Metabolism and chemical composition of mesopelagic ostracods in the western North Pacific Ocean     

Kaeriyama  Hideki; Ikeda  Tsutomu 《ICES Journal of Marine Science》2004,61(4):535-541

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In situ measurement of incoming solar radiation by voluntary ships in the western Pacific     

Naoto Iwasaka  Susumu Kuwashima  Hirotaka Otobe  Kimio Hanawa  Hideki Hagiwara  Ruri Suzuki 《Journal of Oceanography》1994,50(6):713-723

We have been performingin situ measurement of downward short wave radiation (solar radiation) in the western Pacific Ocean in cooperation with voluntary ships since autumn 1990 in order to obtain much more precise knowledge of downward short wave radiation at the sea's surface than before. Preliminary result of the observation from autumn 1990 through spring 1992 is shown in this paper. The comparison of observed daily mean downward short wave radiation with that estimated from observed cloudiness by using Reed (1977) formula is also presented to show the necessity ofin situ measurement in the study of the downward short wave radiation at the sea's surface.  相似文献   

The Kyucho in the Bungo Channel,Japan —Periodic intrusion of oceanic warm water     

Hidetaka Takeoka  Hideki Akiyama  Takahiro Kikuchi 《Journal of Oceanography》1993,49(4):369-382

Kyucho is a sudden and swift current which is usually accompanied by rise of water temperature. Several features of the Kyucho in the Bungo Channel, Japan, are presented through field observations. The Kyucho in the Bungo Channel is an intrusion of warm water from the Pacific Ocean into the eastern half of the Bungo Channel, being driven gravitationally and advancing along the eastern coast of the channel. The Kyucho occurs usually in summer and seldom occurs in winter. It occurs at neap tides showing the prominent spring-neap periodicity. The modulation of the vertical mixing intensity associated with the variations of tidal current, wind and surface heating etc. is supposed to be a main cause of springneap and seasonal periodicities.  相似文献   

The ocean/continent transition along a profile through the Lofoten basin,Northern Norway     

Andreas Goldschmidt-Rokita  Knut J. F. Hansch  Hans B. Hirschleber  Takaya Iwasaki  Toshihiko Kanazawa  Hideki Shimamura  Markvard A. Sellevoll 《Marine Geophysical Researches》1994,16(3):201-224

The Cenozoic margins of the Norwegian-Greenland Sea offer ideal conditions for passive margin studies. A series of structural elements, first observed on these margins, led to the concept of volcanic passive margins. Questions still remain about the development of such features and the location of the boundary between oceanic and continental crust. Despite the thin sediment cover of the margins, seismic reflection data are not able to image the deeper structures due to the occurrence of igneous rocks at shallow depth.This paper presents a 320-km long profile perpendicular to the strike of the main structural units of the Lofoten Margin in Northern Norway. A geological model is proposed, based on observations made with ocean bottom seismographs, which recorded seismic refraction data and wide angle reflections, along with a seismic reflection profile covering the same area. Ray-tracing was used to calculate a geophysical model from the shelf area into the Lofoten basin. The structures typical of a volcanic passive margin were found, showing that the Lofoten Margin was influenced by increased volcanic activity during its evolution. The ocean/continent transition is located in a 30-km wide zone landwards of the Vøring Plateau escarpment.The whole margin is underlain by a possibly underplated, high velocity layer. Evidence for a pre-rift sediment basin landwards of the escarpment, overlain by basalt flows, was seen. These structural features, related to extensive volcanism on the Lofoten Margin, are not as distinct as further south along the Norwegian Margin. Viewed in the light of the hot-spot theory of White and McKenzie (1989) the Lofoten Margin can be interpreted as a transitional type between volcanic and non-volcanic passive margin.  相似文献   

Precise Positioning of Ocean Bottom Seismometer by Using Acoustic Transponder and CTD   总被引：1，自引：0，他引：1  

