On the Role of Lightning NOx in the Formation of Tropospheric Ozone Plumes: A Global Model Perspective     

Didier Hauglustaine  Louisa Emmons  Mike Newchurch  Guy Brasseur  Toshinori Takao  Kouji Matsubara  James Johnson  Brian Ridley  Jeff Stith  James Dye 《Journal of Atmospheric Chemistry》2001,38(3):277-294

A series of ozone transects measured each year from 1987 to 1990 over thewestern Pacific and eastern Indian oceans between mid-November andmid-Decembershows a prominent ozone maximum reaching 50–80 ppbv between 5 and 10 kmin the 20° S–40° S latitude band. This maximum contrasts with ozonemixing ratios lower than20 ppbv measured at the same altitudes in equatorial regions. Analyses witha globalchemical transport model suggest that these elevated ozone values are part ofa large-scale tropospheric ozone plume extending from Africa to the western Pacific acrosstheIndian ocean. These plumes occur several months after the peak in biomassburninginfluence and during a period of high lightning activity in the SouthernHemispheretropical belt. The composition and geographical extent of these plumes aresimilar to theozone layers previously encountered during the biomass burning season in thisregion.Our model results suggest that production of nitrogen oxides from lightningstrokes sustains the NO_x (= NO+NO₂) levels and the ozonephotochemical productionrequired in the upper troposphere to form these persistent elevated ozonelayers emanating from biomass burning regions.  相似文献   

PHANEROZOIC INHOMOGENEOUS REHEATING OF UPPER MANTLE RESPONSIBLE FOR PACIFIC GENESIS     

Takao YANO  WU Gen-yao 《大地构造与成矿学(英文版)》2001,25(1)

The late Mesozoic two giant events that have synchronously occurred in the Pacific and periphery are the tectono-magmatic activities of the Circum-Pacific mobile belt and the Darwin Rise.Their dynamics analysis indicates that the geodynamics responsible for Pacific genesis has been driven by the gravity instability between a Pacific-wide superplume head and its lithospheric overburden under the influence of eastward asthenospheric flow by the Earth spin.The worldwide activation of mafic magmatism was initiated in the Paleozoic and climaxed around the Jurassic.The separated not worldwide distribution of the magmatism on the Earth suggests the inhomogeneous reheating of upper mantle,as represented by the Pacific-wide superplume head. The Phanerozoic reheating thus put forward the Earth history into a new geotectonic stage,i.e.,the diwa stage.  相似文献   

FORMATIVE MECHANISM OF AKAISHI MOUNTAINS AND ENREI BASIN IN CENTRAL JAPAN     

Yasu'uchi KUBOTA  Takao YANO 《大地构造与成矿学(英文版)》2001,25(1)

1 Introduction It is common in mobile belts that uplifting mountains are neighbored by synchronously subsiding basins.The coupling mechanism of such subsidence and uplift is an important target to clarify the dynamics of mobile belts.We investigate the coupled mountain uplift and basin subsidence in the Central Japan highland,the junction of three island arcs (the Northeast Japan,the Southwest Japan and the Izu-Ogasawara arcs).The highland over 3 000 m in height is composed of mountain ranges,plateaus and intramountain basins (Fig.1).  相似文献   

Comparative study of cataclastic rocks from a drill core and outcrops of the Nojima Fault zone on Awaji Island, Japan   总被引：3，自引：0，他引：3  

Aiming Lin  Toshihiko Shimamoto  Tadashi Maruyama  Motoko Sigetomi  Takao Miyata  Keiji Takemura  Hidemi Tanaka  Shinichi Uda  Akihiro Murata 《Island Arc》2001,10(3-4):368-380

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Deformation mechanisms and fluid behavior in a shallow, brittle fault zone during coseismic and interseismic periods: Results from drill core penetrating the Nojima Fault, Japan   总被引：1，自引：0，他引：1  

Hidemi Tanaka  Shin-Ichiro Hinoki  Kazuo Kosaka  Aiming Lin  Keiji Takemura  Akihiro Murata  Takao Miyata 《Island Arc》2001,10(3-4):381-391

Abstract This paper describes the results of petrographical and meso- to microstructural observations of brittle fault rocks in cores obtained by drilling through the Nojima Fault at a drilling depth of 389.52 m. The zonation of deformation and alteration in the central zone of the fault is clearly seen in cores of granite from the hanging wall, in the following order: (i) host rock, which is characterized by some intragranular microcracks and in situ alteration of mafic minerals and feldspars; (ii) weakly deformed and altered rocks, which are characterized by transgranular cracks and the dissolution of mafic minerals, and by the precipitation of zeolites and iron hydroxide materials; (iii) random fabric fault breccia, which is characterized by fragmentation, by anastomosing networks of transgranular cracks, and by the precipitation of zeolites and iron hydroxide materials; and (iv) fault gouge, which is characterized by the precipitation of smectite and localized cataclastic flow. This zonation implies that the fault has been weakened gradually by fluid-related fracturing over time. In the footwall, a gouge layer measuring only 15 mm thick is present just below the surface of the Nojima Fault. These observations are the basis for a model of fluid behavior along the Nojima Fault. The model invokes the percolation of meteoric fluids through cracks in the hanging wall fault zone during interseismic periods, resulting in chemical reactions in the fault gouge layer to form smectite. The low permeability clay-rich gouge layer sealed the footwall. The fault gouge was brecciated during coseismic or postseismic periods, breaking the seal and allowing fluids to readily flow into the footwall, thus causing a slight alteration. Chemical reactions between fluids and the fault breccia and gouge generated new fault gouge, which resealed the footwall, resulting in a low fluid condition in the footwall during interseismic periods.  相似文献   

