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• SOME SURFACE PROPERTIES OVER THE HEIHE RIVER BASIN DERIVED FROM AVHRR DATA
• Wei Li;Zhong Qiang
• 1989 Vol. 8 (3): 189-194. 
• Abstract ( ) PDF (942KB) ( )
• In this paper some surface properties over the Heihe River Basin are derived from the AVHRR data of July 13, 1983. The spatial variations of the visible and near-infrared reflectances and the brightness temperatures in the infrared window are analyzed; Some radiative properties for some different underlying surfaces are discussed in detaili; Finally we compare the results from the satellite with those from the ground measurements.

• CALCULATION AND STUDY OF DIRECT SOLAR RADIATION FROM THE CLEAR SKIES OVER THE QINGHAI-XIZANG PLATEAU
• Sun Zhian;Xia Yun;Weng Duming
• 1989 Vol. 8 (3): 195-204. 
• Abstract ( ) PDF (625KB) ( )
• According to the data from the scientific experiment of meteorology in the Qinghai-Xizang Plateau from May to August in 1979, the questions have been studied concerning the direct solar radiation from clear skies (DSRCS) over the Qinghai-Xizang Plateau by use of Kast-rov's formula. First of all, the daily-averaged irradiance of DSRCS are determined by means of the data which are elected from the original records and are the values from the clear skies, and with these values obtained as a basis all values of C, a coefficient that appears in Kastrov's formula, are found out by means of the iterative technique for individual stations and months. Then, the empirical expression related C to vapor pressure is worked out. Finally, the DSRCS can be satisfactorily retrieved by use of this expression. In addition, the differences between the possible direct solar radiation determined by use of the wucraintzev approach and the measurements from clear skies are shown in the paper and it is proved that the former is greater than the latter and that the differences reduce as the elevation of the stations rises. In the end of this paper, the geographical distributions of the daily-averaged irradiance of DSRCS over the Qinghai-Xizang Plateau are discussed and the variation of the DSRCS with elevation is analysed.

• NUMERICAL SIMULATIONS OF INFLUENCES OF DIFFERENT THERMAL CHARACTERISTICS ON GROUND SURFACE OF TIBETAN PLATEAU ON THE OVER SE-ASIA
• Liu Xiaodong;Luo Siwei;Qian Yongfu
• 1989 Vol. 8 (3): 205-216. 
• Abstract ( ) PDF (841KB) ( )
• In this paper we have performed numerical experiments of influences of different heating characteristics on ground surface of Tibetan Plateau on the general circulations over SE-Asia using a limited area five-layer primitive equation model with topography and combined P-σ vertical coordinates. The results show that the heating effects enhanced by the albedo, drag coefficient, evaporation coefficient and the ground temperature, can strengthen the atmospheric heating source over Tibet Plateau as well as Bengal region considerably. It causes the Tibet High on upper level of troposphere to strengthen and advance northwestward, tropical easterly jet to intensify and shift northward, the SW monsoon on lower troposphere to enlarge, both the Somali jet and cross-equatorial flow south of India and north of Australia to enhance, and the sea-level low on land to be deepened as well. Meanwhile, over Indo-China peninsula and valleys of both Yangtse River and Huai He, the upward motion becomes stronger and precipitation gets heavier, but over SE coast of China, the reverse is true.

• COMPARISON EXPERIMENTS OF KUO TYPE CUMULUS PARAMETERIZATION SCHEMES AND LATENT HEATING EFFECTS
• Qian Zhengan;Yan Hong;He Chi
• 1989 Vol. 8 (3): 217-227. 
• Abstract ( ) PDF (765KB) ( )
• In this paper a nested fine mesh model under complex terrain condition and the FGGE level-IIIb data in 1979 were utilized to conduct some comparison experiments of both vertical heating distribution functions and moistening coefficients of Kuo type cumulus parameterization scheme for a chosen case with heavy rain. The effects of condensation latent heating were also analysed. The results show the θ1e difference scheme is the best one in four kinds of vertical heating distribution functions chosen in the paper. Its main heating appears at upper layer of troposphere, it causes the air columns to become stable gradually, suppresses the developments of cumulus convection finally, and has a good performance. The section-to-section linear function scheme is the best in three kinds of moistening coefficients chosen here. The calculated moistening coefficient, b, according to it is reasonable and has a good forecast as well. Heating of condensation latent heat of water vapour will make mean temperature of air columns rise, upward motion intensify, air flow converge and pressure decrease on lower troposphere, air flow diverge and pressure increase on upper troposphere.

• THE BASIC METHOD OF FORECASTING YEARLY PRECIPITATION WITH SOIL TEMPERATURE
• Zhou Yajun;Tang Maocang
• 1989 Vol. 8 (3): 228-240. 
• Abstract ( ) PDF (729KB) ( )
• This thesis devises a qualitative method which forecast yearly precipitation in whole country with soil temperature anomalies (T' _3.2) at 3.2m. It's basic point is calculating the yearly variation of the heat conductivity of soil and the values of forecasting period τ by formula ^[1]τ=π·Z _m ²/K _S. So, for a certain year's precipitation forecasting,we can use T' _3.2 at previous different periods, and then put them on the same figure. At last we analyse the axes of maxima and minima of soil temperature anomalies which is corresronding to the axes of precipitation maxima and minima during forecasting year. By the results of 1982-1987 year, the ratio of the same symbol between T' _3.2 and precipitation anomalies, for the whole country, is 0.71, if northeast area is not included, it's ratio is 0.73.

