Current Issue

• New Advances in Shouthwest China Vortex Research
• CHEN Zhong-ming;MIN Wen-bin;CUI Chun-guang
• 2004 Vol. 23 (s1): 1-5. 
• Abstract ( ) PDF (213KB) ( )
• The southwest vortex is one of the major heavy rain systems in China during summer. The new advances on research of formation, development and structure of the southwest vortex is presented. The obtained results about studying southwest vorlex in recent 10 years were simply summarized in this paper, and there are some questions to be point out in order to deepen the research on the southwest vortex.

• Short-Range Ensemble Simulation of "2003.8.28" Heavy Rain on the East Side of Qinghai-Xizang Plateau
• CHEN Jing;LI Chuan;FENG Han-zhong;HE Guang-bi
• 2004 Vol. 23 (s1): 6-14. 
• Abstract ( ) PDF (1480KB) ( )
• Using the non-hydrostatic MM5 version and the global model T213 of National Meteorological Center of China, we explore the impact of parameterization schemes of diabatic physics on a heavy rain occurringon the east side of Qinghai-Xizang Plateau on 28~29 August 2003. The short-range ensemble prediction had been made by using different kinds of physic to establish some science base for deep ensemble perturbation method in this area. The results show the physical parameterized scheme of model have obvious impacts on results of meso-scale precipitation forecast, including local precipitation intensity, spatical distribution pattern and time-varying characteristic and so on. As the model resolution rising, the scheme of cumulus convection parameterization will increase 1~5 mm rainfall areas to lead the false precipitation. Considering the level of numerical prediction on present stage, the high resolution ensemble prediction system should focus on the ensemble prediction of heavy rainfall.The results indicate that the ensemble simulations can improve the unstable determinate predictions of heavy rain and provide more useful and valuable prediction information for heavy rainfall forecast.

• Numerical Simulation of Heavy Rain in Northwest Sichuan Basin on 8 August 2003
• HE Guang-bi;CHEN Zhong-ming
• 2004 Vol. 23 (s1): 15-22. 
• Abstract ( ) PDF (1476KB) ( )
• The NCAR MM5 mesoscale model was used to simulate a heavy rain process ocurring in Northwest Sichuan Basin on August 8 ~10, 2003.The results show that MM5 can forecast the heavy rain process in Northwest Sichuan Basin, the centre intensity and location of the forecast precipitation are close to the observation. Accumulated instability energy in the Basin is the internal condition of the heavy rain ocurring. Converging of the cold and warm air is the trigger factor of the heavy rain ocurring. The transportations of continuous water vapor and cold advection lead the heavy rain in the region. MM5 has operational application prospect over the complex terrain area on the east side of Plateau.

• Application of Convection Model to Evolution Law of Kunming Precipitation
• TAO Yun;LIU Yu;MA Zhen-feng
• 2004 Vol. 23 (s1): 23-27. 
• Abstract ( ) PDF (211KB) ( )
• Applying convection equation describing local precipitation anomaly system and real-time meteorological observatory data, the nonlinear oscillation equation describing Kunming precipitation anomaly system was derived and retrieved. According to the nonlinear oscillation theory and the obtained equation, the nonlinear characteristics and evolution law of Kunming precipitation anomaly system were studied.The results show that Kunming precipitation anomaly systemis a positive damping system with weak nonlinear oscillation. Its natural period is 65 days. Without the exernal forcing, it will go to a stable point a ₁(0, 0). With the exernal forcing, it will oscillates with the exernal force oscillation.

• Unsymmetrical Characteristics of Divergence Fields at Low and High Layers in Mesoscale Severe Rain Systems
• CHEN Zhong-ming
• 2004 Vol. 23 (s1): 28-30. 
• Abstract ( ) PDF (133KB) ( )
• Using the divergence equation the evolution of divergence fields of mesoscale severe storm rainfall system in upper-and-low levels is studied from dynamics. The results show that the physical mechanism of divergence in upper level is more than that of convergence in low level in mature stage of severe mesoscale rainfall system.

