Current Issue

• Weather Abnormal and Evolutions of Western Pacific Subtropical High and South Asian High in Summer of 2003
• LIU Huan-zhu;ZHAO Sheng-rong;ZHAO Cui-guang;LU Zhi-shan
• 2006 Vol. 25 (2): 169-178. 
• Abstract ( ) PDF (1998KB) ( )
• By comparing with the climatic mean circulations over East Asia,it is demonstrated that,before and during the Meiyu period of 2003,the subtropical anticyclone over Western Pacific(SAWP) is stronger than normal and shifted westwards,presenting more dynamic features in its configuration with convergence in the upper troposphere,divergence and descending motions in the middle and lower tropospheres,and a northward tilting ridge surface with increasing height.The rainbelt associated with the Meiyu front that is located over the northwest of the 500 hPa SAWP is related to a strong upper tropospheric subtropical jet and the eastward extension of the South Asia High(SAH).The negative vorticity advection along the ridgline of the eastward extended SAH produces the upper layer convergence,in favor of the westward development of the SAWP.The dynamic impacts of the upper layer westerlies and the SAH can also induce the short-term zonal movement of the SAWP.The development of the deep convective precipitation over the northwestof the SAWP intensifies the in situ vertically non-uniform heating,contributing to its westward movement as well.Besides,the development of the deep convection in the tropical monsoon trough also affects the maintenance and intensification of the SAWP.It is concluded that the anomaly of the SAWP in theearly summer of 2003 is forced dynamically as well as thermody namically by the interactions among the weather systems in different latitudes.

• NCAR-NCEP Data Quarity and Abrupt Changes of East Asia Low in Summer of 1970's
• FANG Zhi-fang;ZHANG Li
• 2006 Vol. 25 (2): 179-189. 
• Abstract ( ) PDF (1289KB) ( )
• The tendency variation for 500 hPa and 1000 hPa geopotential height fields of the Northern Hemisphere during the summer months(JJA) were calculated for the period of 1968-2002 based on the NCEP-NCAR dataset.The center was located on the typical East Asia low area over 35°~55°N,90°~115°E on 1000 hPa and 35°~55°N,70°~110°E on 500 hPa,defined as Summer East Asia Low index(SEAL1 and SEAL5).The SEAL1 and SEAL5 time series of 500 hPa and 1000 hPa were calculated during 1958-2002 based on the NCEP-NCAR dataset,both have an obvious dramatist increases as much as 60 hPa from 1958 to 1968,then they tend smoothly.
  Discussing the NCEP-NCAR data quarity,the NCEP-NCAR data/the ERA-40 of the ECMWF/China NMA data were be used during 1958-2002,and the SEAL1 and SEAL5 indexeswere calculated.Comparing with the SEAL1 and SEAL5 indexes for the three data during 1958-1968,there not exist relationship between the NCEP-NCAR data and another two data,only the NCEP-NCAR data have a dramatist increases,the another two data not have the variation.For 1968-2002 the three time series values of these data are very similar,and have increasing trend,and were passed the reliability test.Therefore the 1968-2002 data were analyzed in the studying.During 1968-2002,both SEAL indexes for 500 hPa and 1000 hPa geopotential heights have a fast increase 30 gpm on 1968-1977.Then it strays near mean geopotential meters during 1977-2002.It means that there exists an obvious decadal change for the Summer East Asia Low in later 1970's.Based on the difference fields on 500 hPa and 1000 hPa heights between the two periods,the main changes are characterized by a huge positive difference center over the north-middle of China and Mongolia around 35°~50°N,90°~115°E.The Summer East Asia Low was weaked in later 1970's,it will effect on the moisture flux transfer,and influence on the intensity and position of precipitation in China.It means that the rainfall was obviously decreased near the lower reach of the Yellow River and increased in the south of Henan province and the north of Hubei province.

• Atmospheric Water Circulation Equations
• ZHANG Xue-wen
• 2006 Vol. 25 (2): 190-194. 
• Abstract ( ) PDF (204KB) ( )
• The precipitation at any place of the world may come from any water evaporation that happened at any part of the globe.In order to describe the complicated process of the water circulation in the atmosphere quantitatively,two conceptual tools,the water convergent function and the water divergent function in the atmosphere,are introduced;and an equation system,which can be used to describe the water circulation in the atmosphere,has been found.

