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161.
Velocity structures and transports of the Kuroshio and the Ryukyu current during fall of 2000 estimated by an inverse technique 总被引:7,自引:0,他引:7
An inverse calculation using hydrographic section data collected from October to December 2000 yields velocity structure and
transports of the Kuroshio in the Okinawa Trough region of the East China Sea (ECS) and south of central Japan, and of the
Ryukyu Current (RC) southeast of the Ryukyu Islands. The results show the Kuroshio flowing from the ECS, through the Tokara
Strait (TK), with a subsurface maximum velocity of 89 cm s−1 at 460 dbar. In a section (TI) southeast of Kyushu, a subsurface maximum velocity of 92 cm s−1 at 250 dbar is found. The results also show the RC flowing over the continental slope from the region southeast of Okinawa
(OS) to the region east of Amami-Ohshima (AE) with a subsurface maximum velocity of 67 cm s−1 at 400 dbar, before joining the Kuroshio southeast of Kyushu (TI). The volume transport around the subsurface velocity maximum
southeast of Kyushu (TI) balances well with the sum of those in TK and AE. The temperature-salinity relationships found around
these velocity cores are very similar, indicating that the same water mass is involved. These results help demonstrate the
joining of the RC with the Kuroshio southeast of Kyushu. The net volume transport of the Kuroshio south of central Japan is
estimated to be 64∼79 Sv (1 Sv ≡ 106 m3s−1), of which 27 Sv are supplied by the Kuroshio from the ECS and 13 Sv are supplied by the RC from OS. The balance (about 24∼39
Sv) is presumably supplied by the Kuroshio recirculation south of Shikoku, Japan. 相似文献
162.
Wave-induced currents may drive nearshore mixing and transport processes, including coastal pollutant dispersion, littoral drift, and long-term morphological changes through beach erosion and accretion. In this study, a numerical model is newly developed to simulate wave climate and localized currents in complicated coastal environments. The model developed is based on a quadtree grid system. The two-dimensional hydrodynamic governing equations are solved by using an explicit Adams-Bashforth finite difference scheme. Effects of wave breaking, shoaling, refraction, diffraction, wave-current interaction, set-up and set-down, turbulent mixing, bed friction, and shoreline movement are incorporated in the model. Results are presented for set-up at a beach in a flume due to normally incident waves, and longshore currents generated by oblique waves on a plane beach. 相似文献
163.
Minkyu Moon Taekyu Kim Juhan Park Sungsik Cho Daun Ryu Sanguk Suh Hyun Seok Kim 《山地科学学报》2016,13(6):1024-1034
It is difficult to scale up measurements of the sap flux density (Js) for the characterization of tree or stand transpiration (E) due to spatial variations in JS and their temporal changes. To assess spatial variations in the sap flux density of Korean pine (Pinus koraiensis) and their effects on E estimates, we measured the Js using Granier-type sensors. Within trees, the Js decreased exponentially with the radial depth, and the Js of the east aspects were higher than those of the west aspects. Among trees, there was a positive relationship between Js and the tree diameter at breast height, and this positive relationship became stronger as the transpiration demand increased. The spatial variations that caused large errors in E estimates (i.e., up to 110.8 % when radial variation was ignored) had varied systematically with environmental factors systematic characteristics in relation to environmental factors. However, changes in these variations did not generate substantial errors in the E estimates. For our study periods, the differences in the daily E (E D) calculated by ignoring radial, azimuthal and tree-to-tree variations and the measured E D were fairly constant, especially when the daily vapor pressure deficit (D_D) was higher than 0.6 kPa. These results imply that the effect of spatial variations changes on sap flow can be a minor source of error compared with spatial variations (radial, azimuthal and tree-to-tree variations) when considering E estimates. 相似文献
164.
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166.
