Surface currents around Hokkaido in the late fall of 1981 obtained from analysis of satellite images     

Yuji Hatakeyama  Sotaro Tanaka  Toshiro Sugimura  Tsukasa Nishimura 《Journal of Oceanography》1985,41(5):327-336

This paper describes the characteristics of currents around Hokkaido using a current vector map compiled by chasing the displacement of sea marks on a pair of successive thermal infrared images taken from a satellite, NOAA-6. The points of some sea surface patterns showing distinctive features which can be commonly identified in both images are called Sea Marks≓. This sea mark chase method≓ has a great advantage over velocity measurements by boats or buoys, in that it gives a synoptic view of the velocity distribution over a broad sea area extending for some hundreds of miles on a short time scale of half a day.In order to investigate the current in the late fall of 1981, we used the data taken at 19:05 JST on 30 October and at 7:20 JST on 31 October. With these data taken with a 12 hr difference, the measurement accuracy of the speed of sea marks reached ±0.1 knot through geometrical correction. The velocity vectors of sea marks agreed with results of GEK measurements performed on those days, and also with the mean current pattern obtained in the past based on sea surface data.The most distinct features recognized were some cyclonic and anticyclonic eddies of the order of 100 km in diameter which dominated in the Kuril Basin of the Okhotsk Sea. They appeared clearly in the original NOAA images and their physical parameters were determined quantitatively from the vector map. These eddies were located in the region of decay of the Soya Warm Current and were rotating at a speed nearly as large as that of the current. The problems of what feeds energy to these eddies and how long they live remain to be solved in future studies.  相似文献   

Iron K-emission line from Cygnus X-2     

T. Hirano  S. Hayakawa  F. Nagase  Y. Tawara 《Astrophysics and Space Science》1986,119(1):77-80

The iron K-emission line of Cyg X-2 was detected from the TENMA observation. The centre energy, the equivalent width and the intrinsic line width are 6.7 keV, 30 eV, and less than 0.6 keV, respectively. These properties indicate that the observed line is mostly due to helium-like iron and the electron scattering depth of the line emitting region is smaller than three.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.  相似文献   

Foreword     

Toshiro Saino 《Journal of Oceanography》1998,54(5):381-382

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Water content of primitive low-K tholeiitic basalt magma from Iwate Volcano,NE Japan arc: implications for differentiation mechanism of frontal-arc basalt magmas     

Takeshi Kuritani  Takeyoshi Yoshida  Jun-Ichi Kimura  Yuka Hirahara  Toshiro Takahashi 《Mineralogy and Petrology》2014,108(1):1-11

The water content of low-K tholeiitic basalt magma from Iwate volcano, which is located on the volcanic front of the NE Japan arc, was estimated using multi-component thermodynamic models. The Iwate lavas are moderately porphyritic, consisting of ~8 vol.% olivine and ~20 vol.% plagioclase phenocrysts. The olivine and plagioclase phenocrysts show significant compositional variations, and the Mg# of olivine phenocrysts (Mg#78–85) correlates positively with the An content of coexisting plagioclase phenocrysts (An_85–92). The olivine phenocrysts with Mg# > ~82 do not form crystal aggregates with plagioclase phenocrysts. It is inferred from these observations that the phenocrysts with variable compositions were primarily derived from mushy boundary layers along the walls of a magma chamber. By using thermodynamic calculations with the observed petrological features of the lavas, the water content of the Iwate magma was estimated to be 4–5 wt.%. The high water content of the magma supports the recent consensus that frontal-arc magmas are remarkably hydrous. Using the estimated water content of the Iwate magma, the water content and temperature of the source mantle were estimated. Given that the Iwate magma was derived from a primary magma solely by olivine fractionation, the water content and temperature were estimated to be ~0.7 wt.% and ~1,310 °C, respectively. Differentiation mechanisms of low-K frontal-arc basalt magmas were also examined by application of a thermodynamics-based mass balance model to the Iwate magma. It is suggested that magmatic differentiation proceeds primarily through fractionation of crystals from the main molten part of a magma chamber when it is located at <~200 MPa, whereas magma evolves through a convective melt exchange between the main magma and mushy boundary layers when the magma body is located at >~200 MPa.  相似文献   

Phase F, a New Hydrous Magnesium Silicate Synthesized at 1000 °C and 17 GPa: Crystal Structure and Estimated Bulk Modulus     

Y. Kudoh  T. Nagase  S. Sasaki  M. Tanaka  M. Kanzaki 《Physics and Chemistry of Minerals》1997,24(8):601-601

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Morphology of intergranular pores and wetting angles in pelitic schists studied by transmission electron microscopy   总被引：2，自引：0，他引：2  

Takehiko Hiraga  Osamu Nishikawa  Toshiro Nagase  Mizuhiko Akizuki 《Contributions to Mineralogy and Petrology》2001,141(5):613-622

