Current Issue

• Precipitation Simulation Using Different Cloud-Precipitation Schemes for a Landfall Typhoon
• XU Guo-qiang;LIANG Xu-dong;YU Hui;HUANG Li-ping;XUE Ji-shan
• 2007 Vol. 26 (5): 891-900. 
• Abstract ( ) PDF (3207KB) ( )
• The typhoon Sinlaku which was the strongest and landfall one in China in 2002 is simulated with WRF model which is the new generation mesoscale model developing in United States.Input data of model are taking from the T213L31 presented by National Meteorological Center,the initial time of model integrating is at 08:00(Beijing time) on September 7,2002.Four numerical tests are designed with the differences of precipitation schemes and then cloud-precipitation schemes are examined through precipitation simulation of the typhoon.Sesults show that the application of convective scheme together with microphysic scheme (Kessler scheme) are better than only using convective scheme as grid length is small properly.The convective precipitation produced by Kain-Fritsch scheme is rapider than by Betts-Miller scheme in the initial steps of model integration and that is closer the observation.Along with the typhoon landing time extended,sub-grid scale convective precipitation is diminishing and grid scale precipitation is gradually increase.The reason may be that exchange and mixing of high level air and low level is more sufficient which result in convective instability weak.However,it is to be indicated that the results of the paper are just from a case of typhoon simulation with WRF model.The conclusions need validation with more cases.

• The Dipole Relationship between the Summer Precipitation over Northwest and North China and Its Circulation Features
• TANG Guo-li;LIN Xue-chun
• 2007 Vol. 26 (5): 901-909. 
• Abstract ( ) PDF (1156KB) ( )
• Based on the precipitation data of 672 stations in excess of 35 years,the relationship between the summer precipitation over Northwest and North China and its circulation features have been analyzed and discussed.The main conclusions are as follows:(1) There is a dipole relation like a seesaw structure between the summer precipitations over Northwest and North China,that is,the more precipitation in summer over North China and the less precipitation over Northwest China and vice versa.The correlation coefficient is 0.28 between the summer precipitation indexes of North and Northwest China.It has passed the confidence level of 0.05.If the time series of the indexes are processed by means of 10-year running means,their correlation coefficient is up to 0.61.After the oscillation from decade to decade is filtered from the index series,the correlation coefficient is 0.23,having close to confidence level of 0.05.These facts indicate that the dipole relation between the summer precipitations over North and Northwest China is mainly caused by the interdecadal oscillation of climate,but then the interannual change is not also a negligible factor.(2) The results elicited from circulation analysis show that the dipole relation between the summer precipitation over North and Northwest China is related to a couple of the positive and negative anomalies at 500 hPa levels,in summer,which locates in the southern region(8 grid points between 45°~55°N and 80°~110°E) of Lake Baikal and Lake Balkhash region(5 grid points between 35°~40°N and 70°~90°E).And their difference(G-D) forms a circulation index that denotes the dipole relation between the summer precipitations over North and Northwest China. By using the circulation index,the dipole relation of precipitations occurring in summer can be rationally explained.

• The Characteristics of Spatial-Temporal Variations of the Global Cross-Tropopause Mass Flux
• WANG Wei-guo;FAN Wen-xuan;JING Jian-de;SUN Ji-hua;XIE Ying-qi;YUAN Min;WANG Hao-yue;LI Xiao-lu
• 2007 Vol. 26 (5): 910-920. 
• Abstract ( ) PDF (1304KB) ( )
• Using the 44-year(19582001) datasets of pressure and temperature at tropopause,calculating the global cross-tropopause mass flux(CTF) by Wei formula,and analyzing its space changes,seasonal and interannual variations.The results are as follows:(1) The global CTF presents zonality,and mostly cooperate with global general meridional circulation.The downward mass flux is very complicated in the tropopause break.The space variation of STE in Southern Hemisphere is even,and variation of Northern hemisphere has many peak values.The CTF over Eastern Asia plays an important role in the global CTF.(2) The upward peak values of tropical tropopause zonal mean mass flux are 0.873×10^-4kg·m^-6·s^-1 in 5°S and 0.155×10^-3kg·m^-2·s^-1 in 10°N,and the downward peak values in arctic tropopause are 0.510×10^-3kg·m^-2·s^-1 in 62.5°S,-0.365×10^-3kg·m^-2·s^-1 in 75°S and 0.257×10^-3kg·m^-2·s^-1 in 55°N,-0.234×10^-3kg·m^-2·s^-1 in 75°N;the upward peak values over the two poles are 0.355×10^-3kg m^-2·s^-1 in 87.5°S and 0.300×10^-3kg·m^-2·s^-1 in 90°N;and the net mass flux in tropopause break are-0.416×10^-3kg·m^-2·s^-1 in 35°S and -0.333×10^-3kg·m^-2·s^-1 in 35°N.(3) The seasonal and annual variations of net mass flux between Southern and Northern hemispheres are complete contrary,and global net mass flux shows unsymmetrical seasonal wave. The annual means STE of mass in the Arctic tropopause is-3.55×1017kg·a^-1.(4) Global average CTF present remarkable characteristic of QBO,annual evolution of CTF is very obvious over Southern and Northern Hemispheres,in particular,the catastrophe of mass flux amplitude appears during the middle of 1970's to the middle of 1980's.

