Vol.4, NO.3, 1989

Display Method:
A Study of the Extraordinary Ekman Spirals and the Characters of the Turbulent Second-Order in the Stable Boundary Layer
1989, 4(3): 225-233.
The characters of the Ekman spirals over a slopped terrain have been discussed by using the second–order model. The results show that under a certain condition of environmental geostrophic wind field, the Ekman spirals will change into counter clock–wise ones in the northern hemisphere. In addition, effects of the terrain on the structure and the vertical distribution of the turbulent second–order in the stable boundary layer have been discussed.
Experiments of the 30–Day Long–range Numerical Weather Prediction in a Seven–level Spectral Model
1989, 4(3): 234-246.
The present model with the considerations of more physical processes is largely is largely based on the northern hemispheric seven-level spectral model. An efficient method in the model has been given to overcome the problems involving small differences between the two large magnitudes occurring in the divergence equation, as well as in the calculation of the pressure gradient force terms in a σ-coordinate in the vicinity of mountains. The method of calculating nonlinear terms is excellent. The 30-day long-range numerical weather predictions utilizing the present model with initial conditions based on real data on lst May and 7th July 1982 have been made, and the results are satisfactory. The RMS errors of the forecasts are consistently less than those of persistence method even in lower latitudes during the entire 30–day forecasting period.
The Relations Between Richardson Number and the Stability of Mesoscale Perturbations
1989, 4(3): 247-256.
In this paper, the relations between the Richardson number and the stability of mesoscale perturbations are acquired by linearly solving the primitive equations in the log-pressure coordinate system with expansion of the small parameters, and then the symmetrically instability criterions under conditions of zero-order and first-order approximations and the baroclinic instability criterions under conditions of zero-order approximations are discussed.
Attenuation of Sound and Atmospheric Sounding
1989, 4(3): 257-263.
The attenuations of sound by molecular absorption (ASMA) in the mean monthly climatic fields of Beijing. Wuhan, Shanghai and Hankou cities are calculated. The results show that ASMA have complicated nonlinear relation with atmospheric temperature and moisture, and they should not be ignored in the detection of turbulent structure coefficient of mixing layer by acoustic radar, but it can be estimated with the surface meteorological data. An approximative method of calculating the attenuations of sound by turbulence is given. When both the attenuations of sound by molecular absorption and turbulence are considered, the magnitude of in unstable conditions obtained from echosonde is more close to the observations from Kaimal et al.
The Influence of Atmospheric Stratifications on Turbulent Features in the Surface Layer over the Tibetan Plateau
1989, 4(3): 264-272.
This paper is to describe the distribution features of turbulent parameters, friction velocity u* , characteristics temperatureθ* , and Monin–Obukhov length L, and Richardson number Ri at the various levels with different stratified conditions in the surface layer at Lhasa and Naqu sites during June and July 1986 by using the data from the Tibetan Plateau Meteorological Experiment 1986 (TIPMEX–86). The results show that there are a variety of turbulent motion forms under various conditions of the stratification, and the adjustment of thermal process is faster than that of dynamical process. It has also been found that under stable conditions, the change of u* , orθ* with height respectively is larger than that under unstable conditions. The turbulent parameter values for L0, the former is smaller than the later.
The Thermal Characteristics over Zhangye Region During the Summer of 1984
1989, 4(3): 273-282.
In this paper, an analysis is presented concerning the thermal characteristics over the Zhangye region of China during the summer of 1984. The mean sensible and latent heat transfer, the drag coefficients of heat and moisture are estimated in this period by using the thermal equilibrium method. In this region, sensible heat flux and heat drag coefficient increase with height, but latent heat flux and moisture drag coefficient decrease with it. The thermal parameter variation indicates a 3—5 day medium–range oscillation period just as the radiant parameter, and the phase difference between the two parameters is very small and their coherences are above 50% mostly. Therefore, the mean values of sensible heat and latent heat transfer in surface layer can be estimated by using the average radiant parameters. It is shown that the mean characteristics of thermal regime in Zhangye region coincide with those got from QXPMEX–79.
The Influence of ENSO and Volcanic Eruption on Summer Monsoon Rain Belts in the Eastern China
1989, 4(3): 283-290.
