Current Issue

• Numerical Simulation of Dependence of Earth's Orbital-Scale Climate Variability over Qinghai-Xizang Plateau Region on the Orography
• MAO Xiao-liang;LIU Xiao-dong;CHEN Guang-shan
• 2006 Vol. 25 (1): 1-8. 
• Abstract ( ) PDF (1772KB) ( )
• Using the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM 2.01),a set of numerical experiments were conducted to examine dependence of the orbital-scale climate variability over the Qinghai-Xizang Plateau region on the orography by changing the plateau topography and the Earth's orbital parameter (precession).The result shows that the response of climatic elements related to the humidity (such as precipitation,runoff,snowfall and snowdepth) is much stronger in a high-orography case than in a low-orography case tothe same precession forcing.When the date of perihelion is changed to January from July,the summer precipitation and runoff increase significantly in the mid-south part of the Qinghai-Xizang Plateau.Meanwhile, winter's snowfall and snowdepth increasein the west-north part but decreasein the mid-south part of the Qinghai-Xizang Plateau.The above climatic variations are found to be related with changes in the atmosphere circulation induced by the precession.These modeling results may be helpful to understand the modulation of the uplift of the Qinghai-Xizang Plateau to the regional climate variability reflected by relevant geological records.

• Chaotic Characters and Predictability of 33 Mode Lorenz System
• WANG Ge-li;YANG Pei-cai;Lü Da-ren
• 2006 Vol. 25 (1): 9-15. 
• Abstract ( ) PDF (294KB) ( )
• An ideal non-noise spatio-temporal series (33 mode Lorenz system) is used in this paper,and its chaotic property is tested with the calculation of power spectrum,dimension and Lyapunov exponent and its predictability character is also analyzed,it shows that the predictability ability can not be improved by means of averaging for the chaotic time series.

• Analysis on Dry Intrusion in Heavy Rain and Huang-Hai Cyclone
• YANG Gui-ming;MAO Dong-yan;YAO Xiu-ping
• 2006 Vol. 25 (1): 16-28. 
• Abstract ( ) PDF (2648KB) ( )
• Using the water vapor (WV) image,isentropic flow,potential vorticity (isentropic potential vorticity,moisture potential vorticity) and θ_se,a heavy rain process during Meiyu period is analyzed to reveal the effect of dry intrusion on heavy rainfall and Huang-Hai cyclone.The main results are as follows: (1) Dark zone in WV image is a good predictor for heavy rain and extratropical cyclone. (2) The development and change of vertical flow overlapped with relative humidity can clearly reflect the relationship between dry intrusion and heavy rain.It is a good predictor for very short-range forecasting.Dry intrusion triggers the heavy rain and the dry zone above middle-level corresponds well with dark zone in WV image. (3) The airflow on 340K and 330K isentropic surfaces indicates the characteristics of dry intrusion in the middle and top of troposphere and Huang-Hai cyclone,respectively.The jet sliding along the ridge on isentropic surface is consistent with the dark zone in WV image.The big value of IPV relates well with the initiation and development of cyclone.It's distribution provides the features of dry intrusion. (4) The temporal and specialcross-section of MPV1 on isobaric surface can reflect the evolution of dry intrusion.Heavy rain occursin the southern 2-latitude when the area of MPV1 greater than 0.4 PVU extends downwards. (5) Dry intrusion can strengthen the rainfall near the cyclone.It is almost the same time for the happening of the heavy rain and the big value of MPV1.This indicates that the effect of dry intrusion on the heavy rain near and far from cyclone is different.Heavy rain often appear in the area of sharp and dense θ_se.

• Improvement to a η-Coordinate Rainstorm Model and It Forecast Testing
• HUANG Hong;ZHANG Ming
• 2006 Vol. 25 (1): 29-33. 
• Abstract ( ) PDF (433KB) ( )
• The block-terrain theory of Prof.Zeng Qingcun is introduced and improved,the calculation of pressure-gradient force is improved,based on a η-coordinate rainstorm model.A new calculation scheme isdeducedand the corresponding programme is rewritten.The testing of forecasting shows that the change can partly improve the prediction of storm rainfall on the steep terrain.