• Numerical Experiment of the Influence of Tibetan Plateau on the North Edge of Asian Summer Monsoon
• TANG Xu;ZHAO Bing-ke;SUN Guo-wu;LIANG Ping;QIAN Wei-hong
• 2007 Vol. 26 (5): 921-927. 
• Abstract ( ) PDF (1232KB) ( )
• Using the spectral atmospheric circulation model SAMIL(R42L9) developed by LASG/IAP,the effects on north edge of Asian summer monsoon with or without the Tibetan Plateau are simulated.The results show that the existence of the large topography resulted by the Tibetan Plateau has important impacts on the activities of Asian summer monsoon.With(without) the Tibetan Plateau,the northward wind on the east side of the Tibetan Plateau is comparatively strong(weak),which is(isn't) in favor of steering and strengthening the northward of Asian summer monsoon and thus makes on the north edge side of summer monsoon more northward(southward).At the same time,with(without) the Tibetan Plateau,the west Pacific High is northward and westward(southward and eastward),which is also beneficial for the summer monsoon's northward movement to the Chinese mainland and thus also helpful to the more northward(southward) for the north edge side and the corresponding rainfall areas of summer monsoon.

• Observation and Analysis of the Land Surface Radiation and Energy Balance over the Loess Plateau Mesa Region
• LIU Yuan-yong;WEN Jun;WEI Zhi-gang;LI Zhen-chao;ZHANG Tang-tang;LIU Rong
• 2007 Vol. 26 (5): 928-937. 
• Abstract ( ) PDF (1007KB) ( )
• The characteristics of land surface radiation and energy flux over the Loess Plateau mesa region was analyzed based on the data collected during land surface process field experiment of the Loess Plateau mesa region,which was conducted from July to September 2005(LOPEX05).During the experimental period,the surface average albedo over the Loess Plateau mesa region is ranged from 0.08 to 0.22 over the bare soil surface and the millet field.There are not evident differences of surface energy fluxes between the mesa and bottom of the mesa over the same bare soil surface,but obvious differences were founded between the bare soil surface and the millet field.Comparing with the bare soil surface in daytime,latent heat and sensible heat flux of the millet are all bigger than soil heat flux.In order to improve the land surface energy balance closure,the energy storage terms including soil heat storage above the soil heat flux plate(S_g)and canopy heat storage(S_c) were calculated and their proportions in total net radiation were obtained.When all of the storage terms were considered,the energy closure,which is denoted by slopes of the 1:1 line between net radiation and the partitioned fluxes(latent,sensible,ground,and storage),increased 11.0% and the correlation coefficient decreased 3.0%,this means the storage terms make a large contributions in energy balance closure over the Loess Plateau mesa region.

• Characteristics of Energy Transfer and Micrometeorology in Near Surface Layer in Dingxin Gobi of Lower Reach of Heihe River
• WANG Hui;HU Ze-yong;GU Liang-lei;LI Dong-liang
• 2007 Vol. 26 (5): 938-945. 
• Abstract ( ) PDF (575KB) ( )
• Using the field data during the Oasis System Energy and Water Cycle Field Experiment in the surface layer over Dingxin Gobi at Jinta county of Jiuquan,Gansu province,the surface radiation and energy budget characteristics under typical weather conditions are analyzed.Furthermore,several important surface parameters,such as surface aerodynamics roughness length,surface albedo,momentum and heat bulk transfer coefficients are calculated and compared with those in other areas.The main results show:(1) Each component of surface radiation balance appears obvious diurnal variation,the peak value of solar radiation reaches more than 1000 W·m^-2 and the net radiation is up to 526 W·m^-2 under fair weather in May.(2) Each component of surface energy balance also appears obvious diurnal variation and the peak value of sensible heat flux reaches 400 W·m^-2 which is bigger two magnitudes than latent heat flux in daytime;the soil heat flow reaches above 100 W·m^-2;there is a phenomenon of negative water-vapor transfer in the afternoon and at night.(3) Surface aerodynamics roughness length, momentum and heat bulk transfer coefficient is 1.44×10^-3m,2.1×10^-3 and 1.8×10^-3,respectively,under neutral condition.(4) albedo is 0.217 in May.

