Vol.14, NO.4, 2003

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REMOTE SENSING OF TOTAL COLUMN PERCEPTIBLE WATER VAPOR WITH TWO SUN REFLECTANCE CHANNELS OF FY-1C SATELLITE
Zhang Gong, Xu Jianmin, Huang Yibin
2003, 14(4): 385-394.
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Abstract:
Remote sensing of the total column perceptible water vapor with the imaging spectrometer on the FY-1C polar orbiting satellite is realized based on the algorithm suggested by R. Frouin et al. (1990). With the two sun reflectance channels (a water absorption channel and a window channel), the total column perceptible water vapor is derived. The water absorption channel is at the wavelength of 0.90 to 0.965μm, and the window channel at 0.84 to 0.89μm. The basic formula used is: In the formula, r, the ratio of observation values between the water absorption channel and the window channel, is known. At the locations around radiosonde stations, the total water vapor amount along the observation path is also known. Coefficients A and B can be derived by means of the statistic method. At other locations far from radio sonde stations, m is calculated with coefficients A and B. Factors affecting A are the atmospheric profiles of temperature, pressure and humidity and the channel response function of the imaging spectrometer. The factor affecting B is the surface reflectance. These factors are time-and location-related. Statistic calculation is performed respectively at different time periods and locations. The possible errors that otherwise may be introduced from the incorrect navigation of the images are limited by the quality control measure. Reality examination with independent radiosonde samples shows that the bias is about 15% to 20%, and the correlation coeffecient is above 90%.
TRANSFER OF METEOROLOGICAL SATELLITE DATA THROUGH NETWORK PROGRAMMING
Zhao Licheng, Guan Tong
2003, 14(4): 395-401.
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Abstract:
The meteorological satellite application system is a heterogeneous distributed system consisting of multi-functional subsystems such as data ingesting, transferring, processing and archiving. Using network programming to transmit data amongst subsystems can reduce transferring time and improve processing efficiency, so that the products can be delivered to users in time.
BACKGROUND CONCENTRATION OF ATMOSPHERIC CO2, CH4 AND N2O AT MT.WALIGUAN AND XINGLONG IN CHINA
Cheng Hongbing, Wang Mulin, Wen Yupu, Wang Gengchen
2003, 14(4): 402-409.
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Abstract:
In order to study the characteristics of regional distribution and variation of greenhouse gases, including CO2, CH4 and N2O on the China continent and their relationships with human activities, the variations of atmospheric concentrations of CO2, CH4 and N2O were measured at China Atmosphere Watch Baseline Observatory at Mt. Waliguan (36°18′N, 100°54′E, 3810 m) and at Astronomical Observatory at Xinglong (40°24′N, 117°30′E, 940 m) during the period of 1995 to 2000 with stainless steel sampling canisters by means of the gas chromatographic method. The results show that the average atmospheric concentrations of CO2, CH4 and N2O at both Xinglong and Mt. Waliguan are 376.7×10-6 and 373.5×10-6, 1886×10-9 and 1831×10-9, 316.7×10-9 and 314.9×10-9, respectively. From 1995 to 2000, the average annual increments of CO2, CH4 and N2O at Xinglong are 1.95×10-6 mol/mol, 9.02×10-9 mol/mol, and 0.75×10-9 mol/mol, respectively. The average annual increments of CO2, CH4 and N2O at Mt. Waliguan are 1.41×10-6 mol/mol, 9.95×10-9 mol/mol and 0.82×10-9 mol/mol respectively. The atmospheric concentrations of CO2, CH4 and N2O and the average annual growth rates are closed to the monitoring results from the similar global observatories. On the other hand, the results reveal the difference of the environmental background between Xinglong and Mt. Waliguan to some extent.
AN ALGORITHMFOR LOAD BALANCING IN A HETEROGENEOUS SYSTEM
Jin Zhiyan, Wang Dingxing
2003, 14(4): 410-418.
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Abstract:
Load balancing is a crucial problem in a heterogeneous system such as PC or workstation clusters, which has been widely used in the research and development of numerical weather prediction. A load balancing algorithm, based on feedback, is presented to eliminate the influence of uncertainty of processor speed, which is difficult to measure precisely. The influences of variation of processor speed, load distribution, errors of tested processor speed, etc., have been calculated. The results show that this method is quite robust. The diffusion equation and the simulated physical processes are used to test the algorithm, which shows that it is feasible and can balance the load quite weill.
RESEARCH ON OBJECTIVE FORECAST MODEL OF REGIONAL HEAVY RAINFALL IN FUJIAN PROVINCE DURING PRECEDING FLOOD SEASON
Liu Aiming, Pan Ning, Zou Yan, Zhang Mingxi
2003, 14(4): 419-429.