ENSO event occurring in winter—spring greatly influence the following summer weather of China. When the Southern Oscillation (SO) in winter—spring is weaker and accompanied with ENSO, it will lead the west Pacific high (WPH) in the following summer to strengthen and extend westward through the action of enhanced Hadley cell located in mid–equational Pacific. And the location of the ridge line of WPH in mid summer (July—August) and the monsoon rain belt in eastern China in the northern side of WPH are controlled by two factors, both the preceding SOI in late spring and the direct solar radiation (S) of clear sky indicating the stratospheric volcanic dust content. Owing to the significant annual variation of S, the difference of location of the monsoon rain belt in eastern China in mid summer will be considerable during the ENSO periodes. Based on this analysis, the seasonal forecast for the summer rainy tendency in the mid–lower valley of Changjiang river and Huaihe river in 1987 (ENSO year) has been made.
An Analysis of a Severe Rain Storm by Two MESO—αVortices
1989, 4(3): 291-299.
In this paper, a case study of the process of a severe rain storm in North China by two meso–αvortices has been made. It is found that the heavy rain has been caused by the interaction between a meso–αvortex coming from northwestern China and a meso–αvortex from southwestern China located in the same longtitude. It is also found that the inertic gravitational wave instability and condition symmetric instability may have a contribution to the suddenly heavy rainfall in the north of north China plain
A Study on Climatic Productivities of Crops in Hilly and Mountainous Areas in the East of Subtropics of China
1989, 4(3): 300-310.
Based on the data of gradient observation in the mountain areas during April 1983—March 1986 and taking into account the matched relationship among sunlight, heat and water resources, an estimation model is established for the climatic productivities of crops in the different elevations, slope orientations and mountain areas. In the model, meteorological elements of temperature, precipitation and sunshine in the mountain are amended, and the climatic productivities of rice, corn and winter wheat are estimated. The results show that in generally, in the hilly and mountainous areas in the east of subtropics of China, climatic productivities of single cropping of rice, double cropping of rice and summer corn in the south of slope orientation are higher than in the north, and those in the west of slope orientation are higher than in the east. Climatic productivities of spring corn and winter wheat in the north slope are higher than in the south, and those in the east slope are higher than in the west. Climatic productivity of late double cropping of rice is higher than early rice, that of summer corn is higher than spring corn (except for the Shen–Nong Jia mountain). It is necessary to point out that the high output of rice in some typical sites can come to over 60 percent of climatic productivity, while the outputs of corn and winter wheat are only about 30—50 percent of their climatic productivities. It is shown that the potential of agroclimatic resources exploitable in the mountain areas is still rather high. The quantitative results in this paper would be useful for the efficient exploitation of climatic resources, the rational adjustment of agricultural distribution and the enhancement of yield per unit area in mountain areas.
A Study on the Theoretical Bases and Technological Gists for Hail Suppression by Explosion
1989, 4(3): 311-318.
After the analysis of effective facts reported by scientists of China and USSR in the experiments of hail suppression, an obvious impression has been built. This point is that the explosive effect may play an important role except that of ice–crystallization by seeding. Therefore, the research of explosion effects on the meteorological phenomena has been emphasized in China and USSR. Some important results of this study can be enumerated as follows: The force effect on the airflow at the surrounding of explosion point which may damp the airflow at the speed of 3—4 m/s to zero. The lubrication effect on the motion regime of precipitation particle in the air which may lead on to the increase of fallspeed of hailembryo. There is a region whthin the hailcloud where the hailstone’s traveling trajectories of large hailstones in the growth processes appear to concentrate, and the relatively horizontal wind speed is equal to zero in the direction of hailcloud motion. From above, the technological gists of hail suppression by the method of explosion have been suggested briedfly
An Evaluation of Typhoon Operational Forecast in China
1989, 4(3): 319-327.
In this paper, using the typhoon data during 1985—1987, the current operational forecasting status has been evaluated. Also, the errors of the typhoon forecasting with different methods for the moving direction and speed have shown. According to the verification of typhoon forecast, the names of arrangement in the order of their scores have been given. Therefore, the forecasters could be to understand the performance for the methods and to improve the operational forecast.