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Abrupt climate change and collapse of ancient civilizations at 2200BC-2000BC

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Progress in Natural Science:Materials International 2005年第10期15卷 46-52页

作者： WANG Shaowu (Department of atmospheric Science, School of physics, Peking University, Beijing 100871, China) Department of atmospheric Science School of Physics Peking University Beijing 100871 China

Plentiful evidence of historical, archaeological and palaeoclimatic studies proved that an abrupt change from wetter to drier climate occurred over the Nile Valley,the Mesopotamia, the Indus Valley and Huanghe River Valley at 2200BC-2000BC. The abrupt change was developed based on the general lowering of temperature in the middle latitudes, and was a strong cold event since the beginning of the Megathermal (8.5-3.0 kaBP). Collapse of Nile civilization appeared at the First Intermediate Period (2181BC-2040BC). Civilization of Mesopotamia began collapse following the disintegration of Akkadian Empire. This process lasted to the foundation of Babylon Kingdom from 2200BC to 1900BC. Indus civilization abruptly fell off at 1800BC. A widespread alternation of archaeological cultures happened in China at ca. 2000BC except only in its central part. Longsheng culture was replaced by the Erlitou culture, which is now acknowledged in China as Xia Culture. Foundation of Xia Dynasty at 2070BC opened a new chapter in the development of Chinese civilization. Studies indicated that abrupt climate change may be caused by the weakening of the Thermohaline Circulation (THC).

关键词： 2200BC-2000BC abrupt climate change collapse of ancient civilization.

THE CISK-OVERSTABILITY CONVECTION

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Science in China,Ser.B 1984年第5期27卷 501-510页

作者：李崇银 institute of atmospheric physics Academia Sinica Beijing

A kind of the conditional instability of the second kind (CISK)--overstability convec-tion presented in the hurricane model is investigated in this paper. The structure of thisunstable mode and the basic conditions to excite it are also shown for discussion. In the tropical atmosphere, the cumulus convection could excite the CISK oscillatoryunstable mode through the CISK mechanism, and the cumulus friction (cumulus momentummixing) gives a fundamental effect to produce this overstability convection. Some meteorologists assumed that the waves in the lower stratosphere in the tropicalatmosphere may be caused by the forcing of the condensation heating. The present investi-gation shows from the dynamic angle that the CISK-overstability convection excited by thecumulus convection heating, especially by the cumulus momentum mixing, through the CISKmechanism is a fundamental factor to drive the waves in the equatorial stratosphere and theoscillatory phenomena in tropical atmosphere.

关键词： mode THE CISK-OVERSTABILITY CONVECTION

Maximal possible accretion rates for slim disks

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Science China(physics,Mechanics & Astronomy) 2009年第12期52卷 2054-2058页

作者： LIN YiQing1 & JIAO ChengLiang2 1 Department of Mathematics and physics,Xiamen University of Technology,Xiamen 361024,China 2 Department of physics and institute of Theoretical physics and Astrophysics,Xiamen University,Xiamen 361005,China 1. Department of Mathematics and physics Xiamen University of Technology Xiamen 361024 China 2. Department of physics and institute of Theoretical physics and Astrophysics Xiamen University Xiamen 361005 China

It was proved in the previous work that there must be a maximal possible accretion rate $ \dot M_{max} $ for a slim disk. Here we discuss how the value of $ \dot M_{max} $ depends on the two fundamental parameters of the disk, namely the mass of the central black hole M and the viscosity parameter α. It is shown that $ \dot M_{max} $ increases with decreasing α, but is almost independent of M if $ \dot M_{max} $ is measured by the Eddington accretion rate $ \dot M_{Edd} $ , which is in turn proportional to M.

关键词： accretion disks black hole physics hydrodynamics

The tri-band high spectral resolution spectrometer with gratings in tandem for the charge-exchange recombination spectroscopy diagnostic system on HL-2A tokamak

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Plasma Science and Technology 2024年第6期26卷 103-110页

作者：刘亮余德良马倩何小斐 Maarten DE BOCK Manfred von HELLERMANN Michael WALSH 陈文锦何小雪魏彦玲张能李栋魏会领 the HL-2A Team Southwestern institute of physics Chengdu 610041People’s Republic of China College of physics and Optoelectronic Technology Baoji University of Arts and SciencesBaoji 721000People’s Republic of China ITER Organization Route de Vinon-sur-VerdonCS 90046St.Paul Lez Durance Cedex 13067France Fusion Spectroscopy Markgraf-Albrecht Str.14Berlin 10711Germany

