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articel

• From the Clasic Theory of Turbulence to the Nonequilibrium Thermodynamic Theory of Atmospheric Turbulence
• HU Yin-Qiao;CHEN Jin-Bei;吕Shi-Hua
• 2012 Vol. 31 (1): 1-27. 
• Abstract ( ) PDF (4900KB) ( )
• The turbulence is one of the ubiquitous natural phenomena in everyday experience, and a puzzle that is not yet fully resolved in classical physics. All the more so, it is a basic characteristic of the atmospheric motion. This paper reviews by the numbers the develop history of classic theory of atmospheric turbulence, further more introduces detailedly the nonequilibrium thermodynamic theory of atmospheric turbulence. In the nonequilibrium thermodynamic theory of atmospheric turbulence, the entropy equilibrium equation of atmospheric system with dynamic processes is introduced, and then Fourier′s and Flick′s laws, Newton′s Law deducted by, and both the Dufour and the Soret effects, the cross coupling effect between the dynamic and turbulent transport processes in the atmosphere, and the turbulent intensity theorem are uniformly proved by atmospheric nonequilibrium thermodynamics. These laws and theorem are partially validated by using observed data, further to determine their phenomenological coefficients. The turbulent intensity theorem reveals that the macroscopic cause of the development of fluid turbulence is a result of the shearing effects of velocity together with temperature and proves that both Reynolds turbulence and Rayleigh-Bé nardturbulence coexist in the atmosphere. The discovery of the coupling effect phenomenon between the thermodynamic and dynamic processes breaks through the viewpoint of the theories of traditional turbulent transport, Fourier′s and Flick′s laws, and Newton′s Law, i.e., the transport flux of one kind of macroscopic quantity is equivalent to the gradient turbulent transport flux of this macroscopic quantity. Moreover, the coupling principle between the thermodynamic and dynamic processes deems that the transport flux of one kind of macroscopic quantity should include the velocity coupling transport in addition to the gradient turbulent transport flux of this macroscopic quantity. Consequently, the vertical transport flux of energy and matter should count in the cross coupling effect of the vertical velocity, i.e., convergence and divergence motion, in addition to the turbulent transport flux caused by their vertical gradient. The earth′s surface is characterized by spatial heterogeneity over a wide range of scales.The heterogeneityof underlying surface brings on the advection to lead the convergence and divergence motion. It may be an important cause of the imbalance of energy budget of the ground surface. The cross coupling principle of the vertical velocity and vertical turbulent transport may offer a possible clue to the theory of atmospheric boundary layer with heterogeneousunderlying surface and to overcome the difficulties encountered in the imbalance problem of ground energy budget and in the parameterization of boundary layer with the heterogeneousunderlying surface.

• Suitability of Local Similarity of Boundary Layer in Homogeneous Grassland Underlying Surface
• WANG Bing-Lan;HU Fei;CHENG Xue-Ling;ZHU Rong
• 2012 Vol. 31 (1): 28-37. 
• Abstract ( ) PDF (934KB) ( )
• The applicability of local similarity of the boundary layer of in the underlying surface Homogeneous grass land is examined using the turbulence observation data at meteorological tower. The height of constant flux layer is estimated. The extension of suitability of Monin-Obukhov  and local  similarity theories in the boundary layer upper constant flux is also discussed. The results show that the height of constant flux layer is about 50 m. The heat flux length scale is proportional to the buoyancy length scale both in the stable and unstable boundary layers. In contrast, the local Monin-Obukhov length is more suitable in describing the stability dependence of the similarity functions upper 50 m boundary layer than the buoyancy length scale.

• Study on the Threshold Friction Velocity of Dust Emission in Horqin Sand Land Area in the Inner Mongolia
• LI Xiao-Lan;ZHANG Hong-Sheng
• 2012 Vol. 31 (1): 38-46. 
• Abstract ( ) PDF (971KB) ( )
• Based onthe observations of dust concentration and micro-meteorological factors in the surface layer that were obtained from a duststorm station located in the Horqin sand land area in Inner Mongolia during the springsof 2008 and 2009, the variations in dust concentration and friction velocity during various dustevents wereinvestigated, and the evolution indownward short-waveradiation and net radiation for different dust weatherswere analyzed. Distinguishing local and non-local dust emission by using the dust concentration observations at two levels avoided an underestimation on dust emission thresholds. The resultsshowedthat the values of friction velocity u* and dust concentration were both low before dust emission,and u*  rapidly increased, while the values of dust concentration maintained smallduring the pre-emission stage. Then dust concentration quickly increased asu* was high duringthe dust emission stage, and dust concentration decreased nearly linearly with thedecreasing u* at the decay stage. The threshold friction velocity u*t and threshold velocity ut in the Horqin sand land area were estimated to be 0.62 and 9.5m·s-1, respectively. The thresholds slightly increased from blowing dust, dust storm to severe dust storm. In comparison with clear days, downward short-wave radiation and net radiation obviously decreased.

