Vol.1, NO.3, 1990

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Display Method:
Sensitivity Experiments as Simulated with an Energy Balance Model
1990, 1(3): 225-231.
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Abstract:
Changes of the global temperature induced by the changes ice and snow areas, solar constant, surface albedo, carbon dioxide and aerosol have been simulated with a one–dimensional energy balance model. The effects of several factors on the ice age temperature have been analysed. Possible numerical results of the global temperature change induced by the natural variations and human activities are shown. Therefore, some reference values are given to protection of the atmosphere and environments
Investigation of Mesoscale Convective Cloud Cluster in South China
1990, 1(3): 232-241.
[FullText](3531) [PDF 610KB](1313)
Abstract:
The statistical characteristics of 176 mesoscale convective cloud clusters in South China, which are classified into three types in terms of their size, are analysed based on the short interval GMS images and conventional data during April－October, 1980－1988. Two composite model charts are presented for their formation and development, and two typical cases are studied. Some conclusions can be drawn as follows: ① Mesoscale convective cloud cluster is a major menmber of severe mesoscale convective systems in South China. ② The convergences of wind and moisture fields in the surface layer and orographic forcing are the trigger mechanism for the genesis of cloud clusters. ③ Low-level jet and monsoon cloud swell are the most important factors for the development of cloud clusters
Numerical Simulation of the 26—27 June 1986 Heavy Rainfall in Beijing-Tianjing-Heibei Area
1990, 1(3): 242-252.
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Abstract:
By use of the transplanted mesoscale model (MM4) from PSU/NCAR, a strong rainfall event during 26—27 June 1986 in Beijing-Tianjin-Heibei area is simulated. The results show that the reduction in wind speed near the convective region in upper levels and passage through the rainfall center of the intensifying LLJ played crucial role in the event. The mergence of meso-low which convergence region ahead of the LLJ, feedback of latent heat release, and fluxes of heat and moisture from the underlying surface were also responsible for the event whereas the northwest low did not contribute much to precipitation.
Development of GMS Stretched VISSR Data Receiving and Real-time Processing System
1990, 1(3): 253-259.
[FullText](3494) [PDF 417KB](1466)
Abstract:
A GMS S-VISSR data receiving and real-time processing system has been developed to fit the transmission change from HR-FAX to stretched VISSR. This paper has analysed the features of S-VISSR data format, and described the layout, characteristics and experimental results of the developed system
Reconstruction of the 18th Century Summer Monthly Precipitation Series of Nanjing, Suzhou and Hangzhou Using “Clear and Rain Records” of Qing Dynasty
1990, 1(3): 260-270.
[FullText](4337) [PDF 495KB](1892)
Abstract:
In this paper the Qing weather records “Clear and Rain Records” were used to reconstruct the 18th century summer (June—August) precipitation and monthly precipitation series of May—August for Nanjing, Suzhou and Hangzhou. The nature of these records and the technique of transforming them into numerical codes are described. The procedure of converting these descriptive records into quantitative monthly precipitation and its scientific basis are given in detail. The reliability of the precipitation series obtained is also examined.
Observational Study on the Two–cell Structure of Tropical Meridional Circulation in Summer
1990, 1(3): 271-278.
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Abstract:
The structure of tropical meridional circulation in summer and its regional differences and interannual variations are studied by using the July 1980—1983 ECMWF data. It is found that the tropical meridional circulation show a two-cell structure. In the lower troposphere, there are monsoon circulation in the monsoon region and Hadley circulations in the non-monsoon region; while in the upper troposphere, there is an independent circulation in both monsoon and non-monsoon regions, with its center located in the Northern Hemisphere for monsoon region and in the Southern Hemisphere for non-monsoon region. This two-cell structure always exists in normal years. However, in the abnormal year (1983), the circulation in the upper troposphere is much weaker and can hardly be recognized, and the strong vertical motion results in a one-cell meridional circulation throughout the troposphere.
Comparative Study of Objective Analysis Methods for Mesoscale Wind Field
1990, 1(3): 279-288.
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Abstract:
The strong and weak points of direct-difference, variational calculus and direct-adjusting divergence methods for mesoscale wind field have been evaluated by numerical experiments. The major results of experiments are as follows: (1) As shown in other experiments, the direct-difference method can get a wind field of minimum integral divergence with a short computer time, but the vertical motion obtained in the upper calculation area is overestimated. (2) The variational calculus method is able to overcome the above disadvantage, but the computer time needed is too much. (3) The direct-adjusting divergence method possesses the advantages of the former two methods and can get a reasonable divergence wind field with a compromising computer time.
Comparative Experiments on Methods for Calculating Logarithmic Surface Pressure Gradient in Spherical Coordinates
1990, 1(3): 289-292.