Shiobara  Hajime  Nakanishi  Ayako  Shimamura  Hideki  Mjelde  Rolf  Kanazawa  Toshihiko  Berg  Eivind W. 《Marine Geophysical Researches》1997,19(3):199-209

We have obtained precise estimates of the position of Ocean Bottom Seismometers (OBS) on the sea bottom. Such estimates are usually uncertain due to their free falling deployment. This uncertainty is small enough, or is correctable, with OBS spacing of more than 10 km usually employed in crustal studies. But, for example, if the spacing is only 200 m for OBS reflection studies, estimates of the position with an accuracy of the order of 10 m or more is required.The determination was carried out with the slant range data, ship position data and a 1D acoustic velocity structure calculated from Conductivity–Temperature–Depth (CTD) data, if they are available. The slant range data were obtained by an acoustic transponder system designed for the sinker releasing of the OBS or travel time data of direct water wave arrivals by airgun shooting. The ship position data was obtained by a single GPS or DGPS. The method of calculation was similar to those used for earthquake hypocenter determination.The results indicate that the accuracy of determined OBS positions is enough for present OBS experiments, which becomes order of 1 m by using the DGPS and of less than 10 m by using the single GPS, if we measure the distance from several positions at the sea surface by using a transponder system which is not designed for the precise ranging. The geometry of calling positions is most important to determine the OBS position, even if we use the data with larger error, such as the direct water wave arrival data. The 1D acoustic velocity structure should be required for the correct depth of the OBS. Although it is rare that we use a CTD, even an empirical velocity structure works well.  相似文献   

Distribution of Phyllosoma Larvae (Crustacea: Decapoda: Palinuridae,Scyllaridae and Synaxidae) in the Western North Pacific     

Nariaki?Inoue  Hideki?Minami  Hideo?SekiguchiEmail author 《Journal of Oceanography》2004,60(6):963-976

Phyllosoma larvae were identified and their distribution was examined, based on the larvae in ichthyoplankton samples collected in the Japanese Eel Expedition to the spawning area of A. japonica in the western North Pacific from August 30 to September 13, 1986 (Leg. 1), and from September 22 to 25, 1986 (Leg. 2), on board the R/V Hakuho-maru. Phyllosoma larvae belonged to 3 families (Scyllaridae, Palinuridae and Synaxidae) representing 6 genera and 14 species. A total of 336 palinurid and synaxid phyllosoma larvae were collected, of which 233 larvae (about 70%) were identical with P. longipes s. l, while a total of 362 scyllarid phyllosoma larvae were collected, of which 274 larvae (about 76%) were identical with S. cultrifer. Phyllosoma larvae of P. longipes s. l and S. cultrifer showed a similar distribution to each other. The larvae were abundant in the water close to Mariana Islands, although late stage examples were abundant in waters of Luzon and eastern Taiwan. Distributions of these larvae may be related intimately with the North Equatorial Current existing along 15°N. The North Equatorial Current approaches the eastern coast of the Philippines and then separates into two branches of northward and southward flows. The northward flow contributes to generating the Kuroshio Current while the southward flow goes to generate the Mindanao Current. Judging from distributions of phyllosoma larvae in the present study, it is assumed that the larvae of the above two species may have been released in Mariana Islands and transported westward from there through the North Equatorial Current. These larvae may then be transported to eastern Taiwanese waters.  相似文献   

Preface     

Seiya Nagao  Shigeyoshi Otosaka  Hideki Kaeriyama 《Journal of Oceanography》2017,73(5):527-527

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Electrokinetic phenomena associated with a water injection experiment at the Nojima fault on Awaji Island, Japan   总被引：2，自引：0，他引：2  

Hideki Murakami  Takeshi Hashimoto  Naoto Oshiman  Satoru Yamaguchi  Yoshimori Honkura  Norihiko Sumitomo 《Island Arc》2001,10(3-4):244-251