• Research on Application of Chebyshev Polynomial Filtering Method in Smooth Topography of GRAPES Model
• TU Ni-Ni;CHEN Jing;HE Guang-Bi
• 2012 Vol. 31 (1): 47-56. 
• Abstract ( ) PDF (1390KB) ( )
• Using the Chebyshev polynomial filtering method to obtain relatively smooth topography which was used in GRAPES model,a heavy rainstorm occurred in Sichuan Province during 20～22 July 2008 was simulated to discuss the impact of topography on precipitation according totopographysensitive test, as well as the applicability of smooth topography to the GRAPES model. The results show that Chebyshev polynomial filtering method through  reducing the height of mountain and upliftingthe height of depressions to achieve a smoothterrain, change of terrain height makes the vertical velocity change, thus causing changes in precipitation, increase in ascend exercise intensity is increased (or decreased) in the region caused by the rain intensity is enhanced (or weakened). The results of 26-day experiment during 2～28 July 2008 show that, Chebyshev polynomial filtering method has improved effect on light rain and moderate rain of GRAPES model, has smaller improved effect on heavy rainstorm and  rainstorm. In generally, the Chebyshevscheme has the effect to the precipitation forecast.

• Respons of Water Level in Qinghai Lake to Climate Change in the Qinghai-Xizang Plateau
• YUAN Yun;LI Dong-Liang;AN Di
• 2012 Vol. 31 (1): 57-64. 
• Abstract ( ) PDF (1032KB) ( )
• The increase of the intensity departure index of surface heating field in Qinghai-Xizang Plateau in the period from May to June helps to the  strengthen of the Plateau summer monsoon. The wind speed of Qinghai Lake basin and Buha river flow are the main factors  affecting the changes of  interannual difference of water level in winter and spring. However, the interannual difference of water level in summer and autumn is affected jointly by precipitation, wind speed and flow. With the increasing of the basin precipitation and Buha river flow, and decreasing of basin wind speed, the interannual difference of water level in Qinghai Lake displays an upward trend (slower decline of the water level). So a concept model has been get up by above research, this model explain that how the thermal in the Qinghai-Xizang Plateau effects on the water level in Qinghai Lake  through basin climate change.

• Numerical Simulation of Effect of WRF Land Surface Parameter Disturbance on a Rainstorm in Northwest China
• LI An-Tai;HE Hong-Rang;ZHANG Yun
• 2012 Vol. 31 (1): 65-75. 
• Abstract ( ) PDF (1210KB) ( )
• To test the sensitivity of the rainstorm to the disturbance of NOAH land surface parameter MAXSMC in Northwest China，  the rainstormprocess in southeast of Gansu during 1~2 July of 2005 are numerically simulated using NCEP 1°×1° reanalysis data and WRF V3.1 mesoscale model. The results indicate that the rianstorm is more sensitive to the disturbance of the parameter MAXSMC(maximum volumetric soil water), the increased MAXSMC will not improve simulation of precipitation, and if the initial value decreases by 20%, the simulated  precipitation will be more close to the observation. The soil moisture in shallow layer,  lower-level meteorological factors and surface flux to disturbance MAXSMC are of certain sensitive, but the sensitivity is significant different because of the various underlying surfaces. The most important influence on rainstorm is the changes of the direct transport of surface flux and indirect water vapor transport caused by lower level instability, and due to the different proportionsof direct transport of surface flux and indirect water vapor transport resulted from underlying surface properties, precipitation will appear completely different trends in different regions.

• Study on Improvement of Ageostrophic Wet Q Vector in Inhomogeneous Saturated Atmosphere by Considering Convective Latent Heating
• CAO Yu;MIAO Chun-Sheng;YUE Cai-Jun;SHOU Shao-Wen
• 2012 Vol. 31 (1): 76-86. 
• Abstract ( ) PDF (1377KB) ( )
• Combining a torrential rainstorm process, which was caused by typhoon ‘Morakot’ (No.8 in 2009)  landing Fujian Province, the improvement of ageostrophic wet Q vector in inhomogeneous saturated atmosphere (Qum) is carried out considering convective latent heating. The results are as follows: (1) Typhoon ‘Morakot’ land at Fujian Province from 08:00 on 9  to 08:00 on 10 August in 2009, which cause wide range heavy rainfall in most of parts of Zhejiang Province and middle and north of Fujian Province. The precipitation process is successfully simulated by the Weather Research and Forecasting (WRF) model. (2) The divergence field of Qum vector on 850 hPa is a good indicator to the counterparts of the precipitation area. The variation of convergence intensity of Qum vector divergence is highly correlated with that of precipitation throughout the rainstorm. (3) There is a lot of convective latent heating release during this heavy  precipitation  process, and the maximum center located at 600 hPa. (4)  Qum vector is improved by considering convective latent heating release. The analysis shows that the ability of simultaneously reflecting and diagnosing precipitation of the convergence field of the modified Qum vector divergence has been significantly enhanced.