• Analyses on "2003.8.28" Heavy Rain in the Upper Reach of Yangtze River
• WANG Li;CHEN Jing;LI Shu-jun
• 2004 Vol. 23 (s1): 31-36. 
• Abstract ( ) PDF (279KB) ( )
• Based on the T213 objective analysis data, the causes of heavy rain in Sichuan from 28 August to 1 September of 2003 have been analyzed. The results show that the building of south low-level jet provided abundant vopour transfer and convergence for the heavy rain. The cold advection in low- and mid-levels and the wind of low-level jet are and trigger mechanism of the heavy rain process. South-West (SW) vortex occurred after heavy rain. The pumping effect resulted from low-level convergence and upper-level divergence caused stronger upward current, the coupling of convergence region with positive vorticity make SW vortex to develop and maintain, leading to more rainfall in Sichuan Basin.

• Numerical Simulation Experiment about A Typical Heavy Rain Process on the East Side of Qinghai-Xizang Plateau
• KANG Lan;SHEN Tong-li;CAI Xin-ling;PU Ji-guang
• 2004 Vol. 23 (s1): 37-45. 
• Abstract ( ) PDF (1533KB) ( )
• Using the mesoscale model(MM5), the numerical simulation and a series of sensitive experiments are carried out to the typical heavy rainstorm on the east side of Qinghai-Xizang Plateau on July 4~5 1998. The results showed that the MM5 model can successfully simulate the process of heavy rain and the mesoscale system related to the process; the low-level convergence flow is weakened after getting rid of cold air, making the precipitation weakened abviously; increment of internal energy in basin can promote the form of mesoscale systems. The experiment of varying vapour content of low-level in different regions at initial time demonstrated that the collective degree of vapour before the heavy rain process and the existence of maintaining vapour transport mechanism in the heavy rain process are to judge one of key factors of rainfall dessity in a heavy rain process. Terrian experimentation prove, when the large terrian is obviously changed, the location and intensity of influential systerm, low jet flow, the moving path of cold air will obviously change also. Deducing from this, the special climate charateristics in Sichuan basin is determinated by its peculiar geographic condition.

• Analyese on A Heavy Rain Process on the East Side of Qinghai-Xizang Plateau
• GAO Qing-yun
• 2004 Vol. 23 (s1): 46-52. 
• Abstract ( ) PDF (1643KB) ( )
• Using the hourlysatellite images and physical quantity field data, the cloud characteristic and physical structure for the heavy rain in Sichuan basin on the east side of Qinghai-Xizang Plateau during 8~9 June, 2002 are analyzed. The results show that the heavy rain was caused by two mesoscale convective storm complexes(MCC) in occurring the environment of warm and wet, and it is found that there is the dynamical structure of upper-level strong divergnce (negative vorticity) and low-level convergence (positive vorticity) in physical field. The development and maintenance of the MCC and heavy rain were closely related to the superposition by the asending branchs of the direct circulation in the entrance region of upper-level jet and the secondary circulation in the exit region of low-level jet.

• Verification of Some Numerical Models to Precipitation in the Mid-and-South Parts of Qinghai-Xizang Plateau in Summer of 2003
• WANG Yu
• 2004 Vol. 23 (s1): 53-58. 
• Abstract ( ) PDF (663KB) ( )
• The predictive products of precipitation for various numerical simulation modles at home and abroad to the predictive ability in the mid- and south-parts of Qinghai-Xizang Plateau in summer of 2003 were detailly verified. The results of accumulated verification show that TS score of light rain area is the highest of all areas in China, but that of moderate rain or over are lower. The main reason is that the forecasted area of each model is clear larger than the observed one and false alarm ratio is highter. And so, whether it is forecaster and global model, or local model; whether it is Japan and German models, or T213 HLAFS25 and HB-MM5 of China, all of them have no obvious superior to the prediction of precipitation.

