Current Issue

• Q-VECTOR ANALYSIS FOR A PROCESS OF TROUGH OVER THE NORTH SIDE OF THE QINGHAI-XIZANG PLATEAU
• Yu Shuhua
• 1993 Vol. 12 (4): 337-441. 
• Abstract ( ) PDF (313KB) ( )
• By using Q-vector analysis for a process of the trough activity over the north side of the Qinghai-Xizang Plateau in July 24-29,1982,it is found the favorable results are:(1) there is a zone of Q-vector convergence(▽· Q ₅₀₀<0) on 500 hPa and a center or a range of Q-vector divergence(▽· Q ₂₀₀>0) on 200 hPa in front of the trough when the trough spreads southward over Plateau.(2) there is a center of cold frontogenetical area in south of the trough.(3) the maintenance and intensification of ascending motion and cold frontogenesis are important factors for the trough spreading southward over the Qinghai-Xizang Plateau.

• INFLUENCE OF SNOW COVER IN WESTERN CHINA ON PRECIPITATION IN THE FLOOD PERIOD IN CHINA
• Wei Zhigang;Luo Siwei
• 1993 Vol. 12 (4): 347-354. 
• Abstract ( ) PDF (584KB) ( )
• In this paper the monthly data series of snow cover in western China for 30 years have been built by satellite and ground data.It is the best and longest at present and has supplied better base to study monthly and annual variations.The correlation coefficients between the snow cover in winter and spring in western China and the precipitation during flood period are negative in the mean.Its distribution in June is more regular.When the snow in winter and spring is more(less),the precipitation in June is less(more) in the southern of China,the Qinghai-Xizang Plateau and the upstream of Yangtze River,and more(less) in the other area.When geopotential height at 500 hPa in June in more(less) snow years is dropped(risen) over northern Qinghai-Xizang Plateau,risen(dropped) over subtropic,and this is(not) advantageous to the cold air in high latitude area moving southward and the subtropical ridge moving westward and northward.Then the precipitation increase(decrease) in north of the midstream and downstream of Yangtze River,and decrease(increase) in the southern China,the Qinghai-Xizang Plateau and upperstream of Yangtze River.

• SOME CHARACTERISTICS OF THE MESO-SCALE INTENSE RAIN-BAND IN THE MEI-YU SEASON
• Li Yunfei
• 1993 Vol. 12 (4): 355-360. 
• Abstract ( ) PDF (432KB) ( )
• In this paper,by using the data of the conventional weather maps,the radiosonde sounding,weather radar and actual precipitation,the activity characteristics of the meso-scale intense rain-band in the process of 6 heavy rainfall events have been analysed in the Mei-Yu season of 1991.Some significant results are obtained.

• NON-LINEAR ROSSBY WAVES IN THE ZONAL SHEAR BASIC FLOW
• He Jianzhong;Guo Pingwen
• 1993 Vol. 12 (4): 361-366. 
• Abstract ( ) PDF (325KB) ( )
• In this paper,base on the semi-geostrophic approximation,the non-linear Rossby waves in zonal shear basic flow are discussed,and the conditions of shear basic flow with a wave sloution and initial perturbation are gained.

• THE SEASONAL VARIATION OF ATMOSPHERIC RADIATIVE HEATING FIELDS OVER THE QINGHAI-XIZANG PLATEAU
• Gu Benwen;Ji Guoliang
• 1993 Vol. 12 (4): 367-377. 
• Abstract ( ) PDF (724KB) ( )
• In this paper,a radiation and cloud parameterized model newly developed in the Department of Meteorology,University of Utah,U.S.A.has been used to compute the atmospheric radiation fluxes and heating rate from August 1982 to July 1983 at Garze,Nagqu,Lhasa over the Qinghai-Xizang Plateau and Nanjing in the eastern plain.Analyses of the seasonal variation characteristics of atmospheric radiative heating fields over the Plateau and relations with weather and climate,and simple discussion of a few main factors affecting atmospheric radiative properties,are also presented.

• NUMERICAL SIMULATION FOR TARGET AREA OF PRECIPITATION STIMULATION IN WARM STRATUS
• Sun Xudong;Qin Ying;Liang Gu
• 1993 Vol. 12 (4): 378-383. 
• Abstract ( ) PDF (431KB) ( )
• In this paper,the microphysical rule for devolopment and variation of stratus precipitation,and the areas of precipitation increasing by salt-seeding are simulated by using two-dimension non-stationary numerical model.Then the impact and method of precipitation stimulation are studied and some valuable results are gained.