• Analysis on Microclimate and Surface Radiation Characteristics over Eastern Qinghai-Tibet Plateau in Winter
• SHANG Lun-yu;Lü Shi-hua;ZHANG Yu;AO Yin-huan;LI Suo-suo;YANG Sheng-peng;CHEN Shi-qiang
• 2007 Vol. 26 (5): 946-951. 
• Abstract ( ) PDF (618KB) ( )
• Using the land-atmosphere interaction experiment data observed at Maqu station,the microclimate and surface radiation characteristics over Eastern Qinghai-Tibet Plateau in winter were analyzed.The results show that there are obvious local circulation in Eastern Qinghai-Tibet Plateau in winter and radiation inversion and inverse humidity phenomenon at the night.Radiation budget components of the Eastern Qinghai-Tibet Plateau in winter are less than that of the Western Qinghai-Tibet Plateau in winter.There are obvious daily variation of downward shortwave radiation and upward shortwave radiation at clear day.

• The Retrieval of Soil Moisture from TRMM/TMI Data in Central of Tibetan Plateau
• ZHAO Yi-zhou;MA Yao-ming;HUANG Zhen;YUAN Tie;HU Xiao;LI Ying;MA Wei-qiang
• 2007 Vol. 26 (5): 952-957. 
• Abstract ( ) PDF (594KB) ( )
• Denoting the polarization difference,a polarization index(PI) of microwave radiance from the terrain surface is derived from the radiative transfer model.The PI shows the radiance effects of the soil surface moisture,surface roughness,vegetation canopy and atmosphere,and can be focused on map PI ng the land surface moisture.Statistics of the monthly average <PI> from multitemporal 6-year data of the TMI observations at the lowest 10.7 GHz channels obtained to individually demonstrate variation of the land surface moisture.Through this result,the interannual/seasonal variation as well as dry/wet season variation images of the volumetric moisture are retrieved in this area.It can help us evaluate the Mv variation in Tibetan Plateau well from the large scale.When the monthly average <PI> and the ground truth of average volumetric moisture of the region are available,it is tractable to retrieve the land surface moisture by using the PI data at the same month and the same region without much knowledge of surface roughness,vegetation canopy and others.

• Modification of the Soil Characteristic Parameters in Heihe River Basin and Effects on Simulated Atmospheric Elements
• GAO Yan-hong;CHENG Guo-dong;LIU Wei;CUI Wenrui;LIU Yuan-pu;LI Hai-ying;PENG Hong-chun;WANG Sui-chan
• 2007 Vol. 26 (5): 958-966. 
• Abstract ( ) PDF (1031KB) ( )
• The sand-clay percentage was obtained at maintype lever corresponding to USDA classification based on 53 soil sample data collected in Heihe river basin.The soil characteristic parameters were gotten in Heihe river basin using the method described by Cosby(1984).The two datasets of Cosby and Heihe parameters were used in MM5 model coupled with Noah land surface model to simulate the effects on atmospheric fields.The following conclusions were obtained that: The retention curve and saturated hydraulic conductivity changes lead to temperature fields change in larger extents than others.While,porosity and saturated metric potential affect humidity fields larger than other parameters.The main difference concerning temperature locates at regions covered with sandy and silt loam soil.The main difference concerning water vapor exchange locates at oases covered by silt loam or silt soil.Simulation results were compared with observations.It is obtained that the simulated air temperature,specific humidity and wind fields were closer to observation using Heihe data than Cosby data.