• Climatic Features of Asian Upper Westerly Jet Activities and Their Relationship with Summer Precipitation in Partly Areas of China
• WEI Lin-Bo;ZHOU Gan-Lin;WANG Shi-Gong;SHANG Ke-Zheng;MA Yu-Xia
• 2012 Vol. 31 (1): 87-93. 
• Abstract ( ) PDF (768KB) ( )
• To better explore and understand the activity features of Asian Upper Westerly Jet (AUWJ) and their application to the weather forecast, the climatic features of pentad-to-pentad activities of AUWJ and their relationship with precipitation in partly areas of China were analyzed utilizing the 200  hPa wind speed of the NCEP/NCAR reanalyzed data from 1948 to 2008. The main conclusions are as follows:  (1) The AUWJ moves northward from 30°N to 45°N from winter to summer; then southward back to  30°N again after summer. When moving northward, there are two fast-moving periods especially at the longitude about 90°E, one is from mid-April through the end of May, and the other is from June to July. The latter period corresponds to the Meiyu period in Changjiang-Huaihe River (CHR). (2) The center of AUWJ usually stays at about 140°E for majority time of the whole year, while it moves quickly westward in mid-June; it moves to the upper of CHR in late June and Tianshan region of Xinjiang in the end of July, and then it moves eastward quickly back to  140°E again. It stays at the Asian continent just for about two months every year. (3) There is certain relationship between the AUWJ center latitude position and precipitation in CHR during the Meiyu period. Averagely, when the AUWJ center position is more westerly than normal in January, and the AUWJ axis is more southerly from April to May, it may be heavy Meiyu in CHR; vice versa. (4) There is also certain relationship between the strength and latitude position of AUWJ and the precipitation in Xinjiang in summer. When the AUWJ axis over Xinjiang is more northerly from mid-April to late May, and the axis is more southerly and AUWJ is stronger than normal in summer, the precipitation of Xinjiang in summer will be more than normal; vice versa.

• Abnormal Characteristics of Blocking High during Durative Low Temperature, Snowfall and Freezing Weather in Southern China
• LI Yan;WANG Shi-Gong;JIN Rong-Hua;WANG Jin-Yan;LI Jiang-Ping
• 2012 Vol. 31 (1): 94-101. 
• Abstract ( ) PDF (792KB) ( )
• During the early 2008, southern China was hit by durative  low temperature, snowfall and freezing weather disaster, which was a rare weather extreme in history because of its wide influencing area, high strength and long durative time. Blocking high in three key regions of the Eurasia played very important role in the general circulation of this disaster, with three abnormal characters: Comparing with character of blocking high during the same period from 1950 to 2008, in early 2008, the blocking days were more in Ural Mountain and Lake Baikal, while no blockings occurred in Okhotsk Sea; blocking high was stronger in Ural Mountain and weaker in Lake Baikal and Okhotsk Sea; the biggest PV-θ blocking index was east of that in the most blocking years in Ural Mountain, but west of that in the most blocking years in Lake Baikal which indicated that blocking high were concentrated in the Ural Mountain and western Lake Baikal during this extreme weather disaster. Abnormal characteristics of blocking days, strength and blocking location, brought more action of small trough and cold air supplied to the cold waves by long time persistence. Accompanying with other abnormal factors of general circulation, it eventually caused such durative low temperature, snowfall and freezing weather disaster.

• EOF Analysis on Interannual Variation of 500 hPa Long Wave in Northern China in Spring and Summer
• WEI Hong;WEI Zhi-Gang;LIU Hui;LI Zhen-Chao;WANG Chao
• 2012 Vol. 31 (1): 102-112. 
• Abstract ( ) PDF (1382KB) ( )
• The spatial distribution and time evolutionof long wave in Northern China in spring and summer were calculated by Empirical Orthogonal Function (EOF) and harmonic wave analyses to daily data from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis for 1958-2008. The results showed that: (1)  In spring, a complete wave lies from Aral Sea to Japan, that is to say, there is a ridge acting mostly from Lake Balkhash to Lop Nur and a trough in Northeast China, both of ridge and trough enhanced. In summer, there is a ridge in Ural Mountain and the  Okhotsk Sea, and a trough in Lake Baikal, the trough acting mostly from Mongolia to North China, however, the trough weakened in the past 51 years. (2) The long wave departure has an anti-correlation relationship between Northwest China and North China and their upper and lower regions in spring, and in summer, the center of long wave departure moves toward east comparing with the spring.

articel

• Numerical Simulation of Effect of Sea Spray on Typhoon ‘Morakot’ Structure
• WANG Ping;CHEN Bao-De;ZENG Zhi-Hua;FAN Guang-Zhou
• 2012 Vol. 31 (1): 113-125. 
• Abstract ( ) PDF (1609KB) ( )
• A sea spray flux parameterization scheme is included within a non-hydrostatic meso-scale model WRF (weather research and forecasting). Typhoon  ‘Morakot’ was simulated using the coupled atmosphere-sea spray model to study the effect of sea spray on structure and intensity of the typhoon. The results demonstrate that, regardless of whether sea spray flux parameterization is included or not, the model can always simulated the track well, indicating that the sea spray has little impact on its track. If taking into account of sea spray flux in the model, the tangential, radial, and vertical wind, vorticity, cloud water mixing ratio and rain water mixing ratio are all increased, showing a clear effect of sea spray on structure evolution of ‘Morakot’. The largest effect of sea spray is in the lower troposphere with significant increase in low level wind speed, especially within strong wind zone. The evaporation of sea spray lead to a significant increase of heat flux in the air-sea interface, particularly, the latent heat flux and the area with high latent heat flux is corresponding to the maximum wind speed near the typhoon center. Due to enhancement of water vapor and heat fluxes, cloud water and rain water around typhoon eye are increased in the sea spray experiment, which is closely associated with more precipitation.