• Structure and Causes of "02.6" Extremely Heavy Rain in the Southern Shaanxi Province
• BI Bao-gui;BAO Yuan-yuan;LI Ze-chun
• 2006 Vol. 25 (1): 34-44. 
• Abstract ( ) PDF (1238KB) ( )
• Using the NCEP reanalysis data,thermal and dynamical structures of heavy rainstorm in the southern Shaanxi province during 8~9 June 2002 (02.6) are analyzed.Results show that the severe precipitation is closely related to the monsoon burst and the intensification of cross-equatorial flow,which bring plentiful water vapor and meet with cold masses at the eastern of northwest China on 8,June causing extremely heavy rain.There is a vertical secondary circulation crossing lower-lever jet whose ascending branch is at the area of heavy rain.The water vapor comes from southerly and easterly flow which converge at the eastern of northwest China with convergence mainly in lower levels and PBL.The high value of the whole-level apparent heat source <Q₁> is near the area of heavy rain in the direction of northeasterly-southwesterly agreeable to shear line very well and the condensation latent heat releasing is main heat source with vertical advection item playing key role in Q₁ and Q₂.The construction of convection instability and conditional symmetry instability results that there is not only deep thermal instability,but also moisture influx and triggering mechanism of thermal instability causing strong torrential rain.

• Dynamic and Thermodynamic Diagnostic Analysis about "98.5" Heavy Rainstrom of SouthChina in Pre-Summer Flood Season
• WEN Li-juan;CHENG Lin-sheng;ZUO Hong-chao;Lü Shi-hua
• 2006 Vol. 25 (1): 45-51. 
• Abstract ( ) PDF (315KB) ( )
• In order to understand the heavy rainstorm processes of South China in pre-summer flood season,the total vorticity,the apparent heat source and the apparent moist source were diagnosed.The results are as following: The total vorticity was similarwith the vorticity,their centers were both above the precipitation.The positive total vorticity meant the vorticity would be developing.In the components of the total vorticity,the vection of the absolute vorticity and the distortion term were the negative contribution,and the others were opposed.The rain was under the centers of the apparent heat source and the apparent moist source,and they had similar configuration that meant the latent heat was the energy source producing this rainfall.The sub-grid turbination was favorable to the development of the convection.In their components,both the vertical terms were dominating.The vapor was transferredto high levels by the vertical motion.The cloud water fields was corresponded with the apparent moist source.Not included the ice,when the apparent moist source was the biggest,the altitude of the other fields also reached the top,and the intensity of some is maximum.

• Analysis of the Influence of a Typhoon and Meso-Scale Vortex in Inner-Mougolia Irrigation Area of Yellow River on Rainstorm in North Shaanxi
• ZHANG Hong;CHEN Wei-dong;SUN Wei
• 2006 Vol. 25 (1): 52-59. 
• Abstract ( ) PDF (1461KB) ( )
• Through the analysis of influence of a typhoonand meso-scale vortex in Inner-Mongdia irrigation area of Yellow River on rainstorm the northof Shaanxi,the results are as follows: The vertical structureof convergence-divergencefromlow-level troposphere to high level and unstable air in Hetaolow eddy provide advantageous conditions for developmentand maintenance of upward current near rainstormarea.The vapour and energy channel formed east-ward wind current on the north side of low-pressure circulation of low-level tynoon product the severe vapour convergence in North Shaanxi and result in the accumu lation and release of unstable energy that directly cause the rainstorm far from tynoon.The rainstorm forming is closely related to the mesoscale convergence system in surface stream field and meso-β-scale convective system in satellite cloud picture.

