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Possible mechanism of the effect of convection over Asian-Australian “land bridge” on the East Asian summer monsoon onset

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Science China Earth sciences 2006年第11期49卷 1223-1232页

作者： HE Jinhai1, WEN Min2. DING Yihui3 & ZHANG Renhe2.1. Jiangsu key laboratory of {2. Disaster (KLME), Nanjing Institute of Meteorology, Nanjing University of Informa- tion Science and Technology, Nanjing 2.0044, China 2. State key laboratory of severe weather (LaSW), chinese academy of {2. sciences, Beijing 100081, China 3. National Climate Center, chinese {2. Administration, Beijing 100081, China 1. Jiangsu key laboratory of {2. Disaster (KLME) Nanjing Institute of Meteorology Nanjing University of Information Science and Technology Nanjing 210044 China 2. State key laboratory of {2. weather (LaSW) Chinese Academy of Meteorological Sciences Beijing 100081 China 3. National Climate Center Chinese Meteorological Administration Beijing 100081 China

The Asian-Australian “land bridge” is an area with the most vigorous convection in Asian monsoon region in boreal spring, where the onset and march of convection are well associated with the onset of East Asian summer monsoon. The convection occurs over Indo-China Peninsula as early as mid-April, which exerts critical impact on the evolution of monsoon circulation. Before mid-April there are primarily sensible heatings to the atmosphere over Indo-China Peninsula and Indian Peninsula, so the apparent heating ratios over them decrease with height. However, after mid-April it changes into latent heating over Indo-China Peninsula due to the onset of convection, and the apparent heating ratio increases with height in mid- and lower troposphere. The vertical distribution of heating ratio and its differences between Indo-China Peninsula and Indian Peninsula are the key factors leading to the splitting of boreal subtropical high belt over the Bay of Bengal. Such mechanism is strongly supported by the fact that the evolution of the vertical heating ratio gradient above Indo-China Peninsula leads that of 850 hPa vorticity over the Bay of Bengal. Convections over Indo-China Peninsula and its surrounding areas further increase after the splitting. Since then, there is a positive feedback lying among the convective heating, the eastward retreat of the subtropical high and the march of monsoon, which is a possible mechanism of the advance of summer monsoon and convection from Indo-China Peninsula to South China Sea.

关键词： Asian-Australian 'land bridge', tropical convection, Indo-China Peninsula, the splitting of boreal subtropical high belt, East Asian summer monsoon onset.

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Typhoon Cloud Image Enhancement by Fuzzy Technique

Typhoon Cloud Image Enhancement by Fuzzy Technique

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第2.届中国气象学会年会灾害天气事件的预警、预报及防灾减灾分会场

作者： Changjiang Zhang1,2. Juan LU1 (1. College of Mathematics, Physics and Information Engineering, Zhejiang Normal University, Jinhua, China 32.004 2. State key laboratory of {2. weather, chinese academy of meteorological sciences, Beijing, China 100081)

A new kind of image measure function is proposed by combing fuzzy theory with other some measures. We use it as the overall fitness function of genetic algorithm to adaptively optimize the nonlinear transform parameters in the nonlinear transform function. Thus an optimal gray transformation curve is obtained to enhance the region of interest for a typhoon cloud image. Experimental results show that the proposed method has higher adaptability and intelligence. The proposed method is better than the classical image enhancement methods in overall performance. Enhanced typhoon cloud images by the proposed method can be used to accurately locate the center and predict intensity of the typhoon.

