Vol.9, NO.4, 1998

Display Method:
Characteristics of Atmospheric Methane Concentration Variation At Mt. Waliguan
Zhou Lingxi, Tang Jie, Wen Yupu, D.Worthy, N.Trivet, Zhang Xiaochun, Ji Jun, Zheng Ming, P.Tans, T.Conway
1998, 9(4): 385-391.
By using gas chromatographic method, in-situ atmospheric CH4 was measured continuously at China Global Atmosphere Watch Baseline Observatory at Mt. Waliguan. Combining with FLASK CH4 data obtained from NOAA/CMDL, the variation features of atmospheric background CH4 concentration in the inland plateau of China are presented. The results show that the CH4 concentration at Mt. Waliguan are in the range of 1780×10- 9 ~ 1840×10- 9, it is in accord with the CH4 distribution in the area of mid and high latitudes. CH4 concentration at Mt. Waliguan has evident diurnal fluctuation, its pattern and amplitude in summer are different from those in winter and spring; there appears no obvious seasonal variation, and it is dissimilar to the feature of seasonal variation and to the geographical distribution of variation amplitude for global atmospheric CH4 background concentration. The results also show that there are distinct interannual variations. CH4 mean annual concentration increases with years and the variations of annual growing rate correspond with the trend of mean variation for atmospheric CH4 in the Northern Hemisphere.
Construction of Mean Annual Temperature Series for the Last One Hundred Years in China
Wang Shaowu, Ye Jinlin, Gong Daoyi, Zhu Jinhong, Yao Tandong
1998, 9(4): 392-401.
Mean annual temperature series from 1880 to 1996 were constructed for ten regions: Northeast, North, East, South, Taiwan, Southcentral, Southwest, Northwest, Xinjiang and Tibet on the basis of temperature observations, documentary data, ice core data and tree-ring data. A series of temperature in China was obtained by average of the ten regional series in considering area size of the region. The temperature series shows more significant warming trend in the last one hundred years (0.44℃/100a), which is much greater than that obtained in 1990 (0.09℃/100a). This is because the new series includes Xinjiang and Tibet regions, where the temperature was quite low in the later of last century and early of this century. Furthermore, the trend was also increased by the rapid warming in 1990s.
Identification About Four Kinds of Cloud Systems in GMS Images Based on Neural Network
Bai Huiqing, Fang Zongyi, Wu Rongzhang, Zheng Junli
1998, 9(4): 402-409.
Based on the theory of neural network, four kinds of cloud systems in GMS images are successfully identified. Comparing neural network with traditional maximum likelihood method, we can draw the conclusion that the neural network is even better for identifying cloud systems. Some problems about neural network itself are also studied, and some experiences for designing neural network are obtained.
Influences of the Snow Cover Anomaly During Winter in Mid-latitude Region of East Asia on the Circulations of Early Summer
Yang Qiuming
1998, 9(4): 410-416.
The influences of the snow cover anomaly during the winter in the mid-latitude region of East Asia on the variations of the dominant low frequency modes with seasons of the Eastern Hemisphere in early summer are studied based on the data from 1973 to 1994, and the differences of the intensity of 30~50 days low frequency oscillation over extratropical Eastern Hemisphere and the summer rainfall over China in snowy and less snowy years are discussed. The interannual variations of winter snow cover at mid-latitude in East Asia appear linear increasing and to have the quasi-biennial oscillation superimposed, and the relationships between its variation and the evolutions of the dominant low frequency modes are linear or nonlinear correlation at the same time. The intensities of low frequency oscillation are stronger for the most regions of Eurasian continents, but weaker in northeastern Asia in snowy years.
Water Consumption and Stochastic Control of Irrigation for Cotton
Zhu Zixi, Zhao Guoqiang, Deng Tianhong, Fang Wensong, Niu Xianzeng
1998, 9(4): 417-424.
Based on experimental data for 5 years, the parabolic relations between cotton yield and water consumption are analysed, and the optimal water consumption for cotton is determined. According to the variations of stoma resistance, transpiration of leaves, abcission of squares and bolls in different soil moistures, the suitable soil moisture and drought indices in different stages of cotton are decided. The stochastic control model of irrigation for cotton could be used to predict dynamically effective soil water content and actual evapotranspiration of cotton and make the decision aiming at obtaining maximum economic benefit and water utilization efficiency
Synthesizing Dynamic Cloud Pictures with Double Time Level GMS/IR Data
Zhang Mingxi, Lin Zhongmin, Zhou Xinyu, Liu Aiming, Yang Hui, Zhu Yingzhen
1998, 9(4): 425-430.
