Relationship between the path of the Kuroshio in the south of Japan and the path of the Kuroshio Extension in the east   总被引：2，自引：0，他引：2  

Shusaku Sugimoto  Kimio Hanawa 《Journal of Oceanography》2012,68(1):219-225

A relationship between paths of the Kuroshio and Kuroshio Extension (KE) is investigated, using the satellite-derived altimetry dataset of 1993–2008. When the Kuroshio takes the nearshore nonlarge meander path or typical large meander path and resultantly goes through the deeper channel (about 2500 m) of the Izu-Ogasawara Ridge, the KE path adopts a relatively stable state with the two quasi-stationary meanders. On the other hand, when the Kuroshio takes the offshore nonlarge meander path and then passes over the shallower part of the Ridge (about 1000 m), the KE path tends to be convoluted, i.e., an unstable state.  相似文献   

A new method of snowmelt sampling for water stable isotopes   总被引：1，自引：0，他引：1       下载免费PDF全文

D. Penna  M. Ahmad  S. J. Birks  L. Bouchaou  M. Brenčič  S. Butt  L. Holko  G. Jeelani  D. E. Martínez  G. Melikadze  J. B. Shanley  S. A. Sokratov  T. Stadnyk  A. Sugimoto  P. Vreča 《水文研究》2014,28(22):5637-5644

We modified a passive capillary sampler (PCS) to collect snowmelt water for isotopic analysis. Past applications of PCSs have been to sample soil water, but the novel aspect of this study was the placement of the PCSs at the ground‐snowpack interface to collect snowmelt. We deployed arrays of PCSs at 11 sites in ten partner countries on five continents representing a range of climate and snow cover worldwide. The PCS reliably collected snowmelt at all sites and caused negligible evaporative fractionation effects in the samples. PCS is low‐cost, easy to install, and collects a representative integrated snowmelt sample throughout the melt season or at the melt event scale. Unlike snow cores, the PCS collects the water that would actually infiltrate the soil; thus, its isotopic composition is appropriate to use for tracing snowmelt water through the hydrologic cycle. The purpose of this Briefing is to show the potential advantages of PCSs and recommend guidelines for constructing and installing them based on our preliminary results from two snowmelt seasons. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Formative conditions and sedimentary structures of sandy 3D antidunes: an application of the gravel step‐pool model to fine‐grained sand in an experimental flume     

Miwa Yokokawa  Kazuyoshi Hasegawa  Satoru Kanbayashi  Noritaka Endo 《地球表面变化过程与地形》2010,35(14):1720-1729

Antidunes and their sedimentary structures can be useful in reconstructing paleo‐hydraulic conditions, especially for large discharge events. However, three‐dimensional (3D) antidunes in sand‐sized sediments have not yet been studied extensively, as compared to either two‐dimensional (2D) antidunes or antidunes in gravel‐sized sediments. In this study, we estimated formative conditions of gravel step‐pool morphologies and applied them to the formation of 3D antidunes over a sand bed. Formative conditions are expressed in terms of a relationship between the water discharge per unit width and the bed slope. Flume experiments demonstrated that 3D mound‐like antidune configurations and their associated internal sedimentary structures could be preserved. Internal sedimentary structures were characterized by shallow lens‐like structures whose bases were erosional. Although gently‐dipping concave‐upward lamination was dominant, convex‐upward lamination was occasionally observed. The dimensions of lenticular lamina‐sets can be used to estimate antidune geometry. Thus if 3D antidunes can be interpreted in the stratigraphic record, it is possible to estimate the paleo‐hydraulic parameters such as water discharge and bed slope more precisely than previously. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Velocity distributions of high-velocity ejecta from regolith targets     

Satoru Yamamoto  Toshihiko Kadono  Takafumi Matsui 《Icarus》2005,178(1):264-273

We measured the velocity distributions of impact ejecta with velocities higher than ∼100 m s⁻¹ (high-velocity ejecta) for impacts at variable impact angle α into unconsolidated targets of small soda-lime glass spheres. Polycarbonate projectiles with mass of 0.49 g were accelerated to ∼250 m s⁻¹ by a single-stage light-gas gun. The impact ejecta are detected by thin aluminum foils placed around the targets. We analyzed the holes on the aluminum foils to derive the total number and volume of ejecta that penetrated the aluminum foils. Using the minimum velocity of the ejecta for penetration, determined experimentally, the velocity distributions of the high-velocity ejecta were obtained at α=15°, 30°, 45°, 60°, and 90°. The velocity distribution of the high-velocity ejecta is shown to depend on impact angle. The quantity of the high-velocity ejecta for vertical impact (α=90°) is considerably lower than derived from a power-law relation for the velocity distribution on the low-velocity ejecta (less than 10 m s⁻¹). On the other hand, in oblique impacts, the quantity of the high-velocity ejecta increases with decreasing impact angle, and becomes comparable to those derived from the power-law relation. We attempt to scale the high-velocity ejecta for oblique impacts to a new scaling law, in which the velocity distribution is scaled by the cube of projectile radius (scaled volume) and a horizontal component of impactor velocity (scaled ejection velocity), respectively. The high-velocity ejecta data shows a good correlation between the scaled volume and the scaled ejection velocity.  相似文献   

Hydrogen flicker and associated high-energy radiation     

Satio Hayakawa  Daiichiro Sugimoto 《Astrophysics and Space Science》1968,1(2):216-229