• Atmospheric Heat Source/Sink Change Characteristics Over Qinghai-Xizang Plateau and Its Vicinity Region in Summer of 2001 and 2003
• Lü Ya-qiong;GONG Yuan-fa
• 2006 Vol. 25 (2): 195-202. 
• Abstract ( ) PDF (373KB) ( )
• Using the NCEP/NCAR data,the atmospheric heat source and convergence(Q₁) of the Qinghai-Xizang Plateau and its vicinity region in 2001 and 2003 were computed.Through the method of CEOF,the differences of Q₁ between 2001 and 2003 were analyzed.The results show that:(1) In April,the initial time of season change,the distribution of Q₁ in 2001 and 2003 is similar,but intensity is different.In June,the time after season change,the distribution of Q₁ is obvious different and the intensity is different too.(2) There is high value center on the south side of Qinghai-Xizang Plateau to the north Bengalese gulf and the Arabian sea eastern regions to the peninsula west side of India in 2001 and 2003,respectively,but intensity is obvious different: The change of heat source of Bengalese gulf region in summer of 2001 is stronger than the Arabian sea region but summer of 2003 is contrary.(3) During the period of season change from May to the end of June,the change trend of Q₁ of the Plateau and its south side is different too.the maximum value appears the end of June in 2003,the amplitude has already reach a strong level in the middle of May to beginning of June in 2001,and suddenly down in the last ten days of June.(4) the space of the first characteristic vector 1> in 2001 and 2002 is also different.In 2001,there are two main paths: one is from the south of India peninsula to the southwest of Bengalese gulf,and another face to west from the north of Arabian Sea.In 2003,the main path face to north from the south of India peninsula.These differences of heat source(convergence) of atmosphere in 2001 and 2003 may be exactly the reason for difference of our country weather and atmospheric circulation.

• The Nonlinear Dynamical Features of Annual Precipitation Climate Oscillation in China
• YAN Hua-sheng;CHEN Lin-ling;CHENG Jian-gang
• 2006 Vol. 25 (2): 203-208. 
• Abstract ( ) PDF (243KB) ( )
• According to the observational data,with the application of quadratic dynamical system,we have retrieved the nonlinear dynamical equations that describing the precipitation climate oscillation at 17 stations in China.Then the considering without external forcing, these equations are qualitatively analyzed.Results of the analysis show that most of the annual precipitation climate oscillation system in China exist the weak nonlinear oscillation feature.This system can be seen as a positive damped dynamical system,and its energy transformation is beyond zero.That is to say,without external forcing,the movement of this system could always be wane.The natural period of the system is from 4.4 to 10 years,and its distribution is like a wave from west to east.At the 17 stations,the annual precipitation climate oscillation systems of Lanzhou,Chengdu,Chongqing,Nanning,Shanghai,Fuzhou and Wenzhou are gradual-soft elastic systems.But those of Kunming,Changchun,Haerbing,Beijing,Guangzhou,Xian,Xiamen,Changsha,Nanjing and Hangzhou are gradual-hard elastic systems.Finally using the nonlinear dynamical equations,the series of the annual precipitation climate oscillation at 17 stations in China are simulated.

• Climate Change of Arctic Atmospheric Circulation in Last 30 Years and Its Effect on Strong Cold Events in China
• LI Feng;JIAO Mei-yan;DING Yi-hui;JIN Rong-hua
• 2006 Vol. 25 (2): 209-219. 
• Abstract ( ) PDF (785KB) ( )
• Based on the NCEP reanalysis data and the cold air outburst processes in each year provided by Central Meteorological Observatory(CMO) in 1971-2000,the climate changes of Arctic atmospheric circulation feature and its effect on strong cold events in China are studied.Results show that atmospheric temperature markedly change during the winter-half-year of 1971-2000,it reflects the polar vorticity(PV) shifting.Extent of PV is larger than normal prior to mid of 1980's,it trends to reduce later and PV intensity change adversely.Synchronously,the circulation of mid-high latitude band adjust from low index state to another,trend to zonal pattern,East-Asian trough shift to east about 1 degree and 2.2 degree special in winter,Siberian high(SH) varies correspondingly,it is weaker and small orbit in 1970's,it get stronger and expand in 1980's and in 1990's.SH keeps similar intensity but its south edge reduce 1~2 dgree northward than 1980's,its scope reduce 5%.The findings indicate that the changes result in a decade-scale variation of strong cold event in past 30 years.The cold occur frequently in 1970's,mainly root from North Europe.The frequency reduces evidently in 1980's,root mostly from east of Novaja island by north-west route,departure of temperature is most abnormal and extremecold event is most strong.1990's is the weakest decade though the cold event frequency increase,which is related closely with warming and high background air temperature.The features of strong cold change accord with relationship between extreme event and climate change,according it maybe result and reflect of the globe warming.

