The solar differential rotation and ‘Rossby-type’ waves     

Shoji Kato  Y. Nakagawa 《Solar physics》1969,10(2):476-493

It has been suggested that the solar differential rotation might be maintained by nearly horizontal non-spherical convective circulation called the Rossby-type waves (the wave motions characterized by the close balance of the Coriolis force and pressure gradient in horizontal motions). In this paper, such Rossby-type waves which could be excited in the upper solar convection zone are considered, and the possibility of maintenance of the solar differential rotation by such waves is examined. A numerical estimate, in terms of the rate of conversion of the kinetic energy of such wave motions into the mean rotational motion, indicates this possibility. The implications and limitations of the results are also discussed.Visiting Scientist to the High Altitude Observatory on leave of absence from the Department of Astronomy, University of Tokyo, Japan.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

The topology of force-free magnetic field near bipolar sunspots     

M. A. Raadu  Y. Nakagawa 《Solar physics》1971,20(1):64-77

The topological character of a new type of solution representing a force-free magnetic field near bipolar sunspots is examined. It is shown that some of the observed topological features of chromospheric fibrils and filaments in H can be interpreted in terms of the configuration of the magnetic lines of force of the present solution. In particular, by the examples considered the observed twisted S-shape topology of lower lying fibrils and the orientation of prominences (higher filaments) associated with sunspots are successfully reproduced.Visiting scientist at the High Altitude Observatory.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

Internal structure of the Nojima Fault zone from the Hirabayashi GSJ drill core   总被引：1，自引：0，他引：1  

Tomoyuki Ohtani  Hidemi Tanaka    Koichiro Fujimoto  Takayuki Higuchi  Naoto Tomida  Hisao Ito 《Island Arc》2001,10(3-4):392-400

Abstract The internal structures of the Nojima Fault, south-west Japan, are examined from mesoscopic observations of continuous core samples from the Hirabayashi Geological Survey of Japan (GSJ) drilling. The drilling penetrated the central part of the Nojima Fault, which ruptured during the 1995 Kobe earthquake (Hyogo-ken Nanbu earthquake) ( M 7.2). It intersected a 0.3 m-thick layer of fault gouge, which is presumed to constitute the fault core (defined as a narrow zone of extremely concentrated deformation) of the Nojima Fault Zone. The rocks obtained from the Hirabayashi GSJ drilling were divided into five types based on the intensities of deformation and alteration: host rock, weakly deformed and altered granodiorite, fault breccia, cataclasite, and fault gouge. Weakly deformed and altered granodiorite is distributed widely in the fault zone. Fault breccia appears mostly just above the fault core. Cataclasite is distributed mainly in a narrow (≈1 m wide) zone in between the fault core and a smaller gouge zone encountered lower down from the drilling. Fault gouge in the fault core is divided into three types based on their color and textures. From their cross-cutting relationships and vein development, the lowest fault gouge in the fault core is judged to be newer than the other two. The fault zone characterized by the deformation and alteration is assumed to be deeper than 426.2 m and its net thickness is > 46.5 m. The fault rocks in the hanging wall (above the fault core) are deformed and altered more intensely than those in the footwall (below the fault core). Furthermore, the intensities of deformation and alteration increase progressively towards the fault core in the hanging wall, but not in the footwall. The difference in the fault rock distribution between the hanging wall and the footwall might be related to the offset of the Nojima Fault and/or the asymmetrical ground motion during earthquakes.  相似文献   

Synthetic Silica Glass for Trace Aluminium Determination in Quartz by Electron Microprobe     

Naoya Miyoshi  Hisao Satoh  Yoshiaki Yamaguchi  Harue Masuda 《Geostandards and Geoanalytical Research》2003,27(1):91-98

Five synthetic silica glasses have been prepared for microprobe determination of trace aluminium in quartz. The glasses were synthesized from tetraethoxysilane (TEOS) into which between 0 and 1431 μg g-¹ aluminium had been doped. The aluminium concentrations of the glasses were independently determined by ICP-AES analysis. X-ray wavelength shift in the Al Kα peak was minimised relative to unknown quartz samples when these glasses were used for calibration. A set of these five glasses yielded a linear calibration line, and are available for trace aluminium analysis of quartz in routine microprobe systems.  相似文献   

The Global Stratotype Section and Point （GSSP） for the base of the Holocene Series/Epoch （Quaternary System/Period） in the NGRIP ice core   总被引：4，自引：0，他引：4  

Mike Walker  ;Sigfus Johnsen  ;Sune Olander Rasmussen  ;Jorgen-Peder Steffensen  ;Trevor Popp  ;Philip Gibbard  ;Wim Hoek  ;John Lowe  ;John Andrews  ;Svante Bjorck  ;Les Cwynar  ;Konrad Hughen  ;Peter Kershaw  ;Bernd Kromer  ;Thomas Litt  ;David J. Lowe  ;Takeshi Nakagawa  ;Rewi Newnham  ;Jakob Schwander 《《幕》》2008,31(2):264-267