• Conceptual Model for Regional Flooding in Southwest China
• YU Shu-hua;GAO Wen-liang;YANG Shu-qun
• 2004 Vol. 23 (s1): 59-62. 
• Abstract ( ) PDF (246KB) ( )
• Through analyzing the causes of regional flooding storm rainfall and the day-to-day stream amount in Cuntan at 08:00 in May~September from 1991 to 2001, the obtained results are as follow: 1 The regional flooding in Southwest China mainly occurred in Sichuan basin, its main causing is the bottom water condition in the valley and the surface rainfall amount is caused by storm rainfall, and either one should not be absent. 2 The conceptual model for regional flooding in Southwest China is expressed as the different stream conditions with different interval days and basin precipitation in Cuntan, and also expressed as the different interval days before and after the first regional flooding with different basin precipitation conditions.

• SVM Method and Rain Location Prediction in the Upper Reach of Yangtze River
• FENG Han-zhong;XU Hui-ming;XU Lin-na
• 2004 Vol. 23 (s1): 63-68. 
• Abstract ( ) PDF (529KB) ( )
• On the basis of analyzing the climatic characteristics of area precipitation ineach drainage area in the upper reach of Yangtze River and the relation with the storm rainfall stationsin this region, in according to SVM regression method and using the area precipitation and ECMWF analysis field data, the SVM regression model of area precipitation was established and prediction experiments were made. The experiment results show that SVM regression method can be used in area precipitation forecast. The verification results for system of real-time operational prediction of area precipitation established based on the SVM regression model were given.

• Interdecadal Oscillation of Pacific and Interdecadal Change of Summer Temperature in Yunnan
• QIN Jian;TIAN Yong-li;REN Ju-zhang;WAN Yun-xia
• 2004 Vol. 23 (s1): 69-76. 
• Abstract ( ) PDF (695KB) ( )
• The summer temperature of Yunnan have characters of interdecadal change, and they had been shown by a serial of abnormal high temperature in summer of Yunnan. There is better positive correlation between the decadal variability of summer temperature in Yunnan about 50 years and the index of spring Pacific decadal oscillation, and there is better negative correlation between the location of west-extending ridge of summer west Pacific subtriopical high and the two formers in the same time. The results show that spring Pacific decadal oscillation is an important background of the alteration of summer temperature in Yunnan. When spring Pacific decadal oscillation is in the warm (cold) phase, the sea temperature anomaly of east-and-mid Pacific is positive (negative), the location of west Pacific subtriopical high in summer is westward(eastward), and there is more fair(cloudy and rainy) weather in summer of Yunnan, so it is the period of higher (lower) summer temperature.

• Effects of External Forcing and Initial Condition on Short-Term Climatic Forecast
• FAN Guang-zhou;LI Hong-quan
• 2004 Vol. 23 (s1): 77-79. 
• Abstract ( ) PDF (135KB) ( )
• The short-term climate forecast is very important, but the forecasting result is not famous now. This is mainly for the lack of the theory and method of forecasting the short-term climate change. In this paper, the Lorenz system is used to primarily study the influence of the external force and the initial condition on the short-term climate change. The result shows that the external force strength can obviously affect the long-term action of the climate system. When we forecast the short-term climatic change, we should take different methods according to the external force strength and its duration. If the external force is smaller and the duration is shorter, we could only calculate the initial condition effect; if the external force is great and the duration is long, we could only calculate the external force effect; and if the external force is relative great and the duration is relative long, the initial condition effect can't disappear in a short term. So the external force and initial condition must be all calculated during forecasting short-term climate.

• Surface Air Temperature in China and Its Relation to Arctic Oscillation Index
• WANG Xiao-juan;FANG Zhi-fang
• 2004 Vol. 23 (s1): 80-88. 
• Abstract ( ) PDF (382KB) ( )
• Using the monthly surface mean temperature data at 160 station in 1958_1994, China Meteorological Administration, the interannual and interdecadly changes of air temperature in China in 37 years and its relation to Arctic Ocean oscillation index were analyzed. The obtained results are as follows: 1 since 1958_1994 years, the whole year, autumn and winter temperature in Northeast China obviously rises up, and for winter, the most obvious, the winter temperature in Xinjiang obviously rises up too, the summer temperature in South China obviously rises up. 2 Through the interdecadly change test of temperature in various regions, it is found that the temperature obviously rises up in the whole year, autumn and winter after 1983, and temperature in winter of Xinjiang after 1976, increases too, the temperature in summer of South China after 1976 obviously rise up. (3) on view of the whole nation, climatic warming in the north region of China is more significant than one in the south region of China, specially for winter. (4) There is close relation between Arctic Ocean oscillation(AO) and temperature of Northeast China. When AO index is low, sea level pressure near Icelan in winter is low, region of Siberian high reduce, the winter monsoon in East Asian comparatively weaken, the temperature of Northeast China in winter half year seem to obviously rise up.

