Hydrostatic and non-hydrostatic simulations of moist convection: Review and further study     

T. Kato 《Meteorology and Atmospheric Physics》1997,63(1-2):39-51

Summary Quantitatively comparative experiments of moist convection using hydrostatic and non-hydrostatic models are reviewed and a further study is made of the suitability of the hydrostatic approximation for a high-resolution model when the grid size falls below 20 km. Idealized moist convection is treated, and then the torrential rain that occurred on 6 August 1993 in Kagoshima, southern Kyushu, Japan is simulated by each model. An explicit warm-rain process predicting cloud water and rainwater and the scheme of moist convective adjustment are individually or conjunctively employed in the model. The effect of hydrostatic water loading is also examined in detall.For the simulation of idealized convection, the hydrostatic simulation tends to overestimate and overexpand precipitation in comparison with the non-hydrostatic counterpart, and the drag effect of hydrostatic water loading is more significant for convective development than the non-hydrostatic effect. In the 20-km simulations, however, the hydrostatic simulation with hydrostatic water loading produces results that are comparable to the nonhydrostatic counterpart. For the simulation with real data, the comparative results well correspond to those of idealized convection. Furthermore, the 5 km hydrostatic simulation overestimates total precipitation more than that of dealized convection. On the basis of these results, when developing 1020 km numerical weather prediction (NWP) models, hydrostatic water loading should be evaluated in preference to adopting non-hydrostatic models, and a non-hydrostatic model with hydrostatic water loading is thought to be recommendable for a high-resolution NWP model.With 7 Figures  相似文献   

Monte Carlo Study of Quantitative Electron Probe Microanalysis of Monazite with a Coating Film: Comparison of 25 nm Carbon and 10 nm Gold at E₀= 15 and 25 keV     

Takenori Kato 《Geostandards and Geoanalytical Research》2007,31(2):89-94

Carbon (25–30 nm in thickness) is the most common coating material used in the electron probe microanalysis (EPMA) of geological samples. A gold coating is also used in special cases to reduce the surface damage by electron bombardment. Monte Carlo simulations have been performed for monazite with a 25 nm carbon and a 10 nm gold coating to understand the effect of a coating film in quantitative EPMA at E₀= 15 keV and 25 keV. Simulations showed that carbon-coated monazite gave the same depth distribution of the generated X-rays in the monazite as uncoated monazite, whilst gold-coated monazite gave a distorted depth distribution. A 10 nm gold coating was 1.06 (15 keV) and 1.05 (25 keV) times higher in k -ratio between monazite and pure thorium than a 25 nm carbon coating at an X-ray take-off angle of 40 degrees. Thus, a 10 nm gold coating is a possible factor contributing to inaccuracy in quantitative EPMA of monazite, while a 25 nm carbon coating does not have a significant effect.  相似文献   

东亚夏季一个与鄂霍次克海阻高建立及副高北上相关的遥相关类型     

王亚非 《大气科学进展》2003,20(2):237-244

研究了鄂霍次克海阻高及西太平洋副热带高压的关系，解释了当鄂霍次克海阻高活跃时副热带高压北上缓慢的原因。具体如下(1)通过对鄂霍次克海阻高指数和500hPa高度的相关分析发现，夏季东亚附近容易出现一个类似偶板子的遥相关类型；(2)这个遥相关类型与鄂霍次克海阻高发展时产生的从鄂霍次克海经日本东部海面到副热带方面传播的波列紧密相关；(3)伴随鄂霍次克海高压的发展，此波列的传播形成一个以日本东部海面为中心的气旋式环流，起着削弱副高北缘的重要作用。这个作用可以部分解释为什么1998年夏季副高会非常偏南。  相似文献   

Kurosegawa Terrane as a Transform Fault Zone in Southwest Japan     

Kiyoshi Kato  Yukiyasu Saka 《Gondwana Research》2003,6(4):669-686

The Kurosegawa Terrane intervening in the Jurassic-Early Cretaceous accretionary complexes along the Pacific side of the SW Japanese Islands is a serpentinite mélange zone. It contains various kinds of exotic rocks, for example, granitoids, metamorphic rocks, Siluro-Devonian deposits and is intimately associated with Cretaceous forearc basin deposits. The terrane is regarded as a key to clarify the Mesozoic geotectonic history of the western circum-Pacific orogenic belts. The current model, in which the formation of the Kurosegawa Terrane is attributed to nappe-movement or sinistral strike-slip faulting, can explain neither the mode of occurrence of the Kurosegawa Terrane we observed in eastern Kii Peninsula nor the array of evidence obtained from the Ryoke Terrane southward to the Shimanto Terrane. We suggest a new hypothesis in which the Kurosegawa Terrane was a transform fault zone that originated because of oceanic ridge subduction along the southern margin of the coeval accretionary prism (Butsuzo T.L.) in the late Early Cretaceous. Our model is mainly based on new geological evidence from the Kurosegawa Terrane in eastern Kii Peninsula where the deepest erosion level is exposed due to neotectonic uplift.  相似文献   

