Submesoscale features and their interaction with fronts and internal tides in a high-resolution coupled atmosphere-ocean-wave model of the Bay of Bengal   总被引：1，自引：1，他引：0  

Tommy G. Jensen  Igor Shulman  Hemantha W. Wijesekera  Stephanie Anderson  Sherwin Ladner 《Ocean Dynamics》2018,68(3):391-410

Large freshwater fluxes into the Bay of Bengal by rainfall and river discharges result in strong salinity fronts in the bay. In this study, a high-resolution coupled atmosphere-ocean-wave model with comprehensive physics is used to model the weather, ocean circulation, and wave field in the Bay of Bengal. Our objective is to explore the submesoscale activity that occurs in a realistic coupled model that resolves mesoscales and allows part of the submesoscale field. Horizontal resolution in the atmosphere varies from 2 to 6 km and is 13 km for surface waves, while the ocean model is submesoscale permitting with resolutions as high as 1.5 km and a vertical resolution of 0.5 m in the upper 10 m. In this paper, three different cases of oceanic submesoscale features are discussed. In the first case, heavy rainfall and intense downdrafts produced by atmospheric convection are found to force submesoscale currents, temperature, and salinity anomalies in the oceanic mixed layer and impact the mesoscale flow. In a second case, strong solitary-like waves are generated by semidiurnal tides in the Andaman Sea and interact with mesoscale flows and fronts and affect submesoscale features generated along fronts. A third source of submesoscale variability is found further north in the Bay of Bengal where river outflows help maintain strong salinity gradients throughout the year. For that case, a comparison with satellite observations of sea surface height anomalies, sea surface temperature, and chlorophyll shows that the model captures the observed mesoscale eddy features of the flow field, but in addition, submesoscale upwelling and downwelling patterns associated with ageostrophic secondary circulations along density fronts are also captured by the model.  相似文献   

Characterizing a Sewage Plume Using the 3H-3He Dating Technique     

Stephanie Dunkle Shapiro  Denis LeBlanc  Peter Schlosser  rea Ludin 《Ground water》1999,37(6):861-878

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Detailed models of the binary pulsars J1141−6545 and B2303+46     

Ross P. Church  Stephanie J. Bush  Christopher A. Tout  Melvyn B. Davies 《Monthly notices of the Royal Astronomical Society》2006,372(2):715-727

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Ferric iron in tourmaline     

Stephanie M. Mattson  George R. Rossman 《Physics and Chemistry of Minerals》1984,11(5):225-234

Red Fe³⁺-rich and black Fe³⁺, Fe²⁺-rich tourmalines have been studied by optical and Mössbauer spectroscopies to determine the optical characteristics of Fe³⁺ in tourmaline. Prominent optical absorption features at 485 and 540 nm are assigned to transitions of multiple exchange-coupled Fe³⁺ pairs in several site combinations. These transitions are more intense than those of isolated Fe³⁺ and are polarized along the vector between the interacting ions, thus permitting site assignments. The 485 nm band occurs at an unusually low energy for Fe³⁺ in silicate minerals. Similar behavior has been observed in the spectrum of coalingite, Mg₁₀Fe ₂ ³⁺ (OH)₂₄CO₃·2H₂O, in which Fe³⁺ occurs in related pairs in edge-shared sheets. These lower energies are proposed to result from magnetic exchange in edge-shared geometries. Antiferromagnetic exchange has been confirmed by a variable temperature magnetic susceptibility study of a Kenyan dravite with 3.36 wt percent Fe. The Mössbauer spectrum of this sample is unusual in that it shows a pronounced decrease in width of component peaks from 298 K to 5 K.  相似文献   

Fe2+-Fe3+ interactions in tourmaline     

Stephanie M. Mattson  George R. Rossman 《Physics and Chemistry of Minerals》1987,14(2):163-171

The color and spectroscopic properties of ironbearing tourmalines (elbaite, dravite, uvite, schorl) do not vary smoothly with iron concentration. Such behavior has often been ascribed to intervalence charge transfer between Fe²⁺ and Fe³⁺ which produces a new, intense absorption band in the visible portion of the spectrum. In the case of tourmaline, an entirely different manifestation of the interaction between Fe²⁺ and Fe³⁺ occurs in which the Fe²⁺ bands are intensified without an intense, new absorption band. At low iron concentrations, the intensity of light absorption from Fe²⁺ is about the same for E∥c and E⊥c polarizations, but at high iron concentrations, the intensity of the E⊥c polarization increases more than ten times as much as E∥c. This difference is related to intensification of Fe²⁺ absorption by adjacent Fe³⁺. Extrapolations indicate that pairs of Fe²⁺-Fe³⁺ have Fe²⁺ absorption intensity ～200 times as great as isolated Fe²⁺. Enhanced Fe²⁺ absorption bands are recognized in tourmaline by their intensity increase at 78 K of up to 50%. Enhancement of Fe²⁺ absorption intensity provides a severe limitration on the accuracy of determinations of Fe²⁺ concentration and site occupancy by optical spectroscopic methods. Details of the assignment of tourmaline spectra in the optical region are reconsidered.  相似文献   

