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Vortex genesis over the Bay of Bengal in spring and its role in the onset of the Asian Summer Monsoon

Science china Earth Sciences 2011年第1期54卷 1-9页

作者： WU GuoXiong1, GUAN Yue1,2, WANG TongMei3, LIU YiMin1, YAN JingHui4 & MAO JiangYu1 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china 2Graduate University of Chinese Academy of Sciences, beijing 100049, china 3Department of Atmospheric Science, Sun Yat-Sen University, Guangzhou 510275, china 4national Climate center, china meteorological administration, beijing 100080, china 1. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Atmospheric Science Sun Yat-Sen University Guangzhou 510275 China4. National Climate Center China Meteorological Administration Beijing 100080 China

Physical processes associated with onset of the 1998 Asian summer monsoon were examined in detail using multi-source datasets. We demonstrated that strong ocean-atmosphere-land interaction in the northern Indian Ocean and tropical Asian area during spring is a fundamental factor that induces the genesis and development of a monsoon onset vortex over the Bay of Bengal (BOB), with the vortex in turn triggering onset of the Asian summer monsoon. In spring, strong surface sensible heating over India and the Indochina Peninsula is transferred to the atmosphere, forming prominent in situ cyclonic circulation, with anticyclonic circulations over the Arabian Sea and northern BOB where the ocean receives abundant solar radiation. The corresponding surface winds along the North Indian Ocean coastal areas cause the ocean to produce the in situ offshore currents and upwelling, resulting in sea surface temperature (SST) cooling. With precipitation on the Indochina Peninsula increasing from late April to early May, the offshore current disappears in the eastern BOB or develops into an onshore current, leading to SST increasing. A southwest-northeast oriented spring BOB warm pool with SST >31°C forms in a band from the southeastern Arabian Sea to the eastern BOB. In early May, the Somali cross-equatorial flow forms due to the meridional SST gradient between the two hemispheres, and surface sensible heat over the African land surface. The Somali flow overlaps in phase with the anticyclone over the northern Arabian Sea in the course of its inertial fluctuation along the equator. The convergent cold northerlies on the eastern side of the anticyclone cause the westerly in the inertial trough to increase rapidly, so that enhanced sensible heat is released from the sea surface into the atmosphere. The cyclonic vorticity forced by such sensible heating is superimposed on the inertial trough, leading to its further increase in vorticity strength. Since atmospheric inertial motion is destr

关键词： air-sea interaction spring BOB warm pool monsoon onset vortex inertial oscillation Asian summer monsoon onset

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The onset and advance of the Asian summer monsoon

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Science Bulletin 2006年第1期51卷 80-88页

作者： Lü Junmei1,2,4, ZHANG Qingyun1, TAO Shiyan1 & JU Jianhua3 1. State Key Laboratory of Numerical Modeling for Atmospheric Sci- ences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china 2. Department of Atmospheric Sciences, Yunnan University, Kunming 650091, china 3. china meteorological administration Training Centre, beijing 100081, china 4. Graduate School of Chinese Academy of Sciences, beijing 100039, china State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Department of Atmospheric Sciences Yunnan University Kunming 650091 China Graduate School of Chinese Academy of Sciences Beijing 100039 China china meteorological administration Training Centre Beijing 100081 China

Based on the daily outgoing longwave radiation (OLR) data from national Oceanic and At- mospheric administration (NOAA) satellites, the Cli- mate Prediction center’s merged analysis of pre- cipitation (CMAP) data and the national centers for Environmental Prediction/national center for At- mospheric Research (NCEP/NCAR) reanalysis dataset, the mean intraseasonal variability of the Asian summer monsoon (ASM) is investigated by using power spectrum analysis, band-pass filter, and diagnostic analyses. The processes of the onset and advance of monsoon over the southern part of Indo- china Peninsula, the east coast of Bay of Bengal, the South china Sea and the Indian subcontinent are explored. It is found that there is an abrupt change in OLR, precipitation and zonal wind during the onset and advance of the ASM. It is also indicated that the southern part of Indochina Peninsula and the adja- cent Andaman Sea is the region where the earliest onset of the ASM occurs in the 2nd pentad of May.