• Distribution and Changing Character of Water Vapor over Qinghai Plateau in Summer in Recent 43 Years
• WANG Peng-xiang;WANG Bao-jian;HUANG Yu-xia;GUO Pin-wen;LI Dong-liang
• 2006 Vol. 25 (1): 60-65. 
• Abstract ( ) PDF (470KB) ( )
• on the research about distribution and changing character of water vapor over Qinghai Plateau during the recent 43 years,the obtained results are as follow: (1) In summer,the warm and moist water vapors from Bay of Bengal is transported by the East Asian summer monsoon into the Qinghai Plateau,and the west wind water vapor is transported to this region at the same time too,but because of terrain of Qinghai Plateau blocking off,the total content of water vapor in this region is greatly decreased. (2) The content of water vapor flux is increasing from west to east boundaries,the high value belt of water vapor flux lies to the east part of Qinghai Plateau. (3) The net vapor flux has an increasing tendency in recent 43 years. (4) In the dry year,the decreasing of water vapor is about 10~40 kg·m^-1·s^-1,and the increasing ofwater vapor is about 10~20 kg·m^-1·s^-1 in wet year.The net water vapor flux is positive always,but its content is low about 21.88% than average state in dry year,and is high about 53.99% in wet year.

• Numerical Simulation of Local Circulation in Jinta Oasis in Summer
• CHEN Shi-qiang;WEN LI-juan;Lü Shi-hua;AO Yin-huan;ZHANG Yu;LI Suo-suo
• 2006 Vol. 25 (1): 66-73. 
• Abstract ( ) PDF (386KB) ( )
• Using the mesoscale model MM5,three cases of different background circulations were simulated.Their forms and developmentof oasis effect were analyzed.Simulated results showed the oasis divergent wind gone out of it wasn't easy to appear if the ambient wind field was strong.At the same time the cold center was blown away from the geographic center of the oasis and reappeared in the oasis after a period.Sometimes the wind influenced by the background circulation just diverged toward south and north sides of the background wind field.When the velocity of ambient wind was relatively small,the oasis-desert circulation gradually formed and the boundary obviously moved betweenthe divergent oasis-desert wind and background wind field.Under different background wind field conditions,the oasis temperature and humidity centers didn't coincide with each other.

• The Effect of Interdecadal Variations of Arctic Oscillation on Aridization in North China
• JU Jian-hua;Lü Jun-mei;REN Ju-zhang
• 2006 Vol. 25 (1): 74-81. 
• Abstract ( ) PDF (1686KB) ( )
• The summer rainfall in North China has entered a decadal decreasing stage sincethe middle of 1970's,which occurrences the considerbly droughty trend.The aridization trend in North China hap-pens against a special background of atmospheric circulation.It is characterized by weaker heat lowover East Asia and the weaker East Asian summermonsoon circulation after the middle-1970's.This kind of anomalous atmospheric circulation is mainly caused by interdecadal variations of Arctic Oscillation (AO)and land-sea thermal contrast.AO always keeps at high index phase during the recent two decades.It plays an important role in the anomaly of atmospheric circulation of East Asia and finally cases the droughty exasperation in North China.

• Temporal and Spatial Features of Summer Arctic Oscillation
• YANG Xiao-yi;HU Yue-wen;GUO Pin-wen;MA Zhu-guo
• 2006 Vol. 25 (1): 82-89. 
• Abstract ( ) PDF (930KB) ( )
• Using the NCEP/NCAR reanalysis monthly data of SLP,the seasonal difference of Arctic Oscillation (AO) is studied with the emphasis on the temporal and spatial features of the summer AO.The results indicate that the major discrepancy between the summer AO and winter AO lies on their mid-latitude active centers.The mid-latitude active center in winter AO locates at Atlantic ocean,it shifts over Asian continent in summer.The Asian center of the summer AO is significant only in the lower troposphere.In the upper troposphere,there is no Asian active center,which shows the summer AO stronger baroclinicity in contrast with the winter counterpart.This mode yields the similar spatial pattern,interannual and intermonth.In addition,the summer AO exhibits the strong quasi-22 and 6~7 year periods in the last 50 years,with the quasi-biannual period emerging after 1970's.

