Current Issue

• A STUDY OF THE RELATION BETWEEN RAININESS, EXTINCTION OF RAIN CLOUD AND PARAMETERS MEASURED BY A DUAL LINEAR POLARIZATION RADAR
• Cai Qiming;Xu Baoxiang;Liu Liping
• 1990 Vol. 9 (4): 347-355. 
• Abstract ( ) PDF (540KB) ( )
• Aimed at developing a dual linear polarization radar, we have calculated backscattering, extinction and absorbing cross sections of oblate spheroidal raindrops by using the extended boundary condition method. The scattering intensities and the differential reflectivities ( Z _DR) for different hydrometeors with any spectral parameters have been obtained. We have also given the relationships between rain rates, extinction coefficients and the parameters measured by the dual linear polarization radar. This work has laid the foundation of quantitative measurement of rain rate and the discussion of extinction properties of radar wave in rain clouds.

• THE RELATIONSHIP BETWEEN PERSISTENT WARM ADVECTION IN THE STRATOSPHERE AND BLOCKING SITUATION IN FEBRUARY 1979
• Li Ziqiang;Gao Youxi;Qu Zhang
• 1990 Vol. 9 (4): 356-363. 
• Abstract ( ) PDF (533KB) ( )
• The FGGE gridded data in February 1979 are used in this study to analyze and diagnose the relationship between stratospheric persistent warm advection and blocking situation. The study shows that before the developing of the 500 hPa ridge, stratospheric strong warm advections to the west of the ridge have already occurred for at least more than ten days. They cause the persistent situations of warm advections decreased with height in the troposphere, the strong upward motion extended from troposphere to stratosphere and tilted westward with height, the strong divergence occurred to the rear of the ridge in upper troposphere and lower stratosphere, and result in the blocking event. Namely, the persistent stratospheric warm advections may provide the favorable conditions of formation and maintenance of blocking pattern.

• APPROACH ON THE UNDERGROUND SUDDENLY WARMING RELATIVE TO SHORT-TERM CLIMATIC VARIATIONS
• Tang Maocang;Zhang jian
• 1990 Vol. 9 (4): 364-370. 
• Abstract ( ) PDF (451KB) ( )
• After analysing the Chinese soil temperature data as deep to 3.2 m depth in 1954-1985, it is found that the underground temperature has a abrupt arising in some times and in some places, which can't be explained by the rising of surface ground temperature. The duration of abrupt warming is about 0.5-2 years. When the scale of "abrupt warming region" is larger than 103 km, the yearly precipitation will be abundant in the warming region.

• DISTRIBUTION CHARACTERISTICS OF DIRECT SOLAR RADIATION ON MOUNTAIN SLOPES IN CHINA
• Sun Zhian;Shi Bing;Weng Duming
• 1990 Vol. 9 (4): 371-381. 
• Abstract ( ) PDF (676KB) ( )
• In this paper the formula for calculating direct solar radiation on mountain slopes is changed into S _αβ= S'· K _αβ via simple conversion, where S' is the daily averaged irradiance of the direct solar radiation on the horizontal surface; K _αβ the conversion coefficient of the direct solar radiation on the slopes. The emphasis is mainly placed on variation characteristics of K _αβ with slope directions, slope angles, latitudes and seasons. The expressions for calculating the degree of the hottest slope on south and north sides are presented. Finally, the daily averaged irradiance of the direct solar radiation on the slopes in various months throughout the year is computed for 211 stations throughout China and their distribution patterns are analyzed by taking 20° of south slope as the example.

• TURBULENT SPECTRAL CHARACTERISTICS OF THE STABLE ATMOSPHERIC BOUNDARY LAYER OVER A BASIN TERRAIN
• Yang Lirong;Ren Zhenhai
• 1990 Vol. 9 (4): 382-387. 
• Abstract ( ) PDF (377KB) ( )
• To investigate the influence of the terrain on the turbulent structure, the turbulent characteristics under light wind and stable atmospheric boundary layer conditons over a basin terrain has been examined using wind and temperature fluctuation data obtained with a kytoon-mounted ultrasonic anemometer-thermometer system in the winter of 1986 at Chengde Atmospheric Observatory in North China. The result shows that in the inertial subrange, the logarithmic spectra of velocity components u, w and temperature T fall as f ^-2/3, which agree with Kolmogorov's local isotropy theory. The logarithmic spectrum of lateral velocity component v has an exceptional case. The logarithmic cospectra uw and wT fall as f ^-4/3. The behavior of the reduced peak frequency f _m shows that the turbulence range moves toward high frequency due to the terrain influence. The heavily dependence of spectra or cospectra on height, which exists in flat, uniform, and open underlying surface, disappears in the complex terrains.