• A Case Study on Characteristics of Lightning Activity in a Mesoscale Convective System
• FENG Gui-li;QIE Xiu-shu;ZHOU Yun-jun
• 2006 Vol. 25 (2): 220-228. 
• Abstract ( ) PDF (1000KB) ( )
• The evolution of cloud-to-ground(CG) lightning in a typical mesoscale convective system(MCS) was analyzed by using the data from lightning detection system,Doppler radar and satellite.The result shows that almost all the CG flashes are negative at the first developing stage.The CG flash rate is high(more than 10 min^-1) and negative CG flash predominates along the mature stage of the storm.The CG flash rate declines rapidly with the increase of positive CG lightning ratio at dissipating stage.The CG flashes mainly occur in the region with the temperature less than-50℃ and high temperature gradient in the front of MCS,but there is no CG flash in the cloud with temperature higher than-30℃.Negative CG flashes cluster in the intense echo(40 dBz) region and its duration coincidences with the strong convection,which suggests that the negative CG flash could be used to indicate the strong convective region.Moreover,the dense positive CG flashes can also be observed in the strong echo region,while sparse ones are in the weak and stable echo region or cloud anvil in the rear MCS.The data analysis also shows that the high positive CG flash rate could correspond to a damaging weather.The advent of high positive CG flash rate should be paid more attention in nowcasting of severe convective weather.

• A Model Study of Lightning-Generated NO_X(LNO_X) and It's Transportation
• GUO Feng-xia;YAN Mu-hong;ZHANG Yi-jun
• 2006 Vol. 25 (2): 229-235. 
• Abstract ( ) PDF (455KB) ( )
• Using a three-dimensional dynamic-eletrification coupled model,a thunderstorm is simulated.The characteristics of discharge and transportation of lightning-generated NO_X(LNO_X) by advection and turbulence are discussed.The results indicate that,the upper edge of middle negative charge region correspond with the ambient region of updraft and center of horizontal speed field.Because the transfer distance of discharge is long,strong discharges mostly locate in the region and develop to upper layer.Few discharges take place in the center of negative region and transfer distance is short.LNO_X is transported by advection and turbulence after outflowing from discharge channel,and form density center in weak speed field.The peak value is 9×10^-9.Advection plays an important role in transportation of LNO_X.Turbulence transmission is important under cloud base or at dying stage of thunderstorm.The peak value of LNO_X is 2.7×10^-9 at dying stage of thunderstorm,Which is one magnitude more than the fine.

• Emistation on Dust Emission from Ground Surface in Hunshandake Sandland
• CHENG Tian-tao;Lü Da-ren;XU Yong-fu
• 2006 Vol. 25 (2): 236-241. 
• Abstract ( ) PDF (313KB) ( )
• Dust emission rate and threshold velocity on surface in spring of 2001 were estimated with the soil-derived dust emission model,and the amount of dust emitted into the atmosphere from surface was calculated with two US EPA formulas by inputing pre-processing pedological and climatical data in Hunshandake sandland.The results show that the dust emission threshold velocity is 5.61 m·s^-1,and the mean dust emission rate is 4.40 ×10^-7g·cm^-2·s^-1 in Hunshandake sandland in spring of 2001.The total amount of emitted dust from surfaces in Hunshandake sandland is 3.73 10⁵t·a^-1 in 1986 and 4.87 10⁵t·a^-1 in 1999 respectively,and its annual mean increasingrate during this period is about 2.07%.