• THE DISTRIBUTION OF THE HIGH AND LOW PRESSURE CENTRES IN THE LOWER STRATOSPHERE
• He Huixia;Qu Zhang
• 1993 Vol. 12 (4): 384-391. 
• Abstract ( ) PDF (523KB) ( )
• In this paper,the northern hemisphere stratospheric data of the Meteorological Institute,Free University Berlin,Germany,have been used to analyse the high and low pressure centres at monthly mean map for each month over 20 years,and then to count statistically its frequency on each latitude zone and its frequency on the block areas.The two main results are as follows:(1) In the lower stratosphere of the northern hemisphere,the centres of high pressure prefer to occur over the polar region in summer;the centres of low pressure also prefer to occur over the polar region in winter.These facts,connect with seasonal transition of the large-scale westerly and easterly wind system,the out of the phase of very intense seasonal transition is formed in the lower stratosphere.This seasonal transition of large-scale wind system called stratospheric monsoon.(2) In winter the centres of high pressure in the lower stratosphere prefer to occur over the Pacific etc.,this fact reminds the difference heating by the land and sea,and can reflect in the lower stratosphere which is adjacent to the troposphere,too.

• COMPARISON BETWEEN LOCATION METHODS OF THE PIXEL ON CLOUD IMAGE OF THE GEOSTATIONARY SATELLITE
• Zhong Xiaoping
• 1993 Vol. 12 (4): 392-399. 
• Abstract ( ) PDF (548KB) ( )
• Supposing the accuracy of the grid data for navigation sent by the geostationary satellite GMS-4 is acceptable,location methods are analysed and compared by means of mathematic principle,the sequence of 2-dimension interpolation,and the effect of location.It is discovered that non-linear interpolation have an advantage over the linear interpolation.Error produced along the longitude from linear interpolation is small so that it is reasonable to omit it.But the error along the latitude is very obvious.In the region between 90°-120°E,and 0°-50°N error increases from southeast to northwest.This error is greater than 2 pixels in most of the area.The maximum is greater than 4 pixels,located at 47.5°N,90°E.

• STUDY ON MICROMETEOROLOGICAL CHARACTERISTICS OVER WHEAT FIELD AND SAND DUNE AT NAIMAN,INNER MONGOLIA,CHINA
• Li Shenggong;Yoshinobu HARAZONO;He Zongying;Shen Jianyou
• 1993 Vol. 12 (4): 400-408. 
• Abstract ( ) PDF (595KB) ( )
• In this paper,the micrometeorological characteristics and the heat budget over the wheat field and the sand dune in Yaoledianzi village,Naiman,Inner Mongolia are analyzed.The results show that:(1) Albedo for the wheat field and the sand dune is about 21% and 34%,respectively.(2) Over the wheat field,about 60% of the net radiation in daytime is spent for the latent heat flux,and about 41% of the net radiation at night is supplied by the latent heat flux,about 35% by the soil heat flux.Over the sand dune,48% of the net radiation in daytime is spent for the soil heat,and about 52% of the net radiation at night is provided by the soil heat.(3) Bowen ratio in the early morning and at night is higher than that in daytime.(4) The ratio of the wind speed( u ₅),at the lowest measurement site to that( u ₁) at the highest site is higher in daytime than at night,and higher over the sand dune than over the wheat field.Ratio of the friction velocity( u _*) to the wind speed( u ₁) is lower in daytime than at night,and lower over the sand dune than over the wheat field.

• ON TEMPORAL AND SPATIAL DISTRIBUTION OF THE OPTIMAL TILT ANGLE FOR GLOBAL RADIATION
• Zhu Chaoqun;Ren Xuejuan
• 1993 Vol. 12 (4): 409-417. 
• Abstract ( ) PDF (588KB) ( )
• In this paper,the temporal and spatial variations of the optimal tilt angle for daily total of global radiation in months are analysed based on the insolations on the horizontal surface and albedo measured from fifty-five stations with its analytical expression given before.The main results are found as following:(1) Annual averaged errors of the optimal tilt angles are less than 1.7 and the mean errors of the global radiation amount on the tilted surfaces at the optimal tilt angles are about 0.4% for the all stations.(2) The isotimics of the optimal tilt angles are essentially parallel to the latitude circle,however that is not true in the cloudy areas especially in Sichuan,Guizhou and Guangxi provinces,even they take south-north direction.Therefore it is necessary to take account of the effects of clouds on the optimal tilt angles when they are estimated.(3) The isotropic model is applicable for estimating the total of global radiation falling on the surfaces tilted towards the equator.

