Parametric excitation of alfvén wave by magnetosonic wave with oblique propagation     

Kiyohumi Yumoto  Takao Saito 《Planetary and Space Science》1982,30(2):199-207

A parametric excitation of the Alfvén wave (k^A, ω_a) by the magnetosonic wave (K₁^fs, ω_1fs), which propagates obliquely to the static magnetic field, has been analyzed. The theoretical model for a one-fluid with uniform, unbounded, ideally conducting and compressible plasma is employed. The resonance conditions are chosen such as, $\text{k}{}_1{}^{\mathrm{fs}}\text{=}\text{k}{}_1{}^{\mathrm{fs}}\text{+}\text{k}{}^{\mathrm{A}}$ and ω_1fs ? ω_A = δ ～ ω_2fs. The p wave is assumed to be strong enough, so that the pump wave is given as a constant. In both the case of the standing and the propagating pump the growth rates of the excited waves depend on not only the pump power but also the β-ratio. In the standing pump the threshold pump intensity of the oscillating instability is zero at the perfect matching. It is found that we can obtain a larger growth rate of the parametric excitation of Alfvén wave by the fast magnetosonic pump wave for θ_1f ～ 70–80° and the occurrence regions of parametric excitations are localized at the resonance point in the magnetosphere (β ～ m_e/m_i). It is concluded that the parametric instability of Pc3 range HM-waves is the more possible theory than the linear resonance theory.  相似文献   

Modeling of solute transport and biological sulfate reduction using low cost electron donor     

Osama Eljamal  Kenji Jinno  Tosao Hosokawa 《Environmental Geology》2009,56(8):1605-1613

Serial data from soil–sawdust column experiments were used to develop a mathematical model to describe the biological sulfate reduction processes in porous media. The mathematical model numerically solves the equation of solute transport in one-dimensional saturated state. Solute transport is coupled to sulfate reducing bacteria sub model. Bacterial growth is assumed to follow double Monod kinetic equation. Two bacterial groups (X1 and X2) were described. Bacterial group X1 uses under aerobic conditions oxygen and under anaerobic conditions nitrate as electron acceptor. Under anaerobic conditions bacterial groups X2, use sulfate as an electron acceptor. Sulfate rich wastewater is usually deficient in electron donor and requires external addition of electron donors in order to achieve complete sulfate reduction. The organic carbon as electron donor is one of the most important factors that affect sulfate reduction bacterial activity. In this study the possible source of organic carbon is the solid organic carbon supplied to the system in the form of sawdust. The results of this study indicate that sawdust could be employed as low-cost materials to enhance the biological sulfate reduction processes in porous media. While the availability of organic carbon as electron donor is one of the most important factors that affect the sulfate reducing bacterial activity in porous media, this study demonstrates that using sawdust as a carbon source can improve the bacterial activity and increase the column permeability.  相似文献   

The impact of Eurasian dust storms and anthropogenic emissions on atmospheric nutrient deposition rates in forested Japanese catchments and adjacent regional seas     

Jens Hartmann  Takao Kunimatsu  Jason K. Levy 《Global and Planetary Change》2008,61(3-4):117-134

Bulk precipitation and stream water chemistry data from 1993 to 2005 are used to analyze the relationship between Eurasian dust storms and nutrient deposition rates in the Kutsuki experimental forest (near Lake Biwa). From 2000 to 2005, atmospheric deposition, total nitrogen (TN), total phosphorus (TP) and dissolved silica (DSi) deposition rates increased by 26%, 132%, and 38%, respectively in the Kutsuki experimental forest. These TN and TP increases are associated with three seasonal factors: the increasing frequency and intensity of Eurasian spring dust events (March/April); the annual typhoon period (late August/September); and autumn/early winter (October to December) monsoons. The annual typhoon and monsoon winter periods are drivers for atmospheric TP and DSi deposition due to the correlation between the deposition and precipitation. In addition, increased spring dust deposition is a primarily driver for TN deposition changes. Increased emissions from urbanized areas in China (and likely Korea) affect the chemical properties of aerosols reaching downwind Japanese regions. Aerosol processes are responsible for increasing TN in aerosols, which are affected primarily by anthropogenic emissions. From 2000 to 2005, coal burning emissions from East Asia have contributed to an increase in TP (and possibly DSi) deposition rates. The observed increase in nutrient deposition did not noticeably impact short-term (5 year) stream water fluxes in the Kutsuki experimental forest. Due to plant uptake, the forest ecosystem retained atmospherically deposited N and P. Finally, the observed increases in nutrient deposition rates over the East China Sea and the Sea of Japan may significantly influence intra-annual net primary production. It is recommended that earth system modelling incorporate changes in atmospheric nutrient deposition rates and their impacts on the regional carbon cycle as well as aquatic and terrestrial ecosystems.  相似文献   