• Universality of Quasi-3-year Period of Temperature in Last 50 Years and Change in Next 20 Years in China
• WANG Cheng-Hai;LI Jian;XU Xiao-Guang
• 2012 Vol. 31 (1): 126-136. 
• Abstract ( ) PDF (1660KB) ( )
• The periodicities of annual and winter temperature changes in 8 climate regions of China are analyzed using the wavele from 1961 to 2009, the prediction of temperature change in next 20 years in period of 2010-2029 also are made. The results show that the main periodic lengths of temperature are in high frequency about 3～4 and 7～12 years in 8 climate regions of China, there is a pervasive 3-year cycle, especially, the 3-year periodic signal is significant in winter of China, which is stable. The periodic character of annual temperature has obvious difference between the southern and northern China. The results of period compound extrapolation show that the temperature in China will continue to keep incremental trend in next 20 years, the temperature, in northern region of China including the Qinghai-Xizang Plateau, will increasing greater than that in southern region except for southwest of China. According to the linear trend, the increasing range of temperature will not exceed 1 ℃.

• Application of Excess Rotation Kinetic Energy in Distinguishing the Tornadic and Non-Tornadic Mesocyclones in China
• ZHOU Xiao-Gang;WANG Xiu-Ming;YU Xiao-Ding;FEI Hai-Yan
• 2012 Vol. 31 (1): 137-143. 
• Abstract ( ) PDF (704KB) ( )
• Doppler radar mesocyclone algorithm is designed to detect mesocyclones with diameters from 1.8 to 9.2 km (1~5 n mi). Majority strong tornadoes occur in mesocyclone with supercell, but not all of the mesocyclones can develop into tornadoes. In this paper, the concept of the Excess Rotational Kinetic Energy (ERKE) of a mesocyclone core is introduced. Combining with mesocyclone algorithm and radial velocity products, the temporal variation features of ERKE and weighted height are analyzed in  some tornadic and non-tornadic mesocyclone lifetime, and the initial ERKE value and weighted height of other cases are also calculated. The results show that the ERKE are generally larger and the weighted heights are relatively lower in tornadic mesocyclone, comparing with non-tornadic mesocyclone. Furthermore, the tornadic and non-tornadic mesocyclones in the low- and mid-troposphere layers can be distinguished by the initial ERKE value of mesocyclone with supercell storm effectively, which can be used as the quantificational identification indicator of tornadic mesocyclone. Finally, the ERKE diagram is given on the basis of the climatological mature mesocyclone in China. From the diagram, ERKE value can be quickly gained via the values of rotational speed and the mesocyclone radius. 

• Review of Forecast Result for China Natural Disaster in 2010
• LIAO Liu-Feng;TANG Mao-Cang;GAO Xiao-Qing
• 2012 Vol. 31 (1): 144-149. 
• Abstract ( ) PDF (790KB) ( )
• There are many natural disasters in 2010 in China. The prediction process is summarized based on the disaster(drought/flood/earthquake) forecasting methods which be advanced at the beginning of 2010. The prediction include Yushu microseism on 14 April, continuous drought in southwest of China through autumn to spring during 2009-2010. The severe precipitation of the mid- and lower-reaches of Yangtze River in the flood season which also happened in Qinghai Province, debris flow in Zhouqu which caused by downpour on 7 August. The analyzed results show that the natural disasters, which include drought, flood, earthquake and so on, are related with Benard convection in outer core of Earth. The earthquake process is that the outer core convective fluid uprising the Crust-Mantle layer, so the epicenter maybe is the midpoint of the uplifting and sinking where the horizontal shearing of vertical velocity is the most. The downpour is arosed that the mid-point of two convective uplifting   fluid can constitute a  ‘beat frequency’ effect because of  ‘beat’. The reset (tension) of Crust effects after strong earthquake is the cause of drought. These actions are called as the ‘develop of the deep system below ground’ collectively, so we can distinguish them from the fluid conductivity named ‘Shallow system’ in lithosphere.

• Study of Extinction Property of Atmosphere in Tianjin in Summer
• CAI Zi-Ying;HAN Su-Qin;LIU Ai-Xia;YAO Qing;HUANG He
• 2012 Vol. 31 (1): 150-155. 
• Abstract ( ) PDF (693KB) ( )
• Using the concentration data of black carbon aerosol, NOX, particulates, and visibility and meteorological gradient data at Tianjin boundary layer station in 2010， the discipline of extinction properties and the reason of  low visibility event are analyzed. The result shows that the major pollutants were PM10 and PM2.5 in Tianjin in summer, aerosol extinction coefficient is 529.06 M·m-1, aerosol absorption coefficient is 50.17 M·m-1, aerosol scattering coefficient is 478.89 M·m-1, the gas absorption coefficient is 7.74 M·m-1, single scattering albedo of aerosol is 0.87. There is half time of the atmospheric conditions are neutral or nearly stable, and under this condition, about half  time will be low visibility events (visibility less than 5 km). 

• Vertical Distribution Structure and Characteristic of Aerosol over Arid Region in a Dust Process of Spring
• ZHANG Jie;TANG Cong-Guo
• 2012 Vol. 31 (1): 156-166. 
• Abstract ( ) PDF (1322KB) ( )
• Direct observation of vertical distribution of aerosol and atmospheric condition in the free troposphere are made using the surface Micro-Pulse Lidar (MPL) at Zhangye station(39.08°N, 100.27°E)in the spring of 2008. The results show that the vertical profiles of aerosol over Zhangye can be divided into three parts, namely high layer,  middle layer and  low layer. Aerosol in high layer is appeared from 5 km to 9 km at 08:00~24:00, and it is down trend with  time. Aerosol in middle layer is small height gradient with time that show well-mixed aerosol layer, and ranged from 2.5 km  to 4.5 km. The aerosol in low layer is decreased with height increasing. The  aerosol in high layer is come from outer original, due to being lifted from higher altitude region on upwind direction, and is transported on higher level. The aerosol in middle and low  layers are from outer original or local, due to multi-sand originals and local sand texture. There are three aerosol distribution shapes, aerosol profile shows exponent decreased with height increasing under the stable condition, a small height gradient is well-mixed dust layer, vertical profile of aerosol shows single peak with height increasing under the unstable atmospheric condition. Due to effect of the top of atmospheric boundary, up-boundary of extinction coefficient shows diurnal change of single peak, which is higher in the afternoon and lower in the morning.

