East-west distribution of POC fluxes estimated from <Superscript>234</Superscript>Th in the northern North Pacific in autumn     

Hajime Kawakami  Makio C. Honda  Kazuhiko Matsumoto  Tetsuichi Fujiki  Shuichi Watanabe 《Journal of Oceanography》2010,66(1):71-83

Observations of primary productivity, ²³⁴Th, and particulate organic carbon (POC) were made from west to east across the northern North Pacific Ocean (from station K2 to Ocean Station Papa) during September–October 2005. Primary productivities in this region varied longitudinally from approximately 236 to 444 mgC m⁻²d⁻¹ and clearly indicate the West High East Low (WHEL) trend. We estimated east-west variations in the POC flux from the surface layer (0–100 m) by using ²³⁴Th as a tracer. POC fluxes in the western region (44–53 mgC m⁻²d⁻¹) were higher than those in the eastern region (21–34 mgC m⁻²d⁻¹). However, the export ratios (e-ratios) ranged from approximately 8% to 16% and did not show the WHEL trend. Contrary to our expectation, no relation between POC flux (or e-ratio) and diatom biomass (or dominance) was apparent in autumn in the northern North Pacific.  相似文献   

Erratum: Large-amplitude variables near the Galactic Centre     

I. S. Glass  S. Matsumoto  B. S. Carter  K. Sekiguchi 《Monthly notices of the Royal Astronomical Society》2002,336(4):1390-1390

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Characteristics of SeaMARC II phase data     

Matsumoto  H. 《Oceanic Engineering, IEEE Journal of》1990,15(4):350-360

The dispersion of SeaMARC II phase-difference samples is discussed. They appear to be a function of signal direction, range, noise level, and backscatter strength of the bottom. Field data from a lava flow area and from sedimented areas at different depths are compared. The temporal distribution of the phase-difference samples was skewed and asymmetrical about the model. The angular distribution was symmetrical about the mode, with some phase wrap-around. The field data show the presence of a complicated noise interference field. The amount of phase-difference dispersion was larger than that calculated by using a simple Gaussian isotropic noise model, possibly suggesting an additional phase-dispersion process caused by bottom roughness. The method used to produce bathymetry data from the phase-difference samples was evaluated in light of the phase-difference sample distribution  相似文献   

Alteration of rock by volcanic gas in Japan     

Iwaji Iwasaki  Mitsuei Hirayama  Takashi Katsura  Takejiro Ozawa  Jyoyo Ossaka  Masaakira Kamada  Hatao Matsumoto 《Bulletin of Volcanology》1964,27(1):65-78

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The influence of multiple diffraction on the space group determination of orthopyroxene,spodumene, low omphacite and pigeonite     

Satoshi Sasaki  Takeo Matsumoto  Chikako Sawada 《Physics and Chemistry of Minerals》1981,7(6):260-267

Forbidden reflections of some pyroxenes described as having a lower symmetry than Pbca or C2/c have been examined, mainly using the detailed ψ-scanning method of the four-circle automated diffractometer. All reflections violating the systematic absences of Pbca orthopyroxene, C2/c spodumene, P2/n omphacite and P2₁/c pigeonite were found to be due to the Umweganregung process of multiple diffraction; the Umweganregung peaks observed for the ψ azimuth were indexed in terms of a four-circle geometry. Thus, the space groups of orthopyroxene, α spodumene, low omphacite and low pigeonite were confirmed to be Pbca, C2/c, P2/n and P2₁/c, respectively.  相似文献   

Multicomponent observation of crustal activity in the DPRI 800 m borehole close to the Nojima Fault   总被引：1，自引：0，他引：1  

Hiroshi Ishii  Atsushi Mukai  Kunio Fujimori  Shigeru Nakao  Shigeo Matsumoto  Yasuhiro Hirata 《Island Arc》2001,10(3-4):282-287