• Setup and Validation of the Soil Texture Type Distribution Data in the Heihe River Basin
• GAO Yan-hong;LIU Wei;CHENG Guo-dong;PENG Hong-chun;LI Hai-ying;RAN You-hua
• 2007 Vol. 26 (5): 967-974. 
• Abstract ( ) PDF (913KB) ( )
• The soil texture type in Heihe River basin original Global data on Global soil texture type map could not figure out the soil heterogeneous distribution at different altitudes above sea level in the Heihe river basin.In order to reflect the uneven characteristic,particle percentage of 53 soil sample data were collected in the Heihe river basin.According to the soil triangle,each genetic type was ascribed to the soil texture type of the STASGO classification system.Based on 1：100000 soil map in the Heihe River basin of genetic classification system,soil texture map of the Heihe River basin(Heihe data) was setup as the same standard of origihal global 30 s soil texture classification.The Heihe soil texture data describers soil heterogeneous in the mountainous region and the oasis more exactly than the global data in the Heihe river basin.The mesoscale atmospheric model MM5 coupled with the land model was used and the Heihe soil texture data and STASGO global soil texture map was used as the overlay soil distribution,separately.Effects of the Heihe soil texture data on atmospheric elements simulation were studied and compared with the simulation results by the global soil map.Influence of soil map change on the environmental simulation was studied also.The following conclusions were obtained.In upper reaches of the Heihe river basin,2 m air temperature simulations using the Heihe data are closer to the observations than the global data at 19 meteorological stations.It shows warm bias in the middle reaches. Simulation bias using the Heihe data is more than the global data mostly.It is related to the uncertainty of the local heat and hydraulic parameters and the increased heterogeneous because of the human activities.So,it become the main approaches to raise the land-atmosphere simulation accuracy by the accurate land characteristic parameters and high-resolution soil temperature/moisture distributions providing.Changes of the environmental fields distribution lead by the soil map change show the non-linear relations with the soil texture types map change.2 m air temperature simulation is more sensitive with the soil type change than the other elements.

• Forecast Experiments of Summer Rainfall in China Using Japanese General Ocean-Atmosphere Coupled Model
• YOU Feng-chun;ZHANG Hai-xia;ZHANG Yan-bin;GUO Li-xia;SHI Yin-shan;KONG Fan-chao
• 2007 Vol. 26 (5): 975-979. 
• Abstract ( ) PDF (588KB) ( )
• To improve the forecast capability and the forecast accuracy of summer rainfall in China,the Japan General Ocean-atmosphere Coupled Model(SINTEX-F)was used in forecast experiments on summer rainfall at 160 stations of China from 1982 to 2004.By verifying and comparing with the observations,it shows that this model can predict the summer rainfall in China better,especially to the Yangtze River reaches.It was worthy of consulting in forecasting of summer rainfall to China.

• Observational Analysis for a Torrential Rain Caused by a Landfall Typhoon
• ZHANG Hai-xia;CUI Xiao-peng;KANG Feng-qin;CAI Shou-xin
• 2007 Vol. 26 (5): 980-991. 
• Abstract ( ) PDF (2887KB) ( )
• By the landfall Typhoon Haitang and propagating eastward frontal systems,torrential rains appear near Handan and its adjacent area from the evening of July 21 to the morning of July 23,2005.By analyzing the synoptic features,characteristics of water vapor transportation,evolution of FY2-C infrared satellite images and stratification features,the cause of the torrential rain is discussed.The results show that,interactions among the tropical low,stable subtropical high and troughs on 500 hPa leads to the torrential rain.Cold air masses propagate southwards from middle to high latitudes and meet with the warm and moist air masses transported by the tropical low,then the latter are lifted by its cold counterpart and the Taihang Mountains and mesoscale convections generate in the vicinity of Handan.The analysis of wind vectors from automatic surface observations shows that the mesoscale convergence line between the northerlies and the easterlies in lower troposphere is very important to the torrential rain,which determines the locations and timings of the torrential rain.The water vapor supply of the torrential rain in the western part of Handan is mainly from South China Sea and East China Sea,while the supply in the eastern part of the city is mainly from South China Sea.At last,simple stratification analysis shows that convective instability and conditional symmetric instability may coexist above the torrential rain zones,which provide instable energy for the torrential rains.

• The Physical Ensemble Simulation of the Chinese Anomaly Flood Regional Climate in Summer of 1998
• ZHONG Ke;WANG Han-jie;CAI Qi-fa;YU Qing-ping
• 2007 Vol. 26 (5): 992-1000. 
• Abstract ( ) PDF (765KB) ( )
• Through disturbing five kinds of physical processes of the regional model MM5,a physical ensemble with 19 members is formed in this paper.With this ensemble system the simulation research is applied to the Chinese anomaly flood regional climate in summer of 1998.The ensemble probability forecast has higher accuracy and discrimination ability than the ensemble mean and the higher resolution experiment do,which verifies to certain extent that describing atmospheric state in probability form is more accurate in numerical weather prediction.The physical scheme performing better and the sensitivity distribution among the disturbed physical processes change with the validated aspects of simulation quality;nevertheless,according to the statistical results of all the validated aspects of simulation quality,some physical processes produce strong disturbance more frequently,and some physical schemes perform better than others more frequently.

