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Seasonal variation of global stratosphere-troposphere mass exchange

Progress in Natural science:Materials International 2007年第12期17卷 1466-1475页

作者： Guo Dong1,2. Lu Daren2.and Sun Zhaobo1(1. Institute of Atmospheric sciences,{3.,{2., china 2. LAGEO, Institute of Atmospheric Physics, Chinese Academy of sciences, Beijing 10002., china) Institute of Atmospheric sciences Nanjing University of Information Science and Technology Nanjing 210044 China LAGEO Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

By Wei formula in pressure coordinate, the stratosphere-troposphere mass exchange (STME) is diagnosed globally for 44 years from 1958 to 2.01 using the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis datasets. Regions of mass flux into the stratosphere are found over Indonesia, bay of Bangladesh and the mid-west coast of South Africa. Compensating mass outflow from the stratosphere appears mainly over mid-latitudes near large-scale troughs. Upward and downward transport of mass at the middle and high latitudes accompany with each other. Mass flux into troposphere is stronger in autumn and winter than in spring and summer. Strong downward mass flux into the troposphere occurs in eastern Asia the whole year with nearly stable sites. Although the area of eastern Asia accounts for only 5.6% of that of the northern hemisphere (NH), its net mass exchange reaches 15.83. of that of the NH, which means that research on STME of eastern Asia is greatly important to that of the NH and even the global areas. Air across the tropopause enters more from stratosphere to troposphere than that from troposphere to stratosphere, which is possibly related with systematic bias of the assimilated datasets and with persistent rise of the tropopause height. Contributions of the mass exchange and the mass flux exchange in the NH and southern hemisphere (SH) on their latitudes increase from equator to pole, with larger contributions in the NH. Mass exchange and mass flux exchange per areas at high latitudes are larger than that at low latitudes, which means greater mass exchange efficiency at high latitudes.

关键词： stratosphere troposphere mass exchange seasonal variation.

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Numerical simulation of Meiyu front and the diagnosis of moist vorticity vector

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Progress in Natural science:Materials International 2007年第11期17卷 1341-1347页

作者： Ping Fan1,2.and Luo Zhexian2.1. Institute of Atmospheric Physics, Chinese Academy of sciences, Beijing 10002., china 2. {2. university of information sciences & technology, nanjing 210044, china) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Chin

Moist vorticity vector is introduced to study the development and evolution of mesoscale convective vortex (MCV) in the Meiyu front precipitation with the Advanced Regional Predication System (ARPS). In this study, the heavy rainfall is simulated to investigate the genesis, development and dissipation of middle scale convective vortex, which occurred from 0000 UTC 3.July to 12.0 UTC 5 July over the Jianghuai River valley. Moist vorticity vector (MVV) has zonal, radial and vertical components in its 3. spatial distribution. The simulation shows that the vertical component of moist vorticity vector well demonstrates the spatial distribution characteristics of middle scale convective vortex, especially in the process of Meiyu front precipitation. Diagnosis upon zonal, radial averaged and mass-integrated quantities of MVV shows that its vertical component and the surface precipitating ratio are in phase with a correlation coefficient of 0.68, indicating that the vertical component of MVV is closely associated with the Meiyu front precipitation. In addition, the tendency of the vertical component of MVV is mainly determined by the interaction between the vorticity and the zonal and radial gradient of condensational or depositional heating.

关键词： moist vorticity vector mesoscale convective vortex Meiyu front precipitation

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Interhemispheric atmospheric mass oscillation and its relation to interannual variations of the Asian monsoon in boreal summer

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science china Earth sciences 2010年第9期53卷 1343-1350页

作者： LU ChuHan, GUAN ZhaoYong & CAI JiaXi Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric sciences, nanjing {2. of {3. science & technology, nanjing 210044, china Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric sciences Nanjing University of Information Science & Technology Nanjing China

