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Numerical study of the auroral particle transport in the polar upper atmosphere

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Science china(Technological sciences) 2008年第10期51卷 1759-1771页

作者： CAI HongTao1,2, MA ShuYing1,2 & PU ZuYin3 1 school of Electronic Information, Wuhan university, Wuhan 430079, china 2 Key Laboratory of Geospace Environment and Geodesy, ministry of education of PRC, Wuhan 430079, china 3 school of earth and space sciences, peking university, beijing 100871, china 1. school of Electronic Information Wuhan University Wuhan 430079 China 2. Key Laboratory of Geospace Environment and Geodesy Ministry of Education of PRC Wuhan 430079 China 3. school of earth and space sciences Peking University Beijing 100871 China

Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2), to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of pre-cipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2 ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that recon-structed from electron density measurements by the radar.

关键词： aurora particle precipitation polar upper atmosphere electron transport equation numerical simulation

Phase equilibria of HP–UHP mica-schists in Jiangling, Eastern Dabieshan orogen

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Progress in Natural Science:Materials International 2009年第8期19卷 973-982页

作者： Hang Chu a, Chunjing Wei a, Shangguo Su b a MOE Key Laboratory of Orogenic Belts and Crustal Evolution, school of earth and space sciences, peking university, beijing 100871, china b china university of Geosciences, beijing 100083, china [a]MOE Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space Sciences Peking University Beijing 100871 China [b]China University of Geosciences Beijing 100083 China

The HP–UHP metamorphic terrane of Jiangling, eastern Dabieshan comprises extensively distributed granitic gneisses, mica-schists and numerous eclogite blocks. The mica-schists generally contain garnet, phengitic muscovite, biotite, plagioclase, quartz, rutile and a small amount of epidote and hornblende. Study on petrography and phases equilibria in the NCKMnFMASH system indicates that the present mineral assemblages in mica-schists are not in equilibrium. The earlier stage of mineral assemblage represented by garnet and phengite reflects a HP–UHP condition. The garnet compositions and the phengite Si contents give a PT condition of 580–600 °C at 2.6–2.8 GPa. The garnet zonation records an earlier progressive metamorphic process which may be associated with the appearance of glaucophane, jadeite and lawsonite. The later stage of mineral assemblage characterized by the presence of biotite and plagioclase reflects a PT condition of 620–635 °C at 0.9–1.1 GPa, belonging to the HP amphibolite facies. The main mineral assemblage in micaschists from the Jiangling region has recorded a complete HP–UHP metamorphic process.

关键词： HP–UHP metamorphism Phase equilibria Mica-schist Dabieshan

Development of environmental monitoring satellite systems in china

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Science china earth sciences 2010年第S1期53卷 1-7页

作者： LI GuoPing1 & CAO ChunXiang2 1 school of earth and space sciences,peking university,beijing 100871,china 2 State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of sciences and beijing Normal university,beijing 100101,china 1. school of earth and space sciences Peking University Beijing 100871 China2. State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China

With the increase in global environmental problems,the necessity and urgency of remote sensing technology being applied to environmental monitoring has been widely recognized around the *** has launched the environment and disaster monitoring and forecasting small satellite constellation HJ-1A/B and the FY3 atmosphere and environmental satellite,but they still cannot fully satisfy requirements for environmental *** paper summarizes the current status of satellite environmental monitoring in china and the existing problems of inadequate load design and low data utilization efficiency,and discusses the demand for environmental monitoring *** on the development of foreign satellite systems for environmental monitoring,the future development and key tasks of the environmental monitoring satellite system in china is discussed,as are some related initiatives.