The technical principle and model for synthesizing numerical dynamic cloud picture with double time level GMS/IR data are given. Numerical dynamic cloud picture is a new kind of cloud picture which has the function of displaying both the static and dynamic features of Mesoscale Convective System (MCS) quantitatively, and it is has richer messages than the conventional GMS/IR cloud picture, therefore, it is much more valuable in practice
Influences of Interaction of External Source with Solitary Wave on Blocking
1998, 9(4): 431-440.
A generalized Forcing KdV-Burgers equation including external source and friction dissipation is derived. The analysis shows that the external source with the dissipation would cause variation of mass and energy of solitary wave, and the dissipation would make mass and energy of solitary wave decreased exponentially with time. The numerical results show that the interaction of solitary wave with external source decreases the moving speed of solitary wave, and increases its amplitude. Without dissipation, solitary wave leaves the forcing region of external source quickly, and it is disadvantage for blocking formation, and however, with small dissipation, the interaction would cause solitary wave propagate in the form of oscillation around the forcing region of external source, which would greatly increase the interaction time, and maybe an important mechanism for the formation of regional blocking in the area of external source.
Analysis of the Environmental Conditions for Forming Mesoscale Convective Complexes in Southern North China
Zhu Guanzhong Liu Gongshu
1998, 9(4): 441-448.
According to the diagnostic analysis of MCC on July 30, 1996, the cause for MCC occurring concentrately in southern North China in midsummer was discussed. It is shown that MCC in southern North China was formed in the northwestern margin of the zonality subtropical high controlling over the Huanghe-Huaihe River basin. It was the main mechanism in forming MCC that the southern low-level warm-wet air current was forced to raise over the stationary front which caused the regenerating and combining of mesoscale convective cloud cluster continually. The geographical environment in southern North China, nearby the east of Taihang mountains and by the west of the Yellow Sea and Bohai Sea, was favourable to form the high temperature zone in these areas and the preventing action of Central Shandong Mountains was benefit to form and intensify the surface stationary front. These important local factors caused MCC emerging concentrately in southern North China
Analysis the Cloud Properties Using NOAA/AVHRR Data
Liu Jian, Xu Jianmin, Fang Zongyi
1998, 9(4): 449-455.
The brightness temperature (BT) of NOAA/AVHRR CH3 (3.55~3.93μm), CH4 (10.3~11.3μm) and CH5 (11.5~12.5μm) and their differences between CH3 and CH4 (BTD34) and between CH4 and CH5 (BTD45) can be used to analyze the cloud properties. It is shown that in the case of opaque cloud or cloudless, BTD (BTD34 or BTD45) has a minimum value, in the case of dense cloud, BTD34 would be negative, and while cloud is semitransparent, BTD has bigger value. Moreover, the BTD between channels would be bigger with increasing amplitude of temperature difference scatter diagram between cloud and background surface.
Image-Based Atmospheric Radiation Correction and Reflectance Retrieval Methods
Tian Qingjiu, Zheng Lanfen, Tong Qingxi
1998, 9(4): 456-461.
The image-based atmospheric radiation correction and reflectance retrieval approach were developed using the SPOT HRY data from La Crau radiant calibration site in July 1995. The approach was based on DOS method to calculate the path radiance with the reasonable dark-object reflectance choice. The atmospheric transmittances, the downwelling atmospheric irradiance and atmospheric attenuation were inferred from several atmospheric radiative transfer codes (Lowtran-7, Modtran-3, 6S) with simulated atmosphere. At last the approach was evaluated by comparing surface reflectances measured from La Crau site with that derived from SPOT data
Preliminary Study on the Suppression Effect of EM on Methane Emissions in Paddy Fields
Miao Manqian, Zhu Chaoqun, Mo Tianlin, Wang Yuelian, Teruo Higo
1998, 9(4): 462-469.