The nationwide investigation of endocrine disruptors in sediment of harbours   总被引：3，自引：0，他引：3  

Hosokawa Y  Yasui M  Yoshikawa K  Tanaka Y  Suzuki M 《Marine pollution bulletin》2003,47(1-6):132-138

Various types of endocrine disruptors or environmental hormones flow from their sources down into harbours through rivers and other watercourses, and are accumulated in sediment on the sea bottom. Tributyltin, which has been used as paint for ship bottoms, is considered one of the endocrine disruptors.In close cooperation with the other ministries and agencies, the Ports and Harbours Bureau of the Ministry of Land, Infrastructure and Transport carried out an investigation in 1999 to determine the actual condition of 12 endocrine disruptors in the sediment of 39 harbours, in order to gather fundamental data to be used in future examinations of policy. Furthermore, in 2000 the bureau chose seven harbours out of the above 39 harbours as subjects of an additional investigation regarding the surface distribution of endocrine disruptors in the harbour areas and the synchronistic change of accumulation of dioxin and other substances. As the result of the investigation regarding the surface distribution of endocrine disruptors accumulated in seven harbours, relatively high concentrations were measured in the innermost parts of harbours and the mouths of rivers. Synchronistic changes in the amount of dioxin and other substances accumulated in sediments of five harbours were determined. Small amounts of dioxin and other substances, including an especially small amount of coplanar-PCBs, were found in the layers formed before or around 1950. Relatively large amounts of these substances were measured in the upper layers formed during roughly 1960-1990, though no significant yearly differences in concentration could be identified. This result coincides with the facts that, during roughly 1960-1980, PCP and CNP were used as agricultural chemicals and full-scale production of PCBs started in 1960.  相似文献   

Long-term variations in north-south asymmetry of solar activity   总被引：1，自引：0，他引：1  

Derek B. Swinson  Hisako Koyama  Takao Saito 《Solar physics》1986,106(1):35-42

We present a new set of data on relative sunspot number (total, northern hemisphere, and southern hemisphere), taken for the 37-yr period 1947 to 1983; this constitutes a particularly coherent and consistent set of data, taken by the same observer (Hisako Koyama) using the same observing instrument. These data are combined with earlier data (White and Trotter, 1977) on the variation of sunspot areas for both solar hemispheres from 1874 to 1971. The combined data, covering 110 years and 10 solar cycles, are examined for periodicity in solar activity north-south asymmetry. We show that, in general, northern hemisphere activity, displayed as either An/(An + As) or Rn/(Rn + Rs), peaks about two years after sunspot minimum. This peak is greater during even cycles, pointing to a 22-yr periodicity in north-south asymmetry in solar activity, suggesting that the asymmetry is related to the 22-yr solar magnetic cycle. We demonstrate that the largest and most protracted period of northern-hemisphere activity excess in the last 110 years has occurred from 1959 to 1970; we show that there is a strong correlation between northern activity excess and a cosmic-ray density gradient perpendicular to the ecliptic plane, pointing southward, which is evident in cosmic-ray diurnal variation data from the Embudo underground cosmic-ray telescope.  相似文献   

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   

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

  相似文献   

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   

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