Abstract An 800 m borehole was drilled near the Nojima Fault, on which a strike–slip larger then 1 m occurred during the 1995 Hyogo-ken Nanbu earthquake ( M = 7.2). Crustal activity near the fault has been observed since May 1996 using a multicomponent instrument installed at the bottom of the borehole. Data of three components of strain, two components of tilt and temperature observed from May 1996 to December 1998 were analyzed. Long-term changes of strain and tilt show a north-east–south-west extension and southwards subsidence. As for the Earth tides and atmospheric effect, orientation of the principal axis of strain was mainly east-west and orientation of the maximum subsidence was mainly north-south. The observational data of strain had variations corresponding to a change in temperature at a depth of 800 m. The thermal expansion coefficient of the crust was calculated to be approximately 2.0 × 10⁻⁶/°K.  相似文献   

Morphological and chemical variations of chromian spinel in dunite-harzburgite complexes from the Sangun zone (SW Japan): implications for mantle/melt reaction and chromitite formation processes   总被引：1，自引：0，他引：1  

I. Matsumoto  S. Arai 《Mineralogy and Petrology》2001,73(4):305-323

Summary ?Many ultramafic complexes, some of which have chromitite bodies, are exposed in the Sangun zone in central Chugoku district, Southwest Japan. Harzburgite is always dominant over dunite, but the dunite/harzburgite ratio varies from complex to complex. Large chromitite bodies are exclusively found in relatively dunite-dominant complexes or portions. The degree of roundness, DR#=[area/(round-length)²] (normalized by a circle’s value: 1/4π), of chromian spinel is variable, depending on lithology of the peridotites. Chromian spinel is mostly anhedral or even vermicular (less than 0.4 in DR#) in harzburgite, and is most frequently euhedral or rounded (within the range of 0.7 to 0.9 in DR#) in dunite. The morphology of spinel is correlated with chemistry: the DR# is positively correlated with Ti content and Fe^3+#(=Fe³⁺/(Cr + Al + Fe³⁺)), but is not related to Cr#. When chromitite is present in dunite, the spinel is relatively anhedral (vermicular) and low in Ti and Fe^3+# in the dunite whereas it is relatively euhedral and high in Ti and Fe^3+# in surrounding harzburgite. We define these spinels as “extraordinary” spinels, which are commonly found in Wakamatsu mine area in the Tari-Misaka complex, which exploits the largest chromite body in Japan. The rocks with the “extraordinary” spinels show transitional lithologies (a gradual boundary, one meter to several tens of meters in width) between dunite and harzburgite with “ordinary” spinels. The formation of dunite and chromitite is interpreted as a result of the reaction of harzburgite with a relatively Ti-rich magma (back-arc basin or MORB-like magma) and related magma mixing, as discussed by Arai and Yurimoto (1994). The dike-like occurrence of the dunite and chromitite indicates that the reaction took place along melt conduits (=fractures) less than 200 m in width. Podiform chromitites were formed only when the reaction zone was relatively wide (several tens of meters in width), that is, only when the degree of interaction was relatively high. The magma modified by the reaction percolated, possibly by porous flow from the reaction zone outward, and changed the texture and chemistry of chromian spinel, on the scale of several tens of meters. This type of melt transport, or melt flow through fractures with a melt percolation aureole, may be prevalent in the uppermost mantle. Received February 8, 2000;/revised version accepted December 22, 2000  相似文献   

Seasonal transition of summer rainy season over indochina and adjacent monsoon region   总被引：8，自引：0，他引：8  

Jun Matsumoto 《大气科学进展》1997,14(2):231-245

The mean onset and withdrawal of summer rainy season over the Indochina Peninsula were investigated using 5-day averaged rainfall data (1975-87). The mean seasonal transition process during onset and retreat phases in Indochina, India and the South China Sea is also examined using 5-day mean OLR (1975-87) and 850 hPa wind (1980-88) date. It was found that the onset of summer rainy season begins earlier in the inland region of Indochina (Thailand) in late April to early May than in the coastal region along the Bay of Bengal. This early onset of rainy sea-son is due to pre-monsoon rain under the mid-latitude westerly wind regime. The full summer monsoon circulation begins to establish in mid-May, causing active convective activity both over the west coast of Indochina and the cen-tral South China Sea. In case of withdrawal, the earliest retreat of summer rainy season is found in the central northern part of Indochina in late September. The wind field, on the other hand, already changes to easterlies in the northern South China Sea in early September. This easterly wind system covers the eastern part of Indochina where post-monsoon rain is still active. In late October, the wind field turns to winter time situation, but post monsoon rain still continues in the southern part of the Indochina Peninsula until late November  相似文献   