This paper mainly discusses the experimental results of the suppression effect on methane gas (CH4) released from the paddy field by the Effective Microorganism (EM), and the results show that the suppression effect was more remarkable, averagely more than 59% being decreased in the first year. Moreover, the frequency of negative flux which represents the paddy field as the sink to absorb CH4 from atmosphere increased. It may result from the action of photosynthetic bacteria contained in EM. Furthermore, the experiment revealed that the EM could get a raise in yield of crop without chemical fertilizer.
Analysis for Remote Sensing of Atmospheric Precipitable Water Using Ground-based GPS Receiver
Li Chengcai Mao Jietai
1998, 9(4): 470-477.
The general scheme of remote sensing of atmospheric precipitable water (PW) using ground-based GPS receiver is reviewed. The errors caused by different factors and the corresponding ways to avoid or reduce errors elaborated, and then the stepping of estimating water vapor from zenith wet delay is summarized. The GPS/STORM experiment and two methods to resolve PW are recommended. Finally, a set of solution to experiment and research is provided, and the problems on operational application in China are discussed
Characteristics of Turbulent Diffusion in Atmospheric Boundary Layer over Different Underlying Surfaces
Zhao Zhiqiang, Xu Yumao, Li Zongkai, Zheng Naiting
1998, 9(4): 478-484.
Based on the turbulent observational data of four kinds of different underlying surfaces including sea, gobi, suburb and city areas, some characteristics for turbulent velocity spectra and diffusion parameter are analysed by using the multi-scale turbulence theory and method. The results show that the roughness of underlying surface has great influence on the turbulence characteristics of atmospheric boundary layer, with the increasing of roughness the peak frequency of velocity spectra would shift to high frequency area, and diffusion parameter would increase.
Vicarious Radiometric Calibration of the Remote Sensing Data from Airborne Moderate Resolution Imaging Spectrometer
Zhang Yuxiang, Zhang Guangshun, Qiu Kangmu, Wang Zhiqiang, Zhang Lijun
1998, 9(4): 485-491.
Based on reflectance method, vicarious radiometric calibration of remote sensing data from Airborne Moderate Resolution Imaging Spectrometer (AMODIS) is described. The results show that the calibration coefficients at two flying altitudes from 17 channels of visible and near infrared region were, respectively, in coincidence, and the relative difference was between 0.19% and 3.89%. Also the retrieval values from AMODIS in the model flying experiment were coincided with the observations of surface synoptic station
Relationship Between Torrential Rain and Drought/Flood over Beijing Area
Wu Zhenghua Chu Suolong
1998, 9(4): 492-495.
The relationship between torrential rain and drought/flood of flood period is analysed based on the daily rainfall data of last 100 years in Beijing. It is shown that the frequency and intensity of torrential rain are important for the amount of precipitation in flood period (June ~ August). In three kinds of torrential rain indexes, the number of equivalent torrential rain day has best correlation with drought/flood grade. It is discussed on the necessity that short-range climatic prediction of drought/flood should combine with short-range climatic prediction of torrential rain process.
Monitoring Drought in Qinghai Pastoral Areas Using NOAA/AVHRR Data
Zhou Yongmei
1998, 9(4): 496-500.
The principle of remote sensing of the drought in Qinghai pastoral areas is described, and a method of determining drought region and drought grade is advanced using anomaly vegetation index and drought index. By using this method the drought of Qinghai pastoral areas in 1995 was evaluated which coincided with the drought analysis made from meteorological dekad information.
Operational Environment for NWP Product on Heterogeneous Platform
Tian Hao Zhang Jianchun
1998, 9(4): 501-507.
The problems and technique methods of solving them during setting up a production operational environment for NWP product on heterogeneous CRAY/VAX computing platform are described and some problems still existing in the present production operational environment are pointed out.
Drought/Flood Monitoring and Graphic System
Zhang Qiang, Zhuang Lili, Wang Youmin, Wu Hong, He Sulan
1998, 9(4): 508-511.
Based on the platform of windows the drought/flood monitoring and graphic system is programmed with the languages of Borland C and Foxpro. All functions are controlled by pull-down and pop-up Chinese menu, and the operational interface is friendly. The software structure of the system is flexible and reasonable. The historical database including dekad to dekad precipitation, temperature and drought/flood grade is set up. The system has the functions of collecting and retrieving drought/flood information, and tabling and analyzing graphics. The system assumes the function of real-time and effective monitoring the occurrence and development of drought/flood, and could provide a scientific basis for the government to make decision and measures of preventing drought/flood disasters.