• The Experimental Study of Retrieving Dust Aerosol Size Distribution Using Multichannel MODIS Remote Sensing Data
• FENG Jian-dong;CHEN Chang-he;CHEN Yong-hang;ZHANG Wu;HUANG Ting;ZHANG Lei;GUO Ni
• 2006 Vol. 25 (2): 242-248. 
• Abstract ( ) PDF (356KB) ( )
• In order to retrieve aerosol particle size distribution over land,the spectral reflectance information of the surface water is needed.In this paper,the correction for the water spectral reflectanceof the Liujiaxia Reservoir is conducted by the 6S model with the MODIS data,on clear days under the conditions of low concentrations of aerosol.Supposing that the reservoir water spectral reflectance was less changing during the dry spring,the average results of the correction ofwater surface spectral reflectance of the reservoirwere used to retrieve the atmospheric aerosol particle size distribution.The atmospheric aerosol particle size distribution can be retrieved using the multichannel MODIS data from two days as example.The obvious reason for the explanation of aerosol larger sizeon 11 April 2002 is the dust transfer from the upwind areas,northwest of the study regions,by strong airflow,based on the analysis of the weather processes.

• Non-Linear Retrieval and Assimilation of Satellite Data and Forecasting Experiment of a Severe Precipitation
• HU Wen-dong;SHEN Tong-li;DING Jian-jun;LIU Jian-jun;LU Xiao-jing;CHEN Xiao-juan;WANG Cheng-wei
• 2006 Vol. 25 (2): 249-258. 
• Abstract ( ) PDF (472KB) ( )
• The geostationary meteorological satellite infrared data were applied to retrieve the relative humidity at different levels of atmosphere using the surface observation and sonde data.Two different nonlinear methods to retrieve humidity were developed using the optimal artificial neural network and non-linear regression after optimal fitting transform.The retrieved relative humidity was put into mesoscale nonhydrostatic numerical weather forecast model MM5 after variation analysis and quality control,and a severe convection event was analyzed with the retrieved relative humidity.The precipitation forecast was improved in quantity eminently,the forecasted severe convection area was consistent with the observation,and the spin-up was reduced as much as 25%.The experiment shows that the implement of satellite-retrieved humidity enhanced the ability of numerical model to forecast severe convection in Ningxia.

• Diagnosing Analyses and Topography Simulation of a Sand-Dust Storm Event in Northwest China
• WANG Jian-peng;SHEN Tong-li;LIU Xiao-ying;LI Ming;XUE Chun-fang;MENG Xiao-rong;NING Hai-wen
• 2006 Vol. 25 (2): 259-267. 
• Abstract ( ) PDF (685KB) ( )
• Using the observed initial field,the improved mesoscale model MM4 was employed to simulate the sand-dust storm over Northwest China from 8 to 9 April 2001,its simulated results were analyzed The simulations revealed that these parameters were good collaboration each other,their values and spatial distributions were well-corresponding to the forming,developing and decaying of dust event.The sensitivity experiments of topography showed that the impacts of Qinling mountain on this dust event was ignorable,but Hexi corridor was important,indicating that the narrow lane of Hexi corridor provide an available topography condition for dust storm processing.

• Study on Mesoscale Numerical Simulation of a Heavy Rain Strom over Lower Latitude Plateau of China
• XU Mei-ling;DUAN Xu;ZHANG Teng-fei;YANG Ming-zhu
• 2006 Vol. 25 (2): 268-276. 
• Abstract ( ) PDF (1345KB) ( )
• The mesoscale numerical model MM5V3 was used to simulate the occurrence and development of meso-β scalesystems which resulted in the heavy rain strom at Chuxiong and some other stations of Yunnan from 20:00 on 16 to 08:00 on 17 June 2003.The result indicate that the simulated center of rain strom is basic similar with the real rainfall,but the simulated rainfall intensity is less than that real.The mass convergence at lower layer enhance in advance of divergence at upper layer in initial state of development of meso-β scale,and the convergence at lower layer weaken in advance of divergence at upper layer in weak state,that is the change of divergence filed at lower layer induce that at upper layer.The development,intensification and attenuation ofmeso-β scalesystems mainly are caused by positive vorticity at lower layer.The discrepancy of water vapour distribution at lower latitude is smaller than that high latitude,water vapour convergence result mainly from wind filed convergence,and advection transportation decided durative time of rain strom.The plateau's orography has some influence upon ascending motion and water vapour convergence in the atmosphere,especially in its lee slope,rising motion will weaken,water vapour appear weak divergence.