Charge-exchange(CX) recombination spectroscopy is a powerful tool monitoring ion temperature and plasma rotation with good temporal and spatial resolutions. A compact, new design for a high-throughput, tri-band high spectral resolution spectrometer has been developed for the charge-exchange recombination spectroscopy measurement on the HL-2A tokamak. The simultaneous measurements of He II(468.57 nm), C VI(529.1 nm), and Dα(656.1 nm accompanied by beam emission spectra) with an acquisition frequency up to 400 Hz are achieved by vertically binning the spectrum from each fiber in experiments. Initial results indicate that the system can provide radial profiles of not only ion temperature and rotation velocity,but also concentration of carbon. For the case of helium, the measurements for the ion temperature and rotation velocity are straightforward but the apparent concentration associated with the observed CX intensity is obviously too high. Modeling of the active He II CX feature including plume contributions needs to be carried out to extract the true helium *** spectrometer could become a prototype for the ITER charge-exchange recombination spectroscopy diagnostic and the pilot experiments, as presented here, demonstrate the possibility of impurity concentrations measurements based on the combined measurement of local beam emission and charge-exchange recombination spectroscopy spectra.

关键词： CXRS ion temperature plasma rotation impurity concentration

Approaches to improving critical current density of YBCO superconducting thick films deposited by electrophoresis

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Science China(physics,Mechanics & Astronomy) 2004年第2期47卷 165-172页

作者： ZHU Yabin1,2, ZHOU Yueliang2, LIU Zhen2, WANG Shufang2, CHEN Zhenghao2, L?Huibin2, YANG Guozhen2, XIAO Ling3, REN Hongtao3, JIAO Yulei3 & ZHENG Minghui3 1. Department of physics, College of Science, Beijing Jiaotong University, Beijing 100044, China 2. Laboratory of Optical physics, institute of physics and Center for Condensed Matter physics, Chinese Academy of Sciences, Beijing 100080, China 3. General Research institute for Nonferrous Metals, Beijing 100088, China Correspondence should be addressed to Zhu Yabin (email: ybzhu@***) 1. Department of physics College of Science Beijing Jiaotong University 100044 Beijing China 2. Laboratory of Optical physics institute of physics and Center for Condensed Matter physics Chinese Academy of Sciences 100080 Beijing China 3. General Research institute for Nonferrous Metals 100088 Beijing China

Fabrication of YBCO superconducting thick films by electrophoresis has been widely reported. However, the value of critical current density (J c) is far from what the practical application requires. The superconducting thick films are obtained using top-seeded melt growth method with different proportional Y2BaCuO5 (Y211) addition. High-pressure oxygen has been used in the annealing process to improve the uniformity of the oxygen content in the superconducting thick films. When 40mol% Y211 powder is added to the YBa2Cu3O7–5 (Y123) powder,J c for the superconducting thick film by approaches described above reaches 7.008×103 A/cm2 (77 K, 0 T), which is greater than the value ever reported.

关键词： YBCO thick films, electrophoretic deposition, melt-textured.

Using lightning locating system based on time-of-arrival technique to study three-dimensional lightning discharge processes

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Science China Earth Sciences 2010年第4期53卷 591-602页

作者： ZHANG GuangShu1,WANG YanHui1,QIE XiuShu2,ZHANG Tong1,ZHAO YuXiang1,3,LI YaJun1 & CAO DongJie11 Laboratory for Climate Environment and Disasters of Western China,Cold and Arid Regions Environmental and Engineering Research institute,Chinese Academy of Sciences,Lanzhou 730000,China 2 Laboratory for Middle Atmosphere and Global Environment Observation(LAGEO),institute of atmospheric physics,Chinese Academy of Sciences,Beijing 100029,China 3 Department of physics,Tianshui Normal College,Tianshui 741001,China 1. Laboratory for Climate Environment and Disasters of Western China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China2. Laboratory for Middle Atmosphere and Global Environment Observation (LAGEO) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China3. Department of Physics Tianshui Normal College Tianshui 741001 China

