Vol.3, NO.2, 1988

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A Numerical Simulation of the Impact of SST Anomalies on Low Latitude Circulations
1988, 3(2): 113-119.
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Abstract:
In this paper, by using the 7–level PE–spectral model a simulation of SST anomalies and inhomogeneous distribution in the specific waters concerned has been made. Also the impact of those situations on lower latitude circulations has been discussed. The results are as followeings: A lower latitude Walker cell can be simulated by integrating 7–level PE–spectral model. When SST anomaly in the East Pacific is warm, a disturbance responsive to Walker circulation would occur after 96–hour’s integrating. The intensity of Walker circulation increases with the integrating time, a series of propagating wave westward with alternating between ascending and sinking could be identified. When SST anomaly in the East Pacific is cold, a disturbance and wave series have also been found. The sign of vertical motion of the disturbance is opposite to those of case in the warm SST. A reasonable result can also be obtained in normal (warm or cold) distribution of SST in the East Pacific
Remote Sensing of Temperature Profile and Surface Emissivity over Land
1988, 3(2): 120-128.
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Abstract:
A physical method, based on the simplification of surface radiation terms in remote sensing equations, has been suggested to retrieve surface temperature, vertical temperature profile and surface emissivity from the first eight channel observations of TIROS—N/HIRS-2. Analyses of several examples indicate that much more accurate air temperatures in lower atmospheres than a statistical technique can be obtained by this method. The results of surface temperature and surface emissivity are also reasonable
Numerical Simulation of the Evolution of a Mesoscale Cloudcluster over the Middle and Lower Reaches of the Changjiang River
1988, 3(2): 129-137.
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Abstract:
A five level mesoscale primitive equation model has been used to simulate the initiation, mature and weakening stages of a mesoscale cloudcluster over the middle and lower reaches of the Changjiang River in 1982. The results show that the evolution of the cloudcluster with heavy rainfall can be simulated by this model with observed large scale regular data.Furthermore, the model has been modified to incorporate the orographic effects. In comparison to the numerical experiment without terrain influences, the orographic effects in the model would contribute to the formation of E-W shear line and promote the development of the cloudcluster
A Study on the Ageostrophic Wind During Winter Monsoon over East Asia
1988, 3(2): 138-150.
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Abstract:
A diagnostic study has been made on the ageostrophic wind and the primary factors which can affect the ageostrophic wind in strong cold air outbreak in winter over East Asia. The results has indicated that the ageostrophic wind is one of the most significant factors. It may cause the strengthening of the surface and lower level north wind. Agostrophic secondary circulations are formed near the frontal zones as well as in the entrance and exit regions of the upper level westerly jet, resulting in the strengthening of the jet stream and local Hadley circulation in East Asia. However, the upper level westerly jet in East Asia is subgeostrophic. The allohypsic wind, inertial advection and friction effect are the main factors which influence on the ageostrophic wind. In addition, the local change of the potential temperature, the advection of the potential temperature and diabatic heating play a certain role in the formation of the ageostrophic wind, but the composite wind vector of these three ageostrophic wind components is very small due to the offsetting of them. The ageostrophic wind plays a very important part in the kinetic energy budget in limited areas in East Asia.
A Data Pressing Method of Radar Echo
1988, 3(2): 151-158.
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Abstract:
A pressing method of radar data is introduced in this paper. As the value changed sharply near the borders of echo intensity layers, the isopleth is drawn out by differential processing. Actual process is made for several times. Each time the layer thresholds are altered to keep a certain interval and the quality of the isopleths is highly improved. The points on the isopleth are lined rapidly by comparing the sequence of distance among points and the intersected isopleth is corrected by tracing against a change coordinate. The echo border is filtered by diaphragm method. After filtered the distorted borders are mended and echo structure is more obvious. Optional layer can be filtered and others are kept unchanged. By the method mentioned above only 7 percent original data is used to store or display an echo chart. The pressing rate achieved 93 percent
A Study of the Frontal Snowfall in Zhungeer Basin of Xinjiang in Winter Part II: Theoretical Discussion
1988, 3(2): 159-168.
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Abstract:
A two-dimensional cloud model including detail microphysics is presented. The precipitation processes of stratiform clouds with or without small-mesoscale disturbances (such as generated cells and natural seeding etc.) and artificial seeding are simulated. The results are compared with observations calulations indicate that in the undisturbant stratiform clouds there exists plentiful supercooled liquid water can not transform to snowfall due to lack of sufficient ice crystals, but when the disturgbances act on the stratiform clouds, there will be a great deal of precipitation. Artificial seeding in the stratiform clouds or the disturbant regions of generated cells can increase snowfall in a large amounts. Mechanisms of the precipitation and artificial enhancement is discussed
Clear Air Aerosol Microphysics Features in the Lower Troposphere in Beijing
1988, 3(2): 169-175.
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Abstract:
Clear air aerosol number concentration and its number/size spectrum distribution in the lower troposphere were observed by a airborne instruments in Beijing etc. during April—July in 1982. Results show that the aerosol number concentration of the air coming from west, northwest and north are rather low (10-1—100cm-3 on the average). The number/size distribution has been fitted by =C/DA, with the correlation significance level α≤0.01, most exponential A values are less than 3. Because of the importance of the diameter 0.5 to 2μm particles in the atmosphere, its number/size distribution has also been by =C/DB. It is found that the correlation significance level isα≤0.01 for the most observations, andα≤0.05 for a small parts. The values of A, B and smaller particles (0.5≤D≤1μm) relative number concentration f1 are fairly uniform and steady both is horizontal and vertical direction. When effected by city, the aerosol number concentration in the mixing layer increase evidently, the number/size spectrum distribution is steeper and especially for the smaller particles (D~1μm) the concentration is very remarkable, therefore city effect is a important cause for high aerosol concentration, steep number/size distribution, strong local air pollution and low visibility in mixing layer
Atmospheric Dispersion and Transport Near the Surface in Some Cities of South China
1988, 3(2): 176-182.