• Variational Assimilation of AMSU Data and Its Application to Numerical Simulation of Heavy Rainfall
• ZHANG Li-hong;SHEN Tong-li;WANG Hong-li
• 2007 Vol. 26 (5): 1004-1012. 
• Abstract ( ) PDF (1016KB) ( )
• GRAPES three-dimensional variational data assimilation system is used in this paper to assimilate AMSU data,then a process of a heavy rainstorm on 4~5 July 2003 is simulated through the WRF mesoscal model(version 2.0),in order to find the impact of AMSU data on numerical forecast of heavy rainfall in our country.By comparing and analyzing the results of assimilation and simulation respectively,the main conclusions to be drawn from this paper are as follows:(1) AMSU-A data contributes mainly to adjusting the temperature of initial fields,and AMSU-B data adjusts its humidity more distinctly;(2) From the adjusting extent to the results of hard rain simulation,the contribution of AMSU-B data is superior to one of AMSU-A data,and the effect of AMSU-A data seems to be less;(3) After assimilating AMSU-A/B data synchronously,the results of torrential rain simulation are improved more obviously than that of only using AMSU-A data or AMSU-B data in the areas and intensity of heavy rains.The analyses above show that AMSU data may advance the quality of the initial fields and increase the accuracy of heavy rainfall NWP in our country.

• The Influence of Topography on Dust Storm and Numerical Simulation
• SHEN Jian-guo;JIANG Xue-gong;SUN Zhao-bo
• 2007 Vol. 26 (5): 1013-1022. 
• Abstract ( ) PDF (2868KB) ( )
• Based on the relation between the topography and dust storm and numerical simulation of a dust storm process,a primary analysis of the influence of topography on dust storm was conducted.The results shown that in the early stage of this process the dust particle mainly came from the areas around Altai-Sayan Mountain and Mongolia.The topography conducted serious influence on the intensity of dust storm.It extended eastward dominantly leaded by the cyclonic cold front.In succession,the dust particle coming from central and western of Inner Mongolia conduced a more serious influence on dust storm.It mainly extended southward leaded by the terrain-forcing rolling stream of Qinghai-Xizang Plateau.Meanwhile,the influence of topography on dust storm induced the dust transportation acted as two different manners.The dust particle raised at eastern Qinghai-Xizang Plateau was transported in the middle troposphere and as a so called Spanning manner.It means the dust particle completed the long distance transportation with little subsiding on its path and a separation of dust layers appeared.On the contrary,the dust storm formed at Mongolia and Inner Mongolia extended in the lowed troposphere down to surface and as a so called Total-Pushing manner.It means the dust layers were separated two different layers in its transporting process.One is in the middle troposphere and the other near the surface.

• Correlation Analysis of Interannual Variability between Spring Dust Storm frequency and Atmospheric Circulation Factors
• MAO Rui;GONG Dao-yi
• 2007 Vol. 26 (5): 1023-1030. 
• Abstract ( ) PDF (862KB) ( )
• The relationship of spring dust storm frequency in Northern China with the previous autumn,the previous winter and the spring atmospheric circulation over the periods of 40 years are analyzed.The point is mainly to examine the correlation between dust storms frequency and atmospheric circulation on the interannual time scale.The results show that the atmospheric circulation factors have close relationship with dust storm frequency in interannual scale,including: Pacific North American pattern (PNA),spring North Pacific (NP) and the area of Asian polar vortex (PVA1) in winter.There is significant positive correlation between PNA and dust storm frequency,and negative correlation of NP and PVA1 with dust storm frequency.These results are not the same with that computed by the original dataset including low frequency variability.The results computed by the original dataset show that the atmospheric circulation factors influencing on dust storm frequency in Northern China mainly are the spring Pacific Decadal Oscillation (PDO,negative correlation),the area of Northern Hemispheric polar vortex (PVA,positive correlation) in spring,PVA1 in spring(positive correlation) and PVA1 in previous autumn(positive correlation).These results imply that the influence of circulation factors on different time scales is different.In addition,besides PNA,NP and PVA1,it seems that ENSO and western Atlantic pattern (WA) maybe have some moderate influence on the dust storm frequency.Interannually the variance of spring dust storm frequency explained by 12 atmospheric circulation factors is 65.3%.