A time-of-arrival(TOA) system based on GPS technology for locating VHF radiation sources from lightning has been developed and used in observation sites in the northern Shandong Province,*** 3D images of the lightning progression have been obtained successfully for the first time in *** 3D-channel evolutions of typical negative CG,positive CG and IC lightning flashes have been discussed together with the data of fast electric field *** was found that significant differences existed between the negative and positive CG lightning flashes in terms of the initiation and propagation of the radiation *** preliminary breakdown of a negative CG lightning flash propagated at a speed about 5.2×104 m/*** stepped leader of negative CG lightning flashes was trigged by negative initial ***,it propagated downward at a speed of 1.3×105 m/*** initial process of the positive CG lightning flashes was also a propagation process of negative *** streamers propagated dominantly horizontally in the positive charge region and accumulated positive charges at the origin of the lightning,and as a consequence,initiated downward positive streamers.A new type of lightning discharge that was triggered by a narrow bipolar pulse(NBP) is discussed in this *** NBP was originated at altitude of about 10.5 km in the upper positive charge *** a distinct difference from normal IC flash,its channels extended horizontally all around and produced a lot of radiation *** source power of the NBP could approach 16.7 kW,which is much greater than that of normal lightning discharge ranging between 100 mW and 500 *** 3D propagation of this new type of lightning discharge was observed and obtained for the first time in *** possible initiation mechanism of this new type of light-ning is discussed here.

关键词： time-of-arrival(TOA) technique three dimensional lightning locating system discharge process narrow bipolar pulse new-type of IC lightning

SIMULATION ON SITE ERRORS'ESTIMATION

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高原气象 1992年第3期11卷 285-293页

作者： Chen Mingli Guo Changming(Lanzhou institute of Plateau atmospheric physics, Chinese Academy of Sciences, Lanzhou, Gansu 730000) 中科院兰州高原大气物理所甘肃兰州

In this paper, using the same simulated conditions that Lopez and Passi (1989) used, the method of Chen et a1.(1991) (CLG’s algorithm) for site error estimation has been performed. The results show that the CLG works well for a four-DF network but still has some shortcomings for a three-DF system. The reason why there is a big difference between a four-DF network and a three-DF network is also discussed and several measures to improve the performance of CLG’s algorithm are suggested. For practice, we have also done the simulated experiment for the Beijing local three-DF network. This is helpful for us to use the data obtained in this network.

关键词： Lightning location system Site errors Cloud-to-ground lightning.

Spatial and temporal distribution of total ozone over China

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Journal of Environmental Sciences 1999年第3期11卷 361-366页

作者： Gao Qing xian, Ren Zhen hai institute of atmospheric physics, Chinese Academy of Sciences, Beijing 100012, China. E mail: gaoqx@*** Zhang Yun gang Center of Satellite Meteorology, Beijing, China Zhang Cheng chang Beijin institute of atmospheric physics Chinese Academy of Sciences Beijing 100012 China Center of Satellite Meteorology Beijing China Beijing institute of Meteorology Beijing China

In this paper the grid data of total ozone mapping spectrograph (TOMS) installed on Nimbus 7 satellite (1978 to 1994) was used and the spatial and temporal distribution of total ozone over China was analyzed. The research indicates that the Qinghai Tibet Plateau destroyed the latitudinal distribution of total ozone of China and the low value closed center emerged over Qinghai Tibet Plateau. Long time change trends of seasonal total ozone of Qinghai Tibet Plateau are provided. It shows that the most obvious decrease of total ozone occurs in winter (Jan.), then in summer (Jul.), the relevant slow change occurs in autumn (Oct.) and spring (Apr.).

关键词： total ozone TOMS Qinghai Tibet Plateau.

An improved δ-Eddington approximation

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Chinese Science Bulletin 1999年第4期44卷 304-309页

作者： QIU Jinhuaninstitute of atmospheric physics , Chinese Academy of Sciences , Beijing 100029, China institute of atmospheric physics Chinese Academy of Sciences Beijing China

Based on an accuracy analysis of two-stream approximations, an improved δ-Eddington ap-proximation is developed. The approximation has much better accuracy than all exiting two-stream ap-proximations as the optical depth is less than unity. As the surface reflectance is zero and the opticaldepth is less than unity, errors in both transmission and reflection calculated by the present approxima-tion are more one time less than those by other two-stream approximations. In the case of aerosol opti-cal depth of2.6%, respectively. The errors are over 41% and one times lessthan those by Eddington or δ-Eddington.

关键词： radiation flux fractional factor of δ-function Eddington approximation.