• Preliminary Numerical Simulation of Influence of Drought Environment over Northwest China on Global Climate Change
• FAN Guang-zhou;LI Hong-quan;CHEN Fang-li
• 2004 Vol. 23 (s1): 89-96. 
• Abstract ( ) PDF (359KB) ( )
• The Northwest China(NWC) drought region is a part of the middle Asian drought region, it is a important study region of the geography, life and environment sciences. In this paper, 3 experiments as DE (changing the NWC surface type to desert), FE (changing the NWC surface type to cold defoliation broad forest) and CTL (control experiment) are made by using CCM3. By analyzing the balance of the radiation on the top of the atmosphere, the balance of the surface energy, the temperature change, the precipitation change and the CO ₂ fluxes of the vegetation physiological process, the influence of the drought environment over the NWC region on the global change is primarily studied. The results show that if the drought environment is developed or reformed, it could affect the global energy balance process and its spatial distribution, and then it would affect the global and the regional climate and its distribution. These characters are obviously behaved by global temperature and precipitation regional change. The variation of the land surface type of the NWC can also affect the global climate change by the biology-geochemistry feedback process. And this influence might be long-term and more important. By all the analysis, it is known that the formation and evolvement of the drought climate and environment over the NWC are important part of the global change. So the study of the NWC drought region must be bring into the global climate and environment study. And then the influence and response of the drought region on the global change can be general understand.

• Climatic Change of Qinghai-Xizang Plateau Region in Recent 40-year Reanalysis and Surface Observation Data——Contrast of Observational Data and NCEP, ECMWF Surface Air Temperature and Precipitation
• LI Chuan;ZHANG Tin-jun;CHEN Jing
• 2004 Vol. 23 (s1): 97-103. 
• Abstract ( ) PDF (309KB) ( )
• The observation data over Qinghai-Xizang Plateau, NCEP/NCAR reanalysis data, ECMWF reanalysis data were applied to compare and analyze the climate change over Qinghai-Xizang Plateau in recent forty years. It is found that the climatic warming of surface observation data selected in recent forty years is obvious, whereas the reanalysis data over Qinghai-Xizang Plateau show no evidence of obvious climatic warming during this period. The interannual change of ECMWF reanalysis surface precipitation data show that the precipitation over Qinghai-Xizang Plateau haven't obvious wet or dry tendency in recent forty years. But it seems ECMWF reanalysis precipitation data in recent ten years is in a comparably wet period over Qinghai-Xizang Plateau.

• Relationship between Drought/Flood in Ganzi, Sichuan and Circulation Characteristics over Qinghai-Xizang Plateau and Its Surroundings
• NIE Guang-rong;LIU Bin-hua
• 2004 Vol. 23 (s1): 104-108. 
• Abstract ( ) PDF (236KB) ( )
• Using the synoptic meteorology method, the relationship between circulation over Qinghai-Xizang Plateau and its surroundings, drought/flood in Ganzi region, Sichuan are studied. The circulation characteristics of close relation between drought flood in Ganzi are obtained. Further more, the causes of drought/flood in 1994 and 1995 are emphatically studied. The results show that: 1the more meridionality of the circulation on the north side of Qinghai-Xizang Plateau is, the more precipitation in Ganzi have. 2the intensity and location of West Pacific subtropical high, in general the ridge line is at 110°E and west ridge point is at 25°N, it favour for precipitation in Ganzi. 3 the intensity and location of Tibetan high pressure move northward along 35°N to be the favorable for precipitation in Ganzi.