• Dynamic Diagnoses and Simulating Analysis of a Severe Sandstorm and Snowstorm Weather Process
• HAN Jing-wei;SHENG Jian-guo;SUN Yong-gang;SONG Gui-ying
• 2007 Vol. 26 (5): 1031-1038. 
• Abstract ( ) PDF (1428KB) ( )
• Adopting the basic meteorological data and T213 numerical prediction productions,the dynamic diagnoses and simulating analysis of weather process mixed with strong wind,sandstorm,severe snowstorm and temperature decreasing in Inner Mongolia.The results shows that the strong cold air action is the main dynamics factor and the upper jet stream is the momentum source of the wind.Pressure gradient wind caused by developing Mongolia cyclone strengthen the wind and sandstorm.The space allocation of intense cold,worm advections intensify the strong wind,sandstorm and temperature decreasing.The space allocation of divergence helps the sandstorm and snowstorm developing.There is trigger and coupling actions for upper westerly jet to lower southwest jet.The establish of lower southwest jet and long distance vapour transportation and convergence are the important condition for east Inner Mongolia occurring snowstorm.The positive vortex advection transport in lower east wind shear zone superpose better vapor transportation and convergence area which enhances the snowfall.The later formation of northwest jet at bottom is important reason of the snowstorm.Numerical simulation shows that the location and intensity of the modeled high and low pressure centers is consistent with the observation.The pressure gradient intensity of cyclone closes to observation.The regional distribution,transportation direction,centers of the cold,worm advections have similar characters with fact.On the other hand,the temperature stratosphere simulation result is slightly bigger than the fact.

• Change Characteristic of Beijing Dust Weather and Its Sand-Dust Source Areas
• YIN Xiao-hui;SHI Shao-ying;ZHANG Ming-ying;Li Jing
• 2007 Vol. 26 (5): 1039-1044. 
• Abstract ( ) PDF (584KB) ( )
• Using the meteorological method,remote sensing method,geographical method,statistical method and HYSPLIT-4 model,the changing trend of dust weather,basic characteristics of sand-dust source areas and the correlation between the frequency of dust weather and the precipitation in Beijing and the sand-dust source areas are studied.The results showed that floating dust,raising dust and sandstorm weathers have an irregular fluctuant decreasing tendency in past 55 years.The cold air and dust entered into Beijing city have mainly three types routes from west,northwest and north routes.Mongolian cyclone along with cold front was the main weather situation that brings the dust weather of Beijing.The sand and dust particles mainly came from Inner Mongolia and the border between China and Mongolia.Besides,there are extensive sand-dust source areas surrounding the central districts and suburbs of Beijing.The correlative analysis showed that precipitation of the sand-dust source areas related closely to the frequency of dust weather of Beijing in spring,and local precipitation exerts an influence on the sandstorm weather mostly.In order to alleviate the calamity of dust weather of Beijing,people should plant trees to set up an outside ecological protective screen in the surrounding areas,strengthen the supervision on sand-dust source areas and predict the coverage and duration of possible dust weathers well in advance time.

• Changes and Relation Analyses of Climate and Vegetation in the Source Region of Yellow River in Recent Several Decade Years
• LIU Yuan-pu;Lü Shi-hua;LI Suo-suo;SHANG Lun-yu
• 2007 Vol. 26 (5): 1045-1051. 
• Abstract ( ) PDF (754KB) ( )
• Analyzing the variations and correlations of temperature,precipitation and NDVI index in the source region of Yellow River.Some results are found,the temperature was ascend significance in the recent 50 years;the precipitation trend was descend in the recent 34 years,the precipitation was more in 1980's,it was much humid in source region of Yellow River;the vegetation was covered badly in the source region of Yellow River and its notheast,it was not easily keeping;but it was covered well in Dari and the southeast of the source region of Yellow River and it was easily keeping in the recent 20 years,the vegetation was positive correlated to temperature and precipitation and the precipitation took more effect on vegetation than temperature.

• Studies on Atmospheric Circulation Anomaly of Flood Period and Prefreshet Period in the Highest and the Lowest Flow Years in the Upper Reach of Yellow River
• LAN Yong-chao;LIN Shu;WEN Jun;CHANG Jun-jie
• 2007 Vol. 26 (5): 1052-1058. 
• Abstract ( ) PDF (1493KB) ( )
• The both Change characteristics of high flow and low flow years since 1920 and their circumfluence characteristics of 500 hPa height fields,OLR fields,Asia blocking high,along with south wind transportation have been analyzed.The results show that in the high flow summer,the Polar vortex always keeps a stronger state from late winter to summer,there are south Asian highs called as east pattern in the upper levels and the Plateau vortex in the lower levels in the the upper reach of Yellow River;there are the strong convection centers move east and north-ward,and the centers trend to strengthened and expanded;the convection activity is stronger in the Qinghai-Tibet Plateau and the east of the northwest China;also there are the blocking highs southerly flow in entire levels over the the upper reach of Yellow River occurring over the Ural Mt.,but the opposite is true in the low-low years of summer.