关键词： typhoon cloud image enhancement genetic algorithm fuzziness

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Interannual variation of annual precipitation and urban effect on precipitation in the Beijing region

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Progress in Natural Science:Materials International 2007年第9期17卷 1042-1050页

作者： Yu Shuqiu(State key laboratory on {2. weather,chinese academy of meteorological sciences,Beijing 100081,China) State key laboratory on {2. weather Chinese Academy of Meteorological Sciences Beijing 100081， China

The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960-2.00 annual precipitation observations at 2. stations in the Beijing *** results show that:the annual precipitation in the Beijing region possesses the large scale variation character with the linear trend of-1.197/10 yr,which corresponds to a total reduction of 2..82.mm in annual precipitation in the 41 years;the local annual precipitation anomalies(percent of the normal 1960-2.00)show a positive center near the urban area,*** precipitation island(UPI),whose intensity increases with the linear trend of 0.662.%/10 yr,opposite to the interannual trend of large scale precipitation over the Beijing region;changes in the UPI are also associated with the intensity of synoptic processes of precipitation,and when the synoptic processes are strong(wet years),the intensity of UPI strengthens,while the synoptic processes are weak(dry years),and the UPI disappears in the Beijing region.

关键词： urban precipitation island effect interannual climate variation precipitation Beijing atmospheric science

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An integrative estimation model of summer rainfall-band patterns in China

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Progress in Natural Science:Materials International 2007年第3期17卷 280-288页

作者： WEI Fengying (State key laboratory of {2. weather, chinese academy of meteorological sciences, Beijing 100081, China) State key laboratory of {2. weather Chinese Academy of Meteorological Sciences Beijing 100081 China

Three variation indices are defined to objectively and quantitatively represent fluctuations of three rainfall-band patterns in summers in China for the period from 1951 to 2.05, and the variation features of these indices are analyzed on both of interdecadal and interannual scales. A new method is proposed to establish an integrative estimation model based on the analysis of rainfall-band indices, and the model is applied to air, ocean factors to estimate their roles on variations of three rainfall-band patterns on different time-scales. The tests of estimation effects show that the fluctuations of three rainfall-band patterns are composed of variations on both significant inter-decadal and interannual scales, of which the interannual variation is mainly influenced by the Elnino/Lanina events, the East Asia monsoon and the ridge locations of subtropical high pressures in western pacific, while the interdecadal variation is mainly controlled by the Pacific decadal oscillation and interdecadal oscillations of the Arctic oscillation, ENSO, Nino3 sea surface temperature and summer monsoon. The estimated results from the integrative estimation model of rainfall-band patterns suggest that the way of estimation first according to each time scale of both the interdecadal and interannual scales, then estimating with an integration, which is proposed in this paper, has an obvious improvement on that without separation of time scales.

关键词： rainfall-band pattern interannual variation interdecadal variation integration estimation model.

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Interdecadal trend turning of global terrestrial temperature and precipitation during 1951-2.02

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Progress in Natural Science:Materials International 2008年第11期18卷 1383-1393页

作者： Xiaohui Shi Xiangde Xu State key laboratory of {2. weather,chinese academy of meteorological sciences,Beijing 100081,China State key laboratory of {2. weather Chinese Academy of Meteorological Sciences Beijing 100081 China

A grid-by-grid counting of interdecadal trend turning(ITT)of annual mean surface air temperature(SAT)and total precipitation at 67,359 terrestrial grids in the period 1951-2.02.is *** analysis of the last ITTs of SAT and total precipitation in the period,in the context of both occurrence time and linear trends after the breakpoint,indicates that a warming trend has become highly significant across most reagent of the world in the late 2.th *** terrestrial grids have recorded an ITT of total precipitation in either the 1970s or 1980s,and 45.7% of the terrestrial grids in the study have seen a decreasing trend in total annual precipitation after the break- point,with the remaining 54.3% having experienced an increasing ***,global terrestrial regions have experienced either an increasingly warm and dry climate or an increasingly warm and wet *** analysis of ITT of regional mean SAT and total pre- cipitation in 2. regions shows that the Northern American continent has become increasingly warm and dry after the last interdecadal ***,the African continent has become increasingly warm and wet,with both Europe and most of Asia having the same *** South America and the West of Australia have experienced an opposite trend in climate,becoming increasingly cold and wet.