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Abstract:
With several kinds of numerical methods commonly used, the logarithmic surface pressure gradient of an ideal earth-atmosphere system is calculated on 192×96 Gaussian grid points Comparative experiments show that, on such grid points, calculations with the spline method are better than those with spectral methods including T21, T42 and T63.
Loss-speed Characteristics of Shipping Movement in Wind and Sea-wave Fields
1990, 1(3): 293-297.
[FullText](3074) [PDF 229KB](2277)
Abstract:
Through studies on the effect of wind and sea-wave motion on navigational speed of shipping, the curve of motion property for different tonnage shipping and the regression equation of loss-speed have been obtained. Those are of practical significance to the choice of optimum sea route for trans-oceanic shipping and navigation simulations
Features of Two Flows Prior to Sustained Fine Periods or Overcast-with-rainy Periods
1990, 1(3): 298-304.
[FullText](3535) [PDF 375KB](1429)
Abstract:
Based on the data about 10 cases of sustained fine periods and 7 cases of sustained overcast-with-rainy periods in spring time 1980—1986 in the middle and lower reaches of Changjiang River, the features are analysed of 700 hPa streamline fields and of the two flows northeast and southeast of the Qinghai–Xizang Plateau. It is found that prior to sustained fine periods, the zonal flow east of the Plateau is weaker, and the north branch flow spreads southward, thus forming the meridional streamline field and initiating the sustained fine periods. Prior to sustained overcast-with-rainy periods, the zonal flow east of the plateau is stronger, and the south branch flow spreads northward. This is the reason why the stronger interfacing motion occurs between the two flows during the sustained overcast-with-rainy periods
On the Evolution of Yellowed Leaves Rate of Spring Wheat and Its Simulative Model
1990, 1(3): 305-312.
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Abstract:
The variation of yellowed leaves rate of spring wheat is one of the important keys in simulative model of crop growth. It directly affects the growth and function of photosynthetic organ—green leaves. Based on the field experiments (1985—1988), the evolution of yellowed leaves rate of spring wheat is analysed. The function relationship between yellowing process of green leaves and growth stages of spring wheat itself is established. Furthermore, modeling and correcting for green leaves yellowing process affected by temperature and moisture status are discussed. Finally, the synthetic model for simulating the dynamic evolution of yellowed leaves rate is constructed, and the numerical experiments show that the modeling effect of the model is satisfactory
Characteristics of the Mesoscale Echo System Ahead of Cold Front and Its Relationship with Heavy Rains
1990, 1(3): 313-316.
[FullText](2684) [PDF 600KB](1619)
Abstract:
Based on the following data: the continuously observed radar echo data from Beijing, Shijiazhuang, Dezhou, etc., 3-hourly satellite cloud pictures from GMS; hourly aviation surface observations in North China; and hourly precipitation records taken from climatological stations in Beijing, Tianjin and some regions of Hebei and Shandong Provinces, the characteristics in the formation and development of the mesoscale echo system in the warm sector ahead of cold front during 3—4 July 1981 are analysed, as well as its regationship with heavy rains
Analysis and Calculation of Extreme Wind Speed and Wave Height for the Design of Marine Engineering
1990, 1(3): 317-323.
[FullText](2939) [PDF 481KB](344)
Abstract:
In this paper, the weather and climate conditions are analysed for creating extreme wind speed and wave height over western Huanghai Sea which can be divided into seven subregions. According to different data sets from these subregions, seven correlation formulas are established to calculate annual maximum extreme wind speeds. Extreme wind speeds can be derived for various recurrent periods of each subregion, by means of the Type-I probability distribution of extreme. With the spectral ocean wave model (SOWM) data, the extreme wave heights during the periods can also be derived for the two grid points, which are reasonable compared with the offshore statistical wave heights
Comparison of Three Methods for Real-time Calculating the Standard Deviation of Wind Direction
1990, 1(3): 324-330.
[FullText](6164) [PDF 596KB](1888)
Abstract:
Three approximate methods for real-time calculating the standard deviation of wind direction are introduced. The ultrasonic anemometer-measured data collected at four sites are analysed with these methods. By comparing the results with those from accurate method, it is found that Yamartino method is the most accurate one for real-time calculating the standard deviation of wind direction.
Stability of Precipitation Resources in Huang-Huai-Hai River Area and Its Surrounding Area
1990, 1(3): 331-336.
[FullText](2812) [PDF 423KB](339)
Abstract:
Based on the 1951—1982 monthly and daily precipitation data at 43 stations, the three indices, i. e. mean anomaly percentage, mean interannual change percentage, and mean anomalies of mean interval days with daily precipitation greater than 5, 10 and 20 mm, are presented to study the stability of precipitation resources in Huang-Huai-Hai river area and its surrounding area. It can be divided into three types: northern, southern and southwestern. Meanwhile, the characteristics of the stability in temporal and spatial distributions are also discussed for each type and each season
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