• THE CHARACTERISTICS OF GROUND FLASHES IN BEIJING AND LANZHOU REGIONS
• Qie Xiushu;Guo Changming;Liu Xinsheng
• 1990 Vol. 9 (4): 388-394. 
• Abstract ( ) PDF (459KB) ( )
• Over twenty thousand lightning location data from Lanzhou region and Beijing area have been analysed.The ratio of positive flashes and total ground flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negtive flashes in Beijing and in Lanzhou, respectively.The peak flash rate oc-cured in late afternoon for both area, but the maximum and minimum flash rate appeared one hour earlier in Beijing than in Lanzhou. The relationship between DF display and lightning radiation electric field and discharge current is obtained.

• CHARACTERISTICS OF ATMOSPHERIC ELECTRIC FIELD AT THE WEST PACIFIC REGION IN Sep.-Nov., 1988
• Yan Muhong;Xiao Qingfu;Shen Qiaonan
• 1990 Vol. 9 (4): 395-404. 
• Abstract ( ) PDF (668KB) ( )
• In this paper, based on the atmospheric electric field data collected at the West Pacific oceanic region, we analysed the characteristics of electric field near the sea surface in fair weather and thunderstorm conditions. It is shown that electric field is positive beneath thunderstorms in most cases: The electric polarity is related to the temperature of cloud top. Positive charges often exist in the lower part of clouds for weaker thunderstorms. Lightning flash rate is low for oceanic thunderstorm, and the number of Lightning flashes recorded by field mill when electric field is positive is larger than that of negative. It is also shown that the fluctuation of electric field is associated with the turbulent motion near the sea surface in fair weather. From the magnitudes of the half width and intervals between peaks of electric field we estimated the scale and interval distance of turbulence, which are in accordance with measurements of turbulent field by other workers.

• A PRELIMINARY ANALYSIS OF THE CHARACTERISTICS OF GROUND DISCHARGES IN THUNDERSTORMS NEAR ZHONGCHUAN, GANSU PROVINCE
• Wang Daohong;Liu Xinsheng;Wang Caiwei
• 1990 Vol. 9 (4): 405-410. 
• Abstract ( ) PDF (405KB) ( )
• The simultaneous four-stations electric field and field change data of a thunderstorm occured on June 28, 1987 near Zhongchuan are analysed in this paper, and the location and the amount of charge brought to the ground by each leader-return stroke are calculated for 8 return strokes. The results show that the altitude of the neutralized charge is about 4 km above the ground for negative flashes (the corresponding ambient temperature is -11.2℃) and 2 km (+4.9℃) for positive flashes. Negative flashes occur usually during the electric field recovery period following cloud discharges and proceed with intracloud processes lasting several hundreds milliseconds in the begining. Upward going positive streamers from lower positive charge region may play an important role in the initiation of negative groud discharges.

• OLR OVER CHINA MAINLAND AND El Nino PHENOMENA
• Li Dongliang
• 1990 Vol. 9 (4): 411-417. 
• Abstract ( ) PDF (445KB) ( )
• In this paper, according to the monthly mean grided OLR data with 2.5°×2.5°Lon./Lat. resolution observed by the US NOAA polar-orbiting satellite during the period of from June 1974 through February 1986, the basic OLR climate features of air-earth system in China mainland, such as the spatial distributions of multi-yearly and quarterly mean values of the OLR and their RMS values, have been calculated and analysed. Meanwhile the difference of the OLR over China mainland between the El Nino years (1976, 1982 and 1983) and anti-El Nino years (1974, 1975 and 1985) were also analysed. Some interesting phenomena were revealed.

• ERROR ANALYSES OF A VERTICAL INTERPOLATION SCHEME OF INITIAL FIELD IN THE NUMERICAL MODEL
• Deng Aijun;Lu Jinghua
• 1990 Vol. 9 (4): 418-423. 
• Abstract ( ) PDF (330KB) ( )
• In this paper, a scheme of successive correction with multi-lagrange vertical interpolating toward constant-σ surfaces and backward constant-P surfaces was utilized to make the initial field interpolated from constand-P to constant-σ surfaces have the minimum errors, the error analyses and a case study for the initial vertical interpolation scheme have also deen carried out. The results show that the scheme costs less computer time and hiher accuracy.

