9-10)

We construct a one-dimensional ecosystem model (nitrate, ammonium, phytoplankton, zooplnakton and detritus) with simple physics and biology in order to focus on the structural relations and intrinsic properties of the food web that characterizes the biological regime in the central equatorial Pacific at 140°W. When possible, data collected during the EgPac and other cruises were used to calibrate model parameters for two simulations that differ in the limiting nutrient, i.e. nitrogen or iron. Both simulations show annual results in good agreement with the data, but phytoplankton biomass and primary production show a more pronounced annual variability when iron is used as the limiting nutrient. This more realistically reproduces the variability of biological production and illustrates the greater coupling between vertical physical processes and biological production when the limiting nutrient is iron rather than nitrogen. The iron simulation also illustrates how iron supply controls primary production variability, how grazingbalances primary production and controls phytoplankton biomass, and how both iron supply and grazingcontrol primary production. These results suggest that it is not possible to capture primary production variability in the central equatorial Pacific with biological models using nitrogen as the limiting nutrient. Other indirect results of this modeling study were: (1) partitioning of export production between dissolved and particulate matter is almost equal, suggesting that the importance of DOC export may have been previously overestimated; (2) lateral export of live biomass has to be taken into account in order to balance the nitrogen budget on the equator at 140°W; and (3) preferential uptake of ammonium (i.e. nitrate uptake inhibition by ammonium) associated with high regeneration of nitrogen (low f ratio as a consequence of the food web structure imposed by iron limitation) largely accounts for the surface build-up of upwelled nitrate.  相似文献   

    

V. A. Gaisky  V. I. Zaburdaev 《Physical Oceanography》1999,9(6):467-492

A brief survey of the thirty-year history of creation and development of hydrologic probes at the Marine Hydrophysical Institute of the Ukrainian Academy of Sciences is given. We describe problems arisen before developers and analyze the principles of design of equipment, algorithmic support, software for data processing, and methodological and metrological support. The results of intercalibration and application of probes in expeditions are presented. Translated by Peter V. Malvshev and Dmitry V. Malyshev  相似文献   

    

Secor  D. H.; Houde  E. D. 《ICES Journal of Marine Science》1998,55(2):228-239

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Bergstad  O. A.; Magnusson  J. V.; Magnusson  J.; Hareide  N. -R.; Reinert  J. 《ICES Journal of Marine Science》1998,55(2):309-318

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F. R. Likht ;A. N. Derkachov ;Yu. D. Markov ;I. V. Utkin 《海洋湖沼学报（英文）》1994,12(4):372-376

The alternations of sedimentogenic and asedimentogenic belts on the continental shelf and slope are distinctive features in the East Asia marginal basins. These sedimentogenesis characteristics are conditioned by the terrigenous material supply and their distribution patterns. Facial analysis of the marginal basins reveals a number of typical facial models which are comparable with the geosynclinal and subplatform formations of the ancient basins. The paragenetical situation and simultaneous coexistence of these facial models in the modem marginal seas indicate that the ancient formation could be deposited in the same way, at the same time and even in the same basin.  相似文献   

    

Fryer  R. J.; Nicholson  M. D. 《ICES Journal of Marine Science》1993,50(2):161-168

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John Cairns ;Paul V. McCormick 《海洋湖沼学报（英文）》1993,11(3):215-228

Although microbes have traditionally been used as models for testing ecological theory, research on the organization of these communities has largely been isolated from other areas of community ecology. Early studies indicated that microbial populations can form dynamic, interacting assemblages. Observations of distributional patterns suggest that certain deterministic forces regulate community structure. It appears that protozoans are tolerant of a wide range of environmental conditions although evidence for this is largely based on gross environmental analyses. Laboratory studies have suggested the importance of negative and positive biotic interactions in determining community membership, but little field evidence for this exists. The importance of transport processes in controlling community composition is being increasingly recognized. All three types of processes likely act to regulate the colonization and successional dynamics of these communities. A simple model is presented to promote the development of synthetic field and laboratory studies to test for different determinants of community structure.  相似文献   

    

K. S. Krishna  G. Prabhakar S Murty  K. Srinivas  D. Gopala Rao 《Geo-Marine Letters》1992,12(1):7-13

The northern parts of the Prathap and Laccadive Ridge system, eastern Arabian Sea, consist of three parallel basement ridge peaks at varied depths. The topographic highs are associated with either well-developed or subdued magnetic signatures. Model studies, constrained by seismic results, determine the varied nature and depth to the top of the causative basement bodies. Similarities of the geophysical signatures of the ridges and their structural resemblance perhaps point to their common origin. Hence we propose that the Prathap Ridge complex may be a part of the Chagos-Laccadive Ridge system and formed because of the Reunion hotspot activity.  相似文献