Current Issue

• A Study on Monsoon Circulations of Drought and Wet Years on the East Side of Qinghai-Xizang Plateau in Early Summer
• MA Zhen-feng;GAO Wen-liang;LIU Fu-ming;LIU Qing
• 2003 Vol. 22 (s1): 1-7. 
• Abstract ( ) PDF (494KB) ( )
• By using NCEP/NCAR data from May to June 1958-1999,compositing and comparing methods,the anomaly circulations of Qinghai-Xizang Plateau monsoon and East Asian monsoon are analyzed.The results are as follows:The characteristics of Plateau monsoon and East Asian monsoon for drought and wet years in early summer are different.The Plateau monsoon was weak/strong in drought/wet years and its low pressure was far westward/eastward.East Asian monsoon in the east part of China was also weak/strong and its trough was far southward/northward.Polar vortex developed/shrank towards south/north in drought and wet years in Sichuan basin and deep trough of East Asia was strong/weak.

• Relationship between Interannual Change over Qinghai-Xizang Plateau Monsoon and Climate Changein Upper Reach of Changjiang River
• MA Zhen-feng;GAO Wen-liang
• 2003 Vol. 22 (s1): 8-16. 
• Abstract ( ) PDF (1138KB) ( )
• By using the Qinghai-Xizang Plateau monsoon index derived from the NCEP reanalysis data,the temperature and precipitation departure data at 22 stations from 1951 to 1995 as well as Mexican Hat Wavelet analysis and maximum entropy methods,the changing characteristic of time-frequency on interannual time scale of the Plateau summer monsoon and the summer temperature and precipitation in the upper reach of Changjiang river valley are studied.Results show that the Plateau summer monsoon,the summer temperature and precipitation in the upper reach of Changjiang river valley exist obvious change in phase.The Plateau summer monsoon has a main 22-year low frequence and 2.5-year high frequence variations,the summer temperature in the upper reach of Changjiang river valley mainly has 2~3 year variations,the summer precipitation in the east and west sections of upper reaches of Changjiang river valley appear as 6~8 year and 2.5-year cycle changes.The above three changes have significatly correlation on time series,that the Plateau monsoon decadal change has significatly influence on the climate change in the upper reach of Changjiang river valley.

• SVD Phase Space Analysis and Its Preliminary Application to Sea-Air Coupling Relationship
• LI Yue-qing;LI Chong-yin;HUANG Rong-hui
• 2003 Vol. 22 (s1): 17-23. 
• Abstract ( ) PDF (1806KB) ( )
• Using the Singular Value Decomposition(SVD) technique and phase space analysis,the relationship between SST in El Niño region over the tropical Pacific and 500 hPa hight field in East Asia is studied.The result shows that there is closely asynchronous coupling relationship between the 500 hPa geopotential height field in winter half year and SST in Niño 1~4 regions in autumn.The first modes derived from SVD indicate the key time-space correlation characteristics of the two fields.When East Asian winter monsoon is stronger(weaker) in preceding winter,El Niño(La Niña) event will occur.East Asian winter monsoon has important effect on ENSO cycle.When El Niño(La Niña) event appears,East Asian winter monsoon will be weaker(stronger) in following winter.El Niño(La Niña) event has also very important effect on East Asian winter monsoon.According to the trigger actions of stronger(weaker) East Asian winter monsoon in preceding winter and previous El Niño(La Niña) event the conceptual model of the interaction between East Asian winter monsoon and El Niño(La Niña) events is set up.Furthermore,it is pointed out that the anomalous variation of East Asian winter monsoon and the effect of ENSO cycle are an important mechanism for the occurrence and development of the other party of the two parties,respectively.In addition,it is presented that a way of phase space analysis based on SVD.It can be not only to analyze the varying processes and anomalous feature of fields themselves but also to reveal the internal interrelation of the two fields on the basis of coupling relation of the two fields.

• Variation of Summer Air Temperature on the East Side of Qinghai-Xizang Plateau and Its Probable Causes
• LI Yue-qing;LI Chong-yin
• 2003 Vol. 22 (s1): 24-31. 
• Abstract ( ) PDF (1445KB) ( )
• Using the Singular Value Decomposition(SVD) technique and correlation method,the variation of air temperature and its forming causes were investigated in Sichuan province and Chongqing city(SC) on the east side of Qinghai-Xizang Plateau.The result shows that the temperature and cloudiness in SC have mainly anticorrelation in summer.The first mode derived from SVD represent the key coupled features of the air temperature and cloudiness fields.The SST over tropical western Pacific are positive(negative) anomalies,the location of subtropical high system to the north(south),the cloudiness in SC decrease(increase),and resulting in the air temperature in SC are warmer(colder) anomalies.Finally,the conceptual model of variation of air temperature in summer was set up in SC.And it is pointed out that the anomalies of SST over tropical western Pacific is also one of the important reasons for the cooling of air temperature in SC on the east side of Qinghai-Xizang Plateau in summer.