关键词： Global terrene Surface air temperature Precipitation Interdecadal trend turning

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The least-square method in complex number domain

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Progress in Natural Science:Materials International 2006年第3期16卷 307-312页

作者： GU Xiangqian, KANG Hongwen and CAO Hongxing (State key laboratory of {2. weather, chinese academy of meteorological sciences, Beijing 100081, China) [a]State key laboratory of {2. weather Chinese Academy of Meteorological Sciences Beijing China

The classical least-square method was extended from the real number into the complex number domain, which is called the complex least-square method. The mathematical derivation and its applications show that the complex least-square method is different from one that the real number and the imaginary number are separately calculated with the classical least-square, by which the actual least-square estimation cannot be obtained in practice. Applications of this new method to an arbitrarily given series and to the precipitation in rainy season at 160 meteorological stations in China mainland show advantages of this method over other conventional statistical models.

关键词： complex least square Fourier transformation forecast in rainy season.

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Image of local energy anomaly during a heavy rainfall event

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chinese Physics B 2017年第11期26卷 565-573页

作者：杨帅左群杰高守亭 laboratory of Cloud-Precipitation Physics and severe Storms (LACS) Institute of Atmospheric PhysicsChinese Academy of Sciences State key laboratory of {2. weather Chinese Academy of Meteorological Sciences

A clear and interesting image of local total energy anomaly(EA) is depicted for a heavy rainfall event in this *** the convection development, it exhibits a positive local EA, implying local total energy(TE) experiences heaping up to prepare for the future system development. As the convection grows, it transforms into an opposite spatial modality with negative EA dominant, which means that the local TE is consumed to feed the convection growth in the middle and lower levels. The local total EA has consistent variation regular in intensity with severe weather system evolution. By utilizing the local TE budget equation in variable density fluid, the flux divergence of energy and its components are investigated, which could account for the local TE variation better. To relax the restriction and complexity introduced by identifying sporadic and alternative positive/negative signals of EA, the method taking the absolute-value operator on energy flux divergence is used to further simplify analyses. The derived characteristic signal of absolute EA is clearer and cleaner than ***, the EA could be illustrated based on the active degree of energy supply/consumption in a generalized sense whatever positive or negative anomaly should be it, which could be used easily to identify and even predict the system development for operational application. Note that, although two sets of methodologies are used to define EA herein, they play absolutely different roles in nature throughout the whole context. For example, the taking-perturbation method provides a diagnostic tool to portray a preliminary sketch and to give sufficient necessity of this research, while tendency equation of local TE illuminates more predictive sense and accounts for future local EA related to following system evolution. Therefore, the latter could be a more effective tool to routine usage.

关键词： local energy anomaly energy budget equation heavy rainfall

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Urban effects and summer thunderstorms in a tropical cyclone affected situation over Guangzhou city

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Science China Earth sciences 2007年第12期50卷 1867-1876页

作者： MENG WeiGuang1,3,YAN JingHua1 & HU HaiBo2.1 Institute of Tropical and Marine Meteorology,chinese meteorological Administration(CMA),Guangzhou 510080,China 2.Institute of Urban Meteorology,CMA,Beijing 100089,China 3 State {2. laboratory of severe weather,chinese academy of meteorological sciences,Beijing 100081,China 1. Institute of Tropical and Marine Meteorology Chinese Meteorological Administration (CMA) Guangzhou 510080 China 3. State key laboratory of {2. weather Chinese Academy of Meteorological Sciences Beijing 100081 China 2. Institute of Urban Meteorology CMA Beijing 100089 China

With data mainly from Guangzhou mesonet Automatic weather Stations(AWS),Guangzhou Doppler Radar and satellite TBB data,characteristics and evolution of the urban heat island(UHI) over Guang-zhou City were analyzed in a tropical cyclone affected situation for early August *** particular,two thunderstorms occurring during this period respectively at the night of 4 August and in the afternoon of 7 August were investigated to study the relationships between the development of thunderstorms and the *** showed that two thunderstorms were associated with the UHI *** induced local air convergence and initiated the thunderstorm *** cases showed a general agreement in time and space for the locations of maximum UHI,convergence,convection,and *** was found to be more favorable to developing in time periods and locations with stronger intensity of *** also showed that,due to the urban effects,both thunderstorms got strengthened when moving over Guangzhou City,with maximum radar echoes observed right over the urban area and precipitation located within the *** these features reveal that two thunderstorms were urban-induced storms.