• SOME FEATURES OF 50 hPa MEAN CIRCULATION AND THEIR SOME CORRELATIVITY WITH 500 hPa CIRCULATION
• Qu Zhang;Zhang Haijun;He Huixia
• 1990 Vol. 9 (4): 424-431. 
• Abstract ( ) PDF (496KB) ( )
• In this paper the multi-year averaged features of both troughs and ridges on 50 hPa over 20 years (1965-1984) and their some correlativities with 500 hPa circulation have been analysed. The results are as follows: 1) The dominated circulation on 50 hPa in all the year around is two wave pattern, especially in mid-and high-latitudes in the months of winter-half year. The strong high ridge over the Tibet Plateau in Summer may have some relation to the Plateau. 2) There are more wave numbers of ultra-long waves in mid-latitudes on 50 hPa than in high-and lower-latitudes, like that on 500 hPa. The some possibly reasons for it was explained. 3) The ratio of mean wave-length on 500 hPa to that on 50 hPa is considerably larger in Winter than in Summer, especially on mid-and high-latitudes. It seems that the interaction between stratosphere and troposphere on mid-and high-latitudes is stronger in Winter than in Summer.

• RELATIONSHIP BETWEEN THE LOCATION FEATURES OF 100 hPa SOUTH ASIA HIGH AND MID-SUMMER RAINFALL IN CHINA
• Chen Guiying;Liao Quansun
• 1990 Vol. 9 (4): 432-438. 
• Abstract ( ) PDF (415KB) ( )
• In this paper, first, the relationships between the positions of 100 hPa South Asia High (SAH) and mid-Summer rainfall in China during the period of 1961-1988 were analysed. According to the indexes of both eastward extending and zonal ridge line for the SAH showing their movements in W-E and N-S directions, there are three patterns of SAH which correspond different precipitation distributions in China in mid-Summer. Then, some antecedent factors which have an important influence on the movements of SAH in W-E and N-S directions in Summer were chosen. Final, an effort forecasting mid-Summer precipitation in China from the above factors was made as well.

• THE STEPWISE REGRESSION METHOD WITH MINIMUM OF FORECAST ERROR: AN EXPERIMENT FOR DROUGHT AND FLOOD FORECASTING IN THE UPPER BASIN OF YELLOW RIVER
• Huang Jiayou;Wang Yunzhang
• 1990 Vol. 9 (4): 439-442. 
• Abstract ( ) PDF (267KB) ( )
• The new stepwise regression method with minimum of forecast error is proposed in this paper. It is more simple, convenient, and easier used in microcomputer than the traditional stepwise regression. The results of forecasting precipitation in the area of the upper basin of Yellow River show that it is more efficient than the traditional method.

• RELATIONSHIP BETWEEN THE DROUGHT IN GANSU PROVINCE IN LATE SPRING AND EARLY SUMMER AND CIRCULATIONS OF ANTECEDENT PERIOD OVER EURASIAN AREA
• Yang Shangong
• 1990 Vol. 9 (4): 443-446. 
• Abstract ( ) PDF (255KB) ( )
• Using the multi-yearly mean data of 500 hPa height and their departure from the normal during the period of from May to June of 1951-1988 and the departure data of 6 representative station temperature and 14 representative station rainfall in Gansu Province at the same period, the intercomparisons of antecedent period circulations on 500 hPa for 5 typical drought and wet years in Gansu Province in late spring and early summer were firstly made. Based on the intercomparisons, the multi-regression equations for rainfall anomaly forecast were found. The trial forecast in late spring and early summer in 1989 show the rainfall anomaly forecast skill is quite good.

• IMPROVING WEATHER MODIFICATION ON THE BASIS OF ADVANCED PRODUCTS OF SCIENCE AND TECHNOLOGY
• Yang Songxi;Xu Baoxiang
• 1990 Vol. 9 (4): 447-448. 
• Abstract ( ) PDF (183KB) ( )

• THE DIGITAL VIDEO INTEGRATED PROCESSOR OF A DUAL LINEAR POLARIZATION WEATHER RADAR
• Wang Jun;Wang Zhijun
• 1990 Vol. 9 (4): 449-451. 
• Abstract ( ) PDF (197KB) ( )
• During the development process of a dual linear polarization weather radar system in my institute, the Digital Video Integrated Processor(DVIP) is quite different from the others of any conventional radar. That is to say, the conventional radar DVIP is replaced by a intelligential DVIP with averaging in both of range and azimuth on the basis of more acquisition data, in order to reduce the signal variation and improve the measurements. The configuration, the characteristics and its development principles of the DVIP for the dual linear polarization radar have been presented here.