The accretion of matter onto stars formed by carbon-oxygen cores triggers hydrogen flicker. The development of hydrogen flicker and the shock generation associated therewith are discussed. If the matter thus ejected is halted by a dense gas surrounding a star, a corona of high temperature is formed. This may take place in dense planetary nebulae and is regarded as an origin of starlike X-ray sources. More violent hydrogen flicker takes place at white dwarfs and may be an origin of novae. Nuclear-reaction products ejected are positron sources and they may provide MeV positrons as strong as 10^–3 cm^–2 sec^–1 sr^–1. Nuclides produced by hydrogen flicker and a part of the carbon-oxygen core ejected may contribute to galactic cosmic rays; their chemical composition is like that observed in cosmic rays.  相似文献   

Vertical distribution of stable isotopic composition in atmospheric water vapor and subsurface water in grassland and forest sites, eastern Mongolia     

Maki Tsujimura  Lisa Sasaki  Atsuko Sugimoto  Dai Matsushima  Mijiddorj Saandar 《Journal of Hydrology》2007,333(1):35-46

  相似文献   

Spatial and temporal evolution of arc volcanism in the northeast Honshu and Izu‐Bonin Arcs: Evidence of small‐scale convection under the island arc?     

Satoru  Honda  Takeyoshi  Yoshida  Kan  Aoike 《Island Arc》2007,16(2):214-223

Abstract   Arc volcanism of the past 10 my in the northeast Honshu and Izu-Bonin Arcs shows several notable features. In the northeast Honshu Arc, the spatial distribution of volcanism exhibits several clusters elongated nearly perpendicular to the arc and the possible migration of volcanism from the back-arc side to the volcanic front side, at least, during the past 5 my. The pattern of clusters seems to have flip-flopped around 5 Ma. In the Izu-Bonin Arc, there are a series of across-arc seamount chains, in which volcanic activity occurred from ca 17 Ma to ca 3 Ma, similar to the clusters of the northeast Honshu Arc, although the recent active rifting occurs almost parallel to the arc. On the basis of studies of numerical modeling, these features might be explained, at least qualitatively, by the small-scale convection under the island arc. Several inferences can be made from our modeling results for the tectonics of the Izu-Bonin Arc. The angle of dip of subducting plate in the Izu-Bonin Arc might have increased. This can explain the disappearance of volcanism along the seamount chains and the recent along-arc volcanism with narrow rifting. The trend of seamount chains, which is oblique to the arc, might not be their intrinsic feature but rather a result of the lateral movement of the back-arc region after their formation. These inferences can be tested by the future detailed morphological and chronological studies of the Izu-Bonin Arc.  相似文献   

Heavy oil exposure increases viral production in natural marine bacterial populations     

Mitsuhiro Yoshida  Satoru Suzuki 《Journal of Oceanography》2014,70(1):115-122

This study examined whether heavy oil (HO) increases viral production and how that change may affect the marine bacterial community. The addition of a relatively low concentration (10 μg/mL) of HO to seawater resulted in the highest degree of viral lysis. Although the composition of the bacterial community did not change upon the viral lysis in terms of the taxa present, the relative abundance of the γ-Proteobacteria family Alteromonadaceae decreased (by 10 %) after the HO exposure, implying that the selective lysis by viruses and induced prophages may be responsible for changes in the composition of the bacterial community.  相似文献   

Origin of felsic volcanism in the Izu arc intra-arc rift     

Satoru?HaraguchiEmail author  Jun-Ichi?Kimura  Ryoko?Senda  Koichiro?Fujinaga  Kentaro?Nakamura  Yutaro?Takaya  Teruaki?Ishii 《Contributions to Mineralogy and Petrology》2017,172(5):25

An intra-arc rift (IAR) is developed behind the volcanic front in the Izu arc, Japan. Bimodal volcanism, represented by basalt and rhyolite lavas and hydrothermal activity, is active in the IAR. The constituent minerals in the rhyolite lavas are mainly plagioclase and quartz, whereas mafic minerals are rare and are mainly orthopyroxene without any hydrous minerals such as amphibole and biotite. Both the phenocryst and groundmass minerals have felsic affinities with a narrow compositional range. The petrological and bulk chemical characteristics are similar to those of melts from some partial melting experiments that also yield dry rhyolite melts. The hydrous mineral-free narrow mineral compositions and low-Al₂O₃ affinities of the IAR rhyolites are produced from basaltic middle crust under anhydrous low-temperature melting conditions. The IAR basalt lavas display prominent across-arc variation, with depleted elemental compositions in the volcanic front side and enriched compositions in the rear-arc side. The across-arc variation reflects gradual change in the slab-derived components, as demonstrated by decreasing Ba/Zr and Th/Zr values to the rear-arc side. Rhyolite lavas exhibit different across-arc variations in either the fluid-mobile elements or the immobile elements, such as Nb/Zr, La/Yb, and chondrite-normalized rare earth element patterns, reflecting that the felsic magmas had different source. The preexisting arc crust formed during an earlier stage of arc evolution, most probably during the Oligocene prior to spreading of the Shikoku back-arc basin. The lack of systematic across-arc variation in the IAR rhyolites and their dry/shallow crustal melting origin combines to suggest re-melting of preexisting Oligocene middle crust by heat from the young basaltic magmatism.  相似文献