• Transboundary Runoff Changes of the Lancang River in Summer and the Relationship between It and the Summer Monsoon
• YOU Wei-hong;ZHAO Fu-zhu;WU Xiang-yun
• 2007 Vol. 26 (5): 1059-1066. 
• Abstract ( ) PDF (1269KB) ( )
• Based on the observed data of the transboundary stream flow from the Lancang River and the U,V wind field data of NCEP/NCAR and the OLR field data of NOAA,and using the statistics method,the transboundary runoff changes of the Lancang River and their relationship with the summer monsoon under the effect of the Longitudinal Range-Gorge are investigated.The results show that the transboundary runoff change of the Lancang River appear obviously a decreasing tendency from 1960's to 1980's.The transboundary flow change of the lancang River appear obvious increasing tendency since 1990's.In summer,the correlation of the transboundary runoff with the U wind field in the lower atmosphere layer is no significant,but with the U wind field in the higher atmosphere layer is significant,and with the V wind field in the middle or lower and higher atmosphere layers is very significant,and with the OLR field is also significant.The summer monsoon circulation indexes influencing the variation of transboundary runoff of Lancang River during summer are established by correlation feature.These indexes can quite good describe the feature and regulation of the variation of transboundary runoff during summer in Lancang River.

• Relationships between Polar Vortex and Oscillation of South Asia High in East and West Directions
• CHEN Yong-ren;LI Yue-qing
• 2007 Vol. 26 (5): 1067-1076. 
• Abstract ( ) PDF (1939KB) ( )
• The relationships between Polar Vortex and the Oscillation of South Asia High(SAH) in east-and west-directions at 100 hPa levels are mainly studied by using composition analyses cross spectrum analysis,Morlet wavelet transform etc.The results showed that the indexes of Polar Vortex are positively correlated with the Oscillation of South Asia High in east-and west-directions.While the area of Polar Vortex became weak,the South Asia High displayed East deviation anomaly,and vice versa.On the other hand,both the polar vortex and SAH had similar interannual period characters.The results of spectrum analyses showed that they have the significant periods at 7.5 and 3-years.Meanwhile,the composed fields of geopotional height,stream line and temperature had dramatic variations in far east-and west-years of the SAH,It shows the different characters of atmospheric circulation in far east-and west-years of SAH.

• Numerical Simulation and Analysis of a Severe Convective Weather in Gansu
• LI Xiao-xia;KANG Feng-qin;ZHANG Tie-jun;WANG You-sheng;WEI Feng
• 2007 Vol. 26 (5): 1077-1085. 
• Abstract ( ) PDF (2472KB) ( )
• The general circulation of a severe convective weather occurred in middle part of Gansu province on May 28,2005 are analyzed,meanwhile,this severe convective weather and its cause are simulated and analyzed using the mesoscale model(MM5).The instability energy area has existed in the morning on 28 May and developped very quickly in the afternoon because of the role of terrain and local heat convection.The surface cold front that through the middle part of Gansu causes the low level flow convergent suddenly and revolving,rising intensely.This triggeres the unstable energy release and provides the dynamic condition for the severe convection weather.Analysis of the relative helicity of storm and the energy-helicity index(EHI) show the severe convection weather usually appear at the right of high area of the relative helicity of storm and late 1~2 h of high area of the energy-helicity index.

• Monitoring Drought in Mid-Western China Using MODIS Land Product LST and NDVI
• TIAN Hui;MA Yao-min;HU Xiao;LU Deng-rong;MA Wei-qiang;LI Mao-shan;SUN Fang-ling
• 2007 Vol. 26 (5): 1086-1096. 
• Abstract ( ) PDF (1198KB) ( )
• Using AQUA-MODIS (Moderate Resolution Imaging Spectoradiometer) land product LST and NDVI,a monitoring drought approach which is called Vegetation and Temperature Condition Index(VTCI) is applied in the mid-western China.The ground precipitation data from the representative stations over the mid-western China are used to validate the drought monitoring method via correlation analysis.The results show that VTCI is not only related to rainfall events within one month but also related to the cumulative impact of the rainfall amount during past two to six months,which indicates that VTCI can be used as a valid and near real time drought monitoring method on a large scale.

