Vol.10, NO.1, 1999

Display Method:
Analysis of the Particle Sizes at Top of Cloud and Fog with Noaa/avhrr Data
Liu Jian Xu Jianmin Fang Zongyi
1999, 10(1): 28-33.
The particle size distributions of cloud and fog are analysed by using the reflected sunlight data from NOAA/AVHRR CH3 (3.55—3.93μm). Compared analysed results with ground observations, it is shown that the area with larger cloud particles at the top of cloud is related to precipitation area, and the area of fog cover is coincided with smaller cloud particles.
Monitoring the Distribution Characteristics of Liquid and Vapour Water Content in the Atmosphere Using Ground-based Remote Sensing
Duan Ying Wu Zhihui
1999, 10(1): 34-40.
Based on the observational data from a newgeneration ground-based microwave radiometer with double channels and coantenna developed by Peking University, the distribution characteristics of integral liquid and vapour water content in the atmosphere are analyzed on the conditions of clear air cloud without rain during April to June from 1992 to 1994 in Shijiazhuang of Hebei Province. The results indicate that the liquid water makes up one percent of the total water content in the atmosphere without rain, the liquid water resources in clouds for artificial precipitation are only little part of the total. Therefore, the analysis shows that the conventional method of using water vapour content in the atmosphere to estimate cloud water resources is very overstatement.
Diagnosis of “96.8” Torrential Rain with the Scale-seperation Kinetic Energy Equation
Yu Yubin Yao Xiuping
1999, 10(1): 49-58.
Using the scale seperation kinetic energy equation, the generations and transformations of kinetic energy during the torrential rain process of North China in August 1996 are calculated. The results show that during the developing process of “96.8” torrential rain, the kinetic energy was gradually decreased, and so was the kinetic energy transformation. Before the torrential rain, GKMS played the most important role, and GKS the second, whereas GKM dissipated a few energy. During the torrential rain, GKMS produced the energy, but less than before apparently, GKM also produced energy, the energy conversions mainly came from low level. After the torrential rain, the producers of the kinetic energy were still greater than zero, at that time GKS was the most important one and the amount was less than the first two periods, and the conversions appeared over upper level. It is shown that during the torrential rain process the total producers of kinetic energy were always positive, they mainly appeared over high level, but the amount of kinetic energy was decreased gradually. The conversion of kinetic energy was from low level to high level, the horizontal term played the main role, and it was an energy transformation process of scale reduction.
A Loss Estimation Method for Agrometeorological Disasters and Its Application in Yield Prediction
Gong Deji
1999, 10(1): 66-71.
Based on the expected yield without meteorological damages, a loss estimation method for agrometeorological disasters was introduced. The determinations of expected yield and its reduction by disasters were also discussed. By analysing the relationship between the yield reduction and several factors including intensity of disasters, influenced area and crop sensitivity to disasters, a constructure-based statistical model to estimate the yield reduction by damages was established.
The Relationship Between General Circulation of the Southern Hemisphere and the Medium-range Activities of West Pacific Subtropical High and Typhoon Group
Zhang Yuanzhen
1999, 10(1): 80-87.
It is found that the close relationships are present between westerly index in middle and low latitudes of the Southern Hemisphere, pressure index of equator and the medium-range activities of West Pacific subtropical high and typhoon group in summer (from May to August) of the Northern Hemisphere by analyzing the data of general circulation of the Southern and Northern Hemispheres for six years. In the active years of typhoon group the variation of general circulation begins at middle latitudes of the Southern Hemisphere, and then at low latitudes of the Southern Hemisphere and equator, the pressure index of equator reaches low value. After that, a series of variations of West Pacific subtropical high over the Northern Hemisphere would appear. The transportation period of the variations mentioned above would be quasi-two weeks.
Impact of the Intensive Observational Data from the Typhoon Experiments on NWP
Zhu Zongshen Ma Qingyun Hao Min Tao Shiwei
1999, 10(1): 106-111.
Based on the basic schemes of the High-resolution Limited-area Assimilation Forecast System (HLAFS) and North China Analysis and Forecast System (NCAFS) developed by National Meteorological Center (NMC), the experiments of Numerical Weather Prediction (NMP) for the cases of typhoons No. 9216 and No. 9406 are made using the intensive observational data of these periods. The experimental results show that the intensive observational data of ground stations could make great improvement for the forecast of NWP system of NWC, especially in the case of high resolution.
Application of GIS to the Evaluation of Vegetable Production Resources and Its Rational Arrangement in Shanghai
Tan Jianguo Lu Xian Yang Xingwei
1999, 10(1): 112-117.
GIS software ARC/INFO is used for synthetical evaluation of the vegetable production resources including climate, soil, fields location, disasterbearing capacity, production technique and water pollution in the suburbs of Shanghai, and the regions for better developing the vegetable production have been selected. Furthermore, the effective referential information has been given in the planning, movement of vegetable base and vegetable production.
Technical Characteristics of NWP Data Archiving Operational System of National Meteorological Center
Wang Xianglan
1999, 10(1): 123-128.
The technical characteristics of NWP data achiving operational system of NWC are described briefly, and a series of technical problems for the software development are studied.
Sudden and Periodic Changes of East Asian Winter Monsoon in the Past Century
Xu Jianjun, Zhu Qiangen, Zhou Tiehan
1999, 10(1): 1-8.
