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771.
The paper discusses the data derived from a numerical experiment on the ocean’s response (between the equator and 64°N) to
the seasonal variability of the atmospheric forcing (wind and heat flux through the ocean surface). A multilayer (7 layers)
non-linear model is used incorporating the upper mixed layer interacting with the internal layers in the regimes of entraining
and subduction. The restructuring of the layer composition, the currents and temperature variability, as well as the alternation
of the entrainment and subduction regimes are analysed.
Translated by Vladimir A. Puchkin. 相似文献
772.
An instrumented tetrapod was deployed for three weeks on the Dry Tortugas Bank at a depth of 26 m in February 1995. Bottom
roughness was dominated by shrimp burrows and worm mounds with rms roughness amplitudes ranging from 0.47 to 1.75 cm. Logarithmic
velocity profiles show apparent total roughness heights ranging from 0.30 to 1.45 cm, values consistent with observed biological
roughness. The bed sediments were weakly bound by an algal crust at the sediment–water interface. When this bound layer was
scraped away by a mooring that was accidentally dragged, sharp-crested wave-induced ripples appeared within the resulting
swath. We conclude that physically induced roughness is biologically suppressed, but if dominant, would be significantly higher
than the prevailing biological roughness. 相似文献
773.
A Stable Carbon Isotope Study of the Food-web in a Freshwater-deprived South African Estuary, with Particular Emphasis on the Ichthyofauna 总被引:1,自引:0,他引:1
The importance of macrophytes as food sources for estuarine nekton is unclear. Previous carbon isotope investigations in the macrophyte-dominated, freshwater-deprived Kariega Estuary showed that the bivalveSolen cylindraceusdid not utilize the dominant estuarine macrophytes found within the estuary as a primary food source. This finding prompted questions as to what the nekton of this estuary utilize as primary energy sources. δ13C analyses of the principal autochthonous and allochthonous primary carbon sources, as well as the dominant invertebrate and fish species, indicate that there are two main carbon pathways within the Kariega Estuary. The littoral community, which incorporates the majority of crustaceans, gobies, mullet and a sparid, utilizes δ13C enriched primary food sources namelySpartina maritima,Zosteracapensis and epiphytes. The channel fauna, which includes the zooplankton, zooplanktivorous and piscivorous fish, utilizes a primary food source depleted in δ13C, which is most likely a mixture of phytoplankton, terrestrial plant debris and C4macrophyte detritus. The C3saltmarsh macrophytesSarcocornia perennisandChenolea diffusa, as well as benthic microalgae, appear to be less important as primary food sources to the nekton of the Kariega Estuary. 相似文献
774.
对冲绳海槽1984-1990年的实测热流值,利用数字滤波方法计算,得到反映该区深部地壳热状态的区域热流值为80-160mW/m^2,用B样条函数法对其作数值模拟,计算出海槽地温场模式,并以此研究冲绳海槽海底高热流的形成机制,得出冲绳海槽热流值的区域性变化与綦中地质构造格局呈正相关,高热流是该区现代构造活动所致,其明显特征是地壳减薄,地幔上拱等结论。 相似文献
775.
This paper focuses on the numerical modelling of tsunami propagation in the open Black Sea. Two types of numerical models
are discussed: a model for the radial propagation of long waves and an evolutionary finite-difference prognostic model. Experimentally
derived numerical data on the model source of tsunamis are reported.
Translated by Vladimir A. Puchkin. 相似文献
776.
V. A. Kalmykov 《Physical Oceanography》1996,7(2):91-97
Zakharov's equation is applied to study numerically the evolution of wave amplitudes. It is demonstrated that, owing to Krasitskii's
new kernel functions, the system of surface waves remains Hamiltonian, in contrast to the former approaches used by Yuen,
Lake, and Zakharov. If surface waves are wind-generated, they grow and become stochastic. If the effect of the waves on the
wind is considered, then the wave amplitude evolution, similar to the no-wind case, continues to be recurrent.
Translated by Vladimir A. Puchkin. 相似文献
777.
A. K. Ambrosimov 《Physical Oceanography》1992,3(5):391-396
Algorithms for the compression and objective classification of low-volume samplings according to the test of their belonging to different statistical populations are given. Samplings are discriminated by thex
2 test. The distributions of the temperature patch horizontal scales in the upper ocean are analysed. It is shown that optimum empirical thresholds exist when the abstract classification mechanism goes over to the objective natural classification.Translated by Mikhail M. Trufanov. 相似文献
778.
779.
780.
ABSTRACT This study investigated the impact of pastoral land use and nutrient and fine sediment inputs on Microcoleus autumnalis and filamentous algae-dominated mats, and benthic chlorophyll-a in streams (lower North Island, New Zealand). Surveying and sampling was undertaken monthly at 61 sites spanning a wide gradient in catchment cover and environmental conditions. Two boosted regression tree models were built. The first models included pastoral land cover and five environmental variables as predictors. In the second model pastoral land cover was replaced by nutrient/sediment data. The abundance of the two mat types and chlorophyll-a increased when pastoral land cover was between 20% and 70% (model 1). Replacement of pastoral land cover by nutrient/sediment data (model 2) slightly improved the model fit for all three periphyton variables. Microcoleus autumnalis-dominant mats increased with dissolved inorganic nitrogen concentrations up to ca. 0.6?mg?L?1, and in streams with more frequent flushes. In contrast, filamentous algal-dominated mats increased with turbidity, and in streams with less frequent flushes. Chlorophyll-a generally followed the response of the dominant periphyton type. Increased knowledge on responses of specific periphyton types, rather than total biomass, to environmental variables is essential to guide effective management strategies. 相似文献