• Mesoscale Structure Characteristic of Heavy Flooding Rainstorm Process in Fujian in Preflood Period of South China
• LAI Shao-Jun;HE Fen;CHEN Hai-Shan;SHEN Tong-Li;WU Wei-Jie;WU Yi-Wei
• 2012 Vol. 31 (1): 167-175. 
• Abstract ( ) PDF (1320KB) ( )
• The infrared brightness temperature of FY-2E at cloud top data, regular observation data, AWS data and  NCEP reanalysis data were used to analyze and discuss the evolution and structure characters of the mesoscale convective systems (MCS) of the heavy  rainstorm that happened from 19 to 20 June, 2010 in preflood period of South China. The obtained result are as follows. Firstly, there were mainly four MCSs  developing and moving eastwardly along shear line on 850 hPa, which provided favorableconditions for the severe precipitation. Secondly, the divergence in upper level and the convergence in lower level promoted the upward movement of the rainy area, furthermore, the condensation latent heat is released by the water vapor of convergence in lower level being in the ascending process which accelerate ascending of water vapor and developping of the low vortex. Those are the dynamical characters of the severe precipitation. Thirdly, the unstable energy at the surface and southwest warm and wet stream moved upwardly by strongly upward motion and cold air from middle and high level toward lower level along isoline of θseencountered in the middle level to form the frontogenesisarea, which is the thermodynamic character of the extreme rainstorm. Fourthly, the diagnostic of the Moist Potential Vorticity (MPV) indicated that the development of convective instability and conditional symmetry instability, which induced the vortex developing and aggravating ascending movement near the severe precipitation area, played an important role in the genesis and maintaining of the severe precipitation. 

• Analyses on Meteorological Elements and General Circulation of Drought in Guizhou Province in Autumn-Winter-Spring from 2009 to 2010
• CHI Zai-Xiang;DU Zheng-Jing;CHEN Zhong-Ming;YU Jun-Wei;SHUAI Shi-Zhang;LONG Xian-Ju;FU Qiong
• 2012 Vol. 31 (1): 176-184. 
• Abstract ( ) PDF (1080KB) ( )
• Based on the surface observation from 88 stations in Guizhou Province, air temperature and precipitation data from 800 automatic weather stations from September 2009 to May 2010, and NCEP reanalysis data, the large-scale circulation background and the meteorological element distribution features during persistent drought period were analyzed, and meanwhile, the degreeof the droughtwas modeled through climate dry-wet index and comprehensive meteorological drought index. The results revealed: It was the west Pacific subtropical high becoming zonal distribution, intensified, westward, with south weaker synoptic system and the path of the cold air tending to more northward and eastward that caused persistent drought taking place in Guizhou. During the drought period in the west of Guizhou Province, the air temperature was positive anomaly, precipitation was negativeanomaly, relative humidity was 38%~73%, and climate dry-wet index was less than 0.6. In the drought period of the east of Guizhou Province, the air temperature was positive anomaly except for Novenber 2009 and April~May 2010, Others were negativeanomaly, precipitation was basically positive anomaly, relative humidity was 60%~81%, and climate dry-wet index was less than 0.6, except for November 2009 and April~May 2010, Others were more than 1.0. In general, the drought in the west of Guizhou was more severethan that in the east.

• Analysis on Variation of Sunshine Duration in Xi′an in Recent 60 Years and Its Influencing Factor
• WANG Zhao;PENG Yan;BAI Ai-Juan;DONG Yan;LI Xing-Min
• 2012 Vol. 31 (1): 185-192. 
• Abstract ( ) PDF (924KB) ( )
• Using the long term record (about 60 years) of meteorological parameters of Xi′an and east of Guanzhong region in Shaanxi Province and nine years of MODIS data, the causes of decreasing trend for sunshine duration during rapid economic developing period have been analyzed. The result shows that there is an obviously decrease of sunshine duration in Xi′an from 1981 to 2001. The decreasing trends are also found in Weinan and Huaxian, east of Xi′an. And there is the good correlation of percentage reduction of sunshine duration at two different stations. But the decrease of sunshine duration is not found in Hua mountain. The cause of the reduction is at height below 2 km. And there is a high value center of AOD on the east side of Guanzhong region in Shaanxi Province, while after eliminating  of fog day, total cloud cover and low cloud cover, there are no obvious increase of fog day and cloud cover based on the increase of aerosol caused by the development of the cities. So the main cause of sunshine duration over east of Guanzhong in Shaanxi Province is not the indirect effect of aerosol, but most probably direct radiation. That means in the special terrain and prevailing wind, anthropogenic aerosol caused by the development of cities in Guanzhong region of Shaanxi Province accumulated in east part of Guanzhong, thus there is a high aerosol concentration layer below 2 km above the surface layer. The existence of high concentration aerosol layer could reduce the amount of solar radiation reaching the earth surface and decrease the sunshine duration. The increasing sunshine duration from 2002 to 2008 probably has some relation with anti-pollution measures and variation of prevailing wind, which need further study.