Geochemical Features of Vein Anhydrite from the Kakkonda Geothermal System, Northeast Japan     

Munetake Sasaki    Koichiro Fujimoto    Hitoshi Tsukamoto    Takayuki Sawaki    Masakatsu Sasada    Masanori Kurosawa  Masahiko Yagi    Yoichi Muramatsu    Osamu Kato  +  Ryo Komatsu  +  Kaichiro Kasai  + Nobuo Doi+ 《Resource Geology》2003,53(2):127-142

Abstract. Cathodoluminescence (CL) color, rare earth element (REE) content, sulfur and oxygen isotopes and fluid inclusions of anhydrite, which frequently filled in hydrothermal veins in the Kakkonda geothermal system, were investigated to elucidate the spatial, temporal and genetical evolution of fluids in the deep reservoir. The anhydrite samples studied are classified into four types based on CL colors and REE contents: type-N (no color), type-G (green color), type-T (tan color) and type-S (tan color with a high REE content). In the shallow reservoir, only type-N anhydrite is observed. In the deep reservoir, type-G anhydrite occurs in vertical veins whereas type-T and -N in lateral veins. Type-S anhydrite occurs in the heat-source Kakkonda Granite. The CL textures revealed that type-G anhydrite deposited earlier than type-T in the deep reservoir, implying that fracture system was changed from predominantly vertical to lateral.
Studies of fluid inclusions and δ³⁴S and δ¹⁸O values of the samples indicate that type-N anhydrite deposited from diluted fluids derived from meteoric water, whereas type-G, -T and -S anhydrites deposited from magmatic brines derived from the Kakkonda Granite with the exception of some of type-G with recrystallization texture and no primary fluid inclusion, which deposited from fossil seawater preserved in the sedimentary rocks. Type-G, -T and -S anhydrites exhibit remarkably different chondrite-normalized REE patterns with a positive Eu anomaly, with a convex shape (peak at Sm or Eu) and with a negative Eu anomaly, respectively. The difference in the patterns might result from the different extent of hydrothermal alteration of the reservoir rocks and contribution of the magmatic fluids.  相似文献   

Aseismic faulting following the 1973 Nemuro-oki earthquake,Hokkaido, Japan (a retrospective study)     

Keichi Kasahara  Teruyuki Kato 《Pure and Applied Geophysics》1980,119(2):392-403

Tidal records at Hanasaki, southeastern Hokkaido, are analysed to clarify the post-seismic crustal vertical movement in the 1973 Nemuro-oki, Japan, earthquake. The result shows that the post-seismic uplift, as speculated byKasahara (1975), terminated in late 1975 and reverted to the previous rate of rapid subsidence of about 1 cm/yr. Ceasing of the post-seismic uplift, which occurred much earlier than previously speculated, could be explained by supplementary mechanisms, such as frictional resistance against creeping at the fault surface. This unexpected mode of movement, however, raises a new question about the accumulation of tectonic movements in this district. Since the subsidence rate extrapolated from geomorphological data for the past several thousand years is almost one order of magnitude lower than the recent rate as mentioned above, we have to provide some alternative explanation for the discrepancy between the two rates. In other words, simple repetition of co-, post- and inter-seismic movements in seismic cycles due to plate subduction, must be modified in this district. Several possible modifications to the subduction process are suggested, and a brief discussion of vertical movements expected in each case is given.  相似文献   

Development of real-time pseudo dynamic testing     

Masayoshi Nakashima  Hiroto Kato  Eiji Takaoka 《地震工程与结构动力学》1992,21(1):79-92

This paper presents a study for the development of a system capable of performing real-time pseudo dynamic testing. The system combines the basics of the pseudo dynamic test with a dynamic actuator, a digital displacement transducer and a digital servo-mechanism. The digital servo-mechanism has been introduced to ensure accurate displacement and velocity control, in which digital feedback control with a time interval of 2 msec has been performed continuously during actuator motion. Using the system, pseudo dynamic tests under sinusoidal and earthquake ground motion are carried out for a structure having a viscous damper, demonstrating that a perfectly real-time pseudo dynamic test can be achieved by incorporating the modified central difference method into an extra buffer operation of the digital servo-mechanism. The responses solved by the pseudo dynamic tests are compared with the responses of the test structure as well as those obtained from post-numerical analysis, and it is found that the real-time pseudo dynamic test conducted in this study is accurate.  相似文献   

Pb and Cs in sediments from Sagami Bay, Japan: sedimentation rates and inventories     

Y Kato  H KitazatoM Shimanaga  T NakatsukaY Shirayama  T Masuzawa 《Progress in Oceanography》2003,57(1):77-95