• Analysis of the Relationship Between Winter Surface Heating in Qinghai-Xizang Plateau and Spring Air Temperature in Sichuan Chongqing Area
• HUANG Yi-fang;LI Yue-qing
• 2003 Vol. 22 (s1): 32-39. 
• Abstract ( ) PDF (382KB) ( )
• Using the Singular Value Decomposition(SVD) technique,the relationship between the surface heating field in Qinghai-Xizang Plateau and 500 hPa geopotential height field of East Asia area and spring air temperature field of Sichuan-Chongqing area and its forming anomalous causes of are studied.The result shows that the first mode,derived from SVD of the surface heating field in Qinghai-Xizang Plateau in previous winter and 500 hPa goepotential height field in next spring,represent the main coupling feature between the two fields with significant time-space correlations.The surface heating field in Qinghai-Xizang Plateau in previous winter result in the anomalies of air temperature of Sichuan-Chongqing area in next spring by influencing 500 hPa geopotential height field.If the surface heating field in Qinghai-Xizang Plateau in winter is strong(weak),the 500 hPa geopotential height field over East Asia area is high(low),and the air temperature of Sichuan-Chongqing area is also high(low) in next spring.This asynchronous connections between the surface heating field,geopotential height field and air temperature field indicate that the variation of the surface heating field in Qinghai-Xizang Plateau in winter,by influencing the general circulation,is the important reason for the anomaly of air temperature of Sichuan-Chongqing area in next spring.

• A Study of Monitoring Land-Atmosphere Interaction in Hilly Region of Sichuan Basin Using Large Aperture Scintillometer
• CHEN Zhong-ming;GAO Wen-liang;MIN Wen-bin;LUO Xiu-ling
• 2003 Vol. 22 (s1): 40-44. 
• Abstract ( ) PDF (255KB) ( )
• By using the gradient and Bruin methods,the ground surface sensible flux,which indicates the land-atmosphere interaction,is calculated respectively from the Large Aperture Scintillometer observed data and meteorological station data in Lezhi county of Sichuan Basin from 2000 to 2001.The monthly average of the two data is compared carefully.Furthermore,the characteristics of ground surface sensible flux change is analyzed according to the LAS data.Some new truths of land-atmosphere interaction have been revealed in hilly region of Sichuan,which can better understand the land-atmosphere interaction mechanism of different regions and have a great help especially in numerical weather prediction and climate analyses.

• Reason Analysis of the Influence of Qinghai-Xizang Plateau Uplifting on Arid Climate Forming in Northwest China(I):Influence on General Circulation of Atmosphere
• FAN Guang-zhou;CHENG Guo-dong
• 2003 Vol. 22 (s1): 45-57. 
• Abstract ( ) PDF (1073KB) ( )
• To understand the forming causes of the Northwest China(NW China) drought area and to study the influence of the Qinghai-Xizang Plateau uplifting on the general circulation NW China.In this paper,the general circulation differences over the Northern Hemisphere,especially the China,among before,during and after the Qinghai-Xizang Plateau uplifting is simulated by 3 numerical simulation experiments of NCAR CCM3.The results show that the uplifting of the Qinghai-Xizang Plateau can clearly effect the general circulation of the Northern Hemisphere especially the NW China,such as the sea level pressure,500 hPa and 100 hPa levels.Before the Qinghai-Xizang Plateau is uplifted or during it is uplifted up to the critical height,about 2 km ASL,the sea level pressure,500 hPa and 100 hPa level heights are all lower than they are now all over the most part of the Northern Hemisphere.And the changes are all consistent with each other in every season.It can clearly effect the general circulation of the Northern Hemisphere,especially the NW China;when the Qinghai-Xizang Plateau is uplifted up to the critical height.This will make the climate condition to be clearly changed.