• Reconstructed Mean Temperature in Mearkang, West Sichuan in July and Its Detection of Climatic Period Signal
• YU Shu-Long;YUAN Yu-Jiang;WEI Wen-Shou;ZHANG Tong-Wen;SHANG Hua-Ming;CHEN Feng
• 2012 Vol. 31 (1): 193-200. 
• Abstract ( ) PDF (867KB) ( )
• Single correlation calculation indicated that the correlation were significant among tree-ring chronologies of Ayilashan and temperature in July at Maerkang and Hongyuan stations in West Sichuan, Considering the hysteresis of temperature about growth of tree, a average temperature series in July of 1597-2005 at Maerkang station was well reconstructed and its explain variance was 41.5% by means of the tree-ring chronology series. It was verified that the reconstructed temperature was reliable by leave-one-out. Some results obtained by analyzing the 409-year reconstructed temperature series are as follows: periods of temperature in July have 3～4， 5～9， 21～28  and 56～76 years. Strong energy of short periods have happened at high temperature age, middle one, in little ice age, and  long one, before the industrial revolution.

• Study on Spatial Interpolation Method of Mean Air Temperature in Xinjiang
• WANG Zhi;SHI Qing-Dong;CHANG Shun-Li;WU You-Jun;LIANG Feng-Chao
• 2012 Vol. 31 (1): 201-208. 
• Abstract ( ) PDF (916KB) ( )
• Based on the sufficient exploratory analysis and experimental interpolation for the perennial mean month or year air temperature at all meteorological stations in Xinjiang from 1981 to 2008, two methods, the ‘multiple regression+residual interpolation+topography regulation’ and ‘elevation effect correction+zero elevation interpolation+topography regulation’, had been used to simulate the spatial distribution of air temperature for multi-yearly month or year mean temperature in the study area, at the same time, cross validation and comparison analysis had been taken for two methods. The results showed that any single deterministic function or geo-statistical method can not precisely simulate the spatial distribution of monthly or annual air temperature  in Xinjiang area, because the simulated result could not reflect the practical situation and the method itself had not considered into some major influence factors; nevertheless, both mixed and comprehensive methods can get fairly accurate spatial simulated results of air temperature, which is consistent with each other in spatial distribution, but have some differencesin months, stable and more accurate in summer and autumn; by testing of cross validation and comparison analysis, both methods have same precision and stability in summer and autumn, from May to October, but the later error is higher than the former, obviously in winter and spring, from November to April, and comparatively speaking, the former is more accurate and stable than the later, however, both methods haveeach advantage and disadvantage, choosing the more appropriate one needs actual applying situation.

• A Single-Station-Based 3D Lightning Channel Imaging System Using Differential Arrival Time of Thunder
• ZHANG Han;WANG Dao-Hong;吕Wei-Tao;MENG Qing;ZHANG Yi-Jun
• 2012 Vol. 31 (1): 209-217. 
• Abstract ( ) PDF (934KB) ( )
• Single-station-based three-dimensional lightning channel imagingsystem, which uses the differential time of arrival of thunder,has been developed. The system consists of a small-size microphone array,a data collection and storage system. The microphone array is consisted of four microphones which work at a frequency rangefrom 15 to 20 kHz. Thunder signals recorded by different microphones are processed by the cross-correlation analysis to obtain the differential time of arrival at different microphones, and the direction  the thunder propagationis calculated byusingthe least square method. Thedistance from the thunder sourceto the array is determined by the time interval between the arrival of the electromagnetic signal and the thunder. Then the three-dimensional thunder sources are obtained by combining the direction and distance of thunder. The thunder signal of a rocket-triggered lightning comparing with 8 return strokeswas recorded by this system, and the lightning channel imaging results have beencompared with the photographs observed by a high-speed camera. The thunder source and  photograph are found to agree fairly well, whichindicates that the system developed in this study is feasible and can be used as a convenientlightning channel 3D imagingtool.

• Analysis on Physical Characteristic of Lightning with Multiple Return Strokes
• QU Hai-Yan;YUAN Ping;ZHANG Ting-Long;QIE Xiu-Shu;ZHANG Yi-Jun;ZHANG Guang-Shu
• 2012 Vol. 31 (1): 218-222. 
• Abstract ( ) PDF (575KB) ( )
• Using the spectrum of cloud-to-ground(CG) lightning with multiple return strokes obtained by a slit-less spectrograph in Tibetan Plateau, the channel temperature and its change have been studied. The results show that the channel temperature oppears obvious difference in different strokes of lightning. Generally, the temperature at initial stage of flash is higher, and then gradually decreases. The spectral characteristic, channel temperature and their correlation with dischargecharacteristicand the thermal effect of current are discussed by combing the spectrum with synchronous electrical information at the first time.It is found that the total intensity of spectrum is directlyproportional to the amplitude variations of radiation electric field,  the total intensity of spectrum should bedirectlyproportional tothe intensity of discharge current,and the correlation between channel temperature  and the energy transmitted in onereturn stroke   is  positive.