The April 1992 Cape Mendocino Earthquake Sequence: Seismo-Acoustic Analysis Utilizing Fixed Hydrophone Arrays     

Dziak  R. P.  Fox  C. G.  Matsumoto  H.  Schreiner  A. E. 《Marine Geophysical Researches》1997,19(2):137-162

The oceanic T-waves of earthquakes associated with the 1992 Cape Mendocino earthquake sequence were recorded and analyzed using fixed hydrophone arrays located throughout the north-east Pacific Ocean. The T-waves of these events were well recorded with high S/N ratios and strong acoustic energy present over a 0–64 Hz bandwidth. The smallest event recorded by the hydrophone arrays from the sequence had a local magnitude of 2.4. The hydrophone records of the three largest shocks in the sequence (ML 6.9, 6.2, 6.5) exhibited both T-waves and lithospheric phases from these events. Low-pass filtering (2 Hz) of the lithospheric phases yielded a clear P-wave arrival for epicentral distances of <10°, but no apparent S-wave. A seafloor cable-break was detected immediately after the second M>6 aftershock, possibly the result of a submarine slide. The direct P-wave hydrophone records from the second large aftershock showed a relatively high-amplitude, high-frequency arrival, consistent with seismic analyses which used this information to infer rupture direction. The rupture direction was toward the location of the cable break, thus rupture directivity possibly played a role in initiating the slide event. Modelling of the T-wave propagation path, using the Parabolic Equation model, produced estimates of the acoustic transmission loss from epicenter to receiver. The transmission loss to the most distant phones is typically 10-20 dB , and can be as large as 50–70 dB for acoustic propagation paths that cross the continental margin. The amount of acoustic energy each earthquake released into the ocean at the seafloor–water interface was estimated applying the transmission loss and instrument response to the recorded T-wave signals. This acoustic source power level was calculated for 41 events with magnitudes over a recorded range of 2.4ML6.9, with 17 of these events having their seismic moment estimates available through the NEIC. Ground displacement spectra were estimated from the acoustic power spectra and showed no indication of a corner frequency. Thus empirical analyses relating source level to magnitude and seismic moment were necessary to quantitatively derive an earthquake's size from hydrophone records. The results of indicator variable regression analyses suggest that T-wave source level increases linearly with the event's local magnitude and seismic moment. Furthermore, the source power level versus magnitude relationships for oceanic and continental earthquakes are significantly different, probably illustrating differences in the seismic and acoustic propagation paths from hypocenter to the hydrophone receivers. The results indicate that acoustic measurements provide a reasonable estimate of magnitude and seismic moment of an oceanic earthquake that was not detected by land-based seismic networks.  相似文献   

Modeling Local Tidal Constituents Using TOPEX/POSEIDON SSH for the Malaysian Marine Region     

Muhammad Nur J. P. Vella  Sahrum Ses  Majid Kadir  Koji Matsumoto 《Marine Geodesy》2001,24(2):99-106

A new Local Ocean Tide Model, has been produced for the Exclusive Economic Zone (EEZ) of Malaysia, which incorporates some of the latest TOPEX/POSEIDON data for the years 1992 to 1998. Local tide gauge data are used as a comparison, along with another leading Global Ocean Tide Model, Ori96. The leading diurnal and semidiurnal constituents M₂, S₂, N₂, K₁, O₁, P₁ and Q₁ are reproduced using TOPEX/POSEIDON Sea Surface Heights (SSH) in a response analysis type least squares derivation following Munk and Cartwright (1966).  相似文献