Current Issue

• Regional Characteristic Calculation of Lightning Production of Nitrogen Oxides(LNO _X)(Ⅱ):Analysis on Calculation Result of LNO _X
• DU Jian;ZHANG Yi-jun;YAN Mu-hong
• 2002 Vol. 21 (5): 433-440. 
• Abstract ( ) PDF (341KB) ( )
• Using the lightning location data of Dongbei,Beijing,Guangdong,the distribution characteristics of N produced by six different kinds of thunderstorms are calculated.The general,seasonal,space distribution and different stages of thunderstorm characteristics are analysed,the results show that because of the lower thunderstorm frequencies of middle and high latitude,the total N quantity produced each year is much lower than low latitude,but the N quantity produced by one thunderstorm is not lower.The seasonal distributions of the thunderstorm produced N in three different regions are very different:The peak months produced N of Beijing and Dongbei are in June and September which are the seasonal exchange periods,the peak months of produced N in Guangdong is in July when the convention is very violent.The main stage of system thunderstorm produced N of low latitude is the mature stage,it is very low in development and dissipiate stages,but in middle and high latitude there is some produced in devlopment and dissipate stages.The main stage of local thunderstorm produced N of middle and high latitude is the development and dissipiate stages,it is very low in the mature stage,but in the low latitude these stages produced are almost the same.The correlations of thunderstorm produced N and several lightning parameters are discussed.We get the regression forecasting equation of positive or negative lightning number and thunderstorm produced N and discuss the error.At last we compare the method used in reference[1] and the method used by Price,the result shows that although his method is much more simple,the error of estimation to different regions and different kinds of thunderstorms is much larger.

• Diagnostic Study on the Characteristics of East Asia Summer Monsoon in Different Phases of ENSO Cycle
• CHEN Yue-juan;JIAN Jun;ZHOU Ren-jun
• 2002 Vol. 21 (5): 441-446. 
• Abstract ( ) PDF (289KB) ( )
• The variation of East Asia summer monsoon in different phases of ENSO cycle has been analyzed by using reanalysis grid data from NCEP/NCAR,sea surface temperature data from NCAR and ground surface temperature data from observational station of China.The effect of abnormal SST on East Asia summer monsoon has been discussed through the variation of land-sea thermal difference and monsoon low pressure.The results show that there are obvious yearly and decadal changes in East Asia summer monsoon index,and there is also good negative correlation between the index and SST in east equatorial Pacific.The East Asia summer monsoon index is bigger in the period after three months of cool Nino1+2 SST than that after the warm Nino1+2 SST.There are also obvious variations of land surface temperature and sea level pressure in Asia continent when east equatorial Pacific SST changes.In the summer,after three months of warm Nino1+2 SST,the land surface temperature is lower in the area north of Yangtze River,the sea level pressure in Asian continent is higher,as well as the summer monsoon depression in Asia is weakened.It is contrary in the case after cool Nino1+2 SST.That means,the oscillation of sea level pressure induced by east equatorial Pacific SST anomaly appears not only in the oceans,but also in the continents.It should be the main reason that leads to the variation of East Asia summer monsoon in different periods of ENSO cycle.