• Simulation of Topographic Effect of Hilly Region to the South of Yangtze River and Yunnan-Guizhou Plateau on the Southweat Vortex during a Heavy Rain Process
• CHEN Gui-chuan;SHEN Tong-li;HE Di
• 2006 Vol. 25 (2): 277-284. 
• Abstract ( ) PDF (1401KB) ( )
• The heavy rain happened in Hunan province on July 22~23,1998 triggered by the Southwest Vortexis numerically simulated using MM5 model.Three numerical experiments are designed-with real topography,without hilly region to the south of Yangtze river,without hilly region to the south of Yangtze River and Yunnan-Guizhou Plateau.The obtained results are as follows: With the last two experiments,the canalization effect of topography disappears,the thermal difference between south and north was reduced.Then,the lower level jet reduces.Reducing of positive vorticity transport by lower level jet to southwest vortex and shear line,combining with the shear lineled by 500 hPa upper trough,the southwest vortex strengthen.All these make the shear line weaker and disappeare finally.The stepped terrain in three experiments are designed also and the canalization effect of hilly region to the south of Yangtze River and Yunnan-Guizhou Plateau was validated further.It could accelerate the forming of lower level jet.

• Low-Frequency Oscillation Characteristics of Precipitation and Water Vapor Transport in the Eastern Part of Northwest China in Spring
• REN Hong-li;ZHANG Pei-qun;LI Wei-jing;GAO Li
• 2006 Vol. 25 (2): 285-292. 
• Abstract ( ) PDF (1085KB) ( )
• The low-frequency oscillation characteristics of the precipitation and water vapor transport in the eastern part of Northwest China(ENWC) in spring are investigated by using the daily precipitation data from NMIC and NCEP/NCAR reanalysis data from 1962 to 2002.By introducing a relative proportion coefficient(prpt) and combined with statistical test,it is verified that 20~60 day low-frequency periods are relatively important and statistically significant in the regions of ENWC,North China,and the middle- and low-reach areas of the Yangtze River during spring,which provides a theoretical basis for the latter study.The analysed results from the case of 2002 show that both the springtime precipitation and divergence of water vapor flux in ENWC have about 20~60 day low-frequency oscillation features which enhance significantly during April~May and is a primary mode of precipitation and water vapor transport on the time scale of intraseason.Simultaneously,it's also found that low-frequency waves clearly propagate eastward and low-frequency water vapor transport is consistent with the anomalous characteristics of the water vapor transport in rainy years.Furthermore,it follows from the multi-year analysis that with different principal periods each other,the features of intraseasonal oscillation are pronounced and their intensities are relatively strong in rainy years.We also see that there is very good corresponding and coherent relationship between the low-frequency precipitation and water vapor transport,but some differences also exist.On the other hand,the most considerable feature with regard to interdecadal variability is that the intraseasonal oscillation is week and unclear from the 1970's to early 1980's.Moreover,the correlation between low-frequency precipitation and water vapor transport is not substantial as other rainy years,which indicates the influence on low-frequency oscillation from climate anomalies.

• Study on Influence of the Lee Wave and Inversion Effect on Formation of Lanzhou Small Anticyclone
• LI Guo-chang;LI Yan-ying;ZHANG Cun-jie;ZHANG Qiang;LI Dong-liang;SUN Ai-zhi
• 2006 Vol. 25 (2): 293-301. 
• Abstract ( ) PDF (370KB) ( )
• Using the meteorological observation data of Lanzhou and Minqin stations in drought year(1995) and wet year(1994) at 08:00 in May~June,the forming and developing mechanismes of Lanzhou small anticyclone are dynamically and thermody namically diagnosed with methods of lee wave effect and inversion level.The results show that there are obvious lee wave and subsidence inversion in Lanzhou and Minqin has the characteristics of stronger inversion level,and frequency of them is more and intensity is strong,the radiation and disturbed inversion level are more obvious,their lee wave and inversion level property have influenced on the formation,scale and location of Lanzhou small anticyclone.Lanzhou small anticyclone is a boundary phenomenon which has the interation of Qinghai-Xizang Plateau large topography and atmospheric circulation,it has an important relation with the stronger inversion and lee wave effect over North of Qinghai-Xizang Plateau.The forecast flow of Lanzhou small anticyclone is obtained using the mesoscale synoptic method that estabilish its diagnostic and predictable concept model.