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Abstract:
In this paper, some features of atmospheric dispersion and transport near the surface and its influence on air pollution in some cities of South China are discussed by using the observations in Guangzhou, Zhanjiang and Shantou during 1980—1983. It is found that the maximum concentration often occurs near source through intensive vertical diffusion, and the values of concentration decrease with the distance downwind rather rapidly. Due to the effects of perturbations, the distribution of air pollution often presents irregular undulations. In addition, the effect of monsoon on transport of pollutant in South China is obvious, therefore, the high areas of the average pollutant concentration change with seasons markedly. The air pollution over coastal cities in South China is also effected by sea–and land–breezes to a certain degree, and therefore, the distribution appears daily variation. The rainwash effect of precipitation is also discussed
The Preliminary Study on the Budget of Regional Atmospheric Energy over West Tropical Pacific
1988, 3(2): 183-190.
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Abstract:
The atmospheric energy budget calculation over west tropical Pacific during the Sino–America Sea–Air Join Investigation has been made. The controlled area is divided into three polygons (east, middle and west areas). Based the data from this investigation during the 9th through 15th of January and 1st to 14th of February, 1986, the horizontal transportation of the atmospheric energy budget is computed day by day. It is pointed that the direction of the atmospheric energy transportation in the west part of west tropical Pacific is from the outer region towards inner region, and it is in an opposite direction in the east and middle parts. It shows that over the west area the warming is obvious during the investigation period. In addition, the regional differents for the local change of atmospheric energy are less than that of the transporting terms
A Numerical Simulation of the Effect of Relief on Atmospheric Circulation
1988, 3(2): 191-198.
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Abstract:
In this paper, a barotropic primitive equations model in the Northern Hemisphere and ideal initial field are used. The altitude of the smooth relief is considered in the model. The equations are integrated through 240 hours for some wave systems in which the wave numbers are 2, 3 (ultra–long wave), 4 and 5 (long wave), respectively. Comparing these solutions with those obtained from the model in which the altitude of the relief is not considered. Four pairs of the solutions show that the effect of the altitude on the evolution of the four sorts of wave types is very obvious. It is confirmed that the effect of the relief on the general circulation and some characteristics of weather types is really one of the key factors. It is also found that some main patterns of atmospheric circulation in the Northern Hemisphere are formed due to the dynamical effect of the relief. For example, the movement of the arctic vortex to North Europe, the maintained troughs over East Asia and North America, and the maintained ridge over Alaska are closely related to the relief. In this model, the effects of the relief present: A trough is in the west and a ridge is in the east of the North Pacific, while a ridge is in the west and a trough is in the east of North Atlantic. The presences of blocking highs and cut–off lows are more frequent and more typical. As m=4, the flow pattern looks like a upside–down Ω, while m=5, the flow pattern is trough–ridge–trough over the continent of Europe and Asia
An Autoregressive Moving Average Model of Monthly Surface Temperature Field over China
1988, 3(2): 199-205.
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Abstract:
For designing a time series of the successive monthly surface temperature in 1952－1980 over China a stochastic model is formulated by an AEMA (p, q) model. The monthly temperature fields composed of records at 60 stations are expanded by means of EOF (Empirical Orthogonal Function) with the various sample sizes 348, 336 and 300 months so as to examine the stability of EOF expansion. Then the first four principal components, i. e. z1, z2, z3, z4 are taken as the variables of multivariate time series, since their total variance contribution is 99.26%. The major periods in first four principal components series are also revealed by using the periodogram and the maximum entropy method. The model identification of ARMA (p,q) for univariate variables zi (i=1,2,3,4) is made by the Pandit-Wu method, Then, the empirical models are obtained. The extrapolations of s models are used for predicting a monthly temperature field. The score of hit ratio of departure forecasts is 78.3%, which is better than that of the recent operational long-range weather forecast.
The Study on Mesoscale Characteristics of Typhoon Inner Core—a Survey
1988, 3(2): 206-214.
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Abstract:
Since 1950’s instrumented aircraft has been used to investigate hurricanes, resulting in many studies of the inner core (eyewall) region. Most of the studies dealt with the structure and dynamics of the eyewall. Recent advances in aircraft instrumentation technology have allowed to study the cloud and mesoscale structure of the mature hurricane in detail. Especially, the evolution of concentric double–eye typhoons has been greatly analyzed and discussed. Numerical simulation on the hurricane eyewall has also made encouraging progress.The paper is to introduce and compare some main observation and research results above mentioned. Meanwhile, the features of hurricane inner core are physically discussed
Relationship Between the Variation of the Antarctic Sea Ice Extent and the Equatorial Sea Surface Temperature
1988, 3(2): 219-222.
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Abstract:
In this paper, the relationship between the Antarctic sea ice extent and the equatorial sea surface temperature (SST) has been examined by means of the harmonic and cross spectral analyses. It is found that there are the quasi-triennial oscillations of the sea ice extent and the SST, and correlations between them as well
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