关键词： Asian summer monsoon intraseasonal variability onset advance.

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HISTORICAL DATABASE OF TYPHOON,STORM RAINFALL AND CYCLONE

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Natural Disaster Reduction in china 1996年第3期 132-138页

作者： Li Zhao-clang and Yak Xuexiang(national meteorological center, china Meteralogical administration, beijing 100081 )

The study of historical database of typhoon, storm rainfall and cyclone belongs to the sub-project 09- 01 - 04- 03 of national Science and Technology Key Project 85- 906. It consists of five secondary bases: the database of tropical cyclone track and its strength in the Northwest Pacific, the precipitation database of tropical cyclone in china, the database of temperate cyclone track and its strength in china, the wind and rainfall database of temperate cyclone and the historical database of important storm rainfall process. The historical database has been set up on the computer and has strong transplanting feature. By adopting FoxBASE with Chinese words in designing management system of the database, it has function of figure display for precipitation data in graphs and being inquired 500 hpa height field data, it is convenient for reference in understanding the circulation pattern of precipitation process at the beginning, sustaining and ending stages. This paper will introduce to the structure, data, rule for choosing cases, using form and function of the historical database of typhoon, storm rainfall and cyclone.

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An improvement on summer regional climate simulation over East china: Importance of data assimilation of soil moisture

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Chinese Science Bulletin 2010年第9期55卷 867-873页

作者： HU YaMin1,2,3, DING YiHui4 & LIAO Fei2 1 Institute of Tropical and Marine Meteorology, china meteorological administration, Guangzhou 510080, china 2 Guangdong Climate center, Guangzhou 510080, china 3 Chinese Academy of meteorological Sciences, beijing 100081, china 4 national Climate center, china meteorological administration, beijing 100081, china

The Newtonian relaxation is used to assimilate data from the Second Global Soil Wetness Project (GSWP2) into the initial field for soil moisture in a regional climate model (i.e., BCC_RegCM 1.0, hereinafter called RegCM). The results show that different nudging parameters can improve the simulation of the air temperature and the precipitation to some extent in summertime season over East china. When the nudging intensity is 0.5 and nudging duration is 5 days, the result is desirable. Introducing the data assimilation of soil moisture into RegCM, the amelioration is not only in the spatial distribution pattern but also in the magnitude of the temperature and the precipitation. More specifically, the assimilation experiments have corrected the systematical cold bias of the air temperature and the precipitation on the low side, which is much closer to the observation compared with the control experiment. On the whole, the assimilation experiments shed light on the fact that the simulated bias in the original RegCM may be affected by the description of soil moisture in the land surface process. Therefore, the effect of soil moisture in RegCM should be paid more attention in the future.

关键词： soil moisture Newtonian relaxation data assimilation regional climate simulation

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Approximate Solution of the Nonlinear Parallel Diffusion Theory of Charged Particles

Approximate Solution of the Nonlinear Parallel Diffusion The...

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第十四届全国日地空间物理学术研讨会

作者： Yu-Ting Zhu1 Gang Qin2 Gui Ming Le3 (1 Chinese Academy of meteorological Science, beijing 100081 ) (2 national space Science center, beijing 100190 ) (3 national center for space weather, china meteorological administration, beijing 100081 )

Charged particles’ diffusion mechanism is one of outstanding problem in the astrophysics. Recently, Matthaeus et al. （ApJ 2003） developed a nonlinear guiding center theory （NLGC） of perpendicular diffusion of charged energetic particles with parallel diffusion coefficient as an input, which agrees with numerical simulations. In addition, Qin （ApJ 2007） developed a nonlinear parallel diffusion theory （NLPA） which if combined with NLGC could be used to solve parallel and perpendicular diffusion simultaneously. However, both of the NLGC and NLPA are in the forms of integral equation and not easy to be adopted in cosmic ray transport models. So that Zank et al. （JGR 2004） provided an approximate solution of NLGC. The solution agrees with the exact solution of the NLGC results very well. In this work we will adopt the similar method from Zank et al. （2004）to approximately solve the NLPA （Qin 2007） so that the solution of both parallel and perpendicular nonlinear diffusion coefficients can be included in numerical codes for cosmic rays transport simultaneously.