• Vorticity Source Diagnoses for the Development of Mesoscale Low Vortex with Shearline during "98.7" Abruptly Extraordinary Heavy Rainstorm
• FENG Wu-hu;CHENG Lin-sheng
• 2002 Vol. 21 (5): 447-456. 
• Abstract ( ) PDF (473KB) ( )
• During the period of 20~23 July 1998("98.7"),an extraordinary heavy rainstorm event occurred in Wuhan surrounding which was direct relationship with the successive generating and intensive developing MαCS and MβCS.The dynamic mechanism of the development of the mesoscale low vortex with shear line in association with an abruptly extraordinary heavy rainstorm was diagnosed byusing the MM5(V2.12) successfully simulated high spatial resolution(20 km) output data.The analyses of vorticity indicated that one of the mainly physical mechanism of the persistent development of the low vortex withshear line was the superposition and coupling of positive vortivty centers over the upper and lowerlevelsof the regions of Wuhan surrounding;diagnoses of the total vorticity sources revealed that there was an almost vertical columnof high positive vorticity sources value generating and maintaining from low to upper levelsover Wuhan surrounding during the intensive genesis and development of the abrupt heavy rainfall.The vertical structure and evolution of the positive vorticity sourcecenters were basically consistent with that of the positive vorticity centers of the vorticitiyfield.This result showed the total vorticity sources played dominantrole in the genesis and development of the mesoscale low vortexwith shear line,which was also an important mechanic of the persistent development of the mesoscale system of the heavy rainfall.The computed componentsof contribution to the total vorticity source indicatedthe divergence term possesses the most contributionbelow 650 hPa,but the contribution of the vertical vorticity advection term is bigger than divergence termbetween650 hPa and200 hPa;whilethe horizontal advection is also positive.The divergence term was negative contribution between 450~250 hPa,the twisting term was negative contribution throughout the troposphere.In the surface layer,there was almost no contribution to the vorticity source concerning the advection terms of the vertical vorticity and horizontal vorticity.The time-averagedand pure perturbation vorticity sourcesplayed important roles forthe genesis of the low vortex with shear line;During the intensive development of the low vortex,the effectof the nonlinear interactive vorticity sourceis the most,the pure perturbation vorticity source is next;The low vortex moveeastward and weakening when the nonlinear interactive vorticity source was decreased,in spite ofthe time-averagedand pure perturbation vorticity sourcewere still positive.

• Remote Sensing Dust Storm Using TOMS Data
• ZHANG Jun-hua;MAO Jie-tai;WANG Mei-hua
• 2002 Vol. 21 (5): 457-465. 
• Abstract ( ) PDF (447KB) ( )
• The method of remote sensing dust storm with TOMS Aerosol Index(AI) is discussed in this paper.Then this method is used to remote sensing a dust storm occurred on April 15,1998.The result shows that this method can detect the occurrence,development,transfer and coverage of the dust storm successfully.It is almost not influenced by cloud and is a new and useful method in dust storm research.

• The Simulation and Analysis of Land-Surface Processes on the Typical Arid Area
• WANG Cheng-hai;DONG Wen-jie;WEI Zhi-gang;MA Wen-ting
• 2002 Vol. 21 (5): 466-472. 
• Abstract ( ) PDF (319KB) ( )
• Using the LSM(Land Surface Model) off-line and the data of Desert station from HEIFE,the property of LSM model in the arid area is tested,and the characteristics of land surface processes in typical arid area is analyzed in spring,summer and winter.A series of off-line tests have been carried out.The simulated results indicate that LSM has good performance and can accurately simulates diurnal and seasonal variation of land surface processes.The sensible heat flux is important,its value is about 230 W·m ^-2 in January and August,and 400 W·m ^-2 in April on the average.In contrast,the latent heat flux,which can be ignored,is about 4~6 W·m ^-2 in January and April.But latent heat flux can be up to 570 W·m ^-2,when precipitation occuring.

• The Radiative Forcing of Atmospheric Dust in North-West China
• CHENG Tian-tao;SHEN Zhi-bao
• 2002 Vol. 21 (5): 473-478. 
• Abstract ( ) PDF (260KB) ( )
• The atmospheric dust is the main composition of atmospheric aerosols in the troposphere.Its radiative forcing was studied by using the radiationmodel(CRM/CCM3).The radiative effects ofthe atmospheric dust is cooling the surface and warming the air in the dust layer,two maximum heating rates were found at the upper part of the dust layer and near the surface respectively.The surface albedoplays animportant role on the radiative forcing of the dust aerosol.The cooling rate of the surface andthe warming rate of the air are higher in the higher surface albedoarea than that in lower surface albedoarea.Forthe earth-atmosphere system,there is a "critical value" of the surface albedo which is about 0.25~0.3.The atmospheric dust decreases the planetary albedo and therefore warms the whole earth-atmosphere system when the surface albedo is higher than that(for example,in Desert),otherwise(for example,in oasis),the atmospheric dust increases the planetary albedo and therefore cools the whole earth-atmosphere system.

