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Evolution of desertification in a two-dimensional energy balance model coupled with thermodynamics and dynamics

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Science china Earth sciences 2010年第11期53卷 1726-1733页

作者： CHAO JiPing1,2 & LI YaoKun3.4 1National Marine Environmental Forecasting Center, beijing 100081, china 2First institute of Oceanography, State Oceanic Administration, Qingdao 266061, china 3.tate Key Laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics, institute of atmospheric physics, chinese academy of sciences, beijing 10002., china 4Graduate University of chinese academy of sciences, beijing 100049, china 1. National Marine Environmental Forecasting Center Beijing 100081 China2. First Institute of Oceanography State Oceanic Administration Qingdao 266061 China3. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China4. Graduate University of Chinese Academy of Sciences Beijing 100049 China

The relationship between desert evolution and change in albedo has been investigated quasi-analytically using a zonal mean two-dimensional energy balance model which considers the radiation transmission process due to thermodynamics and bound- ary layer movement caused by kinetics. A climate state including temperature, zonal wind, meridional wind and vertical wind can be simulated according to the current zonal distribution of albedo. Given desert distribution, characterized by the value and distribution of albedo, the response of climate on albedo has been studied to analyze the evolution of desert climate. One significant result is that the simple model can reproduce mean meridional circulation. Another result indicates that climate corresponds to two equilibria. This happens when the junction temperature between vegetation and desert is higher than a certain critical value. As for the first equilibrium, the desert belt is predicted to move southward in the northern hemisphere with the increasing values of albedo, which corresponds to the current trend of climate change. For the second equilibrium, vegetation will expand northward with increasing values of albedo, which would indicate a narrowing of the desert belt. In order to determine if the two equilibria exist, new physical models are needed.

关键词： two-dimensional energy balance model desertification two equilibria

Precursory SST anomalies associated with the convection over the western Pacific warm pool

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chinese Science Bulletin 2002年第8期47卷 696-699页

作者： LU Riyuinstitute of atmospheric physics,{3., beijing 100080, china (e-mail: lr@***) institute of atmospheric physics Chinese Academy of Sciences Beijing China

The convection over the tropical western Pacific warm pool influences significantly the atmospheric circulation and climate in East Asia. Thus, the precursory signals of the convection may be used in the forecast of summer climate in china. According to the present results, the June-July-August (JJA) mean convection intensity over the warm pool is significantly related to the precursory positive and negative sea surface temperatures (SSTs) in the warm pool and in the equatorial central and eastern Pacific, respectively. It is also related to the simultaneous negative surface temperatures west to the Philippines. The analysis on the SSTs associated with the convection over the warm pool in individual month of summer shows that for the convection in June and July, there are precursory SST signals in the warm pool and the equatorial central and eastern Pacific. Therefore, this study shows that only the convection in June and July, rather than that in August, has precursory SST signals, despite the

关键词： warm pool convection precursory SSTs El Nino.

Differentiation transforming system

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Progress in Natural Science:Materials International 2009年第3期19卷 397-406页

作者： Qiang Chenga,b,c,*, Haibin Zhang d, Bin Wanga, Yonghua Zhao c a LASG, institute of atmospheric physics, chinese academy of sciences, beijing 10002., PR{3. b LSEC, institute of Computing Mathematics, chinese academy of sciences, beijing 100080, PR{3. c SC, institute of Computer Network Information Center, chinese academy of sciences, beijing 100190, PR{3. d College of Applied sciences, beijing University of Technology, beijing 100124, PR{3. [a]LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 PR China [b]LSEC Institute of Computing Mathematics Chinese Academy of Sciences Beijing 100080 PR China [c]SC Institute of Computer Network Information Center Chinese Academy of Sciences Beijing 100190 PR China [d]College of Applied Sciences Beijing University of Technology Beijing 100124 PR China

The differentiation transforming (DFT) system is developed to produce the tangent linear codes, which is used to calculate the Jaco- bian- and the Hessian-vector products with no truncation errors. This paper first gives the introduction of the functionality and features of the DFT system, and then discusses several techniques for the implementation of automatic differentiation tools, including data depen- dence analysis, singular differentiation and code optimization. Finally, the codes generated with DFT used in several applications have been demonstrated.