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Research on the dry intrusion accompanying the low vortex precipitation

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Science china Earth Sciences 2007年第9期50卷 1396-1408页

作者： YAO XiuPing1,2,3, WU GuoXiong1, ZHAO BingKe4, YU YuBin3 & YANG GuiMing2,5 1 LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china 2 Institute of Heavy Rain, china meteorological administration, Wuhan 430074, china 3 china meteorological administration Training center, beijing 100081, china 4 Shanghai Typhoon Institute of china meteorological administration, Shanghai 200030, china 5 national meteorological center of the china meteorological administration, beijing 100081, china 1. LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. Institute of Heavy Rain China Meteorological Administration Wuhan 430074 China 3. china meteorological administration Training center Beijing 10081 China 4. Shanghai Typhoon Institute of china meteorological administration Shanghai 200030 China 5. national meteorological center of the china meteorological administration Beijing 100081 China

By employing the 6.7μm satellite vapor cloud images and NCEP/NCAR 1°×1° reanalysis datasets, the characteristics and mechanism of the dry intrusion, as well as its impacts on the low vortex precipita- tion at the Meiyu front are explored in this paper. It is found that the formation,development and main- tenance of the low vortex precipitation at the Meiyu front are closely related to the evolution of the dry intrusion. The dry intrusion is characterized by high potential vorticity (PV), low humidity and cold air. The dry intrusion exhibits as an obvious dark zone on vapor cloud images, an area in which atmos- pheric relative humidity is lower than 60%. However, the features of the dry intrusion on the vapor im- ages are clearer than that of the humidity field, for the former is the digital vapor cloud images with high temporal and spatial resolution, and it can be used to explore the finer characteristics of the develop- ment, evolution and supplement of the intrusion during the development of the low vortex. The dry intrusion impacts accompanying the low vortex precipitation at the Meiyu front come from all levels of the troposphere, with the strongest intrusion located at the upper troposphere. The dry and cold air intrudes the vicinity of the low vortex from the upper isentropic surface to the lower one, slanting eastward from lower to higher level. The low vortex precipitation region is usually situated in front of the dry intrusion where the relative humidity gradient is higher. The research also reveals that the mechanism of the dry intrusion is that the high potential vorticity descends from the upper troposphere to the lower level, therefore, the dry intrusion can be used as an important index of the high PV forcing. To the west of the low vortex precipitation, the upper level northerlies descend across the isentropic surface, then the dry cold advection can trigger the instable development in the mid-low troposphere. The dry intrusion enhances the low vort

关键词： Meiyu front, low vortex precipitation, dry intrusion, mechanisim, vapor image, potential vorticity, relative humidity

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An analysis of interplanetary sources of geomagnetic storm during November 7-8, 1998

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Chinese Science Bulletin 2010年第9期55卷 853-858页

作者： LE GuiMing1,2,3, TANG YuHua1, ZHENG Liang5 & LIU LianGuang4 1 Department of Astronomy, Nanjing University, Nanjing 210093, china 2 national center for space weather, china meteorological administration, beijing 100081, china 3 Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites, china meteorological administration (LRCVES/CMA), beijing 100081, china 4 North china Electric Power University, beijing 102206, china 5 Graduate University of Chinese Academy of Sciences, beijing 100049, china

