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• DISCUSSIONS IN THE CLIMATOLOGICAL METHODS OF CALCULATING THE GLOBAL SOLAR RADIATION OVER THE QINGHAI-XIZANG PLATEAU AREA
• Zhong Qiang
• 1986 Vol. 5 (3): 197-210. 
• Abstract ( ) PDF (850KB) ( )
• l. In this Paper, the climatological methods of calculating the global solar radiation over the Qinghai-Xizang Plateau area are discussed based on the surface observation data of global solar radiation over this area during the period of Aug.l982-July 1983 and the two-stream appoximation model calculations. 2. Monthly global solar radiation in cloud-free sky for different surface elevations and albedos have been calculated and given for 24°-46°N. 3. Distribution maps of global solar radiation in cloud-free sky for Qinghai-Xizang Plateau area(January, and July) are also shown in this paper.

• A NUMERICAL EXPERIMENTAL STUDY ON THE TRANSFER OF SOLAR RADIATION IN CLOUDY ATMOSPHERE
• Li Yinhai;Zhong Qiang
• 1986 Vol. 5 (3): 211-225. 
• Abstract ( ) PDF (1047KB) ( )
• Based on the radiation model of two-stream approximation(Hense et al. 1982) this paper has investigated the effect of cloud on the solar radiation budget of the earth-atmosphere system and the heating rate of the atmosphere. The reflection and absorption of the clouds having various optical depth is discussed. This model has also been applied for the Plateau Model Atmosphere to investigate the effect of cloud on the solar radiation budget over the Plateau area. The absorption of cloud droplets and aerosol is included in the computation. The vertical distributions of the aerosol attenuation coefficients are adopted in two types, corresponding to visibility of 23km and 8km, respectively. It is shown that the heating rates of the cloud layer having optical depth 10-100 can reach 7-8℃/day. The absorption of cloud droplets and aerosol is an important mechanism for increasing heating rate in cloud layer. The cover of cloud layer has a great influence upon the neatiog rate near earth's surface. The reflectance of the cloud having various optical depth can vary within the range 0.24-0.90 coinciding with observation results basically. The absorptance of the cloud can vary within the range 0.07-0.25.Aircraft observations reveal that the absorptance of the cloud can reach 0.30-0.40. The mechanism responsible for this large absorption remains to be studied in depth. The ratio of the global radiation at the earth's surface in cloudy sky to that in clear sky(Q _c/Q ₀) is determined mainly by the cloud optical depth (corresponding to cloud optical depth increasing from 1 to 100 the ratio Q _c/Q ₀ decreases from 80% to 10%) and secondly by the solar zenith. The ratio Q _c/Q ₀ is much less influenced by the aerosol, surface altitude and cloud altitude and therefore is a adoptable parameter representing the influence of the cloud on the global radiation at the earth's surface.

• NUMERICAL EXPERIMENTS OF THE EFFECTS OF WATER VAPOUR AND MOUNTAINS ON THE TRANSITION OF FROM BREAK TO ACTIVE MONSOONS OVER INDIA
• Li Jun
• 1986 Vol. 5 (3): 226-235. 
• Abstract ( ) PDF (731KB) ( )
• A P-σ incorporated coordinate numerical model was used in this paper to investigate further the effects of-water vapor and mountains on the transition process from break to active Indian Monsoons following the paper [4]. The simulated results show the diabatic heating processes of wet air plays an important role in the change of from break to active Indian Monsoons, and there are more active monsoon and more precipitation in the experiment with mountains than without. If the amount of water vapor in model atmosphere is reduced or mountains are removed in the experiments, the simulated results is quite difference from the ones under the actual vapor amount and mountain, conditions while the latter is more similar to real monsoon transition. Especially in the run with a litter water vapor amount, the initial fields, which was characterized by break monsoon circulation, still have no large changes.

• A COMPARATIVE ANALYSES ABOUT INFLUENCES OF THE DIFFERENT ALBEDO OVER THE TIBETAN PLATEAU AND ITS NEIGHBOURHOOD UPON ATMOSPHERIC CIRCULATION OF EAST ASIA IN MAY
• Luo Siwei;Li Weijing;Tang Zhuqiang
• 1986 Vol. 5 (3): 236-244. 
• Abstract ( ) PDF (579KB) ( )
• A P-σ incorporated vertical coordinate 5-layer limited area primitive equation model was used in this paper to simulate the different albedo over the Tibetan plateau and its neighbourhood in May. The results indicate that changes of general circulation over East Asia in May are obvious when the albedo over the plateau increase and thus heating effect of the plateau decreases. For instance, the 100hPa subtropical westerlies jet shif-tes from north side of the plateau to its south. The air flows at the lower troposphere that converge toward the plateau are weakened remarkably, the "quasi-monsoon cell" at the lower troposphere to the south of the plateau is weakened and lower, and the shear-line to east side of the plateau moves southward. These results show the importance of thermal effect of the plateau on general circulation over the East Asia.

• AN NUMERICAL EXPERIMENT OF THE EFFECT OF TIBETAN PLATEAU ON A SYNOPTIC SYSTEM IN ITS NEIGHBOURHOOD
• Li Weijing;Luo Siwei
• 1986 Vol. 5 (3): 245-255. 
• Abstract ( ) PDF (714KB) ( )
• In this paper, a P-σ incorporated coordinate 2-layer adiabatic limited area numerical model is used to simulate a long westerly trough passing through the Plateau during the period of 19-24 May, 1979. We made some parallel numerical experiments by using the model with different horizontal resolutions of 5°and 2.5°grid size,respectively. The results show that mechanical effect of Tibetan Plateau not oney influences intensity and movement of westerly trough but also cut-off the troughs over west side of the Plateau. Some meso-scale systems can be produced to north and east side of the Plateau, such as the shear lines and southwest low vortexes to east side of the Plateau, and the weak high pressure north of the Plateau.

• POLARIZED SCATTERING PROPERTIES OF SPHEROIDAL RAINDROPS AND HAILS FOR 5 cm BAND
• Cai Qiming;Wu Aisheng;Ye Zongxiu
• 1986 Vol. 5 (3): 256-270. 
• Abstract ( ) PDF (872KB) ( )
• Stokes scattering matrix is an useful method for description of the polarized properties of electromagnetic waves. The computational results on the matrices for spheroidal raindrops and hailstones at 5cm wave band have been shown in this paper by making use of the Extended Boundary Condition Method. With rotatively symmetric axes of hydrometeors orienting preferentially along vertical direction and the antenna elevation angle unequal to zero, only 4 independent elements of the matrix have been found in the scattering plane OXZ although 16 non-zero elements are possible in the plane OYZ. It is shown that the scattering characteristics of spheroidal raindrops in the side and backward directions are similar to those of the spheres when their equivalent diameters are less than 0.2cm. This feature may be held up to even larger particles for ice spheroids. The scattering polarizations of hydrometeors become remarkable and the differences between ice and water spheroids appear to be evident, in particular for the elements σ ₃ and σ ₄, when the size and ellipticity of the particles increase.