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Magnetic Energy of Force-Free Fields with Detached Field Lines

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Chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 555-562页

作者： Guo-Qiang Li and You-Qiu HuSchool of earth and space sciences, {3. of science and technology of China, hefei 2.0026 School of earth and space sciences University of Science and Technology of China Hefei 230026

Using an axisymmetrical ideal MHD model in spherical coordinates, we present a numerical study of magnetic configurations characterized by a levitating flux rope embedded in a bipolar background field whose normal field at the solar surface is the same or very close to that of a central dipole. The characteristic plasma β (the ratio between gas pressure and magnetic pressure) is taken to be so small (β = 10-4) that the magnetic field is close to being force-free. The system as a whole is then let evolve quasi-statically with a slow increase of either the annular magnetic flux or the axial magnetic flux of the rope, and the total magnetic energy of the system grows accordingly. It is found that there exists an energy threshold: the flux rope sticks to the solar surface in equilibrium if the magnetic energy of the system is below the threshold, whereas it loses equilibrium if the threshold is exceeded. The energy threshold is found to be larger than that of the corresponding fully-open magnetic field by a factor of nearly 1.08 irrespective as to whether the background field is completely closed or partly open, or whether the magnetic energy is enhanced by an increase of annular or axial flux of the rope. This gives an example showing that a force-free magnetic field may have an energy larger than the corresponding open field energy if part of the field lines is allowed to be detached from the solar surface. The implication of such a conclusion in coronal mass ejections is briefly discussed and some comments are made on the maximum energy of force-free magnetic fields.

关键词： Sun: magnetic fields - Sun: coronal mass ejections (CMEs) -methods: numerical

Sm-Nd and zircon SHRIMP U-Pb dating of Huilanshan mafic granulite in the Dabie Mountains and its zircon trace element geochemistry

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science China earth sciences 2005年第12期48卷 2081-2091页

作者： HOU Zhenhui1, LI Shuguang1, CHEN Nengsong2, LI Qiuli1 & LIU Xiaoming3.1. School of earth and space sciences, {3. of science and technology of China, hefei 2.0026, China 2. The Key Laboratory of Continental Dynamics of the Ministry of Education, Northwest {3., Xi’an 710069, China 3. Faculty of earth sciences, China {3. of Geosciences, Wuhan 43.074, China 1. School of earth and space sciences University of Science and Technology of China 230026 Hefei China 2. The Key Laboratory of Continental Dynamics of the Ministry of Education Northwest University 710069 Xi’an China 3. Faculty of earth sciences China University of Geosciences 430074 Wuhan China

The mafic granulites from Huilanshan are outcropped on the center of the Luotian dome in the northern Dabie Mountains. The Sm-Nd isochron defined by granulite-facies meta-morphic minerals (garnet + clinopyroxene + hypersthene) yields an age of 13. ± 18 Ma indicating the early Cretaceous granulite-facies metamorphism. The cathodoluminescence (CL) images of zircons from the granulite show clearly core-mantle-rim structures. The zircon cores are charac-terized by typical oscillatory zoning and highly HREE enriched patterns, which suggests their magma origin. Some zircon cores among them with little Pb loss give SHRIMP U-Pb ages rang-ing from 753.to 780 Ma, which suggests that the protolith of Huilanshan granulite is Neopro-terozoic mafic rocks. The zircon mantles usually cut across the oscillatory zone of the zircon cores have 3.10 times lower REE, Th, U, Y, Nb and Ta contents than the igneous zircon cores but have high common Pb contents. These characteristics suggest that they were formed by hydrothermal alteration of the igneous zircons. The part of zircon mantles with little Pb loss give a similar SHRIMP U-Pb age (716―780 Ma) to the igneous zircon cores, which implies that the hydrothermal events occurred closely to the magmatic emplacement. In view of the strong early Cretaceous magmatism in the Luotian dome, consequently, the Huilanshan mafic granulite was formed by heating of the Neoproterozoic mafic rocks in mid-low crust, which caused the granu-lite-facies metamorphism underneath the Dabie Mountains. The similarity between the granulite metamorphic age (13. ± 18 Ma) defined by Sm-Nd isochron and K-Ar age of 123.127 Ma given by amphible from the gneiss in Luotian dome suggests a rapid uplifting of the Luotian dome, which may result in further exhumation of the ultrahigh pressure metamorphic rocks in the Dabie Mountains.

关键词： Dabie orogen, granulite, zircon U-Pb ages, Sm-Nd age.