We analyzed the properties of the solar wind appeared during November 7–8, 1998. Results show that the spaceship ACE spotted a shock (hereinafter referred to as the first shock) at 07:33 UT, November 7. The sheath appeared from the first shock to 22:00 UT November 7. A magnetic cloud-like (MCL) was observed during the period from 22:00 UT November 7 to 11:50 UT, November 8. Another shock was observed at 04:19 UT, November 8 (the second shock). It is apparent that the second shock has entered the rear part of the MCL (MCL_2), though the former part of the MCL (MCL_1) was not affected by the second shock. The main phase of the geomagnetic storm is split into three steps for the convenience of SYM-H index analysis. Step 1 covers the period from the sudden storm commence (SSC) at 08:15 UT, November 7 to the moment of 22:44 UT, November 7. Step 2 starts from 22:44 UT, November 7 and ends at 04:51 UT, November 8. The last step runs from 04:51 UT, November 8 to 06:21 UT, November 8. Step 2 has played a key role in the main development phase of the geomagnetic storm. Analysis of the solar wind properties associated with the main phase shows that the three steps in the main phase have sheath, MCL_1, and MCL_2 as their respective interplanetary source. Specifically, the sheath is covered by the solar wind data from 07:33 UT to 22:00 UT, November 7, MCL1 by the solar wind data from 22:00 UT, November 7 to 04:19 UT November 8, and MCL_2 by the solar wind data from 04:19 UT to 05:57 UT, November 8. MCL_1 had a strong and long lasting so UTh directed magnetic field, allowing it to play a key role in the development of the main phase. MCL_2 made a much smaller contribution to the main development phase, compared with MCL_1.

关键词： geomagnetic storm magnetic cloud interplanetary shock sheath south component of interplanetary magnetic field

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Numerical simulations of the bi-level and branched structure of intracloud lightning flashes

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Science china Earth Sciences 2006年第6期49卷 661-672页

作者： TAN Yongbo1, TAO Shanchang1, ZHU Baoyou1, MA Ming2 & LU Weitao2 1. School of Earth and space Sciences, University of Science and Technology of china, Hefei 230026, china 2. Chinese Academy of meteorological Sciences, beijing 100081, china 1. School of Earth and space Sciences University of Science and Technology of China Hefei 230026 China 2. Chinese Academy of meteorological Sciences Beijing 100081 China

Intracloud (IC) lightning flashes have been simulated in fine resolution (12.5 m) by using a bidirectional stochastic lightning parameterization scheme within 2-dimensional domain. The simu-lated results show that the IC flashes have a bilevel channel structure and the altitudes of the hori-zontal channels are at the same heights of potential wells, which are supported by the previous VHF source observations and balloon soundings of electric field profile in the thundercloud. Further con-clusions are: (1) After an IC flash is initiated near the boundary between positve and nagetive charge zone, the negative (or positive) leader tends to propagate into the positive (or negative) charge zone. Both types of positive and negative IC flashes have been reproduced and their polarity depends on the up and down disposition of the positive and negative charge regions. (2) The extension range of leaders is correlative with the cloud charge distribution. The leader is possible to extend through the inverted charge region all over where it is extending, but keeps away from the isolated charge area of the same polarity. (3) The channel structures also depend on the electric potential distributions in the thundercloud. Before propagating into the central area of potential wells, the leader tends to extend along the direction with the maximum of potential gradient. Once extending away from the center of potential wells, the leader tends to extend along the direction with the slowest potential change. (4) The IC flash channels have the fractal feature with fractal dimension 1.45 before leaders pass through the central area of charge regions. The exponent decreases rapidly once leaders extend into the low-density charge regions. (5) The induced charges of opposite polarity are deposited in the leader channels within preexisting positive and negative charge regions during IC flash discharges. This causes a new and complicated charge distribution in the thundercloud, and the potential

关键词： IC, lightning parameterization, branched bilevel structure, fractal feature, propagation tendency.

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A New Approach to the On-Orbit Evaluation of Point Spread Function of Thermal Infrared Images With Applications to FY-2 Satellite Products

A New Approach to the On-Orbit Evaluation of Point Spread Fu...

