Vol.2, NO.3, 1991

Display Method:
Seasonal Characters of Ray Path of Meridional Wave Train of Planetary Scale Stationary Wave and Its Trapping Zone
1991, 2(3): 225-233.
The characteristics of meridional wave train in teleconnection in winter and summer are investigated by using mean westerly profile data. The numerical analysis shows the distinct seasonal characteristics of teleconnection wave train due to seasonal differences between the mean westerly profile in winter and that in summer, i.e. there are distinct seasonal differences in the propagation of rays, trapping zone, variation of wave refractive index with latitude, resonant features of meridional wave train forced by large scale topography and maritime heat source. In this paper, the correlations between large scale topography, heating source and characteristics of meridional wave train in teleconnection are also discussed.
Experimental Modeling for the Impact of Local Air Pollution by the Effluent
1991, 2(3): 234-241.
An experimental modeling study executed in NJU meteorological wind tunnel was described in this paper. Atmospheric pollution affected by the wast gas from a tower located at downtown of a big city has been simulated. By means of measuring the flow field and flow visualization and dispersion test by releasing the tracer, some conclusions concerning the impact of atmospheric pollution on the local environment have been obtained. Based on the experimental data of the dispersion test, a modificative dispersion model has developed in order to explore the actual approach to predict the air pollutant concentration and its distributions. The results show that fluid modeling in wind tunnel is effective and practical method
The Features of the Subtropical Monsoon Circulation Cell and Its Relationship with Summer Circulation over East-Asia
1991, 2(3): 242-247.
In this paper, using the daily grid data of the ECMWF/WMO, we made the composite analysis on 12 mediumrange variation processes of the subtropical high over the western Pacific in summer during 1980—1983. It is found that there is the subtropical monsoon circulation cell over East-Asia. We also discussed its features. The results show that the subtropical monsoon circulation cell is formed through the following process: when one divergent updraft driven by the condensation heating of the continental monsoon rain belt in East-Asia was moving southward, it met another one moving northward from Nanhai sea, and then these two currents has a confluence, and formed a downdraft over the subtropical area. And, it plays an important role in summer circulation over East-Asia
Numerical Experiments on the Formation of the Summer Monsoon in Southeast Asia
1991, 2(3): 248-255.
A two-level spectral model of atmospheric circulation is adopted and the physics processes of the two-level atmospheric general circulation model of the OSU is introduced in this paper. In order to investigate the formation reason of the East Asia summer monsoon, four different experiments have been performed. By comparing and analyzing of all these experiments, it reveals that: (1) the diabatic heating distribution produces weak low-level southwestlies over the monsoon region, (2) there is a mean across-equater airflow between the 45o-90oE, not in the vicinity of 105 oE and the analysis reveals that the affection of the south hemisphere is not important. (3) the mountains have played very important role in the East Asia monsoon circulation. The mechanical effect produces a low or trough on the southeast side of the Plateau, then the thermodynamic effect makes it strengthen and move close to the Plateau, thus the monsoon low or trough is formed
The Urban Moisture Island and Urban Fog of Suanghai
1991, 2(3): 256-263.
By making use of the simultaneous observational meteorological data in 1984 in Shanghai urban and its suburbs, we discussed the formation of urban moisture island and its relationship with urban fog. Three major conclutions are as follows: (1) There are four types of urban moisture island according to formation: a) with less dew deposits in the nighttime, b) with less frost deposits in the nighttime, c) more water evaporation in or after the rain, d) more water evaporation in the fog time. All the above processes are accompanied by the urban heat island. (2) The urban moisture island is a very good indication of radiation fog and advection radiation fog, but there is little relationship with frontal fog.(3) During the radiation fog and advection radiation fog period of autumn or winter, there always exists an urban moisture island
Experiments of an Objective Operational Location Technique of Tropical Cyclone
1991, 2(3): 264-270.
The experiments of an objective technique for estimating the location of a tropical cyclone from a variety of satellite and radar fix reports are described. The western North Pacific climatology and persistence (WPCLPR) track forecast technique is used to get a potential track from each fix. A tentative warning position is interpolated from a smooth curve that is fit to the future and past positions. When multiple fixes are available, the expected accuracy and the timeliness of each fix could be obtained using the weighing polynomia. The technique was tested by the independent data of 1988. The results demonstrate that this technique is a useful tool for the forecasters to determine the present location of the tropical cyclone
A Study of the Numerical Classification of the Climates in China
1991, 2(3): 271-279.
A numerical classification of climates in China is conducted using meteorological data of 30 years at 432 stations. The results are similar to those obtained before with the traditional methods. Thus it is feasible to apply the numerical method to climatic classification in China. In addition, the numerical classification expressed in numerals is objective and quantitative, and thus it is convenient to treat the meteorological data with computers in climate classification. The concept of similarity is also used to compare quantitatively among different climatic types.
The Role of Meridional Cell in the Response of Atmosphere to the SSTA Forcing
1991, 2(3): 280-288.