关键词： Jacobian Hessian Tangent linear model Automatic differentiation

Modeling the impact of Australian Plate drift on Southern Hemisphere climate and environment

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chinese Science Bulletin 2005年第14期50卷 1495-1502页

作者： ZHOU Botao1,5, ZHAO Ping2, JIAN Zhimin3.& HE Jinhai4 1. Nansen-Zhu International Research Center, institute of atmospheric physics, chinese academy of sciences, beijing 10002.,{3. 2. institute of Climate and Environment, chinese academy of Meteoro- logical sciences, beijing 100081,{3. 3. Laboratory of Marine Geology, Tongji University, Shanghai 200092,{3. 4. Department of atmospheric sciences, Nanjing institute of Meteorol- ogy, Nanjing 210044,{3. 5. Graduate School of the chinese academy of sciences, beijing 10003.,{3. Nansen-Zhu International Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Graduate School of the chinese academy of sciences Beijing 100039 China institute of Climate and Environment Chinese Academy of Meteorological Sciences Beijing 100081 China Laboratory of Marine Geology Tongji University Shanghai 200092 China Department of atmospheric sciences Nanjing Institute of Meteorology Nanjing 210044 China

Using a global atmosphere-ocean coupled model with the present-day and 14 MaB.P. oceanic topogra- phy respectively, two experiments are implemented to inves- tigate the effect of different locations of Australian Plate on the atmospheric circulation in middle-high latitudes of the Southern Hemisphere. The results show that when Austra- lian Plate lay south at 14 MaB.P., both anticyclone circula- tions in the subtropical oceans and cyclone circulation around 60°-70°S are strengthened. Subtropical highs and circumpolar low pressure appear stronger, which results in much stronger Antarctic Oscillation and shorter period of Antarctic Oscillation Index (AOI) at 14 MaB.P. The rainfall and the surface air temperature also change correspondingly. The precipitation decreases around 40°S and increases around 60°-70°S, and the surface air temperature rises in high latitudes of the South Pacific and descends over the Weddell Sea and its north side. Besides, due to the changes of the temperatures and winds, Antarctic sea ice coverage also changes with its increasing in the Ross Sea and its west re- gions and decreasing in the Weddell Sea.

关键词：半球气候地球环球澳大利亚漂流物海洋地形学

THERMALLY STIMULATED SHAPE MEMORY BEHAVIOR OF POLYMERS WITH PHYSICAL CROSSLINKS

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chinese Journal of Polymer Science 1999年第3期17卷 203-213页

作者： Mao Xu Feng-kui Li Polymer physics Laboratory, institute of Chemistry, chinese academy of sciences, {3. 100080, china chinese Acad Sci Inst Chem Polymer Phys Lab Beijing 100080 Peoples R China

The shape memory effect of polymers was investigated for the purpose of improving the processing conditions of their preparation and broadening the list of polymers for shape memory applications. Emphasis was put on the possibility of using polymers with physical crosslinks as shape memory materials and their structure-function relationships. Segmented block polyurethanes and polyethylene/nylon 6 graft copolymers were used as examples of polymers with physical crosslinks. It was found that these copolymers can really be used as thermally stimulated shape memory materials with large recoverable strain and high final recovery rate. The main advantage of using copolymers is their improved processing conditions as compared with polymers with chemical crosslinks. As only physical crosslinks are introduced, all conventional processing techniques for thermal plastics can be used, and the materials become easily reusable. The results indicate that the high crystallinity of these copolymers at room temperature and the formation of stable physical crosslinks are the two prerequisites for these polymers to exhibit shape memory effect. The successful use of block and graft copolymers imply the possibility of using polymers of various structure and properties as shape memory materials.

关键词： shape memory effect segmented polyurethanes polyethylene nylon graft copolymers

Semi-analytical analysis of the response of the air temperature over the land surface to the global vegetation distribution

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chinese Science Bulletin 2009年第14期54卷 2499-2505页

作者： LIU Fei1,2 & CHAO JiPing3.4 1 institute of atmospheric physics, chinese academy of sciences, beijing 10002.,{3. 2 Graduate University of chinese academy of sciences, beijing 100049,{3. 3.National Marine Environmental Forecasting Center, beijing 100081,{3. 4 First institute of Oceanography, State Oceanic Administration of{3., Qingdao 266061,{3. institute of atmospheric physics{3. Beijing 100029 China Graduate University of chinese academy of sciences Beijing 100049 China National Marine Environmental Forecasting Center Beijing 100081 China First institute of Oceanography State Oceanic Administration of China Qingdao 266061 China