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作者： Qiang Guo,Changjun Yang,and Caiying Wei the national Satellite meteorological center,china meteorological administration,beijing 100081,china,the Key Laboratory of Radiometric Calibration and Validation for Environmental Satellite,china meteorological administration,beijing 100081,china

Spatial characteristics of thermal infrared(TIR) images are generally described by image-derived point spread function(IDPSF) for sampled imaging *** investigators working on IDPSF on-orbit evaluation focus on visible and near-infrared images and pay little attention on TIR ones,the reason of which lies on the fact that the assumption of an observed target with an ideal step profile is not suitable for TIR band. A new approach for TIR images is proposed here based on a more common slope-profile model,where the transition features, i.e.,the sample number(N) and the beginning position of slope interval,are extracted from the observed *** results show that the estimation performance will be increased, with lower noise level as well as higher system modulation transfer function value at half of normalized spatial frequency(MTF) or smaller *** a good performance system with noise squared-root variance(SRV) no more than 1.0 count and MTF between 0.3 and 0.4,the relative error between simulated and estimated MTF\s is less than 20%.The IDPSF of FY-2C satellite TIR band is estimated,and the derived MTF0.5 is properly close to on-ground testing *** image quality of FY-2C TIR band has been improved by using Wiener filtering and the estimated IDPSF,which eventually benefits the cloud detection product with more detectable low fractus and increased detection accuracy by about 1%in *** a step-profile target as a special case of this model,the proposed approach is also suitable for visible and near-infrared images.

关键词： Index Terms—Infrared imaging optical image processing optical transfer functions.

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A new type of Shipboard meteorological Satellite Receiving-processing System

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Acta Oceanologica Sinica 2000年第1期19卷 35-46页

作者： Xie Simei Hao Chunjiang Zou Bin Jing Qiyi Liao Xiaohong Sheng Xiaowen Zhang Canrong (1. national Research center for Marine Environment Forecasts, beijing 100081, china 2, Second Institute of china Aerospace Corporation 3. beijing Chuanyi Electric Compan Natl. Res. Ctr. Mar. Environ. F. Beijing 100081 China Second Inst. of china Aerosp. Corp. China beijing Chuanyi Electric Company Chinese Academy of Sciences Beijing China

The Shipboard meteorological Satellite Receiving-processing System (SMSRPS) is specially developed for the navigation meteorological safeguard of the Antarctic exploration ship over the sea ice area of the forth Ocean. This system can suit to the climate environment of very high temperature high moisture and very low temperature - supersaturation; it has a self-protection ability to against the hurricane - force wind over force 12 and the strong vibration during icebreaking, as well as strong magnetic disturbance. It has two sets of receiving-imagery processing systems for polar orbit low-resolution and quasi-stationary high-solution satellites. The key creation Points of this system are as follows: 1. the active gyro-control stabilization platform and a mixed mounting system of three rotating a - B and x -- y axes are used. It solved the tracing difficulties both in the low elevation angle and very high elevation angle of polar-orbit satellite, even in the status of ship moving with continuously changing its poition, direction and ship roll and pitch. 2. Imagery processing subsystem. The newest BORLAND-- DELPHI language and PASCAL language pro gramming software are used under WINDOWS 95 environment. It has a dynamic positioning nested-grid system and electric mapping grid data system. It can show the latitude-longitude of any point on the map, and marks any object such as ship, station or island, and draws the route. It can monitor cloud and temperature, forest fire, anomalous change of ocean and land. It can output satellite cloud maps of 24 bit with very high clarity. This system is very advanced in technique for the whole structure with the features of small volume, light weight and very low cost. It suits to very bad climate and ocean environment. Its imagery process ing system has complete functions with high resolution and being very easy to operate. It is not only suit to land use, but also and specially to all kinds of ship over the sea. It can be exte

关键词： Shipboard meteorological Satellite Receiving-processing System imagery processing system active gyro-control platform

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