• Simulation of Influence of Qinghai-Xizang Plateau Uplifting on NW China Arid Climate Forming(Ⅱ):Changing of atmosphere hydrological cycle and Dynamical and Thermal Effects of Plateau
• FAN Guang-zhou;CHENG Guo-dong
• 2003 Vol. 22 (s1): 58-66. 
• Abstract ( ) PDF (480KB) ( )
• The study of the influence of the Qinghai-Xizang Plateau uplifting on the NW China arid climate is benefit to the understanding of the arid climate and environment forming.In this paper,the differences of the atmosphere hydrological cycle of NW China and the dynamical and thermal effects of the Plateau among pre-,during-and post-the Qinghai-Xizang Plateau uplifting are studied by using some numerical simulations.The results show that before the Plateau uplifting or when it is uplifted to the critical height,the net entering water vapor fluxes of the NW China area from the east,west,south and north boundaries are more than now.And the vorticity of 700 hPa level is greater.The ascending motion over the Qinghai-Xizang Plateau is weaker than now and the sinking motion over the NW China is also weakened.All of these are benefit to the precipitation of NW China.

• Influence of the Qinghai-Xizang Plateau Uplifting on Precipitation Change in Northwest China
• FAN Guang-zhou;CHENG Guo-dong
• 2003 Vol. 22 (s1): 67-74. 
• Abstract ( ) PDF (584KB) ( )
• The Uplifting of Qinghai-Xizang Plateau is a very important geological event in the geological history.It very clearly influences the forming and changing of the arid climate and environment in drought area of Northwest China.The CCM3 is used to simulate the differences of the precipitation and temperature over NW China among before,during and after the Qinghai-Xizang Plateau is uplifted.From the researches,we can simply study the influence of the Plateau uplifting on the climate change in NW China.The results show that the uplifting of Qinghai-Xizang Plateau can clearly effect on the precipitation of the area.The annual precipitation is more about 150 mm than now before the Plateau is uplifting.And following Plateau is uplifted up,the precipitation is reducing.When the Plateau uplifted up to the critical height,the annual precipitation is reduced about 77 mm,but it is still more than now about 73 mm.The changes of the precipitation are different in different seasons.

• Analysis on Application of Statellite Vapour Image to Weather Prediction over Plateau
• YU Shu-hua;HE Guang-bi
• 2003 Vol. 22 (s1): 75-82. 
• Abstract ( ) PDF (487KB) ( )
• By the analysising of the satellite vapour image of Laqu vortex activity on August 4~5,1998 and Qinghai-Xizang Plateau(Plateau) shear line on July 18~20,1998,as well as numerical experiments of improving the mid-upper troposphere humidity over the ocean to the south of Plateau before Plateau vortex formation,the result obtained are as follows:(1) the formation of vapour vortex on the vapour image appears earlier than the Plateau vortex on the synoptic map,which has predictive meaning for Plateau vortex.(2) the formation of Plateau shear line vapour band on the vapour image appears earlier than the Plateau shear line on the synoptic map,which has the predictive meaning to the activity of Plateau shear line as well.When the shear line vapour band is broad,and the Plateau shear line is stable.When the shear line vapour band is weak,and the Plateau shear line will move southeastward.(3) the vapour transportation of the mid-upper toposphere layer over ocean to the south of the Plateau can influence on the formation and development of low synoptic system.The variation of vapour gray degree gradient in bigger value areas can predict the variation of heavy precipitation center.(4) the numerical experiments show that improving the humidity on the mid-upper troposphere over ocean to the south of Plateau by using vapour image can improve the numerical prediction to a certain extent.And so we should pay more attention to the application satellite vapour image to weather forecasting of Plateau.

• Analyses on Spatial-Timporal Characteristics of Mud-Rock Flow and Landslip in Sichuan Basin and Its Meteorological Cause
• YU Shu-hua
• 2003 Vol. 22 (s1): 83-89. 
• Abstract ( ) PDF (314KB) ( )
• By analyzing the spatial-timporal charateristics of the mud-rock flow and landslip in Sichuan basin during the period of 1999-2001 and its meteorological cause,the some useful results were obtained from it,which provided a reference for forcasting and warning landslip in advance.The results are as follows:(1) The spatial-temporal characteristics of the mud-rock flow and lanslip in Sichuan basin are to mainly occurs in June~August,mostly in July;frequently-occurring areas of the mud-rock flow and landslip located in southwesten Sichuan basin and then the middle-eastern;no landslip occurs in the lower reach of Ming river and the middle and upper reaches of Tuo river,but there is a trend that the location of the landslip monthly moves from southwester to northwestern Sichuan basin in May~August.(2) So many landslip occurs in Sichuan basin is due to the meteorological reason,namely,the rain areas provide abundant water for it.(3) There is a great possibility with mud-rock flow and landslip occurring if it is a sever heavy rain there,only a heavy rain or even just a rainfall with over 30 mm may trigger landslip in the southwester and middle-eastern Sichuan basin.(4) Besides the mud-rock flow and landslip related to the intensity of rain,geology and geomorphology,and it is also relevant with the preceding-rainfall.