Based on mean sea level pressure (MSLP) data, the East Asian winter monsoon intensity indexes were calculated from 1873 to 1990. The sudden and periodic changes of East Asian winter monsoon were studied by the method of sliding t-test and singular spectral analysis (SSA). The results show that East Asian winter monsoon intensity displays obvious interannual and interdecadal variations. When winter monsoon increases, the temperature in the most regions of China decreases. Mongolian high raises and Aleutian low deepens, and reverse in weak winter monsoon year. Meanwhile, East Asian winter monsoon shows quasi-biennial oscillation (QBO), low frequency oscillation (3~7 years) and interdecadal oscillation (more than 10 years). These three periodic oscillations appear to have strong interdecadal variability.
Estimation and Analysis for Air-sea Fluxes of Heat and Moisture over the Neighbouring Seas of China
Yan Junyue
1999, 10(1): 9-19.
Based on the long-term (1931—1979) and high qualitative marine observational data set and selecting appropriate parameters to the study areas, the air-sea fluxes of heat, moisture and different components of oceanic heat budget over the neighbouring seas of China were computed on a regular 2°×2° latitude/longitude grid and the yearly and monthly distributions and spatial-temporal variations of them were analyzed. According to the heat net budget of the surface, the marine climatic compartments were made.
Low-frequency Waves Forced by Large-scale Topography in the Barotropic Quasi-geostrophic Model
Fu Zuntao Liu Shikuo
1999, 10(1): 20-27.
A barotropic model, including large-scale topography and constant zonal basic flow, was used to discuss the effects of large-scale topography on the low-frequency waves. The results show that the topographic factors which affect low-frequency waves are mostly maximun height of topography and topographic slope. The former makes frequency of topographic Rossby waves decrease, and the latter makes Rossby waves instable. Moreover, when topographic slope is optimum, it could also make Rossby wave turn into low-frequency waves. Constant zonal basic flow also plays a very important role in determining the instability of forced Rossby waves. In all zonal wave numbers, only the wave at large wave number (3 waves or larger) could be low-frequency waves.
The Retrieval of the Horizontal Divergence Field from A Single Doppler Radar Velocity Field
Liu Shuyuan
1999, 10(1): 41-48.
Polar coordinate divergence method is one retrieving divergence from single Doppler radar velocity data in the polar coordinate. Using this method, we can retrieve the components of radial divergence and radial movement without any assumption. Only when calculating the component of tangential divergence, an assumption of a constant wind field within a small sector region is required to retrieve the tangential velocity. The error analysis shows that the calculating error is about one order of magnitude smaller than the retrieved divergence. A retrieving test of divergence is made in a cold front process. The result shows that the method cold be applied in the analysis of mesoscale system.
Preliminary Study of Estimation for Soil Moisture Before Winter Wheat Sowing in Zhengzhou
Lu Houquan, An Shunqing, Liu Gengshan
1999, 10(1): 59-65.
Based on the observational data of 0–200cm soil moisture before winter wheat sowing from 1991 to 1996 in Zhengzhou, the vertical distribution of soil moisture before sowing is simulated by using cubic polynomials. The results show that soil moisture would increase with the depth of soil layer. There is a good correlation between 0–50 cm soil moisture and 0–200 cm soil moisture before sowing, the significance level of which reaches 0.01, therefore the 0–200 cm soil moisture before sowing could be estimated from the 0–50 cm soil moisture.
Dynamic Model to Monitor Soil Moisture Content of Rain-fed Agricultural Region in Inner Mongolia
Hou Qiong, Li Yiping, Shen Jianguo
1999, 10(1): 72-79.
Based on the simulation of soil water balance parameters, a dynamic model was developed to monitor soil moisture content in 0–50 cm soil layer using the observational data for many years. The model uses effective moisture storage of initial soil, precipitation and actual evapotranspiration as basic elements to determine the parameters of the model. Through the test and application of the model in 11 stations, the monitoring accuracy of moisture condition for spring wheat and corn was higher than 80%, and the mean forecast accuracy of soil moisture in 2 stations was 92%.
Monitoring Snow Cover with TOVS Data
Liu Ruiyun, Luo Jingning, Guo Lujun
1999, 10(1): 88-93.
The methods of detecting cloud and monitoring snow cover in clean sky are put forward by using the spectral difference of MSU-1 (Microwave radiometer CH1, the central frequency 50.31 GHz)﹑HIRS/2-8 (High resolution infrared radiometer CH8, central wavelength 11.10 μm)﹑HIRS/2-19 (central wavelength 3.70 μm) and HIRS/2-20 (Central wavelength 0.70 μm) of TOVS. The snow cover charts of the snow processes for eastern China in Jan. 1993 and the eastern Tibet Plateau in Jan. 1991 with the method mentioned above are in accord with the observational data.
Several Problems on Oceanography Linked with Climatic Variability
Zhou Tianjun, Wang Shaowu, Zhang Xuehong
1999, 10(1): 94-105.
Recent diagnostic studies associated with the world ocean circulation and its link to climatic variability are reviewed. The following problems are discussed: the great world ocean conveyor, the role of the word ocean circulation in the heat balance of the planetary climate, the role of the world ocean conveyor in the global water cycle, and the impact of stability and variability of the thermohaline circulation on climatic variability.
Fitting to Wind Velocity of Surface Layer Using Two-parameter Weibull Distribution Function and Its Application
Yang Weijun Wang Bin
1999, 10(1): 118-122.
By fitting to surface wind velocity at 5—146 m tower height, divided into six layers for three years in Wuhan, several methods for obtaining shape and scale parameters of the distribution function are analyzed with two-parameter Weibull distribution function. In comparison with the observational data, it is shown that the empirical method is better than the least square method. Using the empirical method to estimate the wind energy of surface layer, the maximum relative erros is 2.7% and the minimum one is only 0.1% in comparison with the conventional method. At last, the vertical distribution law of wind energy is discussed.