The Greenland ice core from NorthGRIP （NGRIP） contains a proxy climate record across the Pleistocene-Holocene boundary of unprecedented clarity and resolution. Analysis of an array of physical and chemical parameters within the ice enables the base of the Holocene, as reflected in the first signs of climatic warming at the end of the Younger Dryas/Greenland Stadial 1 cold phase, to be located with a high degree of precision.  相似文献   

Giant planet formation     

Nobuya Tajima  Yoshitsugu Nakagawa 《Earth, Moon, and Planets》1994,67(1-3):51-65

The accumulation of giant planets involves processes typical for terrestrial planet formation as well as gasdynamic processes that were previously known only in stars. The condensible element cores of the gas-giants grow by solid body accretion while envelope formation is governed by stellar-like equilibria and the dynamic departures thereof. Two hypotheses for forming Uranus/Neptune-type planets — at sufficiently large heliocentric distances while allowing accretion of massive gaseous envelopes, i.e. Jupiter-type planets at intermediate distances — have been worked out in detailed numerical calculations: (1) Hydrostatic gas-accretion models with time-dependent solid body accretion-rates show a slow-down of core-accretion at the appropriate masses of Uranus and Neptune. As a consequence, gas-accretion also stagnates and a window is opened for removing the solar nebula during a time of roughly constant envelope mass. (2) Gasdynamic calculations of envelope accretion for constant planetesimal accretion-rates show a dynamic transition to new envelope equilibria at the so called critical mass. For a wide range of solar nebula conditions the new envelopes have respective masses similar to those of Uranus and Neptune and are more tightly bound to the cores. The transitions occur under lower density conditions typical for the outer parts of the solar nebula, whereas for higher densities, i.e. closer to the Sun, gasdynamic envelope accretion sets in and is able to proceed to Jupiter-masses.  相似文献   

Incorporation rate measurements of <Superscript>10</Superscript>Be, <Superscript>230</Superscript>Th, <Superscript>231</Superscript>Pa,and <Superscript>239,240</Superscript>Pu radionuclides in manganese crust in the Pacific Ocean: A search for extraterrestrial material     

Norikazu Kinoshita  Yuko Sato  Takeyasu Yamagata  Hisao Nagai  Akihiko Yokoyama  Takashi Nakanishi 《Journal of Oceanography》2007,63(5):813-820

In order to estimate the deposition rate of extraterrestrial material onto a manganese crust in a search for supernova debris, we analyzed the contents of ¹⁰Be, ²³⁰Th, ²³¹Pa, and ^239,240Pu in a sample of manganese crust collected from the North Pacific Ocean. On the basis of the depth profile of ¹⁰Be, the growth rate of the manganese crust was determined to be 2.3 mm Myr⁻¹. The uptake rates of ¹⁰Be, ²³⁰Th, and ²³¹Pa onto the manganese crust were estimated to be 0.22–0.44%, 0.11–0.73%, and 1.4–4.5%, respectively, as compared to the deposition rates onto the deep-sea sediments near the sampling station, while that for ^239,240Pu was 0.14% as compared to the total inventory of seawater and sediment column. Assuming that sinking particles represent 0.11–4.5% of the uptake rates, the deposition rate of extraterrestrial material onto the manganese crust was estimated to be 2–800 μg cm⁻²Myr⁻¹ according to the uptake of ¹⁰Be onto the manganese crust. Further, our estimate is similar to the value of 9–90 μg cm^{− 2}Myr⁻¹ obtained using the integrated global production rate of ¹⁰Be and the deposition rate of ¹⁰Be onto the manganese crust.  相似文献   

III-1 Study on twin-hull-type floating wave energy converter     

Masanori Kobayashi  Hiroyuki Nakagawa 《Ocean Engineering》1985,12(6):566-567

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Growth and sedimentation of dust grains in the primordial solar nebula     

Yoshitsugu Nakagawa  Kiyoshi Nakazawa  Chushiro Hayashi 《Icarus》1981,45(3):517-528

Of the formation processes in the solar system, the process of growth and sedimentation of dust grains in the primordial solar nebula is investigated for a region near the Earth's orbit. The growth equation for dust grains, which are sinking as well as being in thermal motion, is solved numerically in the wide mass range between 10^?12 and 10⁶ g. Any turbulent motions in the nebula are assumed to have already decayed when the sedimentation begins. The numerical simulation shows that the growth and sedimentation proceed faster than was found by Kusaka et al. (1970) but in accordance with the estimate of Safronov (1969) owing to a cooperative interaction of the growth and the sedimentation; that is, at about 3 × 10³ years after the beginning of the growth and sedimentation a dust layer, composed of centimeter-sized grains, is formed at the equator of the solar nebula. Furthermore, the mass density of dust grains floating in the outer layers of the nebula is found to be of the order of 10^?5 after 10⁵ years compared with that before the sedimentation. From these results, it can be estimated that at about 5 × 10³ years after the beginning of sedimentation the dust layer breaks up owing to the onset of gravitational instability.  相似文献   

Spatial trends of nitrate pollution and groundwater chemistry in Shimabara,Nagasaki, Japan   总被引：1，自引：0，他引：1  

Kei Nakagawa  Hiroki Amano  Hiroshi Asakura  Ronny Berndtsson 《Environmental Earth Sciences》2016,75(3):234

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