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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-204.BC). 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.

NONLINEAR MECHANISM OF ABRUPT CHANGE OF atmospheric CIRCULATION DURING JUNE AND OCTOBER

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Science in China,Ser.B 1983年第7期26卷 746-754页

作者：李麦村罗哲贤 institute of atmospheric physics Academic Sinica beijing Department of Meteorology and Physical Oceanography Massachusetts institute of Technology Meteorological Bureau of Gansu Province Lanzhou

By the low-order spectral model, the abrupt change of the circulation in the barotropic atmosphere is studied. In certain parametric combinations, along with the gradual change of the external thermal forcing, the quasi-cusp pattern abrupt changes of both the spectral coefficients and the locations of west jet stream are stimulated, which are similar to the rapid northward jumping and suddenly establishing of the 'South-Branch' jet stream during June and October respectively. Depending on the changes of the parametric combinations, the motional form of the abrupt change can be substituted by that of the gradual change of one stable equilibrium, or by that of the branching phenomena of the multiple equilibria. The abrupt change mechanism of the atmospheric circulation is a nonlinear mechanism which contains the thermal forcing, dissipation, and thermal and dynamic effects.

关键词： NONLINEAR MECHANISM OF ABRUPT CHANGE OF atmospheric CIRCULATION DURING JUNE AND OCTOBER

A method for calculating the total ozone amount in the clear skies

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Journal of Environmental Sciences 1996年第3期8卷 308-312页

作者： Bai Jianhui Wang Gengchen(institute of atmospheric physics, Chinese Academy of Sciences,{3., China) institute of atmospheric physics Chinese Academy of Sciences Beijing 100029 China

A new method for calculating the clear day total ozone amount was obtained by the regression analysis of the observation data of ozone,solar UV radiation, and meteorological *** this method the monthly mean total ozone amounts for the year 1991 in beijing were calculated. Generally, the calculated values agree well with the Dobson spectrophotometer measurements, the average relative deviation between them being less than 2. 2%. According to the F-test,the photochemical reactions in the atmosphere,the solar UV radiation,and the aerosols are three most important factors to affect the column total ozone amount.

关键词： total ozone amount solar UV radiation photochemical reaction.

Covarying modes of the Pacific SST and northern hemispheric midlatitude atmospheric circulation anomalies during winter

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Progress in Natural Science:Materials International 2008年第10期18卷 1261-1270页

作者： Yimin Zhu~(a,b,*) Xiuqun Yang~a Qian Xie~b Yongqiang Yu~c ~a Department of A tmospheric Science,Nanjing University,Nanjing 210093.China ~b institute of Meteorology,PLA University of Science and Technology,Nanjing 211101,China ~c LASG,institute of atmospheric {3.,Chinese Academy of Sciences,{4. 10002.,China Department of atmospheric Science Nanjing University Nanjing 210093 China institute of Meteorology PLA University of Science and Technology Nanjing 211101 China LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The interannual-to-interdecadal relationship between the Pacific sea surface temperature (SST) and the northern hemispheric midlati- tude’s atmosphere represented by the circumpolar vortex was documented with the global oceanic and atmospheric reanalysis data of recent 50 *** covarying modes of the Pacific SST and northern circumpolar vortex anomalies during winter were examined using the sin- gular value decomposition and wavelet analysis *** is the interannual,ENSO-related mode and the other is the interdecadal, North Pacific SST-related mode with a period of around 20 *** two modes exhibit distinct spatial *** the interannual mode,the SST anomaly is characterized by a typical ENSO pattern with the principal signature in the tropical eastern Pacific and secondary one in the central North Pacific,while the atmospheric anomaly is regional,characterized by a Pacific-North American *** the inter- decadal mode,large SST anomaly is located in the central North Pacific,while the atmospheric anomaly is zonally global,associated with the midlatitute’s standing long-wave *** the central North Pacific is colder,the long-wave is stronger,and vice *** investigations suggest that the interdecadal mode could involve an interaction between "two oceans and an atmosphere".

关键词： Sea surface temperature atmospheric circulation ENSO Decadal variability

Computational properties of a new horizontal staggered grid

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Science China Earth Sciences 2005年第9期48卷 1559-1568页

作者： LIU YudiState Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics, institute of atmospheric physics, Chinese Academy of Sciences, beijing 10002., China {3. of Meteorology, PLA University of Science and Technology, Nanjing 211101, China 1. State Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Ph Chinese Academy of Sciences 100029 Beijing China 2. institute of Meteorology PLA University of Science and Technology 211101 Nanjing China

This paper presents a new horizontal staggered grid (LE grid), which defines h at a gridpoint, and both u and v at the same mid-gridpoint along the x and y directions. A general method is used to deduce the dispersion relationships of describing inertia gravity waves on LE grid and Arakawa A―E grids, which are then compared with the analytical solution (AS) in re- solved or under-resolved cases, using two-order central difference or four-order compact differ- ence scheme from the frequency and group velocity. Results show that in both resolved and under-resolved cases, no matter whether two-order central difference or four-order compact dif- ference scheme is used, the frequency and group velocity discrete errors on LE grid in describing inertia gravity waves are smaller than those of Arakawa A―E grids. At the same time, it is only on LE or Arakawa grid C that the employment of a compact difference scheme of higher difference precision can improve their accuracy in describing inertia gravity waves. However, as for the other four grids (Arakawa A,B,D and E), when the difference precision increases, the accuracy of simulating inertia gravity waves decreases.