• Differential Phase Data Quality Control of Mobile X-Band Dual-Polarimetric Doppler Weather Radar
• XIAO Yan-Jiao;WANG Bin;CHEN Xiao-Hui;CAO Jun-Wu;YANG Xian-Ming
• 2012 Vol. 31 (1): 223-230. 
• Abstract ( ) PDF (1016KB) ( )
• The specific differential propagation phase is an important parameter for meteorological applications, because it is not affected by propagation attenuation and closely related to rain intensity. To estimate the specific differential propagation phase requires to compute the derivative of range profiles of the differential phase. The existence of possible phase wrapping, ground clutter, noise, backscattering phase and associated fluctuation in the differential phase makes the derivative evaluation having an unstable numerical process. In this paper, for mobile X-band dual-polarimetric doppler weather radar in the alternative transmission mode developed by Anhui Sun-Create Electronics Co., Ltd., a set of algorithm is presented to control the data quality of the differential phase, including ground clutter removing, phase unfolding, initial phase adjusting and phase filtering. Two cases are studied to evaluate the algorithm. The results show the algorithm can remove effectively the ground clutter, unfold wrapped phases and filter fluctuations associated with noise and backscattering phase.

• Analysis on a Severe Storm of Wenzhou Similar Tornado in The Outer-Region of the Super Typhoon ‘Sepat’
• ZHENG Feng;ZHONG Jian-Feng;ZHANG Ling-Jie
• 2012 Vol. 31 (1): 231-238. 
• Abstract ( ) PDF (1149KB) ( )
• 
  A similar tornado event during 23:10 to 23:20 on 18 August 2007 induced in Longgang of Wenzhou city in the peripheral of Super Typhoon ‘Sepat’(0709) is analyzed using the NCEP/NCAR 1°×1° 6 h reanalysis data, Doppler radar data and TBB data of FY-2C satellite. The physical diagnosis shows that this event occurred in the environment characterized by such as upper-level divergence, lower-level convergence, strong upward motion extending from lower to upper levels, and strong vertical wind shear in the very low altitude. Doppler radar monitoring shows that a mesoscale cyclone appeared in Longgang town, 40 km away from the radar station, associated with significantly adjacent azimuthal velocity shear, and the radar continuously tracked and detected the phenomenon of cyclonic speed developing from middle to lower levels. Although it had no indicators of the tornado vortex characteristics (TVS) from the radar observation, but the strong rotational wind rapidly developed and transported downward from upper to lower levels in a very short time, and it thus caused the supercell tornadogenesis.

• Comparative Analysis on Supercell Storm Structure of a Severe Hail Shooting in Fujian Province in Early Spring of 2010
• FENG Jin-Qin;YU Xiao-Ding;FU Wei-Hui;CAO Chang-Yao
• 2012 Vol. 31 (1): 239-250. 
• Abstract ( ) PDF (1769KB) ( )
• Using T-lnp, the environmental physical field and the  CINRAD/SA data  of Jianyang, Longyan and Changle, two supercell storms with 5 cm severe hail in the middle-north of Fujian on 3 March 2010 have been comparative analyzed. The result shows that  the dry and warm lid, strong vertical wind shear,positive vorticityin middle-upper levels and mesoscale low pressurein surface provided the better environmental conditions for the supercell storm. Two supercell storms developed from multiple cellsand moved to right at the mature stage, which belonged to long-life right moving storm. The first supercell  went through three strengthening phases because of the terraineffection and new cell incorporation.A typical hook echo  appeared   in the low level and the three-body scatter spike  appeared in middle-upper levels. The second supercell went through three stages which are multicell storm, supercell storm and multicell storm. The supercell storm appeared the obvious inverted ‘V’ shape in the low level and  anvil to the right in the middle-upper level. The mesocyclones of two supercell storms developed from middle level. When the mesocyclone intensity continuously strengthened, the thickness of  mesocyclone increasedand the strongest shear  center suddenly dropped to cause hail and gale. From the analyses of the first supercell storm air flow, the updraft of storm front and back and inflow in low level formed obvious convergent rotation effection. When the dry cold updraft further promoted the  warm stream in low level, the strong inflow was formed, and the strong divergent rotation on the upper level was produced. The supercell storm maintained long time. In the storm dissipating stage of the second supercell storm, the  mesocyclone at right side storm is  splitted, then weakened and vanished. Duringthe severe weather, the storm behaved the three-body scatter spike, strong divergent rotation on the upper level and high VIL density.

• Typhoon Detection of Radar Improved Using Ultra Low Elevation Angle
• XU Ba-Lin;LIU Li-Ping;WU Chang-Dao;WANG Gai-Li;JIE Li-Yan
• 2012 Vol. 31 (1): 251-257. 
• Abstract ( ) PDF (1024KB) ( )
• Using the ultra-low-elevation angle data of changle radar, the ultra-low-elevation of typhoon ‘Haitang’ and ‘Jangmi’ and difference of PPI echo with 0.5° elevation angle are analyzed. The obtained results are as follows: (1) It can improve the remote detection, judge the construction and evolution of typhoon. (2) It can help to forecastthe intensity and development of typhoon,improve the early warning system and nowcasting. (3) Itcan help to find out the development and change of typhoon cloud system. For the typhoon ‘Jangmi’, comparing with 0.5° elevation angle, the remote detection area has been enhanced for 1.09 times, thetotal estimated precipitation  increase between 2.1%~7.9%. Ultra-low-elevation angle can improve the weakness of routine scan way on detecting ability of remotelow radar echo. Inthe meantime,  the ultra-low-elevation angleisalso vulnerable to detect the impact of close-wave clutter, judgmentthe construction of typhoon can be interfered sometimes. Through radar detecting of typhoon the ‘Haitang’and ‘Jangmi’, the ultra-low-elevation angle can improve the remote detection and early warning of typhoon.