关键词： environmental satellite environmental monitoring global climate change specialty load satellite system

The developmental trend of labrum and median eyes of Orsten-type preserved Phosphatocopina (Crustacea)

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Science china earth sciences 2010年第1期53卷 18-26页

作者： LIU Zheng 1,2 & DONG XiPing 1,2 1 school of earth and space sciences,peking university,beijing 100871,china 2 State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of sciences,Nanjing 210008,china 1. school of earth and space sciences Peking University Beijing 100871 China2. State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China

The Phosphatocopina (Crustacea,Arthropoda) is an important group of 'Orsten-type' preserved *** is resolved as the sister-group of *** we study the labrum,the median eyes,and the inner lamella of Phosphatocopina based on the selected specimens respectively from western Hunan,South china,and *** labrum characters of different species exhibit interspecific *** ratio of labrum length/shield length is significant to the reconstruction of the ontogeny of *** labrum characters should be introduced to the diagnosis of *** the earliest growth stage,the median eyes were inconspicuous,almost as flat as the other area of the ***,with the growth of the individuals they became *** were two obviously concave structures on the ventral side of the hypostome in later stages,which were the positions where the median eyes should have been *** addition,the two modes of preservation of the inner lamella,i.e.,that of shrinking and that of bulging up,are interpreted as the preservational artifact herein.

关键词： Phosphatocopina Crustacea Orsten-type preservation morphology ontogeny Cambrian South china Sweden

Paleoceanographic evolution recorded in the northern South china Sea since 4 Ma

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Science china earth sciences 2005年第12期48卷 2166-2173页

作者： HUANG Baoqi1,2, JIAN Zhimin2 & WANG Pinxian2 1. school of earth and space sciences, peking university, beijing 100871, china 2. Laboratory of Marine Geology, Tongji university, Shanghai 200092, china 1. school of earth and space sciences Peking University 100871 Beijing China 2. Laboratory of Marine Geology Tongji University 200092 Shanghai China

Upper water structure over the last 4 million years in the northern South china Sea (SCS) was reconstructed by sea surface temperature (SST) and primary productivity estimated by changes in the abundance of planktonic foraminifer, planktonic foraminifer transfer function, and the accumulation rate of benthic foraminifera. Results of SST and primary productivity show that SST gradually decreased since 4 Ma, but differential seasonal temperature and primary productivity increased in steps mainly at about 3.1, 2.7, 2.1, 1.6, 0.9 and 0.5 Ma. Comparison with tectonics and orbital variations indicates that phased rising of the Tibet since 3.6 Ma, closing of Panama and Indonesian seaways, and orbital changes were responsible for the changes of upper water structure in the SCS, respectively.

关键词： northern South china Sea, upper water structure, Late Pliocene, planktonic foraminifer, ODP 1146.

The attenuation anisotropy of mudstones and shales in subsurface formations

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Science china earth sciences 2005年第11期48卷 1882-1890页

作者： SHI Ge1 & DENG Jixin1,2 1. The Key Labratory of Orogenic Belts and Crustal Evolution, school of earth and space sciences, peking university, beijing 100871, china 2. Geophysical Prospecting Key Lab (CNPC), university of Petroleum, beijing 102249, china 1. The Key Labratory of Orogenic Belts and Crustal Evolution School of Earth and Space Sciences Peking University 100871 Beijing China 2. Geophysical Prospecting Key Lab (CNPC) University of Petroleum 102249 Beijing China

We have measured the relationships in the laboratorial condition between the at-tenuation in three samples of mudstones and shales as well as two samples of layered sand-stones and the alteration in direction, confining pressure and pore fluid. The relative contributions of different attenuation mechanisms are also discussed. Studies show that the attenuation in dry and saturated samples is strongly related to pressure and direction. The attenuation coefficient of P-wave propagating parallel to bedding (PH ) is less than that of P-wave propagating vertical to bedding (PV ), while the attenuation coefficient of S-wave both propagating and vibrating parallel to bedding (SH ) and that of S-wave propagating vertical to bedding while vibrating parallel to bedding (SV1) are less than that of S-wave propagating parallel to bedding while vibrating verti-cal to bedding (SV ). Under oil saturated conditions, the Biot flow attenuation acts as the domi-nant mechanism for waves propagating parallel to bedding, while the frame anelastic attenuation and squirt flow attenuation seem to play important roles in condition of propagation vertical to bedding.