Lithospheric mantle signatures as revealed by zircon Hf isotopes of Late Triassic post‐collisional plutons from the central Korean peninsula,and their tectonic implications 下载免费PDF全文
Chang‐Sik Cheong Namhoon Kim Hui Je Jo Moonsup Cho Sung Hi Choi Hongying Zhou Jian‐zhen Geng 《地学学报》2015,27(2):97-105
The Mesozoic tectonic architecture of the Korean peninsula is largely governed by the continental collision between the North and South China blocks. Zircon Hf isotopic compositions presented in this study and whole‐rock geochemical and Sr‐Nd isotope data in the literature collectively suggest that the lithophile‐elements‐enriched signature of the Late Triassic post‐collisional plutons from the Gyeonggi massif in central Korea is a primary feature inherited from the metasomatized mantle lithosphere. Highly negative zircon εHf (t) values (?23 to ?19) of plutons from the middle and eastern parts of the massif indicate an ancient metasomatism of their mantle source. Distinctly higher zircon εHf (t) values (?15 to ?12) from the southwestern plutons are ascribed to a contribution from an accreted component of the South China‐like block. The involvement of asthenospheric mantle is not recognized in zircons from either group. The implications of these isotopic features are discussed in the context of Mesozoic collisional tectonics. 相似文献
167.
168.
Jason Timmons Young Min Cho Timothy Townsend Nicole Berge Debra Reinhart 《Geotechnical and Geological Engineering》2012,30(1):95-105
Commercially available hydraulic total overburden pressure cells were installed in the sand drainage layer of a municipal
solid waste landfill and monitored for a period of 3,110 days. Both overburden pressure and temperature were measured in the
landfill as it was filled with compacted waste. Topographic surveys of the landfill were periodically conducted to measure
the height of waste above the pressure cells and to determine the landfill volume for indirect unit weight estimation. The
average ratio of measured to theoretically-predicted overburden pressure was 0.6, indicating that on average the pressure
cells underestimated the load. The overburden pressure measured near the toe of the landfill was greater than that predicted
by the unit weight of landfilled material, while most of the overburden pressure measurements further inside the landfill
were less than predicted. Several possible causes for this phenomenon are discussed, including the uneven distribution of
forces resulting from the heterogeneous nature of the waste and cover soil. The earth pressure cells were capable of detecting
the placement of individual waste lifts. 相似文献
169.
Performance-based design demands accurate prediction of soil deformation under a working load condition. The nonlinear stress–strain behavior needs to be analyzed quantitatively to advance the understanding of complex soil behavior in the pre-failure condition. The singular value decomposition technique is introduced to quantitatively analyze the compliance matrix representing the strain response envelope (SRE). The rotation of the ellipse of the SRE relates to the anisotropic response of the soil deformation. The off-centered SRE provides evidence of the kinematic hardening plasticity. Quantitative data on the movement of SREs provide us with crucial information to investigate the effect of stress history and the evolution of stiffness anisotropy in soil deformation. 相似文献
170.
Kim Y Cho S Kang HD Kim W Lee HR Doh SH Kim K Yun SG Kim DS Jeong GY 《Marine pollution bulletin》2006,52(6):659-665
The mineralogical effect on the (137)Cs reaction with marine sediment has not been systematically studied yet, even though illite has been known to adsorb Cs preferentially on its frayed edge sites in a low Cs concentration. Ninety-three marine sediment samples were collected near Yangnam, Korea for quantitative X-ray-diffraction (XRD), gamma-ray, and total organic carbon (TOC) analysis. Illite content was in the range of 0-23 wt.% and those of (137)Cs and TOC were minimum detectable activity (MDA) approximately 7.19 Bq/kg-dry and approximately 3.32%, respectively. The illite content in the marine sediment showed a good relationship with the (137)Cs content (R(2)=0.69), but with an increase in the illite content, the relationship became less linear. This trend can be clearly shown in two groups of samples with different size fractions (< and >5Mdvarphi). For the samples of larger particle sizes (low contents of illite), the relationship is linear, but for the samples of the smaller particle sizes (high illite content) it is less linear with a decreased slope, indicating that increase in illite content does not significantly contribute to the fixation of (137)Cs in marine sediment. Rather, the TOC has a more linear relationship with (137)Cs content with no slope change in all particle size ranges. This may indicate that humic materials in marine sediment block the access of (137)Cs to the frayed edge site and reduces the adsorption of (137)Cs on illite and that the organic materials in marine sediment play more important roles in adsorbing Cs than illite. 相似文献