• Contrast and Calibration of Remote Sensing Production NDVI of NOAA/AVHRR and EOS/MODIS
• ZHANG Jie;GUO Ni;WANG Jie-min
• 2007 Vol. 26 (5): 1097-1104. 
• Abstract ( ) PDF (655KB) ( )
• Using the MODIS data of Terra and Aqua satellites,AVHRR data of NOAA-16 and NOAA-17,data calibration are done in allusion to influence of zenith and azimuth angle of sun and sensors,scatter of aerosol particle,and attenuation of sensor on NOAA satellites.By calibration,some NDVI values are gained,NDVI of Terra and NOAA-17,NDVI of Aqua and NOAA-16 are analyzed,the relations of NDVI with spectral response function are also analyzed.The results show that NDVI from Terra and Aqua change with observing angles,average NDVI is a perfect composite arithmetic,which represent NDVI within ±30° angle.Angle calibration of NDVI is done again.NDVI from NOAA-16 and NOAA-17 are less than it from MODIS,referred to MODIS NDVI,the NDVI from NOAA is normalized according to spectral response functions,normalized NDVI is very closed to NDVI from MODIS,which means that it is a perfect method to continue NDVI production.

• A Column Cloud Liguid Water Content Measured by Airborne Upward-Looking Microware Radiometer
• LIANG Gu;LEI Heng-chi;LI Yan;YUE Zhi-guo;ZHANG Xiao-qing;GAO Bei
• 2007 Vol. 26 (5): 1105-1111. 
• Abstract ( ) PDF (714KB) ( )
• Using a single wavelength(0.95 cm) column cloud liquid water content by Airborne Upward-looking Microwave Radiometer measures the Cloud Liquid Water Content in stratiform clouds(CCLWC) in Yan'an area on April 18,2003.The analyzed results show that the average supper-cooled cloud liquid water content(SCCLWC) is 0.0171 g·m^-2.It was found that it had a high value range on the vertically CLW by analyzing the CLWC had changed in stratiform cloud.Which range was contribute to the operations of precipitation-enhancement,be good for enhancing ice crystal's,improving effective on operations of catalyze.The Airborne Upward-looking Microware Radiometer is compared to the PMS radar and the 711 numerical radiometer on the ground surface,and its results are shown that the Airborne Upward-looking Microware Radiometer and PMS radar have the same measured;and that the Airborne Upward-looking Microware Radiometer is more topical of the PMS radar by measuring of the vertically range,and testimony tallies with the results of the 711 numerical radiometer on the ground surface.

• Comparison Analyses on the Radar Retrieved and Simulated Water Content in a Severe Converctive Storm
• YU Hua-ying;NIU Sheng-jie;LIANG Ming-zhu;WEI Ming;GU Song-shan
• 2007 Vol. 26 (5): 1112-1118. 
• Abstract ( ) PDF (576KB) ( )
• The fully elastic three-dimensional convective storm model(IAP-CSM3D) established by the Institute of Atmospheric Physics(IAP),Chinese Academy of Science was used to simulate severe convective storm that occurred in Hunan province on April 23,2004.The reflectivity observed by the Doppler weather radar was used to retrieve the water content,and established two display modes,which are CAPPI and VCS.Calculation field is defined as the cuboid grid box centered by the radar station,with the horizontal lateral lengths of 150 km,with the heights of 30 km,and with the resolution of 1 km×1 km×1 km.To retrieve the case water content in comparison with the water content from the numerical modeling.The result is as follows: The constant value line distribution of the retrieved water content is parallel to the simulated output as a whole no matter in the development stage or in the strong stage of the storm,and the strength in the storm center as well as the height position is consistent well,that reflect the storm structure on the whole and the retrieve effect is rather perfect.

• The Relationships between the Position of West Pacific Subtropical High and Ground Temperature Field of China Summer
• ZHAO Hong-yan;YANG Yu-feng;ZHANG Jiu-lin;LIANG Dong-sheng;LI Rong-qing
• 2007 Vol. 26 (5): 1119-1122. 
• Abstract ( ) PDF (309KB) ( )
• Based on the data of monthly 500 hPa height and ground temperature at 3.2 m depths during 1951 to 2003,the relationship between the location of west Pacific subtropical high(WPSH) and China ground temperature field are analyed.The results show that the relationships between the latitudes of ridge line of WPSH and ground temperatures of some regions in China are clear,and the high correlation regions are near the region of 100°~115°E,30°~45°N.In the relation field of June,there is a quasi transmeridional high relation axes along 30°~35°N,and it moves northward to 34°~40°N in July and to 40°~45°N in August.Like to this,there are similar high relation regions and axes on the relation field between north border of west Pacific subtropical high and ground temperature of China.In the years that the latitude of ridgeline of west Pacific subtropical high is on the north or south side,the ground temperatures in selected region are different.The ground temperatures are high when the ridge line of west Pacific subtropical high is on the north side,and lower when that on the south side.And so,the annual variations are also opposite in two groups.