Vol.3, NO.4, 1992

Display Method:
Numerical Simulation and Dynamic Analysis of Influence of Upper-Tropospheric Cold Vortex on the Track of Typhoon
1992, 3(4): 385-393.
By six-level dry baroclinic model, the influences of upper-level cold vortex on the typyhoon motion are simulated. The diagnostic analyses are carried out by using vorticity equation. It is found that the influence of upper-level cold vortex on typhoon motion is produced through changing the circulation structure around typhoon center. The results also show that the motion is directly related to total vorticity tendency, and this relationship is stable. Meanwhile, it is revealed that total vorticity tendency mainly comes from the horizontal advection of vorticity and divergent term, which means that typhoon motion is controlled by barotropic dynamic factors.
Automatic Method and Its Application of Recognizing Satellite Typhoon Imagery
1992, 3(4): 402-409.
Both image processing technique and statistical analysis are employed analysis to discuss quantitatively the VISSR imagery of geostationary meteorology satellite. The results show that the mesoscale features of typhoon such as scope, shape, structure, intensity etc. can be clearly identified and measured by using this method
A Laboratory Study of Explosion Effects on Cloud Droplets Coalescence
1992, 3(4): 410-417.
A set of experiments is designed and conducted in 2m3 cloud chamber to study the possible effects of explosion on cloud droplets coalescence. A simulating explosion is used to generate shock wave and precipitation method and FSSP probe of PMS are used to monitor the droplet spectra. The data show that the droplet spectra become broader and the larger droplet concentrations increase in 2 minutes after explosive shock wave influence (acoustic pressure is about 130dB). It seems that explosion in cloud could promote the droplet coalescence process and produce some larger droplets which would grow through further coalescence. The result could provide an explanation of explosion effects on warm cloud modification.
Canopy Structures and Radiation Regimes and Their Variations
1992, 3(4): 424-430.
A mathematical model was introduced to describe the vertical distribution of leaf area densities of tea, wheat, and cinnamon canopies and it fitted the data very well although their patterns are considerably different. Therefore, this model is theoretically significant. Leaf declination angles of tea, with a great covariance, tend to be a normal distribution. Radiation regimes vary notably in different canopies; however, light conditions in the lower part of the canopies are the best around noon when extinct coefficient is the smallest. The extinct coefficients being greater for photosynthetically active radiation (PAR) than those for total radiation (TSR) are closely related to the inverse proportion of solar altitudes (sinh0) during one day. Consequantly, under rational consideration of daily variation of the extinct coefficients, traditional exponentially extinguishing relationship is still a good mathematical model for describing radiation regimes within plant canopies with the advantages of being simple, practical, and trustworthy.
The Heat Island Circulation in Unstable Urban Boundary Layer
1992, 3(4): 431-436.
The heat island circulation induced in unstable stratification is investigated by using thermodynamic and dynamic equations of atmosphere in log-pressure coordinate. The basic features of heat island such as spatial structure of vertical motion, horizontal motion and temperature are given. The results testify in theory the possibility that heat island circulation also occurs in unstable urban boundary layer. The results show that (1) ascending motion is in the urban, sinking motion in the suburbs, a closed center in the lower layer (z=150m), (2) the flow field appears to be a wave over the urban, the wave length is four times the half width of city, (3) the high temperature zone is in the downwind of the urban, and there is no any inversion layer
Stability of Precipitation Resources in Western China
1992, 3(4): 451-458.
Annual and monthly precipitation data from 132 stations of western China during 1958 to 1989 are used to do some statistical calculation. The characters of spatial and temporal distributions and stabilities for monthly precipitation are estimated. It is found that there is an abundance of monthly precipitation in southeast of western China and few in northwest. In the abundant precipitation areas and seasons, the precipitation is stable, but in the drought areas and seasons, the precipitation is short and unstable.
Quasi—Operational Limited Area Objective Analysis Scheme in the National Meteorological Center
1992, 3(4): 459-467.
The scheme of quasi-operational limited area analysis-forecast system in the National Meteorological Center is described. Three dimensional optimum interporation method is used in this scheme. The full horizontal analysis grid has dimensions of 42 by 28, with a resolution of 1.875o×1.875o longitude-latitude grid. The multivariate analysis of geopotential and wind fields for 12 standard pressure levels from 1000 hPa to 50 hPa, and the univariate analysis of relative humitity for the lowest 6 standard pressure levels are made. The verification results show that satiafactory analysis values are provided for predication model using this scheme
The Influence of Air Pollution on Solar Insolation in the Datong City
1992, 3(4): 468-472.