• The Prediction of Aridifcation Tendency in North China
• ZHANG Fang;SU Bing-kai
• 2002 Vol. 21 (5): 479-487. 
• Abstract ( ) PDF (378KB) ( )
• The authors firstly got the possible jump points of the precipitation in the three north areas of China from 1951 to 1998 on 32-year scales and 16-year scales by wavelet analysis;secondly,ascertained the real jump years by the means of Yamamoto checking;thirdly,got the corresponding jump time of drought-flood by making a statistical-dynamical model and lastly predicted the drought and flood tendency.The results showed that,on 32-year scales,the drought starting from 1999 will continue until 2052 in East-North China,from 1965 until 2010 in North China and from 1995 until 2016 in West-North China and that,on 16-year scales,the drought starting from 1999 will sustain until 2025 in East-North China,from 1999 until 2014 in North China and from 1995 until 2012 in West-North China.The prediction results in 1999 and 2000 are almost corresponding to the facts.

• Simulating Diagnostic Analyses for Frontogenesis and Surface Sensible Heat Flux of a Sand-Dust Storm Process
• SUN Jun;YAO Xiu-ping
• 2002 Vol. 21 (5): 488-494. 
• Abstract ( ) PDF (353KB) ( )
• The sand and dust storm is a disastrous weather phenomenon which often occurs in the northwest of China spring.The diagnostic analysis of a sand-dust storm case,which occurred on 16 May 1995,is studied by using of the PSU/NCAR non-hydrostatic mesoscale model MM5 improved by NMC.The results show that the dust storm is a process of strong frontogenesis when the cold front move to the northwest China region.The sensible heat flux is very greater than the latent heat flux in the PBL air.The case study also indicates that the thermal factor play an important role on the producing process of the dust storm through removing the surface flux from the MM5.

• The Current Developing Situation of Polarization Radar and Its Application Potential
• WANG Zhi-jun
• 2002 Vol. 21 (5): 495-500. 
• Abstract ( ) PDF (252KB) ( )
• The polarization weather radar is a new kind of weather radar.It's development bring about a great advance in radar meteorology and cloud as well as precipitation physics,and strengthen the capacity of understanding meteorological disaster by peoples.This paper discusses the current developing situation and application potential of circle and elliptical and dual-linear polarization weather radar in research of cloud and precipitation physics as well as weather modification.It will be useful for the development and application of polarization radar in our country.

• Mechanism and Estimation of Lightning-Generated NO _X in Chinese Inland Area
• ZHOU Yun-jun;QIE Xiu-shu
• 2002 Vol. 21 (5): 501-508. 
• Abstract ( ) PDF (339KB) ( )
• The physical mechanismand chemical process of generation of NO _X from lightning are summarized.Latitudinal and longitudinal distributions of estimated production of lightning-generated NO _X in Chinese inland area have been obtained by utilizing the theory of lightning physics and CG lightning data.The results show that the annual average latitudinal distribution of estimated NO _X generated by lightning per 100 km ² in the Chinese inland area(WLNO _X) reduces with latitude heightening from south to north,and the maximums in Guangdong,eastern Gansu,Beijing,as well as Dongbei area are 6.41 10 ⁶ gN/100km ²/yr,4.26 10 ⁶ gN/100km ²/yr,3.65 10 ⁶ gN/100km ²/yr,and 3.52 10 ⁶ gN/100km ²/yr respectively.NO _X from lightning mainly appears to the south of 35°N area.NO _X produced by lightning from eastern Gansu to Guangdong area takesabove 2/3 of whole production in Chinese inlandarea.The estimated annual average lightning-generated NO _X in whole Chinese inland area is 3.84 10 ¹¹ gN/yr.Production of NO _Xfrom lightning in month with more thunderstorm activitiesin Guangdong area is one magnitude greater than that in month with rare thunderstorm area activities.The peak value of NO _X concentration in one certain thunderstorm process is during the mature stage without exception because of higher lightning frequencies.