Holocene environmental changes of the Hwajinpo Lagoon on the eastern coast of Korea     

Jong-Gwon Yum  Keiji Takemura  Takao Tokuoka  Kang-Min Yu 《Journal of Paleolimnology》2003,29(2):155-166

Lithologic and geochemical data of a core from the Hwajinpo Lagoon, located on the eastern coast of Korea, provided the evolutionary history of the lagoon related to Holocene sea-level changes of the East Sea (Sea of Japan). Grain size analysis, water content analysis, and soft X-ray analysis of core samples were used to reconstruct sedimentary environments, as were total organic carbon, C/N, S and C/S chemical records. Assemblages of mollusc and diatom remains also provided paleoenvironmental information. The reconstruction of paleoenvironments from these multi-proxy data allows the establishment of an evolutionary model of the Hwajinpo Lagoon. The environmental changes of the Hwajinpo Lagoon can be divided into seven different depositional facies: (l) Exposed basement rock; (2) Estuarine; (3) Stagnant brackish lagoon (isolated); (4) Oxic condition lagoon (organic activity); (5) Fresh water lake; (6) Oxic brackish lagoon (recent condition); (7) Prograding river delta. These environmental changes can be related to sea-level change during the Holocene. The trends of sea-level change in the Hwajinpo Lagoon from this study can be compared to those of the Japanese coastal areas located on the other side of the East Sea such as Lakes Shinji and Nakaumi.  相似文献   

Dual-beam echo integration method for precise acoustic surveys     

Takao  Yoshimi; Furusawa  Masahiko 《ICES Journal of Marine Science》1996,53(2):351-358

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Seismotectonics and tectonic history of the andaman sea     

Takao Eguchi  Seiya Uyeda  Tadashi Maki 《Tectonophysics》1979,57(1):35-51

The Andaman Sea is considered as an actively spreading back-arc basin. Seismicity and newly determined focal-mechanism solutions in the Andaman Sea area support this view. The tectonic history of the region is inferred from magnetic lineations in the northeastern Indian Ocean and the northward motion of Greater India. The mid-oceanic ridge which migrated northward along the east side of the Ninetyeast Ridge collided with the western end of the “old Sunda Trench” in the Middle or Late Miocene (10–20 m.y. B.P.). This ridge—trench collision released much of the compressional stress in the back-arc area and the continued northward movement of India that collided with Eurasia exerted a drag on the back-arc region, causing the opening of the Andaman Sea. In appearance, the subducted ridge jumped to the back-arc area. Thus, the Andaman Sea is not an ordinary subduction-related back-arc basin, but probably a basin formed by oblique extensional rifting associated with both ridge subduction and deformation of the back-arc area caused by a nearby continental collision.  相似文献   

Measurements of the ionization intensity due to beta-radiation near the ground     

Takao Iida  Dr. Minoru Kawano 《Meteorology and Atmospheric Physics》1972,21(2-3):195-210

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Time‐lapse video observation of erosion processes on the Black Marls badlands in the Southern Alps,France     

Takao Yamakoshi  Nicolle Mathys  Sébastien Klotz 《地球表面变化过程与地形》2009,34(2):314-318

In order to clarify the erosion processes on a marly bare slope in the Southern Alps, the erosion processes in a steep and erodible slope composed of the Black Marls Formation were observed by a time‐lapse video camera. The observations revealed that miniature debris flows (MDFs) occurred at the time of the rainfall‐runoff event in which the most severe erosion took place in the whole observation period of 3 months. Analysis of the camera images showed some characteristics of the MDFs, and these are discussed in the context of real rainfall‐runoff phenomena observed at the outlet of a small experimental basin including the visually observed slope. The following results were obtained. (1) A rough estimation of the total amount of sediment discharge by the MDFs showed that it was not negligible quantitatively. (2) The MDFs occurred only during the rising limb of the hydrograph during 6 minutes. (3) Based on this observation and a review of the literature, in a very steep and highly erodible slope, MDFs or similar phenomena might play an important role in the erosion and transport processes. Copyright © 2008 John Wiley and Sons, Ltd.  相似文献