Using NCEP/NCAR reanalysis and precipitation records of Chinese stations, we have investigated the relationship of interhemispheric oscillation of air mass (IHO) with global lower-level circulation and monsoon anomalies in boreal summer. Our results show that the summer IHO explains a greater portion of variance in the abnormal distribution of atmospheric mass over 3.°S-60°N as well as the Antarctic. The IHO strongly correlates to the variations of sea level pressure (SLP) in these regions. It is shown that IHO has some influences on both atmospheric mass transports and water vapor fluxes over 3.°S-60°N in association with three anomalous cyclonic circulations over land areas of the eastern hemisphere, which is in close relation to the changes in summer monsoon intensity in eastern Asia and western Africa. Composites of summer rainfall anomalies in china for high and low IHO-index years indicate that the eastern Asian summer monsoon is more intense, with positive precipitation anomaly centers in northern and northeastern parts of china, as opposed to the negative center over the mid-lower reaches of the Yangtze River (MLRYR) in stronger IHO years. In weak IHO years, a feeble summer monsoon appears in eastern Asia, leading to positive center of precipitation anomalies displaced into the MLRYR. Furthermore, a teleconnection in wind fields between the western African and eastern Asian monsoon regions was observed in the middle and higher troposphere in the scenario of IHO. The anomalous cyclonic (anticyclonic) circulations along the path of this Africa-East Asia teleconnection were found to be just over the diabatic heating (cooling) centers, suggesting that diabatic forcings are responsible for the formation of this Africa-East Asia teleconnection.

关键词： interhemispheric oscillation Asian monsoon precipitation china boreal summer

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RECONSTRUCTION OF PRECIPITATION SERIES AND ANALYSIS OF CLIMATE CHANGE OVER PAST 500 YEARS IN NORTHERN china

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Journal of Hydrodynamics 2005年第6期17卷 737-745页

作者： RONG Yan-shu TU Qi-pu College of water Resources and Environment Hohai University Nanjing 210098 China Tianjin Institute of Meteorological science Tianjin 300074 China nanjing university of {2. {3. and technology Nanjing 210044 China

It is important and necessary to get a much longer precipitation series in order to research features of drought/flood and climate change. Based on dryness and wetness grades series of 18 stations in Northern china of 53. years from 1470 to 2.02. the Moving Cumulative Frequency Method （MCFM） was developed, moving average precipitation series from 1499 to 2.02.were reconstructed by testing three kinds of average precipitation, and the features of ell mate change and dry and wet periods were researched by using reconstructed precipitation series in the present paper. The results showed that there were good relationship between the reconstructed precipitation series and the observation precipiration series sincc 1954 and their relative root mean-square error were below 1.89%, that the relation between reconstructed series and the dryness and wetness grades series were nonlinear and this nonlinear relation implied that reconstructed series were reliable and could became foundation data for researching evolution of the drought and flood. Analysis of climate change upon reconstructed precipitation series revealed that although drought intensity of recent dry period from mid- dle 1970s of 2.th century until early 2.st century was not the strongest in historical climate of Northern china, intensity and duration of wet period was a great deal decreasing and shortening respectively, climate evolve to aridification situa- tion in Northern china.

关键词： reconstruction series dryness and wetness grades series precipitation series climate change Northern china

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Deterministic secure quantum communication without unitary operation based on high-dimensional entanglement swapping

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science china({2. sciences) 2012年第2期55卷 360-367页

作者： LIU ZhiHao1,CHEN HanWu1,LIU WenJie2.XU Juan1 & LI ZhiQiang3.1School of Computer science and Engineering,Southeast university,{2. 2.1189,china 2.chool of Computer and Software,{2. university of information science & technology,{2. {13.,china 3.ollege of information Engineering,Yangzhou university,Yangzhou 2.5009,china School of Computer science and Engineering Southeast University School of Computer and Software Nanjing University of Information Science & Technology

By analysis of the basic properties of entanglement swapping of high-dimensional Bell states,a universal and general deterministic secure quantum communication(DSQC)protocol is proposed,in which unitary operation is not *** making use of the results of high-dimensional Bell measurement,the sender and the receiver can encode and decode the message respectively by performing the modular addition and *** mutually complementary bases are constructed;and according to the property of mutual complement,a method for checking security of the high-dimensional quantum channel is put *** common attack strategies are analyzed,and the corresponding error rates are *** the upper bound of the threshold of error rate is deduced.

关键词： deterministic secure quantum communication high-dimensional Bell state entanglement swap-ping high-dimensional Bell measurement

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information Fusion in Biometrics: A Case Study in Fingerprint

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微计算机信息 2005年第18期 151-153页

作者： (nanjing university of {2. {3. and technology,Department of {2. and Engi- neering, nanjing 210044, china)Wang, Xiaoyan Fu, Desheng

Biometrics is an emerging topic in the field of signal processing. Multibiometric systems can improve the performance of identification by integrating information presented by single or multiple biometric indicators and a lot of researchers are working on it. As fingerprints is one of the most studied and popular biometrics, researches that have approached the challenges in fingerprints from an information fusion perspective is provided in this paper.