• Diagnostic Study on an Abrupt Heavy Rainstorm Process in the Loess Plateau
• LIU Yong;DU Chuan-li
• 2006 Vol. 25 (2): 302-308. 
• Abstract ( ) PDF (497KB) ( )
• Using the routine sounding,the satellite image and surface observation data,an abrupt heavy rainstorm process occurred in Fugu,Shaanxi province on 30 July 2003 were diagnosed and analyzed.The results show that the subtropical high was strong and controlled the Loess Plateau in the earlier stageof rainstorm.The convection appeared when the cold air of westerlies met the southwest air flow in the west of subtropical high.The southward and eastward air flow on 850 hPa provid the plentiful vapor for the heavy rainstorm.The sub-circulation caused by coupling of jet flow on 200 hPa and 700 hPa supplied a continuous and powerful updraft.There is a meso-α-scale convective cloud cluster in satellite cloud image.

• Analyses on General Circulation Character of Precipitation Anomaly in Northeast China Flood Season
• JIA Xiao-long;WANG Qian-qian
• 2006 Vol. 25 (2): 309-318. 
• Abstract ( ) PDF (877KB) ( )
• To better understand and predict the flood season(July~August) precipitation in Northeast China,the general circulation in the years with above- and below the normal precipitation is analyzed.The results show that,on lower layer(850 hPa),the common action of cyclonic(anti-cyclonic) anomaly circulation in Southeast of Mongolia,the southwest(northeast) wind anomaly in East of China and anti-cyclonic(cyclonic) anomaly circulation in south of Japan have strengthened(weakened) the convergence of southwest warm and humid air flows of low layer in Northeast China region in more rain year of flood season.On middle layer(500 hPa),the meridional movement of westly belt in high-middle latitudes strengrhen(weakened),there are +-+wave train distributions from the high latitude region to the north of Baikal to the height field near Japan.The circulation pattern in August is easier resulting in severe drought and flooding than in July.The developing and weakening of blocking highs in low reach of Okhotsk and Japan seas are to cause an important facter of precipitation anomaly in August.Considering with the evolution of drought and flooding patterns,we have special attention to the "wave train" allocation of-+-+-westeast-ward.There are obvious differences for the divergence,vertical velocity felids,and vapour condition of high-and low-layers in more and less rain years.

• TBB Features of Yunnan Rainy Season Onset and May Rainfall
• XIE Ming-en;LU Ya-bin;CHENG Jian-gang;GUO Rong-fen
• 2006 Vol. 25 (2): 319-324. 
• Abstract ( ) PDF (463KB) ( )
• Using 17-year TBB data and monthly precipitation data in Yunnan,the relations between tropical regional TBB evolution and rainy season onset date and May rainfall in Yunnan are studied.The results show that rainy season onset in most of Yunnan when the north boundary with TBB≤-10℃,the major convective cloud tide over Bay of Bengal and Indochina Peninsula,has passed steadily northward 20°N,the one with TBB≤-20℃,thestrong convective area,has moved northward near 18°N,and the one with TBB≤-5℃,the convective area,has already covered Yunnan.If the location of TBB≤-10℃ convective cloud tide over the Bay of Bengal and the Indochina Peninsula is something southward than normal and TBB distribution shows positive anomaly pattern over the Bay of Bengal and the Indochina Peninsula and Yunnan in May,then the May of the year is the less precipitation years in Yunnan,the convective activities in these areas is weaker.And more rain May in Yunnan vice versa.At last,the way of observing and forecasting Yunnan rainy season onset are obtained by using tropical TBB data.

• Spatial and Temporal Variations in Pre-Summer Flood Period Precipitation of South China
• MA Hui;WANG Qian-qian;CHEN Zhen-hua
• 2006 Vol. 25 (2): 325-329. 
• Abstract ( ) PDF (451KB) ( )
• Using the monthly precipitation data at 160 stations in China during the period of 1951-2000,16 stations are selected as representative stations in South China.Based on the analysis of seasonal variation of precipitation in South China,the interannual and interdecadal variations of the precipitation in the pre-summer flood period in South China are emphatically studied in this paper.It is found that:(1) The distribution of precipitation in South China is asymmetrical,the rainfall of the 16 stations are very difference.The most rainfall in the pre-summer flood period and annual are both happen in Heyuan.The least rainfall in the pre-summer flood period and annual are both happen in Baise;(2) There are four positive or negative abnormity centers in the pre-summer flood period in South of China,they are all locate Heyuan,Guilin,Beihai,Yangjiang.The most rain station of positive abnormity frequency center happens in Heyuan.The most station of positive(negative abnormity of precipitation is Heyuan(Guilin)).(3) The total rainfall tendency has change,but not obvious.The flood periods are in the beginning of 1950's,in the middle of 1960's and the beginning of 1980's;the droughts periods are from the middle of 1950's to the middle of 1960's,and from the middle of 1980's to the beginning of 1990's;(4) The precipitation anomalies have 3,5,7,14 year periodic variations in the pre-summer flood period in South China;(5) The precipitation in the pre-flood period in South China is opposed to that of most areas of China.