• The Effect Urban Heat Island on Change of Regional Mean Temperature in Gansu Province,China
• BAI Hu-zhi;REN Guo-yu;ZHANG Ai-ying;WANG De-min
• 2006 Vol. 25 (1): 90-94. 
• Abstract ( ) PDF (226KB) ( )
• Using the data of monthly mean temperature at 38 stations in Gansu Province,the effect of increased urban heat island magnitude on the regional annual and seasonal mean temperature series as constructed based on the national basic/reference stations and six urban stationsin 1961-2002 was analyzed.It has been found that the trendsof temperature change as calculated using data from national basic/reference and urban stations are generally larger than that of rural stations.The rural stations consist of six "pure" countryside stations across the province.The contributions of increased urban heat island magnitude to the trendsof regional mean temperature change calculated based on data from national basic/reference stations and six urban stations are estimated as being 18.5%,and 37.6%,respectively.It is also interesting to note that,on the basis of national basic/reference stations records,maximum warming rate of the regional seasonal mean temperature occurred in wintertime,and maximum urban warming rate occurred in wintertime,but the largest relative contribution of increased urban heat island magnitude to theregional warming rate was in springtime.

• Numercial Simution of Forming Mechanism for the Torrential Rain in Shandong Province in August 1999
• ZHAO Yu;GONG Dian-li;LIU Shi-jun;SUN Xing-chi
• 2006 Vol. 25 (1): 95-104. 
• Abstract ( ) PDF (1296KB) ( )
• The simulation was successfully made for the torrential rain process in Shandong province during 11~12 August 1999 using the two-way nested grid MM5V3 model.Using the simulated high resoulutin information,the forming mechanisms of the torrential rain and mesoscale vortex were analyzed.The results suggest that weak cold air spreading into typhoon circulation and tropical convergence streaching northward resulted in torrential rain.Slantwise vorticity development is an important mechanism that the torrential rain and mesoscale vortex occurred and developed.Beneficial terrain of southeastern of Shandong has important effect on the information of mesoscale vortex.Strong convergence on the top of the typhoon depression trough first triggered ascending motion and caused heavy rainfall.The heavy rainfall always lie where cyclonic shear is very evident.The releasing of latent heat from rainfall made upper atmosphere warm and resulted in intensifying of upper divergence,which made lower mesoscale vortex to develop intensively and amplified the rainfall.So CISK is another mechanism for torrentioal rain and mesoscale vortex development.

• An Experiment to Derive Cloud Motion Vectors from Satellite Images with 2-D Fourier Phase Analysis Technique
• ZHANG Hong;WANG Zhen-hui;XU Jian-ming
• 2006 Vol. 25 (1): 105-109. 
• Abstract ( ) PDF (457KB) ( )
• The 2-D Fourier phase analysis is used to process 1 minute intervalIR imagery in order to retrieve the cloud motionwind field.Histogram of the cloud top heights is used to assign CMW vectors onto three levels,such as high-,middle- and low-level clouds.Comparing with the 2 wind fields derived from 3 adjacent images based on continuity analysis,unreasonable wind vectors in wind direction and speed would be eliminated and heights assigned can be modified.

