Vol.9, NO.2, 1998

Display Method:
A Method of Calculating Surface Moisture from GMS and AHHRR
1998, 9(2): 197-204.
The change of soil surface temperature with time from GMS infrared channels is the most sensitive to soil moisture and has negative correlation with vegetation index from polar orbiting satellite, so that a Drought Condition Index (DCI) with six classifications to estimate surface moisture is put up. The correlation coefficients between DCI and the observed soil moisture or precipitation classification in Jiangsu and Jilin Provinces are more than 0.7.
The Role of Upstream Equatorial Westerly Wind in the Summer Monsoon Onset over the South China Sea
Xie An
1998, 9(2): 129-140.
Interannual variation of summer monsoon onset over the South China Sea (SCS) were studied based on the seventeen years (1979~1995) NMC global analysis data and Outgoing Longwave Radiation (OLR) data observed from NOAA polar-orbit satellites. Based on the criteria defind in this paper for the SCS summer monsoon onset, the average onset date from 1979 to 1995 was around the fourth pentad of May. During the SCS monsoon onset, the most direct impact from the vicinity of the SCS is the equatorial westerly winds in the Indian ocean through their eastward extension and northward movement. Meanwhile, there are also indirect impact of the enhancement of the Somali cross-equatorial flow and the vanishing of the Ariabian high at sea, which change the equatorial westerly winds, in the SCS onset. There are quite significant interannual variation in the SCS onset. It is shown that the impact of the equatorial westerly winds in the Indian ocean on the SCS summer monsoon onset and its interannual variation is very important. It has also been found that the interannual variation of the SCS onset are closely related with the ENSO events.
Researches on the Influence of Parameterization of Physical Process on Modeling Typhoon and Its Dynamical Structure
Liu Huanzhu, Chen Dehui, Teng Qiaobin
1998, 9(2): 141-150.
The numerical experiments and their diagnostic analyses of the NMC’s typhoon track numerical prediction model, with different parameterization scheme of physical processes were presented. The numerical experiments on Janis (1992) and Herb (1996) typhoons showed that tracks and their landfall locations could be well simulated by this model. Moreover, by using the model with the improved parameterization scheme of physical processes, the thermal regime on high and low level nearby the typhoon center could be better described than that in the original one. Meanwhile, the results from the diagnostic analyses of both the real and simulated typhoon exhibited that the absolute value of first term of MPV1 at 500 or 700 hPa was well related to the intensity of the typhoon. Moreover, the location of the pressure energy and the ascending motion center could indicate the direction of the typhoon’s movement in the next 6~12 hours. Furthermore, results from analyzing 3D thermodynamic structure and the wind field across the typhoon centre showed that the process of strong ascending motion→condensing of warm and moist air→releasing of latent heat→increasing of the temperature→divergence at the high level→dropping of surface pressure→stronger convergence at low level→ascending motion may be a positive feedback mechanisim which caused the typhoon moving forwards to the strong convergence ascending motion area.
Numerical Simulation Study on the Potential Impact of Climate Change on Double Cropping of Rice in the South of Yangtze River Valley of China
Qiu Guowang Wang Futang
1998, 9(2): 151-159.
Based on the validation of dynamic growth simulation model for double-rice through field experimental data, and jointing the climatic change scenarios derived from GCMs outputs and historical climatic data (1960~1990) with double cropping of rice model, objective impact assessment and quantitative simulation experiments on grid points are carried out in the main double-rice areas of the south of Yangtze river valley. Moreover, the effect of a grotechnical adjustment (such as, changes of sowing date and cultivars) on alleviating the impact of climate change are preliminarily estimated and discussed. The results indicate that in the future climatic change scenarios, and under the current planting varieties and agrotechniques, the output of double-harvest rice would be reduced to a different extent. The spatial distributions of yield variation have not only some regularity, but also obvious complexity. Adjustable countermeasure analyses show that the used varieties with long growth duration could increase double-rice yield. Apart from the mentioned above, the sensitivity test with changes of sowing date is also conducted.
A Study of Radiative Features at the Great Wall and Zhongshan Stations of Antarctica
Bian Lingen, Lu Longhua, Lu Changgui, Xue Zhengfu, Jia Penqun, Wang Yong
1998, 9(2): 160-168.