• The Characteristics of Maximum and Minimum Temperature Change and Distribution in Northwest China
• MA Peng-li;WANG Ruo-sheng;WANG Bao-ling;YANG Xiao-li
• 2002 Vol. 21 (5): 509-513. 
• Abstract ( ) PDF (227KB) ( )
• Using the maximum and minimum temperature data from 1961 to 1990 at 70 stations in Northwest China,the departure values are caculated and analysed.The result shows that the temperature change at nighttime in Northwest China is obvious,the variation trend is consistent with the global changs.Moreover,it is found that the maximum and minimum temperature variation in Northwest China is more significant in higher elevation areas,but the maximum and minimum temperature variation in Wulumuqi,Delinha is the best significant in the whole Northwest China in recent 30 years.

• Similarity Analysis of Atmospheric Turbulent Intensity over Grassland Surface of Qinghai-Xizang Plateau
• MA Yao-ming;MA Wei-qiang;HU Ze-yong;LI Mao-shan;WANG Jie-min;Hirohiko Ishikawa;Osamu Tsukamoto
• 2002 Vol. 21 (5): 514-517. 
• Abstract ( ) PDF (195KB) ( )
• The variance similarities of wind velocity( u, v and w),air temperature and air humidity over the grassland surface of Qinghai-Xizang Plateau are analyzed with the data observed in the IOP of GEWEX Asian Monsoon Experiment in Qinghai-Xizang Plateau(GAME/Tibet).In addition,they are compared with the results for the land surface of HEIFE and South China sea surface.Some new concepts about the variance similarity for the high altitude area are obtained.

• The Linear Function Method for Detecting Transit Jump Point of a Time Series
• CAO Jie;TAO Yun;TIAN Yong-li
• 2002 Vol. 21 (5): 518-521. 
• Abstract ( ) PDF (162KB) ( )
• After introducing the linear step polynomial,a new method for detecting transit jump point of a time series was pointed out.The significant transit jumps in time series can be partly detected with this method.The new method was used to detect the transit jumps temperature anomaly series in Northern Hemisphere,and its series of 11 year running average,the May rainfall series of Kunming meteorological observatory and its series of 11 year running mean,respectively.The results indicated that the annual mean temperature anomaly in Northern Hemisphere,occurred interannual transit jumps in 1879,1889,1939 and 1973,and that of transit jumps of inter-decade scale in 1878,1941,and 1972;Because the May rainfall of Kunming can not be detected any transit jump point but it's rainfall occurred transit jumps of interannual scale.

• The Application of a Composite Technique for Short-Term Climate Forecasts
• JI Ting-yan;XIONG Fang;HUANG Ji-yong
• 2002 Vol. 21 (5): 522-525. 
• Abstract ( ) PDF (174KB) ( )
• Based on the synthetic decision plan of recurrent positive weights,many predicting methods are filtered and the steady and more effective methods are composed,then the result is written in Micaps data format and showed in graphics mode.The score result shows that,the composite method is more effective than the composite method of mean weights to the temperature and disaster index prediction,but it is the same to the month rainfall and the season rainfall predictions,the season rainfall and temperature predictions,it enhances greatly the forecasting precision.Additionally,by Micaps working platform showing the composite result in graphics mode,it is not only objective and quantitative,but also visual.

• Research on Distinguishing between Cloud and Snow with NOAA Images
• YING Qing-jun;YANG Ying-lian;XU Wei-xin
• 2002 Vol. 21 (5): 526-528. 
• Abstract ( ) PDF (129KB) ( )
• Based on the research results that already have,the new cloud and snow identificating factors were presented through analysing the spectrum characteristics of cloud and snow in the NOAA AVHRR image,moreover,the experiment proved that the identificating method between snow and cloud is good enough in southern Qinghai,it gained expected effect.