关键词： information fusion Biometrics Recognition Multi- modal

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MMSE relay precoding schemes based on quantization error compensation for multi-relay system

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science china({2. sciences) 2010年第12期53卷 2548-2556页

作者： LI Ting 1,2.& YANG LuXi 2.1 College of Communication and information Engineering,{3. {2. of Posts and Telecommunications,{3. 2.0003.china 2.School of information science and Engineering,Southeast {2.,{3. 2.0096,china College of Communication and information Engineering Nanjing University of Posts and Telecommunications School of information science and Engineering Southeast University

In order to deal with the performance degradation resulting from the quantization error,this paper introduces the statistics of Grassmannian codebook's quantization error into relay precoding design for multirelay *** on the two-step MMSE optimization algorithm for relay precoding and receiver equalizing with full feedback under QoS requirements,we first propose a limited feedback two-step MMSE optimization scheme for relay precoding and receiver equalizing with quantization error compensation,and then we propose a limited feedback joint MMSE optimization scheme for relay precoding and receiver equalizing with quantization error compensation subject to a global power constraint at the output of *** results show that the proposed joint MMSE optimization scheme with quantization error compensation has a much lower bit-error rate than the two-step MMSE optimization scheme with quantization error compensation and the joint MMSE optimization scheme without quantization error compensation.

关键词： multi-relay precoding limited feedback minimum mean square error

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ANALYTICAL SOLUTION OF NONLINEAR BAROTROPIC VORTICITY EQUATION

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Journal of Hydrodynamics 2008年第4期20卷 530-535页

作者： WANG Yue-peng SHI Wei-hl College of Mathematics and Physics Nanjing University of Information Science and Technology Nangjing210044 China Jiangsu Key Laboratory of Meteorological Disaster Nangjing University of Information Science and Technology Nangjing 210044 China Department of Mathematics Shanghai University Shanghai 200072 China

The C^k （k ≥ 3. stability of nonlinear barotropic vorticity equation was proved. The necessary and sufficient conditions for the initial value problem to be well-posed were presented. Under the conditions of well-p... 详细信息

关键词： nonlinear barotropic vorticity equation stability well-posedness analytical solution

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Performance analysis of variable-power adaptive modulation in space-time block coded MIMO diversity systems

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science china({2. sciences) 2010年第10期53卷 2106-2115页

作者： YU XiangBin 1,2.& SHI HuiBin 1 1 College of information science and {2., nanjing university of Aeronautics and Astronautics, nanjing 2.0016, china 2.National Mobile Communications Research Laboratory, Southeast university, nanjing 2.0096, china College of information science and {2. Nanjing University of Aeronautics and Astronautics National Mobile Communications Research Laboratory Southeast University

In this paper, the performance analysis of multi-antenna MIMO systems with variable-power (VP) adaptive modulation and space-time coding is presented. The fading gain value is partitioned into a number of regions by which we decide the transmission power according to the region the fading gain falls in. The optimum fading gain region boundaries (switching thresholds) for maximizing spectrum efficiency (SE) under a target BER and average power constraint are derived. It is shown that the Lagrange multiplier in the constrained SE optimization will be unique if the existence condition for multi-antenna systems is satisfied, and is unique for single antenna systems. A practical iterative calculation method based on Steepest Descent Algorithm for finding the Lagrange multiplier is proposed. With the switching thresholds, the closed-form expressions of the SE and average BER, respectively for VP system and constant-power (CP) system are achieved. Simulation results for SE and average BER are in good agreement with the theory analysis. The results show that VP adaptive modulation with space-time coding provides better SE than the counterpart with CP under a target BER and average power constraint.

关键词： adaptive modulation variable power space-time block code constant power multiple input multiple output (MIMO)

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Performance analysis of network coding for multicast relay system over Nakagami-m fading channels

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science china({2. sciences) 2011年第11期54卷 2338-2348页

作者： ZHAO Rui 1,YANG LvXi 2.& HUANG YongMing 2.1 School of information {3. and Engineering,Huaqiao {2.,Xiamen 3.102.,china 2.School of information {3. and Engineering,Southeast {2.,nanjing 2.0096,china School of information science and Engineering Huaqiao University School of information science and Engineering Southeast University

The outage probability performance of network coding for multicast relay system is analyzed in Nakagami-m fading *** transmission strategies,i.e.,complex field network coding (CFNC) and amplify-and-forward network coding (AFNC),are applied in the system,and the approximate expressions of outage probability are derived at high SNR and the conclusion is reached that the system diversity gains of two transmission strategies are both 2.,as is verified by numerical *** results also show that CFNC can outperform both AFNC and direct transmission without relay in the performances of system outage probability,sum rate and symbol error ratio.

关键词： multicast relay system network coding outage probability diversity gain

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