New satellite derived sea ice motion tracks Arctic contamination     

W. J. Emery  C. Fowler  J. Maslanik  Stephanie Pfirman 《Marine pollution bulletin》1997,35(7-12):345-352

Sea ice has been reported to contain contaminants from atmospheric and nearshore sediment resuspension processes. In this study successive passive microwave images from the 85.5 GHz channels on the Special Sensor Microwave Imager (SSM/I) were merged with drifting buoy trajectories from the International Arctic Buoy Program to compute Arctic sea ice motion in the Russian Arctic between 1988 and 1994. Smooth daily motion fields were averaged to prepare monthly maps making it possible to compute the 7-year mean and mean seasonal ice motions as well as principal components of directional variability of sea ice motion for the entire Arctic and surrounding basins. These mean motion vectors are used to simulate the advection of contaminants deposited on or contained within the sea ice and subsequently transported into the Arctic Ocean in order to predict both their mean trajectories and dispersal over time. The 3-year displacement of contaminants from a number of Russian sites and one American site display various behaviours from substantial displacement and dispersal to almost no movement. This computational procedure could be applied to realtime SSM/I and ice buoy data to provide detailed, all-weather, vector motion maps of ice circulation to predict the path and dispersal of any new substance introduced to the sea ice and transported into the Arctic or Antarctic ocean surface.  相似文献   

The Impact of Sediment-Laden Snow and Sea Ice in the Arctic on Climate     

Tamara Shapiro Ledley  Stephanie Pfirman 《Climatic change》1997,37(4):641-664

Sea ice formed over shallow Arctic shelves often entrains sediments resuspended from the sea floor. Some of this sediment-laden ice advects offshore into the Transpolar Drift Stream and the Beaufort Gyre of the Arctic Basin. Through the processes of seasonal melting at the top surface, and the freezing of clean ice on the bottom surface, these sediments tend, over time, to concentrate at the top of the ice where they can affect the surface albedo, and thus the absorbed solar radiation, when the ice is snow free. Similarly, wind-blown dust can reduce the albedo of snow. The question that is posed by this study is what is the impact of these sediments on the seasonal variation of sea ice, and how does it then affect climate? Experiments were conducted with a coupled energy balance climate-thermodynamic sea ice model to examine the impact of including sediments in the sea ice alone and in the sea ice and overlying snow. The focus of these experiments was the impact of the radiative and not the thermal properties of the sediments. The results suggest that if sea ice contains a significant amount of sediments which are covered by clean snow, there is only a small impact on the climate system. However, if the snow also contains significant sediments the impact on sea ice thickness and surface air temperature is much more significant.  相似文献   

Detecting sampling outliers and sampling heterogeneity when catch-at-length is estimated using the ratio estimator     

Vigneau  Joel; Mahevas  Stephanie 《ICES Journal of Marine Science》2007,64(5):1028-1032

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On the solution of the carbonate chemistry system in ocean biogeochemistry models   总被引：3，自引：0，他引：3  

Michael J. Follows  Taka Ito  Stephanie Dutkiewicz   《Ocean Modelling》2006,12(3-4):290-301

We present a simplified method for solving the local equilibrium carbonate chemistry in numerical ocean biogeochemistry models. Compared to the methods typically used, the scheme is fast, efficient and compact. The accuracy of the solution is dictated by the number of species retained in the expression for alkalinity and there is almost no computational penalty for retaining minor contributions. We demonstrate that this scheme accurately reproduces the results of the commonly used method in the context of a three-dimensional global ocean carbon cycle model. Using this model we also show that neglecting the regional variations in surface dissolved inorganic phosphorus and silicic acid concentrations can lead to significant systematic bias in regional estimates of air–sea carbon fluxes using such models.  相似文献   

Creation of an artificial carbonate sand     

Khaled Grine  Stephanie Glendinning 《Geotechnical and Geological Engineering》2007,25(4):441-448

This paper deals with the efficacy of creating artificial carbonate sand from crushed chalk to model the natural carbonate sand. Direct drained shear using 100 mm shear box and compressibility tests using 150 mm Rowe cell have been performed on artificial carbonate sand in order to determine the shear stress-strain and compressibility characteristics of the artificial material. These are compared with data from natural carbonate sands given in the literature. The results obtained demonstrate that shear stress-strain and compressibility characteristics of the artificial material closely mirror that of natural carbonate soils. The artificial carbonate sand shows generally similar characteristics, which are in the range of the natural carbonate material.  相似文献