Profiles of the radioisotopes ²¹⁰Pb and ¹³⁷Cs were determined in 15 sediment cores collected from Sagami Bay, Japan. The activities of ²¹⁰Pb_ex (unsupported) in core top sediments increased with water depth from 25 dpm g⁻¹ on the upper continental slope off the mouth of Tokyo Bay to an average of 283 dpm g⁻¹ at the deep-sea station SB. The high ²¹⁰Pb trapping efficiency of settling particles expected from the results of the sediment trap experiment near the SB site suggests that effective ²¹⁰Pb enrichment in surface sediments may occur during resuspension and lateral transportation of particles via the benthic nepheloid layer on the continental slope. In several cores, ¹³⁷Cs profiles showed an increase, a distinct peak, and then a decrease to an undetectable level downcore. These profiles can be compared with the temporal change of bomb-produced ¹³⁷Cs fallout.The mean sedimentation rates estimated by the ²¹⁰Pb_ex inventory method, rather than using ²¹⁰Pb_ex profiles, ranged from 0.06 g cm⁻² y⁻¹ to 0.14 g cm⁻² y⁻¹. The average value of the rates in SB cores was calculated to be 0.11 g cm⁻² y⁻¹, which was similar to that calculated under the assumption that the age of the ¹³⁷Cs peak corresponds to its maximum fallout year in 1963.Although ¹³⁷Cs inventories represented one tenth of the anthropogenic fallout of ¹³⁷Cs until 1997, they correlated with the increase in ²¹⁰Pb_ex inventory. This suggests that the scavenging of refractory ¹³⁷Cs as well as ²¹⁰Pb by settling particles in the water column can lead to the formation of a time marker layer even in deep-sea sediment core, such as at the SB site.  相似文献   

Hg, Zn and Cu levels in the muscle and liver of tiger sharks (Galeocerdo cuvier) from the coast of Ishigaki Island, Japan: relationship between metal concentrations and body length     

Endo T  Hisamichi Y  Haraguchi K  Kato Y  Ohta C  Koga N 《Marine pollution bulletin》2008,56(10):1774-1780

We analyzed Hg, Zn and Cu concentrations in the liver and muscle of tiger sharks (Galeocerdo cuvier) from the coast of Ishigaki Island, Japan. The Hg concentration in the muscle increased proportionally with body length in the tiger sharks, whereas that in the liver increased rapidly after maturity (defined by a length of over 2.7 m). Muscle Hg levels were higher than liver concentrations in immature sharks, with the inverse trend observed in mature sharks. Notably, the Zn and Cu concentrations in the liver tended to decrease with increasing body length. This rapid increase in hepatic Hg concentration concurrent with the onset of maturity in sharks may result from the continuous intake of Hg via food and the slower growth of mature sharks. The high concentrations of the essential metals Zn and Cu in immature sharks may be explained by the physiological demands related to rapid growth.  相似文献   

Geochemical constraints on the origin of bimodal magmatism at the Okinawa Trough, an incipient back-arc basin   总被引：23，自引：0，他引：23  

Ryuichi Shinjo  Yuzo Kato   《Lithos》2000,54(3-4):117-137

The magmatism at the axial zone of the middle Okinawa Trough, a young continental back-arc basin, comprises a bimodal basaltic–rhyolitic suite, accompanied by minor intermediate rocks. We report major and trace element and Sr–Nd isotopic data for the intermediate to silicic suites, to provide constraints on their petrogenesis. The rhyolites, recovered as lava and pumice, fall into three geochemical groups (type 1, 2, and 3 rhyolites). Type 1 rhyolites have ⁸⁷Sr/⁸⁶Sr (0.7040–0.7042) and ¹⁴³Nd/¹⁴⁴Nd (0.5128–0.5129) identical to those of associated basalts, and are characterized by highly fractionated REE patterns. Petrogenesis of type 1 rhyolites is explicable in terms of fractional crystallization of the associated basalt. In contrast, type 2 rhyolites and andesite have slightly higher ⁸⁷Sr/⁸⁶Sr (0.7044–0.7047) but similar ¹⁴³Nd/¹⁴⁴Nd (0.5128) compared to those of the basalts. The compositions of type 2 rhyolite and andesite can be explained by assimilation and fractional crystallization (AFC) processes of the basalt magma; quantitative analysis suggests assimilation/fractional crystallization (M_a/M_c) ratios of ≤0.05. Hybrid andesite generated by mixing of evolved basalt and type 1 rhyolite is also present. We emphasize that mechanical extension in this part of the Okinawa Trough involves gabbroic lower crust that resulted from fractionation of mantle-derived basaltic magmas. Type 3 rhyolite occurs only as pumice, which makes its derivation questionable. This rhyolite has major and trace element compositions and Sr–Nd isotopic ratios, which suggests that it may be derived from volcanic activity on the southern Ryukyu volcanic front, and arrived in the Okinawa Trough by drifting on the Kuroshio Current.  相似文献