A simple model is developed including the effect of the meriodional cell. The global zonal mean fields are calculated from the data of EWMFC of 1982. A series of numerical experiments show that when the SSTA forcing locates at equatorial regions, the waves from the SSTA diabatic forcing can propagate towards both hemispheres. But when we consider the effect of Hadley cell, the characteristics of wave propagation have obvious changes in both the spatial phases and amplitudes, and they conform with actual atmospheric anomalies all the more. When the SSTA forcing locates at the northern (or southern) hemisphere, if we don’t consider the Hadley cell effect, the diabatic forcing can not have a strong atmospheric response in the southern (northern) hemisphere. But when the Hadley cell is considered, the waves from the diabatic forcing can propagate towards the other hemisphere. Furthermore, the seasonal effects on atmospheric response to the diabatic forcing are also discussed
Characteristics of Hydrological Cycle in North China
1991, 2(3): 289-293.
This paper studies the characteristics of hydrological cycle for 40 years in north China with the water balance principle of land-atmosphere system under considering the effect of the natural climate change and anthropogenic activities. In the high flow period of 1950s, the rainfall is more than evaporation, the relationship among precipitation, run-off and evaporation was in balance. After 1960s the rainfall became less than evaporation. The negative value of (P—E) inhenced with decreasing of rainfall and increasing of amount of groundwater extracted. During the drought years the value of moisture outflow is more than that of inflow ever north China. The loss of moisture in the atmosphere could be compensated by the excess evaporation from the lost amount of ground water in this area
A Study on Simplified Simulation Model of the Spring Wheat Growth
1991, 2(3): 294-300.
There is a close relationship between crop growth, development and yield formation and weather environmental conditions. In this paper, the mathematical equations describing micro-growth processes of crops (such as photosynthesis, respiration, leaf area growth, accumulation and distribution of dry matter and so on) have been established on the basis of the field experiments, laboratorial analysis and computer’s modeling tests with time interval of ten days for several years (1986—1989). It is a preliminary simplified simulation model of spring wheat growth under the optimal water and nutrient conditions. The field experiments show that simulation results of this simplified model are satisfactory.
Application of Meteorological Satellite Data for Forecasting Medium-range (3—5 days) Rain Storm over the Changjiang River
1991, 2(3): 301-307.
This paper presents three kinds of evolutionary cloud patterns summarized from GMS images and two kinds of OLR pentad mean fields from POS for the mediumrange rain storm prediction over the upstream reaches of Changjiang river based on the analysis of all eleven cases in the summers from 1978 through 1987. It is revealed that the interaction among the cloud systems of synoptic scales even larger scales over the middle or lower latitude areas is very important condition. In addition, in order to verify the mentioned above, we used the severe rain data in early July 1989. The results are satisfactory
A Review on the Supply of Water Vapour to Heavy Rain Process in Arid Regions of China
1991, 2(3): 308-314.
Arid regions are often far from sea and ocean, the patterns of supply of water vapour to heavy rain area are generally different from those in humid regions. Several major patterns were summarized and the effect of precursory light rain on the following heavy rain process, the effect of low-level easterly wind on the occurrence of heavy rain, the role of advected (external) moisture, and especially the importance of recycled (internal) moisture in south Xinjiang were also discussed
A Practical Lidar System
1991, 2(3): 315-318.
A three wavelengths lidar system was proposed. Its performance was studied by numerical simulation method. It is shown from the calculated results that the system can be used for atmospheric boundary layer and stratosphere sounding. The numerical simulation method used here can be sued in any mie scattering lidar system design.
Climatic Characteristics and Forecast of the Flow of Heihe River in the Hexi Corridor Area
1991, 2(3): 319-324.
Using the data set of the flow of Heihe river, we have analyzed the persistence, periodicity and annual variation of the flow. It is shown that there is a good positive correlation between the flow of Heihe river in April and surface heating field over the Qinghai-Xizang Plateau in February of the year. The departure characteristics of 500 hPa in March have the predictability to the flow of Heihe river for coming May.
A Study of Offshore Fog Forecasting in Ningbo Region
1991, 2(3): 325-330.
Using the twenty-four-hour numerical prebaratic charts from Japanese FSAS, two schemes containing both the optimum analog of daily grid points and the analog of mean pressure field in different ranks of fog were developed to forecast the offshore fog in Ningbo region. The experimental forecast has been conducted based on the independent samples of 1987. And, the schemes were used in the operational forecasting test in 1988
Parallel Computing in the T42 Quasi-operational System
1991, 2(3): 331-335.
This paper describes that the model and postprocessing calculations are executed parallelly at JOB level on the computer M360-AP with two additional processors in the T42 assimilation forecasting quasi-operational system in the National Meteorological Center (Beijing). The results show that the multitasking parallel computing technique makes 5-day NWP completed at least 60 minutes ahead of time and its speed-up factor is equal to 1.23