• The Numerical Experiments of Remote Sensing Atmospheric Aerosol Particle Size Distribution over Waters Using Multichannel MODIS Data
• FENG Jian-dong;HUANG Ting;CHEN Chang-he;ZHANG Wu
• 2006 Vol. 25 (1): 110-115. 
• Abstract ( ) PDF (258KB) ( )
• Using the spectral dependence of the satellite observed radiances inverses the atmospheric aerosol particle size distribution,the primary task is to found the inversion procedure and tests it.In this paper according to the algorithm of Tanré et al.Dealing with the MODIS data over the dark ocean surface,and the observed MODIS radiation signals over the reservoirof land by satellite;using 6S radiation model buildsa Look-up table (LUT) to retrieval atmospheric particle size distribution;then testing the built LUT and discussing the feasibility of the algorithm by designing numerical experiments.The numerical experiments show that the LUT has its inversion ability to the continental aerosol model,but the fitting error ε_sl is increased with the increase of the aerosol optical depth.

• Analyses of the Influence of Sand Dust Aerosol on Vegetation Remote Sensing in Northwest China
• ZHANG Jie;GUO Ni;HAO Zhi-yi
• 2006 Vol. 25 (1): 116-122. 
• Abstract ( ) PDF (339KB) ( )
• Some representative MODIS data are picked up and atmosphere correction is done by using 6S model.The influence of sand dust aerosol on VI in Northwest China is analysed.The result showed that sand dust aerosol is of some radiation characteristic,which lead to reflectivityρ1,ρ2,ρ3 increased,and the values of NDVI and ARVI are decreased if the atmosthere correction is did.The value of NDVI is minished by influencing of sand dust,and the maximum value is 0.246,the value of ARVI is minished by influencing of sand dust,and the maximum value is 0.231.By using the some data in clear sky,a linearity relation between ARVI and NDVI is established,this relation is used well in sandy day.

• Digital Terrain Model-Based Temporal and Spatial Distributions of Solar Radiation in Mountainous Area
• ZHANG Xiu-ying;FENG Xue-zhi
• 2006 Vol. 25 (1): 123-127. 
• Abstract ( ) PDF (551KB) ( )
• As the most important energysource,the astronomical solar radiation (ASR)is the main force to driveatmosphere movement and it influences the heat condition of the earth-atmosphere system.The main problem that researchers met withsolar radiation calculating in small drainage basin is the influence of slope,slope direction and the shadow to the spatial distribution of ASR.This paper introduces an application in effecing the effect of shadow determined ArcGIS on different slopes and slope direction lands and gets good result.The correlative analysis shows that slope direction is a key factor influencing the solar radiation receiving.Because it is not only a factor participating the solar radiation calculating,but also a factor indirectly though shading influencing receiving the solar radiation;the ASR changes with seasons and the degree of terrain factors influencing the distribution of ASR changes also with seasons,but has no obvious rule.

• Discussion on Cloud Seeding Area of Atificial Precipitation Enhancement in Cyclone
• WANG Yi-lin;WANG Jian-guo
• 2006 Vol. 25 (1): 128-137. 
• Abstract ( ) PDF (2811KB) ( )
• It is analyzed the perpendicular structure of a Huanghuai cyclone.Using the ice-water conversion theory in seeding of cold cloud,the conditions of ice crystal growing up are discussed in different times and positions of cyclone by condensation or sublimation.The methods of confirmation seeding area in cyclone are made before operation.When the temperature is below 0℃,in nascent period of cyclone,it is showed there are fine water vapor conditions anywhere in cyclone.In developing period of cyclone,there are fine water vapor conditions at the fore of cold and warm fronts.After cyclone occlude,there are only fine water vapor conditions at fore warm front and cyclone center.But there are always much liquid water in cold cloud at the fore of warm front.

• Study on Atmospheric Ice Nuclei on North Slop of Mid-Tianshan Mountains in Summer
• ZHANG Jian-xin;LIAO Fei-jia;GAO Zi-yi;WANG Wen-xin
• 2006 Vol. 25 (1): 138-142. 
• Abstract ( ) PDF (418KB) ( )
• By using a millipore filter method,the essay makes ice nuclei observations on the North slop of Mid-Tianshan Mountains area Xinjiang from June 12 to July 31, 2001.it is found that the observed atmospheric ice nuclei is so thin in the area,it is only 0.32·L^-1.The analysis shows that the concentration of atmospheric ice nuclei maintains close links with activity of air mass,precipitation and wind directions.