Response of the air temperature over the land surface to the global vegetation distribution is investigated, using a three-dimensional governing equation to simulate the steady, large-scale, limited amplitude perturbation of the free, inviscid and adiabatic atmosphere. The adoption of the static equation leads to a temperature governing equation in the terrain following coordinate. With the prescribed temperature as the upper boundary condition and the radiation balance as the lower boundary condition, the semi-analytical solution of the global circulation temperature can be calculated. In this article, only the air temperature (at 2 m height) over the land surface is analyzed, and the result suggests that this model can simulate the air temperature pattern over the land surface reasonably. A better simulation occurs when a simple feedback of the albedo on the temperature is included. Two sensitivity experiments are analyzed through this model. One suggests that the air temperature over the land surface descends obviously when the land surface is covered with ice all over, while another suggests that the air temperature rises a little when the land surface is covered with forest except the ice-covered area. This model appears to be a good tool to study the response of the air temperature to the vegetation distribution. Limitations of the model are also discussed.

关键词：空气温度植被分布陆地表面反应解析分析模拟模式控制方程边界条件

Multisymplectic Structure and Multisymplectic Scheme for the Nonlinear Ware Equation

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Acta Mathematicae Applicatae Sinica 2002年第1期18卷 169-176页

作者： Yu-shun WANG, Meng-zhao QINLASG, institute of atmospheric physics, chinese academy of sciences, beijing 10002.,{3.institute of Computational Mathematics, academy of Mathematics and System sciences, chinese academy of sciences, beijing 100080,{3. LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China institute of Computational Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China

The multisymplectic structure of the nonlinear wave equation is derived directly from the variational principle. In the numerical aspect, we present a multisymplectic nine points scheme which is equivalent to the multisymplectic Preissman scheme. A series of numerical results are reported to illustrate the effectiveness of the scheme.

关键词： Multisymplectic structure Multisymplectic schemes Nonlinear wave equation

Finding Signals for Plant Promoters

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Genomics, Proteomics & Bioinformatics 2003年第1期1卷 68-73页

作者： Weimou Zhenginstitute of Theoretical physics, chinese academy of sciences, {3. 100080, china {3. Genomicsinstitute, chinese academy of sciences, {3. 1013.0, china institute of Theoretical physics Chinese Academy of Sciences Beijing 100080 China beijing Genomics institute Chinese Academy of Sciences Beijing 101300 China

The strongest signal of plant promoter is searched with the model of single motif with two types. It turns out that the dominant type is the TATA-box. The other type may be called TATA-less signal, and may be used in gene finders for promoter recognition. While the TATA signals are very close for the monocot and the dicot, their TATA-less signals are significantly different. A general and flexible multi-motif model is also proposed for promoter analysis based on dynamic programming. By extending the Gibbs sampler to the dynamic programming and introducing temperature, an efficient algorithm is developed for searching signals in plant promoters.

关键词： for on is as et Pro Finding Signals for Plant Promoters been of into

Trend and seasonal variations of atmospheric CH_4 in beijing

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Journal of Environmental sciences 2000年第3期12卷 369-374页

作者： WANG Yue\|si, WANG Ming\|xing, LUO Dong\|mei, ZHENG Xun\|hua, ZHOU Li (institute of atmospheric physics,{3., beijing 10002., china) 中科院大气物理所北京 1 0 0 0 2

The atmospheric CH\-4 in beijing is still increasing, even though its increasing rate has significantly decreased from 1.76%/a during 1985—1989 to 0.50%/a during 1990—1997. The seasonal variation of CH\-4 concentration showed a double\|peak pattern, one peak appearing in winter and the other in summer. It is evident that the annually seasonal variations of atmospheric CH\-4 in beijing are different. From 1986 to 1997, the atmospheric CH\-4 increased by 185 ppbv, 3.% and 21% of which were due to the increase in winter and in summer, respectively. After 1993. the annually seasonal increasing rate of CH\-4 concentration in summer (due to emission from biogenic sources) is negative while the increasing rate in winter (due to emission from non\|biogenic sources) is positive about 25 ppbv/a. As a result, the increase of CH\-4 emission from non\|biogenic sources in winter is the major reason that caused the annually seasonal increasing rate from 1993.to 1997. The biogenic sources in beijing are shrinking while the non\|biogenic ones (such as fossil fuel combustion) are enlarging.

关键词： atmospheric CH\-4 increasing rate seasonal variation annually seasonal variation