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Abstract:
By means of sliding-window Chebyshev expansion, a series of expansion coefficients and time variables of the polynomial is obtained. Through correlation analysis, a set of forecast factors and elimination factors with clear physics meaning and good correlativity is derived. Based on the multi-form combination of predictors, a forecast model of regional heavy rainfall during the preceding flood season in Fujian Province is developed. The results are as follows: it is rational and feasible to construct a forecasting model of regional heavy rainfall during the preceding rainy season in Fujian Province with Chebyshev expansion coefficients of the height field; the independent field factors can be quantificationally derived from the features contained in the element field through Chebyshev orthogonal polynomials; by using the Chebyshev expansion technique with sliding windows, the multi-scale characteristics may be obtained as a result of making the utmost use of the field information, thus to gain more comprehensive knowledge of predictands.
STEPWISE DISCRIMINATION ANALYSIS OF POTENTIAL AREAS FOR RAIN ENHANCEMENT IN STRATIFORM CLOUDS IN NORTH CHINA
Li Yongzhen, Li Maolun, Li Wei, Cui Lian, Chen Zhixin, Wang Zhongfan, Li Lan
2003, 14(4): 430-436.
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Abstract:

By means of the data of the 701 windfinding radar at Stations 07:00 and 19:00 of Changchun Meteorological Office and the 713 digital radar from Meteorological Bureau of Jilin Province in the past nine years, the potential areas of rain enhancement are classified into two categories: Class I (larger) and Class II (smaller), according to the data from cross-cloud observation. Two groups of discrimination functions S1, S2, are given, which include four meteorological factors obtained by using stepwise discrimination analysis method: 500 hPa south wind component, height of echo top, (negative temperature layer echo depth)/ (positive temperature layer echo depth) and (height of 0oC layer)/(height of echo top). Then, by using Microsoft VB6.0, Jinlin Province is divided into nine seeding operation areas according to radar echo parameters and 500 hPa wind from the near-time radiosonde observation; the automatic decoding and the rain enhancement potential calculation and automatic display for pre-seeding and stratifrom clouds are conducted.
ASYMMETRIC CHANGE OF MAXIMUN AND MINIMUM TEMPERATURE IN TIBETAN PLATEAU FROM 1971 TO 2000
Du Jun
2003, 14(4): 437-444.
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Abstract:
Monthly mean maximum (Tmax), minimum temperature (Tmin) and daily temperature differences (△T) at 25 stations over Tibet from 1971 to 2000 are used to analyze the asymmetric change of maximum and minimum temperature in the Tibetan Plateau. The results show: The asymmetry is detectable in the whole Tibetan Plateau, and the typical pattern of asymmetry is he increase of Tmax and Tmin (Tmin increase is bigger then that of Tmax), the increase of Tmax occurs mainly in summer and that of Tmin in autumn and △T decrease because of obviously increasing Tmin, In additon, Tmin increases with increasing altitude; increase is the strongest in the region of 3000 to 4000 m, and △T tends to decrease over 4000 m.
ANALYSIS OF CHARACTERISTICS OF SUMMER MONSOON AND HEAVY RAINFALLOVER SOUTH CHINA IN 2001
Ma Lan, Wu Xiaojing, Jiang Jixi, Zhang Qisong, Li Xiaolong
2003, 14(4): 445-451.
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Abstract:
The diagnoses and analyses of Asia summer monsoon in 2001 are made by means of Black-body temperature (TBB) from Japanese GMS. It is concluded that there are three summer monsoon onsets over the Indochina Peninsula and the South China Sea, and the intensities are stronger than those in the same period of history. The results reveal the characteristics of monsoon onsets and lulls in the three monsoon regions (India-Bengal Bay, Indochina Peninsula, and South China Sea). Analysis is also made on the influence of monsoon on the three heavy rains (from the beginning of June to the middle June, the end of June to the beginning of July, and the end of August respectively) in the South China and the middle and lower reaches of the Changjiang River. The result shows: it is the essential condition of large-area and long-time heavy rainfall over the Southeast China that the monsoon onsets combine with the cool air from the North. According some important clues are provided to make forecast of heavy rainfall in the region.
STRATEGY FOR DESIGNING A NON-HYDROSTATIC MULTI-SCALE COMMUNITY MODEL DYNAMIC CORE
Chen Dehui, Yang Xuesheng, Zhang Hongliang, Hu Jianglin
2003, 14(4): 452-461.
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Abstract:
The strategy for designing a non-hydrostatic multi-scale community model dynamic core is proposed, based on the advances of the numerical weather prediction model and new techniques of radar and satellite observations, etc. There are two approaches in developing community models at present: one is that both global and regional models share a common temporal, spatial discretization approach and codes; the other is to use a single global variable resolution model that can be reconfigured according to applications. Attention is then focused on various desing issues, including the strategy for designing community models, the choice of model equations, the construction of model grid properties, the temporal and spatial discretization, the selection of the vertical coordinate, etc.