In pelitic schists composed mainly of quartz and albite grains, the morphology of intergranular pores, which were filled with water, was studied by transmission electron microscopy (TEM). Although some pores are defined by crystallographic planes (F-face), most of their form has an ideal shape determined by interface tensions between grains and fluid. High-resolution TEM observations demonstrate that pore-free regions at grain boundaries are tight even at the nanometer scale, showing that the wetting angle is larger than 0° in this rock. The pore distribution in two-grain junctions can be compared to a "necklace microstructure" developed by instability of a fluid film along the boundary induced by microcracking. Wetting angles for pores located at grain edges of quartz and albite decrease in the order albite/albite, quartz/quartz, and quartz/albite. The quartz/quartz wetting angle in a calcite-free sample is smaller than that in a calcite-containing sample. This angle also changes due to grain misorientation. Our results confirm that solid-solid and solid-fluid interfacial energies control the geometry of intergranular fluid in natural rocks.  相似文献   

Image Stabilization System for Hinode (Solar-B) Solar Optical Telescope     

T. Shimizu  S. Nagata  S. Tsuneta  T. Tarbell  C. Edwards  R. Shine  C. Hoffmann  E. Thomas  S. Sour  R. Rehse  O. Ito  Y. Kashiwagi  M. Tabata  K. Kodeki  M. Nagase  K. Matsuzaki  K. Kobayashi  K. Ichimoto  Y. Suematsu 《Solar physics》2008,249(2):221-232

The Hinode Solar Optical Telescope (SOT) is the first space-borne visible-light telescope that enables us to observe magnetic-field dynamics in the solar lower atmosphere with 0.2 – 0.3 arcsec spatial resolution under extremely stable (seeing-free) conditions. To achieve precise measurements of the polarization with diffraction-limited images, stable pointing of the telescope (<0.09 arcsec, 3σ) is required for solar images exposed on the focal plane CCD detectors. SOT has an image stabilization system that uses image displacements calculated from correlation tracking of solar granules to control a piezo-driven tip-tilt mirror. The system minimizes the motions of images for frequencies lower than 14 Hz while the satellite and telescope structural design damps microvibration in higher frequency ranges. It has been confirmed from the data taken on orbit that the remaining jitter is less than 0.03 arcsec (3σ) on the Sun. This excellent performance makes a major contribution to successful precise polarimetric measurements with 0.2 – 0.3 arcsec resolution. K. Kobayashi now at NASA/Marshall Space Flight Center, Huntsville, AL 35812, USA.  相似文献   

Biogeochemical evidence of large diapycnal diffusivity associated with the subtropical mode water of the North Pacific     

Chiho Sukigara  Toshio Suga  Toshiro Saino  Katsuya Toyama  Daigo Yanagimoto  Kimio Hanawa  Nobuyuki Shikama 《Journal of Oceanography》2011,67(1):77-85

A profiling float equipped with a fluorimeter, a dissolved oxygen (DO) sensor, and temperature and salinity sensors was deployed in the subtropical mode water (STMW) formation region of the North Pacific. It acquired quasi-Lagrangian, 5-day-interval time-series records from March to July 2006. The time-series distribution of chlorophyll showed a sustained and sizable subsurface maximum at 50–100 m, just above the upper boundary of the STMW, throughout early summer (May–July). The DO concentration in this lower euphotic zone (50–100 m) was almost constant and supersaturated in the same period, becoming more supersaturated with time. On the other hand, the DO concentration at 100–150 m near the upper boundary of the STMW decreased much more slowly compared with the main layer of STMW below 150 m, even though oxygen consumption by organisms was expected to be larger in the former depth range. The small temporal variations of DO in the lower euphotic zone and near the upper boundary of the STMW were reasonably explained by downward oxygen transport because of large diapycnal diffusion near the top of the STMW. Assuming that the oxygen consumption rate at 100–150 m was the same as that in the main layer of STMW and compensated by the downward oxygen flux, the diapycnal diffusivity was estimated to be 1.7 × 10⁻⁴ m² s⁻¹. Nitrate transport into the euphotic zone by the same large diffusion was estimated to be 0.8 mmol N m⁻² day⁻¹. All of the transported nitrate could have been used for photosynthesis by the phytoplankton; net community production was estimated to be 5.3 mmol C m⁻² day⁻¹.  相似文献   

The azimuthal dependence of surface wave polarization in a slightly anisotropic medium   总被引：1，自引：0，他引：1  

Toshiro Tanimoto 《Geophysical Journal International》2004,156(1):73-78

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X-ray emissions from Vela X-1 during its eclipsing period     

N. Sato  S. Hayakawa  F. Nagase 《Astrophysics and Space Science》1986,119(1):81-84

The X-ray pulsar Vela X-1 was observed with TENMA throughout the entire period of eclipse in March 1984. The energy spectra at several phase angles showed the iron emission line at about 6.4 keV throughout the eclipse of Vela X-1 and its intensity at the mid-eclipse to be about 10% of that in the non-eclipsing phase, whereas the continuum intensity was about 1%. The result provides means of studying the contribution of the stellar wind to the fluorescence line and the structure of the stellar atmosphere.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.  相似文献