关键词： mudstone, shale, attenuation, anisotropy, attenuation mechanism

Two new species of Vestrogothia (Phosphatocopina, Crustacea) of Orsten-type preservation from the Upper Cambrian in western Hunan, South china

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Science china earth sciences 2009年第6期52卷 784-796页

作者： ZHANG HuaQiao1,2 & DONG XiPing1,2 1 school of earth and space sciences,peking university,beijing 100871,china 2 State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of sciences,Nanjing 210008,china school of earth and space sciences Peking University Beijing 100871 China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China

Although fossils of Orsten-type preservation represented by Skaracarida and Phosphatocopina were first reported from the Middle and Upper Cambrian in western Hunan, South china in 2005, diversified phosphatocopine species have never been appropriately described and elucidated in terms of their evolutionary relationships. Here, we described two new species of Phosphatocopina, Vestrogothia anterispinata sp. nov. and V. bispinata sp. nov. The evolutionary relationship among all the valid species of Phosphatocopina is discussed and the phylogeny of Phosphatocopina is reestablished using cladistic analysis. Accordingly, phosphatocopines primitively evolved along two lineages: one evolved towards the emergence of lobes; the other evolved towards the emergence of dorsal spines. Respectively, lobes originated independently three times, and dorsal spines originated only once. With regard to the dorsal rims, interdorsum originated first, whereas dorsal furrow originated independently twice on the basis of interdorsum. Probably Hesslandona may represent a polyphyletic group, whereas Vestrogothia a monophyletic group.

关键词： fossils of Orsten-type preservation Vestrogothia Phosphatocopina Crustacea evolution phylogeny Cambrian Hunan

Source time-function as discriminant using empirical Green's function

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Science china earth sciences 2005年第12期48卷 2118-2122页

作者： HE Yongfeng1,2 & CHEN Xiaofei1 1. Department of Geophysics, school of earth & space sciences, peking university, beijing 100871, china 2. North-West Institute of Nuclear Technology, Xi’an 710024, china 1. Department of Geophysics School of Earth & Space Sciences Peking University 100871 Beijing China 2. North-West Institute of Nuclear Technology 710024 Xi’an China

The source mechanism of underground nuclear explosions is remarkably different from that of earthquakes in both spatial radiation pattern and source time-function (STF). Small underground nuclear explosions can be used as empirical Green’s functions (EGF) to isolate the source-time spectrum of a large suspected earthquake occurred in a Nuclear Test Site (target area) by the spectral division method. As this study shows, with high-quality data, the quotient spectrum can be transformed to the time domain, yielding the apparent far-field source-time function of the large suspected event. The relative source time-function (RSTF) of a nuclear ex-plosion is usually a simple pulse with a duration of about 1 s., while an earthquake’s is more complicated with a series of pulses and a longer duration. The RSTF can be used as a nice dis-criminant to distinguish the nature earthquakes from underground nuclear explosions in target areas.

关键词： target-area, empirical Green's function, RSTF.

Zircon SHRIMP geochronology and geochemistry of TTG rocks in Sushui Complex from Zhongtiao Mountains with its geological implications

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Progress in Natural Science:Materials International 2006年第5期16卷 492-500页

作者： TIAN Wei, LIU Shuwen, LIU Chaohui, YU Shengqiang, LI Qiugen and WANG Yueran (Key Laboratory of Orogenic Belt and Crustal Evolution, MOE, school of earth and space sciences, peking university, beijing 100871, china) [a]Key Laboratory of Orogenic Belt and Crustal Evolution MOE School of Earth and Space Sciences Peking Univenity Beijing China

The tonalite-trondhjemite-granodiorite (TTG) rocks in Sushui Complex of Zhongtiao Block can be divided into two series according to their zircon U-Pb ages and geochemical characteristics: one is subduction-related (SR) and the other collision-related (CR) . The SR TTG rocks, together with other Late Archean island arc magmatism, were developed as a result of oceanic subduction between the Eastern and Western blocks in Late Archean; while the CR TTG rocks formed in a thickened crustal environment, which was responding to the collision between the Eastern and Western blocks in Paleoproterozoic. All these features support a model that the Zhongtiao Block is a part of the Trans-North china Orogen in the middle of North china Craton.

关键词： Sushui Complex Zhongtiao Block Trans-North china Orogen zircon U-Pb geochronology trace element simulation.