• Analyese on Climatic Factors of Desertification Development in Northern Qinghai-Xizang Plateau
• LUO Lei;PENG Jun
• 2004 Vol. 23 (s1): 109-117. 
• Abstract ( ) PDF (372KB) ( )
• The development of desertification in Qinghai-Xizang Plateau is intensifying in recent years. Climate factors relating to desertification for the last 47 years such as precipitation, wind velocityetc., were studied at five typical desertification sites through spatial autocorrelation analysis methods with focus particularly on their annual temporal distribution patterns and development trend. Further relational analysis was also conducted to find the correlation between desertification trend and the impact of climate factors and human activities. The result shows that the spatial autocorrelation analysis can be effective to explore the causality of temporal distribution of climate features toward environmental problems such as desertification. Various climatic and human factors as well as changeable ground conditions together contributed to the intensified and complicated desertification process in the northern Qinghai-Xizang Plateau, among them it is the ever obvious unevenness of annul precipitation distribution in temporal dimension as shown by the Moran Index that has the most important role to play.

• Climatic Characteristic of Thunderstorm in Shaanxi Province
• CAI Xin-ling;LIU Yu;KANG Lan;HE Hao;LI Jian-ke
• 2004 Vol. 23 (s1): 118-123. 
• Abstract ( ) PDF (266KB) ( )
• Using the data of the thunderstorm days of 78 stations in Shaanxi province from 1961 to 2002 and applying the REOF analysis method, the basic climatic characteristics of thunderstorm in Shaanxi province are analyzed. The main results are as follows: The annual averaged days of thunderstorm in Shaanxi province are 25.3 days. Thunderstorm mainly occurs from June to August, and its seasonal distribution have the single peak characteristics. Analyses indicate that the general trend of the annual mean thunderstorm in Shaanxi have been reducing in the last 42 years.However, the thunderstorm frequencies under different geographical regions are different from each other.

• Velocity Feature of Convective Echo over Yungui Plateau and Its Developing Tendency
• LUO Qing;ZHOU He-sheng
• 2004 Vol. 23 (s1): 124-129. 
• Abstract ( ) PDF (652KB) ( )
• Using the Dopple radar echo data in Yunnan from 2002 to 2003, the velocity feature of convective echo was analyzed. It is found that, through the max-and-min radial velocity in cell echo and its position liying in the echo, a cell is defined to be in convergence and divergence or cyclone and anticyclone ratations, taking it to predict the developing trend of cell echo. The mothed is used to predict the chang trend of cell echo, its accurate rate reached to 82%.

• Research on Radar Monitoring System of Mud-Rock Flow and Landslip on the East Side of Qinghai-Xizang Plateau
• CHEN Dong;YU Shu-hua;JIANG Yu-hua
• 2004 Vol. 23 (s1): 130-133. 
• Abstract ( ) PDF (179KB) ( )
• Mud-rock flow and landslip often happen on the east side of Qinghai-Xizang Plateau, and the severe precipitation is the main cause of the mud-rock flow and landslip events. Because the distribution of surface rainfall station on the east side of Qinghai-Xizang Plateau is only a few and lack of representation, so it is hard to determine the rainfall for any one of region. But the radar can estimate intensity of precipitation in radar scanning region, it is a way to monitoring the disaster areas where mud-rock flow and landslip often happens. The radar system monitoring of mud-rock flow and landslip over the east of Qinghai-Xizang Plateau has been established through the non-uniform handling technique of different radar parameters, the automatic display of positions and informations of the main stations and mud-rock flow and landslip areas, and contrast analysis of radar echo data at present with automatic record informations in database and so on. The system can estimate precipitation and early signs of the disaster from various angles, which changed the earlier way of depending on subjective judgement mostly. The system raise not only the accuracy of the short time forecast, but also the automatic level of forecast way degree. It can work better with other forecast methods to prevent disasters. However, the system has run just a short period, and should be perfected in practical work in the future.