• Numerical Simulation of Meso-β-scale Convective System of "9.18" heavy Rainstorm on the East Side of Qinghai-Xizang Plateau
• CHEN Jing;JIAO Mei-yan;LI Chuan
• 2003 Vol. 22 (s1): 90-101. 
• Abstract ( ) PDF (772KB) ( )
• By use of PSU/NCAR mesoscale MM5,we have successfully simulated a heavy rainstorm process taking place in Mianyang,Sichuan Province on the east side of Qinghai-Xizang Plateau of Yangtze River on September,18~19 2001.The results show that the high resolution model has a better ability to simulate the meso-β-scale convective system under the complex terrain of Qinghai-Xizang Plateau.Model outputs also indicate that "9.18" heavy rainstorm in Mianyang was accompanied with the development and movement of a mesoscale convergence disturbance in the lower troposphere.The dynamical-thermodynamic structural features of meso-β-scale convective systemare:the extremely intensive ascendant motion and surpassing intensive divergence column with the strong vortex in lower troposphere is cross-coupling development,there is convective instability energy in the lower troposphere andbaroclinic instability energy in middle troposphere,which are very different from that of the middle-andlower-reaches of Yangtze River.

• Circulation Characteristic Analysis on Eeal ier Onset Time of Yunnan's Rainy Season in 2002
• LIU Yu;MA Zhen-feng;TAO Yun;LONG Chun-hua
• 2003 Vol. 22 (s1): 102-109. 
• Abstract ( ) PDF (479KB) ( )
• The onset time in rainy season of Yunnan was earlier,and May precipitation was also more than normal.It was very exceptionally anomalous climate that the onset time in rainy season of Yunnan in continuous fourth years was earlier in 2002.We used the onset time data in rainy season of Yunnan to analyze its interdecadal change characteristics.In addition,100,500 hPa and SLP anomalous fields in January and May were analyzed in earlier and latter years of rainy season onset time.Comparing with the circulations in 2002,some directive results of predicting onset time in rainy season of Yunnan were obtained.There were directive relations between the earlier onset time of Yunnan's rainy season in 2002 and building of Somali jet,which is direct reason for the occurring abrupt change of the upper level mid and lowlatitude circulations.

• Mesoscale Analysis on "2001.9.18" Spate Heavy Rain in West China
• MIN Wen-bin;CHEN Zhong-ming;GAO Wen-liang;HE Guang-bi
• 2003 Vol. 22 (s1): 110-118. 
• Abstract ( ) PDF (623KB) ( )
• By using the conventional and satellite data,the spate heavy rain event in west China during 18~20 September 2001 is analysed.The results are as fallows:(1) The heavy rain event was caused by two meso-β-scale convective cloud clusters that occurred in the same region on 19 September 2003.(2) The steady enhancement of boundary low-level jet and its ageostrophic variance contribute to extreme heavy rain.(3) The relationship between divergence variance and precipitation in future 12 h is closer than vorticity variance.(4) The convergence increase which is enhanced by unbalanced dynamic force is the major dynamic trigger mechanism of meso-β-scale heavy rain system as well as the occurring of the heavy rain.

• Precipitaion Forecast and Numerical Experiments on "200.10.18" Rianstorm Process by Using a η Model
• HE Guang-bi
• 2003 Vol. 22 (s1): 119-125. 
• Abstract ( ) PDF (499KB) ( )
• Adopting the methods of numerical simulation and weather analysis,and according to circulation background and main affecting system of the occurring rainstorm area on October 18 to 20,2002,numerical experiment and contrast analysis of precipitation forecast have been done by a η coordinate model.The results show that the ηmodel has a better performance in the forecast of heavy rainstorm.Under the favorable circulation background of precipitation,the high temperature in the basin and cold air activities near the ground are the keys to the storm rainfall occurrence.The more(less) rainfall is greatly depended on the strong(weak) intensity of the converge of cold and warm air.The existent in upper air jet stream is available for the increasing in precipitation.

• Sensitivity Experiments on Precipitation Forecast of a η-Coordinate Model
• HE Guang-bi;TENG Jia-mo
• 2003 Vol. 22 (s1): 126-131. 
• Abstract ( ) PDF (346KB) ( )
• The sensitivity experiments on a heavy precipitation process in the west of Sichuan Basin on August 23~24,1995 have been done by using a η-coordinate model.The results revealed that when properly relaxing the condition of saturation condensation ratio,the amount of large scale precipitation will be increased,but based on different aeras and seasons,the saturation condensation ratio should been adjusted properly.Lessening character time of cumulus activities will lead to increase in cumulus convective precipitation.When increasing the absolute value of saturation air pressure difference,there have been some improvements in the area,intensity and evolution of precipitation,which is closer the observed.