• NUMERICAL SIMULATION OF PHOTOCHEMICAL SMOG POLLUTION OVER XIGU INDUSTRIAL AREA OF LANZHOU CITY
• Yu Jinxiang;Qiu ChongjianChen;Changhe;Huang Jianguo
• 1989 Vol. 8 (3): 241-251. 
• Abstract ( ) PDF (687KB) ( )
• An air quality model with Semi-Lagrangian type has been developed in this paper. Except for considering the processes of transfer and diffusion of air pollution matter, the model covers the photochemical reaction effects as well. Using the model and monitored data for photochemical smog in Xigu industrial area of Lanzhou city for 6 days of August, 1983, the numerical simulation was run. The results show that the model has a quite good ability to simulate maximum concentration of O ₃ and certain ability to simulate the daily variations and geographical distributious of O ₃ concentration in the area.

• THE STATISTICAL FEATURES OF MESOSCALE-α CONVECTIVE CLOUD CLUSTERS OVER SUBTROPICAL HUMID REGION OF CHINA IN SUMMER
• Chen Qian
• 1989 Vol. 8 (3): 252-260. 
• Abstract ( ) PDF (588KB) ( )
• In this paper the enhanced infrared images of satellite GMS with three hours interval during the period of from May to early September in 1984-1986 are used in order to analyse the statistical features of cloud clusters. Based on smaller area of cloud clusters over China definition of the MCC given by Maddox is modified. Their size (cloud shield with IR temperature≤-33 ℃) is reduced from 100000 km ² to 50000km ². 168 mesoscale-α convective cloud clusters (M _αCCC) over subtropical humid region of China are selected. Their features of temporal and spatial variation have been analysed. The results show that the distributions of monthly genetic and apparent frequences of M _αCCC and their variations are related to both Tibetan Plateau and large scale circulations. The comparison of 55 typical M _αCCCs over China with 69 midlatitude MCCs over U. S. A. shows that daily variations of both are similar but the weather and circulation of M _αCCCs is very different from MCCs.

• RADAR EQUATION SUITABLE TO THE BOUNDARY REGION OF PRECIPITATION FIELD AND THE EFFECTIVE LIMITS OF A RADAR BEAM
• Zhuang Yinmo;Cheng Zhenrong
• 1989 Vol. 8 (3): 261-272. 
• Abstract ( ) PDF (710KB) ( )
• For the demands of studying the rules of returned echo distribution, distortion detective resolution and so on of a digitized radar, a weather radar equation suitable to the boundary region of precipitation field was developed.The new equation has been on the bases of considering unisotropically transmitted energy and for both of within and without the beam width between half-power points in contrast with the convention which was on an assumption of isotropically transmitted energy within half-power beam width only. For model 713 weather radar as an example,the calculations of the effective limits of a radar beam have been done with the new equation considering a given detective accuracy when the radar beam is totally within a precipitation field or a detectable echo intensity when the radar beam is near a boundary region of precipitation. The results were useful for analysing and utilizing radar observation data.

• STEADY STRATUS CLOUD'S DROPLET SPECTRUM EQUATION DERIVED FROM ENTROPY PRINCIPLE
• Zhang Xuewen;Zheng Guoguang
• 1989 Vol. 8 (3): 273-278. 
• Abstract ( ) PDF (364KB) ( )
• According to observational study, the distribution of the dropletd size of the steady stratus cloud normally has a steady figure. This droplet spectrum has a prevalent distribution with single peak and a skew feature. From a statistical physics viewpoint, if a system is in a steady state, it means this system arrives a equilibrium state and at the same time, some entropy which is responsible for the equilibrium state would reach to its maximum value. The entropy mentioned in the paper is the entropy correspond to the surface free energy of the cloud droplet (information entropy, not thermodynamic entropy) . We had derived a formula of the droplet spectrum for steady stratus which based upon the maximized entropy of the droplet's surface energy. This deriving process is quite similar with the deriving of the Maxwell's velocity distribution, from the maximized entropy of the kinetic energy of those molecules. It has been verified that this equation (the formula (11)) was consistent with the observed droplet spectrum from steady stratus clouds.

• STUDY OF THE CHARACTERISTICS OF HAIL SIZE DISTRIBUTION
• Shi Anying;Sun Yuwen;Tian Zhixi
• 1989 Vol. 8 (3): 279-283. 
• Abstract ( ) PDF (280KB) ( )
• In this paper, 315 sets of hailpad data from Zhangjiakou area in 1986 were analysed and fitted statistically to six patterns of the hail size distribution, i. e., exponential function, compound function A and B, logarithmic function, hyperbolic function and Γ-function. All data of the six patterns were successfully tested with correlation method. The results compared with that by Ryde et al. showed a discrepancy of 2-3 orders of magnitude for most data except for exponential function pattern which presented larger deviation.

• THE RELATIONSHIP BETWEEN THE HEAT DIFFERENCE OVER TIBETAN PLATEAU-EQUATOR EAST PACIFIC AND THE DROUGHT OR WATERLOGGING DURING FLOOD SEASON IN SHANXI PROVINCE
• Xu Yuxiang;Li Jianjun
• 1989 Vol. 8 (3): 284-288. 
• Abstract ( ) PDF (291KB) ( )