The radiative components in 1993~1994 at the Great Wall Station (GWS) and Zhongshan Station (ZSS), Antractica are analysed. The results show that the features of seasonal changes of radiation in GWS are almost similar to those in ZSS. Global and surface absorbed radiations in GWS are 51% and 42% of those in ZSS, respectively, because of the difference of climate conditions between the two stations. During the polar days (Nov.~Jan.), the total amounts of global and ultraviolet radiations are greater than those in summer (Jun.~Aug.) for the Qinghai-Xizang Plateau. The positive net radiation in summer half year and negtive in winter half year in the two stations illustrate the climatic features of radiation in the Antarctic oasis area
A New Index for ENSO Monitoring
Guo Yanjun, Zhai Panmao, Ni Yunqi
1998, 9(2): 169-177.
Based on monthly mean SST and OLR data during 1982~1996 and by applying Singular Value Decomposition (SVD) technique and correlation analysis, a new index for ENSO monitoring system is studied. The results show that tropical Pacific SST and OLR fields are significantly correlated. The first models of these two fields derived from SVD clearly indicate ENSO signals. According to the analyses of the structure of OLR anomaly fields in the mature phases of both E1 and La , and the spatial correlation between NINO3 index and the tropical Pacific OLR field, this paper reveals that the pattern of the opposite centers like dipole over the tropical Pacific in OLR field is quite similar to the structure over the equatorial Pacific for the first modes of both OLR and SST. A Convective activities Oscillation Index (COI) is thus derived for the opposite variation striation of OLR between the eastern-central Pacific and the western Pacific. Further analyses have confirmed that COI is a sensitive index to reflect ENSO signal. The correlation between COI and NINO 3 index is higher than the other indices (including SOI) used in operational ENSO monitoring system worldwide
Assessment Methods of Short Range Climate Prediction and Their Operational Application
Chen Guiying Zhao Zhenguo
1998, 9(2): 178-185.
Based on the current situation of shortrange climate prediction, some parameters for assessment of forecast effectiveness are proposed. Using these parameters, the forecast results of anomalous percentage of precipitation and anomaly of mean temperature for monthly, seasonal and interannual scales during the last 20 years in NCC are evaluated. It is shown that the forecasts of temperature is better than those of precipitation for monthly scale, the forecasts of precipitation are better in spring than those in winter and summer for interannual scale, and the forecasts of precipitation for rainy season have a remarkable improvement.
Analysis and Application of GMS-5 Water Vapor Images (I)
Li Dashan, Shi Dingpu, Zheng Xinjiang, Lin Song, Li Chengcai, Fan Ling, Zhao Youhong
1998, 9(2): 186-196.
Experiments and detections of rain enhancement over a long period show that water vapor condition is an important and basic requirement for weather modification. An initiative analysis for three torrential rain processes of Heilongjiang Province in July of 1995, based on the water vapor images of GMS-5 with 6.7 μm channel which were offered recently and combined with the conventional weather data and satellite cloud picture etc, was made. It is shown that the three processes corresponded with three different types, respectively. A synthetical study of the continuous torrential rain process with an obvious water vapor band during 25~30, July was made. The water vapor images provided a clear and object imagery for the water vapor transfer band in warm area during the developing stage of this typical cyclone, therefore, the data for width and length of water vapor transfer band were obtained and the structures of temperature and humidity were analysed. The precipitation efficiency in the warm front was also estimated. Furthermore, the cloud physical characteristics of the precipitation process and the conditions for rain enhancement were analysed. So, the possibility of application of water vapor images in weather modification would be provided
Regional Characteristics of Drought Anomalies in North China
Wei Fengying Cao Hongxing
1998, 9(2): 205-212.
Drought indices of spring and summer for 24 stations in North China were defined by using the monthly precipitation and temperature data during 1951~1996, considering soil moisture and evaporation. The analysis of drought indices for the whole region and individual stations showed that the indices can display drought anomolies objectively. By using rotated empirical orthogonal function analysis, based on the principle of maximum variance, three regional patterns of spring drought and four regional patterns of summer drought were divided. Furthermore, the meteorological meaning of the maximum centers for the various spatial rotated modes was also discussed.