• 2-3 WEEKS OSCILLATION OF SNOW COVER IN WESTERN CHINA AND ITS INFLUENCE ON ATMOSPHERIC CIRCULATION ANOMALIES OVER NORTHERN HEMISPHERE
• Liu Xiaodong;Wei Zhigang;Chen Baode;Jin Jiming
• 1993 Vol. 12 (4): 418-424. 
• Abstract ( ) PDF (495KB) ( )
• In this paper,analysis of snow cover data during 1979-1986 in western China which were derived by NASA from SMMR show:(1)2-3 weeks oscillation exists widely in the 8 years.(2) The oscillation is closely associated with atmospheric circulation anomalies and the linear responses of general circulation to the 2-3 weeks oscillation are very clear in winter.(3) The 2-3 weeks oscillation of snow cover in western China can motivate quasi-permanent Rossby waves at 500 hPa geopotential height field over northern hemisphere and affect atmosphere over North America by energy dispersion of two-dimensional Rossby waves.

• MULTI-STEP FORECASTING MODEL OF TEMPERATURE AND PRECIPITATION BASED ON THE TIME-VARYING INFLUENCE PARAMETER
• Li Zuoyong;Zhang Huijun
• 1993 Vol. 12 (4): 425-431. 
• Abstract ( ) PDF (426KB) ( )
• In this paper,a new multi-step forecasting model of temperature and precipitation series based on the time-varying influence parameter is presented.The approach is based on to consider the influence of the earlier stage values on later stage values.Time-varying parameter K _t is introduced into the model of principal component generated by mean generating function of temporal sequence.The multi-step forecasting model of temperature and precipitation series is developed by the time-varying parameter values K _j+1 calculated with significance periods of K.The models are used to multi-step forecasting of temperature and precipitation in 20 regions of Sichuan.The comparison of fitting test and forecasting results with real values show that this model can be used in multi-step forecasting of time series variate.

• DISTRIBUTION REGULARITY OF PRECIPITATION INTENSITY AND DURATION OVER AN AREA
• Ma Li;Sha La Mai Ti
• 1993 Vol. 12 (4): 432-436. 
• Abstract ( ) PDF (331KB) ( )
• The relationship among the duration the area and the depth of the hard rain is a important research subject in hydrometeorology.Recently,the two negative-index relations have been deduced by the principle of the maximum entropy and confirmed by a lot of observation.In this paper,it is found from analyses for 5 examples that the another two sets of variation in precipitation process obey negative-index relation,too.Namely,the relationship between the different precipitation duration and its area and the relationship between the different precipitation intensity and its area both obey all the negative-index relation.The two sets of new relation are practical worth on the hard rain forecast.

• PRELIMINARY STUDIES ON THE INITIAL ICE CRYSTALS IN SUPERCOOLED CLOUD TUNNEL
• Zhou Yunjun;Gong Naihu
• 1993 Vol. 12 (4): 442-449. 
• Abstract ( ) PDF (524KB) ( )
• This paper describes some characteristics of initial ice crystals whose growth time is within 45 s at a liquid water content of 1.4 gm ^-3 between -4℃ and -16℃ in a supercooled cloud tunnel.The results show that:(1) There are two maximum mass values of the initial ice crystals between -4℃ and -13℃.One is 1.8×10 ^-8 g at -5.7℃;the other is 6.3×10 ^-8g at -11.4℃.There are two minimum values:2×10 ^-9g at -8.4℃,5×10 ^-9g at -13.0℃.(2) There are three maximum concentration values of the initial ice crystals.With the temperature lowering,the values are reducing.They are 1.30×10 ⁷cm ^-3 at -4.2℃,7.8×10 ⁶cm ^-3 at -7.6℃ and 4.54×10 ⁶cm ^-3 at -13.8℃,respectively.(3) The maximum aggregation rate of the initial ice crystals is 12/30 at -8℃.(4) The condition of the absorbed water molecules is same at six axes(a _1-6) on the basal face of ice crystals at vapor diffusion growth stage.If X _CBal-6> X _CPal-6,regular plate crystals should grow;while X _CBal-6< X _CPal-6,the initial ice crystals should be regular columnar crystals.

• STUDY OF DROUGHT,FLOOD AND PRECIPITA-TION TREND IN MONGOLIA FOR LAST 52 YEARS
• Ma Xiaobo
• 1993 Vol. 12 (4): 450-457. 
• Abstract ( ) PDF (496KB) ( )
• In this paper,drought,flood and precipitation trend are studied by using month by month precipitation data for last 52 years(1940-1991) at 25 stations in Mongolia.The results show:mean annual precipitation is 216.1 mm,southern and western parts are arid zone,middle and eastern parts are semi-arid zone;annual precipitation variability is 15.6%-38.0%.It is shown that both drought and flood are very frequent in Mongolia.The frequency of drought is higher then the flood,the frequency of severe flood is the two times of the severe drought.Annual precipitation distribution is normal distribution,and it has the quasi-three years and 11-14 years periods.Annual precipitation increases about 0.34 mm/decade years.Annual precipitation increases in the rate of 5.13 mm/year in 1980's and it continue increases in 1990's.