关键词： horizontal staggered grid, inertia gravity wave, LE grid, Arakawa A-E grid, compact difference scheme, central difference.

Random walk modeling of wake dispersion for the exhaust tower of an underground tunnel in urban area

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Journal of Environmental Sciences 1999年第4期11卷 474-479页

作者： JIANG Wei\|mei\+1, YU Hong\|bin\+1, LI Xin\+2 (1.Department of atmospheric Sciences, Nanjing University, Nanjing 210093. China 2.lapc, institute of atmospheric physics,Chinese Academy of Sciences,{3., China) Department of atmospheric Sciences Nanjing University Nanjing 210093 China lapc Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

In this paper, some experimental studies on the impact of effluent from an exhaust tower of an underground tunnel with special construction are reported. By measuring the flow field downstream of the tower in NJU meteorological wind tunnel, some flow characteristics in the make area were established. Based on these, an advanced random\|walk dispersion model was set up and applied successfully to the simulation of dispersion in the wake area. The modelling results were in accordance with wind tunnel measurements. The computed maximum of ground surface concentration in the building case was a factor of 3.4.higher than that in the flat case and appeared much closer to the source. The simulation indicated that random walk modelling is an effective and practical tool for the wake stream impact assessment.

关键词： exhaust tower air pollution in urban area atmospheric dispersion random walk modelling

A three-dimensional variational ocean data assimilation system:Scheme and preliminary results

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Science China Earth Sciences 2006年第11期49卷 1212-1222页

作者： ZHU Jiang1,2, ZHOU Guangqing1, YAN Changxiang1, FU Weiwei1 & YOU Xiaobao1,3.1. International Center for Climate and Environment Sciences, institute of atmospheric physics, Chinese Academy of Sciences, beijing 10002., China 2. Jiangsu Key Laboratory of Meteorological Disaster, Nanjing University of Information Science and Technology, Nanjing 21004., China 3. {4. {3. of Applied Meteorology, beijing 10002., China 1. International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. Jiangsu Key Laboratory of Meteorological Disaster Nanjing University of Information Science and Technology Nanjing 210044 China 3. beijing institute of Applied Meteorology Beijing 100029 China

A new 3.VAR-based Ocean Variational Analysis System (OVALS) is developed. OVALS is capable of assimilating in situ sea water temperature and salinity observations and satellite altimetry data. As a component of OVALS, a new variational scheme is proposed to assimilate the sea surface height data. This scheme considers both the vertical correlation of background errors and the nonlinear temperature-salinity relationship which is derived from the generalization of the linear balance constraints to the nonlinear in the 3.VAR. By this scheme, the model temperature and salinity fields are directly adjusted from the altimetry data. Additionally, OVALS can assimilate the temperature and salinity profiles from the ARGO floats which have been implemented in recent years and some temperature and salinity data such as from expendable bathythermograph, moored ocean buoys, etc. A 21-year assimilation experiment is carried out by using OVALS and the Tropical Pacific circulation model. The results show that the assimilation system may effectively improve the estimations of temperature and salinity by assimilating all kinds of observations. Moreover, the root mean square errors of temperature and salinity in the upper depth less than 4.0 m reach 0.63. and 0.3. psu.

关键词： data assimilation, 3.VAR, sea surface height, ARGO floats.

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 ,{3., 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 of3.5% and 2.6%, respectively. The errors are over 4.% and one times lessthan those by Eddington or δ-Eddington.

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

Multi-spatial variability modes of the Atlantic Meridional Overturning Circulation

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Chinese Science Bulletin 2003年第S2期48卷 30-35页

作者： ZHOU Tianjun LASG, institute of atmospheric physics. Chinese Academy of Sciences, beijing 10002.. China Chinese Acad Sci Inst Atmospher Phys LASG Beijing 100029 Peoples R China

The multi-spatial variability modes of the At-lantic Meridional Overturning Circulation (MOO are iden-tified in the natural coupled simulation of two climate models,the MOC either oscillates at decadal scales with strong cross-equatorial flow or fluctuates locally at interannual scaleswith weaker cross-equatorial flow. Former studies mainlyemphasize the paleo-environmental and paleo-climatic im-pacts of the meridional overturning states transition; thisanalysis indicates the existence of the multi-spatial variabilitymodes of the MOC at interannual to decadal scales. Furtheranalysis indicates that the conventionally used MOC index,which is defined as the maximum zonal mean meridionalstream-function of the North Atlantic, cannot properly de-scribe the multi-spatial variability characteristics of theMOC.

关键词： Atlantic Meridional Overturning Circulation basin scale local scale.