Based on the facts that the solar insolation and sunshine condition in Datong is getting worse and the smoke screen days is more than before, the influence of air pollution on solar insolation and its variation in Datong are estimated by using the observational data of surface solar insolation from 1963 to 1987. It is shown that the decrease of solar insolation is greatly related to the influence of mixing pollutants and there is a good correlation between the annual variation of solar insolation and the turbidity factor.
Influence of ENSO Events on Weather and Climate of China
1992, 3(4): 473-481.
The review summarizes observational results as well as possible physical mechanisms of relationships between ENSO events and anomalous circulation in East Asia, drought/flood, anomalous typhoon activities and cool summer in China. Some problems associated to the studies on the ENSO influence are discussed as well. It is expected to present a basic appraisal of the ENSO influence and its significance for practical prediction of weather and climate anomalies in China.
Long-Range Forecast for Winter Polar Vortex
1992, 3(4): 482-486.
Using the Northern Hemisphere 500 hPa altitude data and North Pacific sea temperature data, the forecasting of winter polar vortex area index for I area, which would affect air temperature of China significantly, is conducted. The results show that the intensities of North Atlantic west wind circulation in prior March and North American big trough in May are good indication of the winter polar vortex intensity change. When the polar vortex is anomalous strong or weak the North Pacific sea temperature anomaly patterns are opposited. And, the sea temperature meridional balance in the mid-South Pacific and sea temperature zonal balance in the mid-west of North Pacific would influence the polar vortex area index significantly.
The Role of Secondary Circulation in the Initiation and Evolution of Severe Convective Weather
1992, 3(4): 487-491.
The diagnostic research of secondary circulation forced by the background field is made by means of the intensive observation of the severe convective weather process occurred on 28th April, 1983. The data are acquired by the Meso-Scale Weather Experiment of Eastern China. The diagnostic results show that the secondary circulation can trigger off the severe convective weather in the zone of accumulation of geopotential instability energy
The Relationships Between Upper Wind Errors and Balloon Coordinate Errors Sounded by Radar and Their Utilization
1992, 3(4): 496-500.
The comparison between the accurate and the approximate expressions of transfer functions of the wind speed and direction errors with balloon coordinate errors sounded by radar is conducted. The suitable range of approximate expression and its correction method are given. The results show that the 701 type radar can not meet in a certain scope the requirement given by WMO about the accuracy of upper wind vector. If the accuracy of angle–measurement is risen to 0.12o, and the accuracy of distance-measurement to 20m, the WMO’s requirement can be basically reached. It is appropriate to use the 5cm or 3cm radar with angle accuracy 0.06o and distance accuracy 10m for some users.
Analysis of Calculating Formula and Improvement of Empirical Formula for Saturation Vapour Pressure
1992, 3(4): 501-508.
The errors between observed values and values got from Wexlar’s, Goff-Gratch’s and Magnus empirical formulas for saturation vapour pressure are estimated and compared. Practical convenient empirical formulas which derive from fitting calculating values of Wexler’s and Goff-Grath’s formulas are presented.
Characteristics of Heating Distribution and Its Influence on the Frontal Maintenance Nearby the Front with Continuous Rain
1992, 3(4): 437-443.
The character of heating distribution near the front and the action of diabetic heating frontogenesis on the frontal maintenance and movement are estimated by using the objective data. It is indicated that the large-scale latent heat is distributed mainly along the front with band feature in the meridional vertical profile, and that the meso-scale character of frontal structure is given. According to the computation, the action of heating frontogenesis is important to frontal formation, maintenance and its movement. It is also shown that heating frontogenesis is unfavourable to the maintenance of horizontal stable layer in the quasi-stationary front
The Symmetric Instability in Three Layer Model
1992, 3(4): 492-495.
The symmetric instability is studied by means of three layer model. The results show that there exist the greatest growing rate of the instable disturbance when the optimum coupling of air layer depth (i. e. the vertical scale of the disturbance) with its horizontal scale is obtained. However, the smaller Richardson number Ri is, the greater the ratio of the air layer depth to the horizontal scale of the most instable disturbance is