Abstract Self-potential variations were measured to estimate the magnitude of electrokinetic and hydrological parameters (zeta potential and permeability) of the Nojima Fault zone in Awaji, Japan. The study observed self-potential variations that seemed to be associated with water flow from the injection well to the fracture zone, which were induced by turning the injection on and off. Amplitudes of the variations were a few to 0.03 V across 320–450 m dipoles. These variations can be explained well with an electrokinetic model. The quantity k/ζ (permeability/zeta potential) is in the range 1.6 × 10⁻¹³− 5.4 × 10⁻¹³ m²/V. Permeability of the Nojima fault zone can be estimated as approximately 10⁻¹⁶–10⁻¹⁵ m² on the assumption that the zeta potential is in the range –0.01 to –0.001 V.  相似文献   

Biaxial effects in modelling earthquake response of R/C structures     

Haruo Takizawa  Hiroyuki Aoyama 《地震工程与结构动力学》1976,4(6):523-552

Recent studies reveal that R/C structural members subjected to biaxial flexure due to two-dimensional earthquake excitation can deform much more than would be predicted by conventional one-dimensional response analysis. The biaxial flexure may therefore have a significant effect on the dynamic collapse process of structures subjected to intense ground motions. The present paper is intended to develop a new formulation of the two-dimensional restoring force model of R/C columns acted upon by biaxial bending moments, and to discuss the dynamic response properties of R/C structures. The model considered is a two-dimensional extension of various non-linear models for one-dimensional response analysis, including the degrading trilinear stiffness model which is one of the simpler idealizations of the restoring force characteristics of flexural-failure-type R/C structures. The modelling validity is then examined by comparison with experimental data on the biaxial bending behaviour of R/C columns. Calculations are made to study the role of different system properties on the influence of inelastic biaxial bending on the dynamic structural response. It is shown that the inelastic biaxial effect is generally significant and, in some cases, critical in the case of R/C structures with stiffness-degrading properties, while the effect is not so important for the non-degrading inelastic cases.  相似文献   

Geology of the summit limestone of Mount Qomolangma (Everest) and cooling history of the Yellow Band under the Qomolangma detachment     

Harutaka  Sakai  Minoru  Sawada  Yutaka  Takigami  Yuji  Orihashi  Tohru  Danhara  Hideki  Iwano  Yoshihiro  Kuwahara  Qi  Dong  Huawei  Cai  Jianguo  Li 《Island Arc》2005,14(4):297-310

Abstract   Newly discovered peloidal limestone from the summit of Mount Qomolangma (Mount Everest) contains skeletal fragments of trilobites, ostracods and crinoids. They are small pebble-sized debris interbedded in micritic bedded limestone of the Qomolangma Formation, and are interpreted to have been derived from a bank margin and redeposited in peri-platform environments. An exposure of the Qomolangma detachment at the base of the first step (8520 m), on the northern slope of Mount Qomolangma was also found. Non-metamorphosed, strongly fractured Ordovician limestone is separated from underlying metamorphosed Yellow Band by a sharp fault with a breccia zone. The ⁴⁰Ar–³⁹Ar ages of muscovite from the Yellow Band show two-phase metamorphic events of approximately 33.3 and 24.5 Ma. The older age represents the peak of a Barrovian-type Eo-Himalayan metamorphic event and the younger age records a decompressional high-temperature Neo-Himalayan metamorphic event. A muscovite whole-rock ⁸⁷Rb–⁸⁶Sr isochron of the Yellow Band yielded 40.06 ± 0.81 Ma, which suggests a Pre-Himalayan metamorphism, probably caused by tectonic stacking of the Tibetan Tethys sediments in the leading margin of the Indian subcontinent. Zircon and apatite grains, separated from the Yellow Band, gave pooled fission-track ages of 14.4 ± 0.9 and 14.4 ± 1.4 Ma, respectively. These new chronologic data indicate rapid cooling of the hanging wall of the Qomolangma detachment from approximately 350°C to 130°C during a short period (15.5–14.4 Ma).  相似文献