• The Studies on Mountain Mud-Rock Flow Critical Rainfall and Rainfall Zoning of Hubei Provice
• WANG Ren-qiao;ZHOU Yue-hua;WANG Li;KE Yi-ming
• 2006 Vol. 25 (2): 330-334. 
• Abstract ( ) PDF (208KB) ( )
• By analyzing 327 mountain mud-rock flow of Hubei provice in history,the spatial and temporal distributions of them was elicited.Then,80 typical cases since 1980 were collected and used to analyze the differences of rainfall between weather and hydrometric stations.the feasibility of compositive computational method about mountain mud-rock flow critical rainfall was discussed,this method was also used to compute weather stations critical rainfall of 36 cities or counties in Hubei Provice.Lastly,the results were combined with different frequencyes' design rainfall and other rainstorm parameters,which were used to make the rainfall zoning of Hubei provice.

• The Development of Software and Hardware for Digital Weather Radar Virtual Termination
• ZHAO Kun;CHEN Jian-jun;FANG De-xian;GE Wen-zhong;MU Xi-yu
• 2006 Vol. 25 (2): 335-343. 
• Abstract ( ) PDF (725KB) ( )
• The digital weather radar virtual termination system based on PC machine is designed to perform radar signal processing and displaying real-timely instead of traditional radar signal processing machine.In the aspect of the system hardware,we design a three-channel PCI-bus based signal receiving card to satisfy the requirement of massand high speed data transfer.While in the aspect of the system software,using advanced language(C++) and WDM technology,a real-time processing software system-worked on WINDOWS2000/9X operational system is designed to control the work mode of signal receiving card and radar,and perform radar signal processing and displaying real-timely.The experimental results show the virtual termination system characterized by simply structure,friendly user interface,convenient operation and easy update is able to process the signal of conventional radar effectively and real-timely.What's more,the processed echo has better quality and smaller fluctuation.This researchis a preliminary step towards the application of digital weather radar virtual termination system in Doppler radar.

• Experimental Study of Energy and Water Cycle in Tibetan Plateau——The Progress Introduction on the Study of GAME/Tibet and CAMP/Tibet
• MA Yao-ming;YAO Tan-dong;WANG Jie-min
• 2006 Vol. 25 (2): 344-351. 
• Abstract ( ) PDF (727KB) ( )
• The intensive observation period(IOP) and long-term observation of the GEWEX(Global Energy and Water cycle Experiment) Asian Monsoon Experiment on the Tibetan Plateau(GAME/Tibet) and CEOP(Coordinated Enhanced Observing Period) Asia-Australia Monsoon Project(CAMP) on the Tibetan Plateau(CAMP/Tibet) have been done successfully in the past 8 years.A large amount of data have been collected,which are the best data set so far for the study of energy and water cycle over the Tibetan Plateau.The field experiments of GAME/Tibet and CAMP/Tibet are firstly introduced.The research progresses in the land-atmospheric interaction,land surface parameters derived from satellite remote sensing and filed observations as well as the modeling developing areshown in this paper.The existing problems and the solving ways are presented in this paper at the same time.

• Analyses on Correlation between Rain Belts in Winter and Spring
• TANG Mao-cang;ZHANG Yong-jun;LI Dong-liang
• 2006 Vol. 25 (2): 352-355. 
• Abstract ( ) PDF (298KB) ( )
• By analyzing the correlation between the rain belts in winter and spring,the results show that in the southeast quadrant of China,when the earth-atmosphere position is stabilization in winter and spring,the frequency that the rain belt in spring about 73% lies to the south of the rain belt in winter and the distance is about 50~300 km,and the result may be index for predicting rain in spring.At the other hand,when the earth-atmosphere position is instability,the distance between the rain belt in winter and spring may be over 500 km.In that case,the earthquake in winter and spring may be as an index for predicting the rain in spring.