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911.
Mikitoshi Hirabara Hiroshi Ishizaki Goro Yamanaka Hiroyuki Tsujino Ichiro Ishikawa 《Journal of Oceanography》2010,66(5):633-647
An analysis is presented of snapshot data (eastward and northward velocity components: u and v; tracer such as potential temperature: τ) from an eddy-resolving (Rgrid: 1/12°) ocean model experiment, in order to explore a method for improving eddy-permitting
model performance. Horizontal 3 × 3 R-grid averages give the eddy-permitting grid (P-grid: 1/4°) variables: 〈u〉, 〈v〉, and 〈τ〉, where 〈〉 denotes the spatial P-grid scale average. The difference between the horizontal tracer flux across the boundary
face of a P-grid and that across the corresponding faces of R-grids is estimated as F2E. It is found that the correlations among the gradients of u, v, and τ give a good approximation F2C to the estimated flux F2E. The approximated flux is a function of these gradients and the grid size. A method is presented for implementing the F2C for density to an eddying ocean model as an additional advection. Practical experiments were conducted with a realistic configuration.
It is shown that the zonal mean isotherms in the Kuroshio extension region are more flattened in the run using the proposed
method than in another run using the conventional horizontal biharmonic operator, suggesting that the additional flux correction
leads to an enhancement of sub-basin scale mixing. 相似文献
912.
Hiroshi Adachi Hiroya Yamano Toshihiro Miyajima Masahiro Nakaoka 《Journal of Oceanography》2010,66(6):865-872
This article describes a simple, quick, and inexpensive procedure for coring unconsolidated sediment in shallow water (<30
m from water surface). A ∼1 m core is retrieved by a PVC pipe that penetrates sediment in response to the percussive force
of a hand-operated hammering tool or air hammer. After retrieving the first core segment, a casing is inserted to allow access
to deeper sediment layers. Pulverized sediment produced during coring is removed by a water-lubrication system that is powered
by an electric pump attached to a generator. Using this system and procedure, five 2-m-long cores with excellent quality were
retrieved. 相似文献
913.
Cédric Magen Gwénaëlle Chaillou Sean A. Crowe Alfonso Mucci Bjørn Sundby Aiguo Gao Ryosuke Makabe Hiroshi Sasaki 《Estuarine, Coastal and Shelf Science》2010
To establish the relative importance of terrigenous and marine organic matter in the southern Beaufort Sea, we measured the concentrations and the stable isotopic compositions of organic carbon and total nitrogen in sediments and in settling particles intercepted by sediment traps. The organic carbon content of surface sediment in the Chukchi and southern Beaufort Seas ranged from 0.6 to 1.6% dry wt., without a clear geographical pattern. The CORG:NTOT ratio ranged from 7.0 to 10.4 and did not vary significantly downcore at any one station. Values of δ13CORG and δ15NTOT in the sediment samples were strongly correlated, with the highest values, indicative of a more marine contribution, in the Amundsen Gulf. In contrast, the organic matter content, elemental (CORG:NTOT ratio) and isotopic (δ13CORG and δ15NTOT) composition of the settling particles was different from and much more variable than in the bottom sediments. The isotopic signature of organic matter in the Beaufort Sea is well constrained by three distinct end-members: a labile marine component produced in situ by planktonic organisms, a refractory marine component, the end product of respiration and diagenesis, and a refractory terrigenous component. A three-component mixing model explains the scatter observed in the stable isotope signatures of the sediment trap samples and accommodates an apparent two-component mixing model of the organic matter in sediments. The suspended matter in the water column contains organic matter varying from essentially labile and marine to mostly refractory and terrigenous. As it settles through the water column, the labile marine organic matter is degraded, and its original stable isotope signature changes towards the signature of the marine refractory component. This process continues in the bottom sediment with the result that the sedimentary organic matter becomes dominated by the refractory terrigenous and marine components. 相似文献