关键词： summer thunderstorms, urban heat islands (UHI), urban effects, tropical cyclone

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Characteristics of climate change in the “significant impact zone” affected by aerosols over eastern China in warm seasons

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Science China Earth sciences 2008年第5期51卷 730-739页

作者： SHI XiaoHui1, XU XiangDe1, XIE LiAn2.1 State key laboratory of {2. weather, chinese academy of meteorological sciences, Beijing 100081, China 2.Department of Marine, Earth and Atmospheric sciences, North Carolina State University, Raleigh NC2.695-82.8, USA State key laboratory of {2. weather Chinese Academy of Meteorological Sciences Beijing 100081 China Department of Marine Earth and Atmospheric Sciences North Carolina State University Raleigh NC 27695-8208 USA

Through analysis of the distribution pattern and changing characteristics of atmospheric aerosols over the East Asia region during warm seasons in recent 2. a and beyond as well as their possible interac- tive relationship with a variety of meteorological elements, it is found that the high-value zone of aerosol optical depth derived from the Total Ozone Mapping Spectrometer (TOMS), its significant negative correlation zones in terms of sunshine duration (SD) and surface air temperature (SAT) and its significant positive correlation zones with low-level cloud amount (LCC) are co-located in the South China region during warm periods. Based on this finding, the region is referred to as a "significant impact zone" (SI zone) affected by aerosols. Then, a comparative analysis is made on variation differ- ences of observed SAT, SD and LCC, etc. in different regions. It is also found that the LCC is increased and the SD is decreased within the "SI zone" over eastern China during the warm season. These characteristics are more evident than those beyond the zone, while the warming trend within the zone is evidently weaker than that outside it. Studies show that since recent 2. a, under the influence of aerosols, the LCC tend to increase substantially with a clear decrease of SD and an unnoticeable warming trend within the "SI zone". Comparing with the climate change beyond the zone, the difference is significant. Therefore, the effects of atmospheric aerosols on climate is possibly one of the contri- butions to the difference of climate change existed between the southern and northern parts of the Eastern China during a warm season.

关键词： warm season significant impact zone of aerosols climate change

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A semi-implicit semi-Lagrangian global nonhydrostatic model and the polar discretization scheme

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Science China Earth sciences 2007年第12期50卷 1885-1891页

作者： YANG XueSheng1,CHEN JiaBin2.HU JiangLin1,CHEN DeHui1,SHEN XueShun1,ZHANG HongLiang1 1 State key laboratory of {2. weather,chinese academy of meteorological sciences,Beijing 100081,China 2.State key laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Beijing 10002.,China 1. State key laboratory of {2. weather Chinese Academy of Meteorological Sciences Beijing 100081 China 2. State key laboratory of Numerical Modeling for Atmospheric {2. and Geophysical Fluid Dynamics Institute of Atmospheric Physics Beijing 100029 China

The Global/Regional Assimilation and PrEdiction System(GRAPES) is a newly developed global non-hydrostatic numerical prediction model,which will become the next generation medium-range opera-tional model at China meteorological Administration(CMA).The dynamic framework of GRAPES is featuring with fully compressible equations,nonhydrostatic or hydrostatic optionally,two-level time semi-Lagrangian and semi-implicit time integration,Charney-Phillips vertical staggering,and complex three-dimensional pre-conditioned Helmholtz solver,*** the singularity of horizontal momentum equations at the poles,the polar discretization schemes are described,which include adoption of Arakawa C horizontal grid with ν at poles,incorporation of polar filtering to maintain the computational stability,the correction to Helmholtz equation near the poles,as well as the treatment of semi-Lagrangian interpolation to improve the departure point accuracy,*** balanced flow tests validate the rationality of the treatment of semi-Lagrangian departure point calculation and the polar discretization during long time *** and Suarez tests show that the conservation proper-ties of GRAPES model are quite good.

关键词： nonhydrostatic, global model, semi-implicit, semi-Lagrangian, polar discretization, conservation

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