• Analysis on Satellite Retrieval of Cloud Structure in a Severe Squall Line Process
• XU Xiao-Hong;YU Xing;ZHU Yan-Nian;LIU Gui-Hua;DAI Jin;YUE Zhi-Guo
• 2012 Vol. 31 (1): 258-268. 
• Abstract ( ) PDF (1417KB) ( )
• Using  the NOAA AVHRR data, combiningwith  radarand FY-2C geostationary satellite data, a severe squall line process  occurred in Shandong Province on April 28, 2006  was analyzed. The results show: (1) The convective characteristicsof cloud can be seen from the RGB composite image. (2) Based on the comprehensive multispectral analysis, some evidently qualitative signs for severe storm have been summarized that include the convective structure, clear bulbsand anvil, the cloud top mainly composedofsmall particles, the effective radius (Re)growslowly and then decreased with the height. The cloud top Re and its growth rate can be as quantitative indices. This severe storm can be identified 1 h and 2.5 h earlier than the occurrence of hailstormand squallline, 2 h earlier than the Doppler radarbased on these proposed signs and indices, which provide a new way for application of satellite  monitoring and warning of severe storm.

• Hail Shooting Type and Distribution of Correlation Factor
• SUN Yu-Wen;HAN Yang;SUN Xia;YIN Yan;ZHAO Zhi-Jun;SHI An-Ying;JIANG Yan;QI Zuo-Hui
• 2012 Vol. 31 (1): 269-276. 
• Abstract ( ) PDF (665KB) ( )
• Through the rainfall and hail sub-file and simultaneously reading analysis of self-recording paper of 16 times hail weather system detected fromautomatichail and rainfall sub-detector, the 5 types of hail and the distribution of their related factors areobtained： (1) hail shooting intensity is a super large class; (2) hail shooting intensity is in subclass; (3) hail shooting has a large total amount with a devastating disaster; (4) hail shooting amount shows a pulse surge; (5)weak hail cloudsystem with a long duration, a small amount and a weak intensity.It will guide the study forthe structure of hail cloud and the generation of hail embryos, which provides the observational data for the simulation of hail formation and floor.

• Risk Evaluation for Spring Frost Disaster of Winter Wheat in Yellow River-Huai River Regions Based on Crop Model
• ZHANG Xue-Fen;YU Wei-Dong;WANG Chun-Yi
• 2012 Vol. 31 (1): 277-284. 
• Abstract ( ) PDF (956KB) ( )
• The winter wheat spring frost damage mainly occurs in the Yellow River-Huai Riverregions. Based on the winter wheat data, the meteorological data at 54 agrometeoroligical observation stations from 1961 to 2008 and the results of frost-box experiment in the field, the technologies ofspring frost disaster effect on growthof winter wheat bythe WOFOST crop modelare studied, and the influence of the spring frost on different growth periods of wheat is revealed.Using the technologyof extracting the spring frost disaster damage from crop model, risk evaluation model is established with spring frost danger, exposure and fragility as the risk factors, and develops spring frost risk evaluation in recently 50 years in the Yellow River-Huai River regions. The results show that, the areas including western, southwestern, north western and eastern of HenanProvince in Yellow River-Huai River regions are high risk， in which that high risk in western Henan is due to higher yield damage, and higher riskin southwestern Henan results from high frequency of spring frost, and higher risk in northwestern and eastern Henan is because ofhigh frequency and high yield damage.

• Publication Trends of the Journal of Plateau Meteorology in 1982-2011 -----Results and Enlightens Based on Bibliometric Analysis
• NING Bao-Ying;SONG Min-Hong;SHEN Qiao-nan;ZHANG Jing-Hui
• 2012 Vol. 31 (1): 285-293. 
• Abstract ( ) PDF (1100KB) ( )
• The innovative achievements in basic scientific research and applied basic research are mainly published as articles in related specialized periodical.  The Journal of Plateau Meteorology has been published for 30 years, which is concentrated on Tibetan Plateau, atmospheric science and the related questions. This article uses the detailed bibliographic data obtained from database to analyze the publication trend in 30 years. Through quantificational analysis on articles' number, discipline classification, study area, core-author group, research hot spots, cited number and periodicals, funds, influence factor, annual variation of these indices have been illustrated, so do as the research content and direction, research institutes and researchers′ distribution changes. The result indicated that in recent 30 years, the number of articles published in  Journal of Plateau Meteorology assumes the swift growth tendency, this kind of growth is especially obvious since the implements of knowledge innovation project in Chinese Academy of Science; the related research institutes have the obvious subject relevance, as to location distribution, they are mainly concentrates in the Northwestern Region; Tibetan Plateau, numerical simulation and climate change present the three highest frequency key words, Tibetan Plateau is the highest one during 1991-2010 years, which reflected the research hot spots in  Journal of Plateau Meteorology. The results of bibliometric analysis on citing literatures showed that citing frequency by CSCD and SCI and influence factor enhances unceasingly, which further explains the influence′s increasing. However, the core author group of  Journal of Plateau Meteorology has not really formed because of the new researchers′ jointing and the outstanding ones starting to enhance the international influence by submitting their articles to other related journals with higher influence factor, this proposed the new opportunity and the challenge to the future development of the journal.