• Temporal and Special Distributions of Three Kinds of Precipitation Clouds and Circulation Feature in Ningxia
• CHEN Yu-ying;LI Yan-chun
• 2006 Vol. 25 (1): 143-150. 
• Abstract ( ) PDF (430KB) ( )
• Using the medium cloud,low cloud cover,total cloud cover,weather phenomena and precipitation data of routine surface observation at 24 stations of Ningxia in 1971-2000,the temporal-spacial variation characteristics of stratiform cloud,convective cloud and mixed cloud in Ningxia in 30 years are analyzed.At the same time,the circulation characteristics of three kinds of precipitation clouds are diagnostically analyzed by utilizing the NCEP/NCAR (1971-2000) global reanalysis data.The results show that the frequency of stratiform precipitation cloud is obvious larger than the that of convective and mixed ones in 30 years,which is the main type of precipitation in Ningxia,while the precipitation of mixed cloud is the main type of heavy rainfall,the frequencies of convective and mixed clouds in North Ningxia are relative larger.There are notable differences for the month,interannual and interdecadal change characteristics of three kinds of precipitation clouds and their circulation background and inducing systems.

• Study of Meteorological Forecasting and Warning for Landslide and Debris Flow in Zhejiang Province
• DU Hui-liang;NIU Xue-xing;YIN Kun-long;XIE Jian-ming;LIU Li-ling
• 2006 Vol. 25 (1): 151-158. 
• Abstract ( ) PDF (352KB) ( )
• Based on statistic analyses between landslide,debris flow and precipitation,the efficient precipitation which will cause the landslide and debris flow events wasgiven.Then we got efficient precipitation formula,critical efficient precipitation in four high-risk zone for landslide or debris flow in the province.To better forecast landslide and debris flow,we localized mesoscale model,the well-known MM5,and the nowcasting technique of satellite and radar also were utilized.The three methods could supplement each other.After testing daily forecast during the period of 2003-2004,the result showed that the method has a quite good behavior in precipitation forecast and landslide,debris flowforecast.

• Analyses on Characteristics of Consective Hail Day in East of Guanzhong Plain,Shaanxi
• HU Shu-lan;WU Mai-feng;WANG Xu-xian;ZHANG Li-juan;WU Guang-liang
• 2006 Vol. 25 (1): 159-163. 
• Abstract ( ) PDF (216KB) ( )
• Using the data in which there are a station occurring more than three consective hail days in east of Guanzhong Plain,Shaanxi,their spatial and temporal distribution features,circulation patterns and the forecasting points were analyzed and summarized.It put forward that the important reason of more hail and consective hail shooting in Weibei is the result of superposition of orography with lee wave in Qinling.

• Pollution Status of Harmful Components to Frescos in Dunhuang Mogao Grottoes
• WANG Wan-fu;WANG Tao;SHENG Zhi-bao;XIE Jian-ping;XING Jun
• 2006 Vol. 25 (1): 164-168. 
• Abstract ( ) PDF (224KB) ( )
• With monitoring data from 1996 to 2001,analyzing the annual mass concentration change of SO₂,NO_X and TSP that is harmful to Dunhuang frescos,we draw some conclusions as follows.Aver age mass concentration of SO₂,NO_X in the air is 0.0268 mg·m^-3 and 0.0217 mg·m^-3,respectively,satisfying national second standard criteriain GB3095-1996.But the mass concentration of TSP is 0.3077 mg·m^-3 and 153.9% of that of national second standard criteria.The mass concentrationof SO₂ appears a conspicuous rising trend and should pay more attention.We suggest that it should strengthen ecological environment construction in grotto region and link with protection of whole Dunhuang oasis.A good condition for frescos preservation can be created by the means of controlling tourists reasonablyto reduce the content of harmful components.