Research on Adjusting Effect for Different Mathematical Model of Precipitation Series
Song Chaohui
1998, 9(2): 213-218.
Based on the model of successive multiple linear regression, one-variate linear regression, ratio value method and aggregate method the analyses and tests of precipitation series correction are carried out by using the data observed at thirty-one stations in twenty-five Provinces of China. The results show that: the correction effect of multiple linear regression method for annual precipitation data series is better than those of other methods, the average relative fitting error is less than 0.08, and the other is more than 0.11 for monthly data series; if the relative fitting error is less than 0.10, the time of paralled data requested in the equation should be longer than 10 years, the correlation coefficient above 0.05; if the precipitation is above 300mm, the error is less than 0.10 and if below 300 mm, the error is more than 0.11
A Study on Memory Feature of Self-memorial Prediction Model
Feng Guolin
1998, 9(2): 219-224.
Theoretical investigation into memorization in a self-memorial model, which is formulated with a truncation equation of finite-amplitude baroclinic wave, is conducted. A corresponding self-memorization equation is derived. An analytical solution of the equation is obtained under conditions of giving memory function as both linear and decay exponential types, meanwhile, the physical meaning and prediction implication of the solution are discussed. It is proved that the zero-order self-memorization equation is irrelevant to a memory function formulation. By calculating a forget factor, some issues on dynamical predictability and retrospective order etc are studied too, and it is pointed out that these issues can be united to a framework of atmospheric memory theory.
A Possible Impact of Climate Change on Environment and Economy of Tibetan Region
Miao Qilong, Xiang Yuyi, Gu Xianyue
1998, 9(2): 225-230.
Based on the fourty years meteorological data in the region of Yarlung Zangbo Jiang river, Lhasa He river and Nianchu He river of Tibet, climate change of this region is analysed. It is shown that there is the trend of temperature raising and precipitation decreasing. The impacts of future climate change on agriculture, livestock husbandry, water resources and ecological environment are analysed. It is suggested that possible policy and measures should be taken for adapting to the climate change
The Methods of Agricultural Natural Risk Evaluation and Regional Insurance Premium Calculation
Guo Yingchun, Yan Yiling, Wang Wei, Wang Chunyi
1998, 9(2): 231-238.
According to the spatial-temporal distribution regulation of agricultural natural disaster, the grade of disaster and degree of loss are calculated for different regions, crops in the growth seasons. The method to calculate the proportion of crop damage derived from agricultural natural disaster, and regional insurance cost combined with forming division are put forward in the paper. These methods and results can be used as a reference for similar research and operation in other regions
A Review of ENSO Dynamics and Its Numerical Simulation
Ni Yunqi, Shen Xinyong, Yang Xiuqun
1998, 9(2): 239-245.
The present paper has comprehensively reviewed the advances in observations of E1 Nino/Southern Oscillation (ENSO) phenomenon and in dynamics and numerical simulation of the tropical air-sea interaction. Some major scientific problems which need to be emphasized and solved are put forward here.
Analysis of GMS-5 Water Vapor Images During Torrential Rain of Meiyu in June 1995
Zheng Xinjiang, Li Yulan, Du Changxuan
1998, 9(2): 246-250.
The characteristics of water vapor images of torrential rain during the period of Meiyu from middle June to early July of 1995 are analysed by using GMS-5 water vapor images and conventional data. The relationship between water vapor plumes and severe rainfall events is given and the conceptual model of water vapor images of torrential rain during the period of Meiyu is summarized.
Feasibility Research on Estimating Global Paddy Yield Using Remote Sensing
Yang Xingwei, Zhou Hongmei, Li Jun, Wang Zhilan, Wang Changyao, Niu Zheng
1998, 9(2): 251-256.
Utilizing the relationship between the global NOAA data and paddy yield data during the period of 1985~1990, an estimating yield model was obtained. These models were applied to estimate paddy outputs in U. S. A. , Thailand and Viet Nam. The results are satisfactory. Furthermore, the global paddy yield during the period of 1979~1994 was simulated by using the statistical method, the fitting accuracy can reach above 98%.