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• GENERAL FORMS OF DYNAMIC EQUATIONS FOR ATMOSPHERE IN GRID NUMERICAL MODELS WITH TOPOGRAPHY(Dynamic Equation Forms for Atmosphere)
• Qian Yongfu;Zhong zhong
• 1985 Vol. 4 (1): 1-13. 
• Abstract ( ) PDF (841KB) ( )
• The atmospheric dynamic equations have been transformed from the z-coordinate system into a generalized verticcl coordinate system by using a so-called DDD transformation method.Then the generalized system is assumed being pressure, sigma or incorporated pressure-sigma coordinate system and corresponding equations are obtained with the second-order accuracy.It is pointed out that the usual equations are only of the first-order accuracy when their space-differential terms are approximated by central finite differences.Therefore the usual forms of the equations may result in quite large errors on steep slopes of mountains included in a model.

• THE DYNAMICAL AND SYNOPTICAL ANALYSIS OF THE EFFECT OF THE TIBETAN PLATEAU ON A CUT-OFF PROCESSES OF THE TROUGH IN MAY, 1979
• Luo Siwei;Wei Li
• 1985 Vol. 4 (1): 14-22. 
• Abstract ( ) PDF (637KB) ( )
• In this paper the synoptical and dynamical analysis has been made for a long westerly trough passing through the plateau in the period of 19-24 May, 1979.Some physical parameters are calculated and the physical processes of the westerly trough cutoff by the plateau are discussed, too.The analysis point out that as the westerly trough is located west of the Plateau, the orography plays an evident role in splitting, not only to the west flow but also to the jet stream obove 300mb. The plateau's effects on the cut-off of westerly trough are mainly as follows: 1.The climbing effect of the windside, west of the plateau, weakens the trough. 2.The horizontal vorticity advection in the strong westerly flow to the north and south of the plateau is faster than that over the Tibetan Plateau, so the trough moves eastwards slower over the plateau. 3.Due to the shear vorticity turning into curvature vorticity, there is an anticyclonic vorticity generated at the north of the plateau, which makes the trough weaken further and move faster eastward, while the cyclonic vorticity at the south of the plateau makes the trough deepen more and move slower.

• EFFECTS OF THE HORIZONTAL RESOLUTION ON THE FORECAST QUALITY SN A NUMERICAL MODEL WITH TOPOGRAPHY
• Lu shihua;Qian Yongfu
• 1985 Vol. 4 (1): 23-33. 
• Abstract ( ) PDF (716KB) ( )
• The two-layer model developed by Qian et al.has been modified in this paper to study effects of the horizontal resolution on the forecast quality in a numerical model with topography. we made some comparative numeri-cal experiments by using the new versions of the Qian's model With different horizontal resolutions of 5°grid size and 2.5° grid size，respectively. The results show that the higher resolution version gives more realistic forecastings, it makes the speeds and the centers of weather systems closer to the real situations and can describe smaler systems better. The higher resolition and the realistic description of mountains are both important in improving forecastings.The higher resolution version requires more real istic configuration of topography than the lower resolution version in order to match itself.

• THE ATTENUATION OF SOLAR RADIATION IN ATMOSPHERE
• Wang Yaoqi;Shui Dengchao
• 1985 Vol. 4 (1): 34-45. 
• Abstract ( ) PDF (817KB) ( )
• Basing upon the data adopted by The 8th Plenary session of The commission for Instruments and Methods of Observation (WMO) concerning the solar spectral irradiation and also upon the newest material about the. spectral transparency coefficient of ozone and molecular scattering, we make computations on the radiant intensities in various atmosphere and also analysis on the influences of factors which make the direct solar radiation attenuated, and then present here a proper method in compitting the radiation of water vapour absorption and the radiation of aerosol scattering. For convenience in general use,a simple method for the computation of radiant intensities with sufficient precision is also eslablished. The computed values find a good result as compared with the abserved ones.

• ELECTRIFICATION PROCESS WITH ICE PHASE IN HAIL CLOUD
• Yan Muhong;Ge Zhengmo
• 1985 Vol. 4 (1): 46-56. 
• Abstract ( ) PDF (782KB) ( )
• From a lot of recent observations and studies including secondary ice crystal phenomena, we have computed the growth of electric field in cloud from observated hailfall intensity by using the inductive and non-indnuc-tive mechanism. In the model, we have also considered some suppression processes in inductive electrification process, such as downward shift of the electric neutral surface in electrification process,the multiple collission and long time constant for inductive charge transfer due to the low conductivity of ice surface.The results show that this suppression is very weak and the electric field can grow to breakdown value in strong hail cloud. The numerical results show that when the secondary ice crystal appears in hail cloud, for mechanism of surface electric potential difference and of secondary ice crystal electrification, the electric field can grow to breakdown value within a shorter time than that for the inductive mechanism. For about 4000v/m strong hail cloud, inductive and surface electric potential difference mechanism are dominant mechanism.The secondary positive charge region in lower part of cloud is caused by secondary ice crystal electrification.For weak hail cloud, the secondary ice crystal electrification is the dominant mechanism and there is no secondary positive charge region in cloud.

• A SYNOPTIC AND CLOUD PHYSICS ANALYSIS OF A COLD FRONT RAINSTORM
• Li Qitai
• 1985 Vol. 4 (1): 57-64. 
• Abstract ( ) PDF (1008KB) ( )
• A summery cold front rainstorm in western mountainous region of Guizhou was analysed with sounding，radar and cloud physical data by airplane observations.The potential instability before front is not large.The lower jet stream has evident daily variation. Vapor supplies and natural ice-crystal seeding from higher altitude above 4500m are important for the forming of rainstorm. A very large cloud-rain transforming rate is present at the top of rainstorm cloud.The consistency of large granules including ice-crystals and liquid-water content amount to maximum in the overcooling part of rainstorm cloud.But for the ordinary rain cloud, the maximum of above mentioned factors are present in the warm part of cloud.It seems that for the rainstorm the total content of large granule and LWC are unimportant, and the developing altitude of cloud are also not so significant as the thickness of overcooling part.Some effects of plateau topography for the rainstorm forming are also discussed.