Coronal Flux Rope Equilibria in Closed Magnetic Fields

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Chinese Journal of Astronomy and Astrophysics 2003年第3期3卷 241-246页

作者： Zhen Wang and You-Qiu HuSchool of earth and space sciences, {3. of science and technology of China, School of earth and space sciences University of Science and Technology of China Hefei 230026

Using a 2.5-dimensional ideal MHD model in Cartesian coordinates, weinvestigate the equilibrium properties of coronal magnetic flux ropes in background magnetic fieldsthat are completely closed. The background fields are produced by a dipole, a quadrupole, and anoctapole, respectively, located below the photosphere at the same depth. A magnetic flux rope isthen launched from below the photosphere, and its magnetic properties, i.e., the annular magneticflux Φ_p and the axial magnetic flux Φ_z, are controlled by a single emergence parameter. Thewhole system eventually evolves into equilibrium, and the resultant flux rope is characterized bythree geometrical parameters: the height of the rope axis, the half-width of the rope, and thelength of the vertical current sheet below the rope. It is found that the geometrical parametersincrease monotonically and continuously with increasing Φ_p and Φ_z: no catastrophe ***, there exists a steep segment in the profiles of the geometrical parameters versus eitherΦ_p or Φ_z, and the faster the background field decays with height, the larger both the gradientand the growth amplitude within the steep segment will be.

关键词： sun: magnetic fields sun: corona

Two possible mechanisms for vortex self-organization

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science China earth sciences 2006年第2期49卷 202-211页

作者： LUO Zhexian2, ZHOU Xiuji1 & GAO Shouting3.1. Chinese Academy of Meteorological sciences, Beijing 100081, China 2. department of space Information science, Nanjing university of Information science and technology, Nanjing 2.0044, China 3. Institute of Atmospheric Physics, Chinese Academy of sciences, Beijing 100029, China 2. department of Environmental science Nanjing University of Information Science and Technology Nanjing 210044 China 1. Chinese Academy of Meteorological sciences Beijing 100081 China 3. Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The vortex self-organization is investigated in this paper by four groups of numerical experiments within the framework of quasi-geostrophic model, and based on the experimental results two types of possible mechanisms for vortex self-organization are suggested. The meso-scale to-pography may enable separated vortices to merge into a larger scale vortex; and the interaction of meso-γ and meso-β scale systems may make separated vortices to self organize a typhoon-like vor-tex circulation.

关键词： vortex, self-organization, meso-scale topography, interaction of different scales.

TOPOLOGICAL CONFIGURATIONS OF POSSIBLE REAL NETS IN BINARY n+m(m≥3. PHASE MULTISYSTEMS

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science in China,Ser.B 1986年第10期29卷 1096-1109页

作者：程伟基 department of earth and space {3.s university of science and technology of China hefei

This paper further summarizes the method and results developed to find all possible real nets in binary n+3.phase multisystems, and emphasizes that there is a definite relationship between configurations and symbols of stable and metastable invariant points of nets or positions of phases as symbols on the chemographic bar. On the basis of these, a general principle is developed to construct and check possible neets in binary n+m (m>3. phase multisysterns: this sort of nets must be the reasonable combination of one or more than one distinct binary n+3.phase multisystem subnets, in which the number of points missing respectively same m—3.phases in n+3. Therefore, the binary n-4-3.phase nets are basic construction units of the binary n+m(m>3. phase nets. As an instance, the maximum partially closed net in binary n+4 phase multisystems, which has the most stable invariant points, is constructed, and it is indicated that this sort of net is unique.

关键词： PHASE MULTISYSTEMS TOPOLOGICAL CONFIGURATIONS OF POSSIBLE REAL NETS IN BINARY n+m net NETS

Re-Os isotopic system and formation age of subcontinental lithosphere mantle

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Chinese science Bulletin 2000年第3期45卷 193-200页

作者： ZHI Xiachendepartment of earth and space {3.s, university of {3. and technology of China, hefei 2.0026, China Advance Research Center for earth {3. and Astronomy, USTC, Third World Academy of {3., hefei 2.0026, China Laboratory of Chemical Geodynamics, USTC, hefei 2.0026, China department of earth and space {3.s University of Science and Technology of China Hefei China Advance Research Center for earth science and Astronomy USTC Third World Academy of Science Hefei China Laboratory of Chemical Geodynamics USTC Hefei China

The determination of the formation age of subcontinental Lithosphere Mantle (SCLM) is a widely concerned issue in mantle geochemistry. it is difficult to obtain the formation age of SCLM using lithophile isotopic systems such as Rb-Sr, Sm-Nd, U-Th-Pb, ete., but as siderophile elements, the Re-Os isotopic system provides a powerful tool for that work. Here a comprehensive review on the recent development in Re-Os dating for SCLM has been given.