• Division and Prediction of Debris Flow in Mountain Area of Southwest China
• CHEN Ning-sheng;XIE Wang-ying;LI Zhan-lu
• 2004 Vol. 23 (s1): 134-140. 
• Abstract ( ) PDF (294KB) ( )
• The factors which dominates the occurrence of debris flow are different. What we pay attention to in researching and predicting the occurrence of debris flow should not be the same. On the basis of these dominating factors and according to the characteristic in Southwest China, we can divide these areas into four parts, namely precipitation dominating area, earth source dominating area, temperature dominating area and compound factor dominating area. (1) In the precipitation dominating area, the soure of soil is abundant and the function of rainstorm should be mainly considered to predict the debris flow. (2) In the earth source dominating area, precipitation is affluent and the function of accumulated earth amount should be mainly considered to predict the debris flow. (3) In temperature dominating area, glacier debris flows are widely distributed, which are affected by the fluctuating temperature. (4) In the compound factors dominating area, water source and soil source rarely satisfy the debris flow outbreak and the frequency appear low.

• A Method to Identify Water-Body from MODIS Image Data in Upper Reach of Changjiang River
• MIN Wen-bin
• 2004 Vol. 23 (s1): 141-145. 
• Abstract ( ) PDF (877KB) ( )
• The different water bodies and spectral characteristic of main ground objects in channal 1~7 in the upper reach of Changjiang River were analyzed using the moderate resolution imaging spectroradiometer(MODIS) image data. It is found that the mixed water body pixels in being the characteristic of visible spectrum with that of mountain and cloud shades and city have quite similarity. It is not good to identify mixed water-body only using the red and infrared bands. Normalized Difference Water Index (NDWI), Normalized Difference Snow Index (NDSI), and some band methods are used to progressively identify water body and mixed water body pixel.

• Hybrid Stochastic Model Base on Wavelet Analysis and Its Application in Prediction of Runoff Time Series
• WANG Wen-sheng;LI Yue-qing;XIANG Hong-lian
• 2004 Vol. 23 (s1): 146-149. 
• Abstract ( ) PDF (296KB) ( )
• A hybrid stochastic model has been presented. First, the hydrologic time series are resolved into the detail sub-time series with high frequency and outline ones with low frequencyin special scales by using Mallat algorithm. Then, the stochastic model has been constructed for the resolved sub-time series. Finally, the superposition of predicted result is the predicted values of original time series.A case study of annual runoff at Sanmenxia station in the Yellow River is given. The results show that the suggested hybrid model can make full use of the information and the predicted accuracy has higher than the traditional model.

• Analysis on Selecting Intensive Meteorological Observing Station Locations on the East Side of Qinghai-Xizang Plateau
• PENG Jun;MA Zheng-feng
• 2004 Vol. 23 (s1): 150-155. 
• Abstract ( ) PDF (1059KB) ( )
• In order to choose correctly station location and carry out the intensive meteorological observational experiment over the Ganzi, Aba and liangshan prefectures of Sichuan on the east side of Qinghai-Xizang Plateau, the Litang, Hongyuan and Zhaojue were firstly chosen as candidate stations of establishing plateau meteorological observation station for their better representability, scientific significance and feasibility, based on preliminary analysis on the geological characteristics, the distributions of climatic elements, the regional climate change and the impact of weather and climate factors on the sensitive areas.

• Effects of Meteorological Conditions in Western Sichuan Plateau on Rice Qualities
• PENG Guo-zhao;ZHANG Yong
• 2004 Vol. 23 (s1): 156-160. 
• Abstract ( ) PDF (368KB) ( )
• The protein and necessary amino-acid content(NAC) of rice grains are important alimentation components for people. To investigate the effect of meteorological conditions on the rice qualities based on the test data of meteorological conditions in multi-regional experiments with different sowing dates of rice and chemical analyses in laboratory to rice grains, using the orthogonal polynomial integral regression, the changing effect of meteorological factors on the protein and NAC contents of rice are studied in this paper. The result shows that the protein and NAC content are effected greatly by climatic factors and the key period for temperature is from 20 d before tassel to 40 d after tassel, but for the sunshine hours and daily range of temperature is from 30 d before tassel to 40 d after tassel.