A WCSODS-BASED MODEL FOR SIMULATINGWET DAMAGE FOR WINTER WHEAT IN THE MIDDLE AND LOWER REACHES OF THE YANGTSE RIVER
Shi Chunlin, Jin Zhiqing
2003, 14(4): 462-468.
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Abstract:
The correction models of the effect of excess soil water on photosynthetic production, partition of dry matter and green leaf senescence are introduced into the WCSODS to simulate the impacts of soil waterlogging on wheat growth. The modules are validated with experimental data and regional statistical yields, and the results show that the simulated errors are less than 10%. The sensitivity analysis also shows that the wet damage to yield increases gradually with the increasing waterlogging duration. Ten-day waterlogging has little effect on yields, but when the waterlogging duration reaches 30 days, yields reduce 7% to 32%. For the same waterlogging duration, the injury at the booting stage is the greatest, less at filling stage and elongation stage, and the least at tillering stage. These results are in accordance with the opinions of local wheat experts. The early warning of wet damage is also conducted and tested by using the model and the daily meteorological and yield data, and the results are reasonable.
APPLICATION OF THE LEAF PHOTOSYNTHESIS MODEL FOR FORECASTING EFFECT OF DROUGHTON WINTER WHEAT IN NORTH CHINA PLAIN
Liu Jiandong, Wang Futang, Yu Qiang, Mao Fei, Bi Jianjie, Fan Guanghua
2003, 14(4): 469-478.
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Abstract:
The North China Plain is one of the most important food crop production regions in China, and the winter wheat is frequently influenced by droughts during its growth periods. In order to give the accurate drought information, a water stress experiment was made during the jointing stage of winter wheat in the Shandong Agricultural University. The photosynthesis change due to water stress was measured systematically, and a number of agrometeorological indexes responding to the water stress were determined. A combined model is established for simulating leaf photosynthesis based on the data observed with Licor-6400, which includes environmental factors such as CO2 concentration, solar radiation, temperature and soil humidity. Validation of the model shows that it can simulate photosynthetic rate fairly well, and the coefficient of correlation can reach 0.98 with 99 samples. A great deal of observed data is given, which provides basic parameters for establishing the agrometeorological model so to forecast the effect of drought on winter in North China Plain.
DYNAMIC FORECASTINGMODELS OF SOIL MOISTURE IN WINTER WHEAT AND SOYBEAN FIELDS IN SHALLOW GROUNDWATER LEVEL
Mao Fei, Zhang Jiahua, Lu Zhiguang, Jin Zhiqing
2003, 14(4): 479-486.
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Abstract:
The calculating model of phreatic water evaporation in the Jianghuai region is given by means of statistic and water balance methods. According to the water balance principles of crop fields, the dynamic forecasting models of soil moisture in winter wheat and soybean fields with phreatic water evaporation and without phreatic water evaporation are built. The forecasting accuracy of the two models in a condition of shallow groundwater level is compared. The results in 1980 show that the mean absolute errors and mean relative errors of the former for seven periods of two crops are 8.2 mm and 2.8% and the mean absolute errors and mean relative errors of the latter for seven periods of two crops are 20.1 mm and 6.8%. The forecasting accuracy of the dynamic forecasting models of soil moisture in winter wheat and soybean fields including phreatic water evaporation is improved notably.
RESEARCH ON REAL-TIME COLD-DISASTER WATCHING AND PREDICTION IN GUANGDONG PROVINCE BASED ON GIS TECHNOLOGY
Wang Chunlin, Liu Jinluan, Zhou Guoyi, Du Yaodong
2003, 14(4): 487-495.
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Abstract:
Based on GIS techniques and a climatology model using several types of geographic data such as land-use information, longitude, latitude, altitude, slope grade and direction, etc., cold-disaster data are corrected according to specific geographic details. Considering growing conditions and cold-index of winter economic fruit trees, a method is presented, by which when the cold-disaster occurs, its developing condition, intensity and area can be watched and predicted in real time and dynamically. The key techniques and conclusions are: (1) The cold disaster index is defined based on two factors (temperature dropping range and extreme lower temperature during the course) to offset the disadvantage of the conventional operation system. (2) Based on the output of Numerical Forecast Model T213 (developed in China) and the MOS (Model Output Statistics) forecast equation, cold disaster forecast for 86 ground meteorological stations in Guangdong Province is made. (3) The geographical correction model considering slope grade and slope and slope direction information together with three general factors (longitude, latitude and altitude) is adopted and get a good result.
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