• The Effect of Indian Ocean SST Anomaly on Indian Monsoon and Summer Precipitation over Tibetan Plateau
• JIA Lha;ZHOU Shun-wu
• 2003 Vol. 22 (s1): 132-137. 
• Abstract ( ) PDF (321KB) ( )
• The spatial characteristics of sea surface temperature anomaly(SSTA) over Indian ocean have been analyzed by using the SSTA from monthly mean values during the period of 1950 to 1997 in the U.K.Meteorological Office.The relationship between Indian ocean SSTA and precipitation over Tibetan Plateau in summer(June~August) were studied by composite diagram analysis and SVD method.The results show that the Indian monsoon and the precipitation over Tibetan Plateau is obviously influenced by the SSTanomalyover the equatorial Western Indian Ocean in summer.The negative(or positive) spatial characteristics of SSTA over the equatorial Western Indian Ocean in spring or summer lead to the stronger(weaker) Indian monsoon and the more(less) Plateau summer precipitation than usual respectively.

• Preliminary Research on Climatic Change of West Sichuan Plateau in Recent Fifty Years
• LI Chuan;CHEN Jing;ZHU Yan-jun
• 2003 Vol. 22 (s1): 138-144. 
• Abstract ( ) PDF (446KB) ( )
• The observational data in recent fifty years were applied to study climate change in west Sichuan plateau,Lasa and Chengdu.It is found that most areas in west Sichuan plateau become warmer than before one,especially the minimum temperature increase obviously.As for the precipitations of the above areas,there is a slightly increase among the above areas except for Chengdu where precipitation decreases obviously in recent fifty years.

• Seasonal Changes of Vegetation Cover in Lhasa Area Based on NOAA AVHRR NDVI
• CHU Duo
• 2003 Vol. 22 (s1): 145-151. 
• Abstract ( ) PDF (441KB) ( )
• Based on NOAA GLOBAL VEGETATION,GVI of every week,the change trend of GVI in Lhasa,Tibet in 1985-1999 and its relation to the precipitation and temperature were analyzed.There are two sampling bands along 91°E and 30°N to be selected,in which the changes of surface vegetation with season reflected NOAA NDVI of 1 km.The results show that the NOAA AVHRR NDVI of the long time series in 1985-1999 can reflect the vegetation growth of nature vegetation in Lhasa area,including seasonal and interannual variations.From the middle of 1980's to the end of 1990's,there is good change for the vegetation growth in Lhasa area.Finally,the NDVI value is sensitive to precipitation variations in Lhasa area.A marked relation exits between monthly NDVI and monthly precipitation and its correlation coefficient is 0.75,and that of the temperature is 0.63.

• Analysis and Simulation Study on the Influence of Heat Condition over Qinghai-Xizang Plateau on Climate over South-West China
• HUA Ming
• 2003 Vol. 22 (s1): 152-156. 
• Abstract ( ) PDF (260KB) ( )
• Based on the diagnosis and simulation methods,the characteristics of the heat condition over Qinghai-Xizang Plateau(QXP) and its influences on the circulation and precipitation in the region of southwestern have been studied.It is shown that there are different showing methods of the heat condition over QXP which have relationship and restriction between each other.In winter,there are the same period and lag correlations between the precipitation of southwestern China and the heat condition of the Plateau.The growing thermal over Plateau may be one of the reasons why the average temperature in Sichuan basin became somewhat cooling during the middle last century.At the same time,the heat source play an important role in the forming and maintaining of the atmosphere circilation.And possibily it is the main reason of causing the changes of rainfall over QXP and its sourroundings.

• Relationship between Starch Content of Rice and Climatic Conditions on the Southeast Side of Plateau
• PENG Guo-zhao;WANG Jing-bo;BAI Jian
• 2003 Vol. 22 (s1): 157-160. 
• Abstract ( ) PDF (188KB) ( )
• The relationships between climatic conditions and amylose and amylopectin contents of rice breed Hexi-39 are discussed in this paper.The result shows that the influence of key climate factors and important durations on the amylose and amylopectin contents are different from each other.Then the relationship models of them are established.It is useful to the area coverage planning of high quality of rice plants in Sichuan province.