关键词： Re-Os isotopic dating subcontinental lithospheric mantle mantle derived peridotites Re depleted model age whole rock isochronological age.

Mineralogical evidence for continental deep subduction

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Chinese science Bulletin 2003年第10期48卷 952-954页

作者： ZHENG Yongfei School of earth and space sciences, {3. of science and technology of China, hefei 2.0026, China School of earth and space science University of Science and Technology of China China

Discusses the findings of mineralogical investigations into the geodynamic processes of plate subduction and exhumation. Identification of the ultrahigh pressure index minerals in Dabie-Sulu metamorphic rocks; Finding... 详细信息

关键词：矿物学超高压石英地球表面正态重力梯度

Characteristics of low-frequency oscillation intensity of airsea turbulent heat fluxes over the northwest Pacific

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science China earth sciences 2009年第8期52卷 1137-1151页

作者： LI Gen, REN BaoHua, ZHENG JianQiu & WANG Jun School of earth and space sciences, {3. of science and technology of China, hefei 2.0026, China 1. School of earth and space sciences University of Science and Technology of China Hefei 230026 China

Based on the daily turbulent heat fluxes and related meteorological variables datasets (1985-2.06) from Objectively Analyzed air-sea Fluxes (OAFlux) Project of Woods Hole Oceanographic Institution (WHOI), characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific are analyzed by linear perturbation method and correlation analysis. It can be concluded that: 1) the distribution of low-frequency oscillation intensity of latent heat flux (LHF) over the northwest Pacific is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea humidity gradient (Δq′) as well as mean air-sea humidity gradient ( Δ q), while the distribution of low-frequency oscillation intensity of sensible heat flux (SHF) is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea temperature gradient (ΔT′). 2) The low-frequency oscillation of turbulent heat fluxes over the northwest Pacific is the strongest in winter and the weakest in summer. And the seasonal transition of low-frequency oscillation intensity of LHF is jointly influenced by those of low-frequency oscillation intensity of Δq′, low-frequency oscillation intensity of anomalous wind speed (U′), Δ q and mean wind speed (U ), while the seasonal transition of low-frequency oscillation intensity of SHF is mainly influenced by those of low-frequency oscillation intensity of ΔT′ and U . 3. Over the tropical west Pacific and sea areas north of 20°N, the low-frequency oscillation of LHF (SHF) is mainly influenced by atmospheric variables qa′ (Ta′) and U′, indicating an oceanic response to overlying atmospheric forcing. In contrast, over the tropical eastern and central Pacific south of 20°N, qs′ (Ts′) also greatly influences the low-frequency oscillation of LHF (SHF).

关键词： northwest Pacific latent heat flux sensible heat flux low-frequency oscillation

Discovery and analysis of ultra-micro grinding grain texture in slipping lamellae of ductile-brittle zone

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science China earth sciences 2004年第3期47卷 265-271页

作者： GE Heping1, SUN Yan1, LU Xiancai1, ZHU Wenbin1, GUO Jichun1, LIU Deliang2 & Chi-yuen Wang3.1. department of earth sciences, Nanjing {3., State Key Laboratory of Mineral Deposit, Nanjing 2.0093. China 2. department of earth and space sciences, {3. of science and technology of China, hefei 2.0026, China 3. department of Geology and Geophysics, {3. of California, Berkeley, CA 94720, USA Nanjing Univ Dept Earth Sci State Key Lab Mineral Deposit Nanjing 210093 Peoples R China Univ Sci & Technol China Dept Earth & Space Sci Hefei 230026 Peoples R China Univ Calif Berkeley Dept Geol & Geophys Berkeley CA 94720 USA

Based on the observation of the deep bore cores sampled from the State of Cali-fornia, USA, preferred arranged particulate concentration belts were found in the ultra-slipping lamellae. And the same phenomenon was found again later in the bore cores from the petroleum basin in the Northern Shaanxi Province. It may be the product of the dynamic processes involv-ing tumbling, grinding and compresso-shearing functions, so the spherical particulates with ul-tra-size of nm and mm are called grinding grain. The formation of the grinding grains is related with the ductile-brittle deformation, the lateral pressure of the slipping, and the very low grade of dynamic metamorphism of the rocks. Based on the systematic analysis, it is indicated that some elements like Nb and Ta are enriched in the grinding grains in the granitic rocks because of the chemical differentiation, and that the slipping lamellae bearing grinding grains in mudstone with smear efficiency prove a perfect seal for oil and gas reservoirs. Meanwhile, the paper provides bases for the studies on the fast stick-slip movement and shear paradigm.

关键词： slipping lamellae, grinding grain texture, ductile-brittle deformation, smear efficiency.