Current Issue

• CORRECTIVE METHOD OF FGGEⅢbWIND FIELD DATA ON 500 hPa OVER QINGHAI-XIZANG PLATEAU AND ITS ANALYSES
• Luo Siwei;Xu Baoyu;Hui Xiaoying;Zhang Mingjuan
• 1990 Vol. 9 (1): 1-12. 
• Abstract ( ) PDF (814KB) ( )
• Based on paper [1], the FGGEⅢ _b 500 hPa level wind data over the Plateau were firstly corrected by using the QXPMEX'S Data (twice a day from May to August of 1979) and utilizing the Cressman's successive correction method modified by NCAR. These corrected maps were then compared with the odjective analysed weather maps and strean fields respecrively of the same fime. It shows the synoptical systems (especially the mesoscale ones) were well corresponded with each other. The intercomparisons between the correted and the FGGE'S flow fields indicate: (1) The NCAR software package of stream map can correctly describe the grid wind direction.(2) FGGEⅢ _b level wind data can well describe the large-sca'e circulation over the Plateau, but not some subsynoptical scale systems, such as the centers of cyclones and anticyclones, and nearly half of the Plateau vortexes were missed. Some too strong vortexes which are weak or non-existent in FGGE'S flow field maps more often appear over west Plateau as well.(3) There is a active Plateau vortex zone concentrated in zone 30-35° N over the Plateau on the corrected flow field maps; the anticyclones, to the north and south of the zone.(4) In the boundary layer on NE and SW sides of the Plateau there are often terrain-induced troughs oriented in NW to SE direction on the corrected flow field maps. Their formation and development mechanism is worth stuying further.

• THE BASIC CHARACTERISTICS OF THE PLANETARY ALBEDO OVER THE CONTINENT OF CHINA
• Zhong Qiang;Hou Ping
• 1990 Vol. 9 (1): 13-21. 
• Abstract ( ) PDF (562KB) ( )
• In this paper, the basic characteristics of the planetary albedo over the continent of China are investigated for representative regions on the basis of NOAA Radiation Budget Data from August 1982-July 1983. The distribution maps of the planetary albedo are shown in this paper for annual mean, monthly means (January and July), clear sky and cloud sky respectively. The comparison is made between the derived planetary albedo of clear skies and the surface albedo measurements for Tibetan Plateau region.

• RELATIONSHIP BETWEEN THE SURFACE NET RADIATION IN THE WESTERN QINGHAI-XIZANG PLATEAU AND THE PRECIPITATION IN CHINA
• Ji Guoliang;Xu Rongxing
• 1990 Vol. 9 (1): 22-31. 
• Abstract ( ) PDF (667KB) ( )
• In this paper were estimated the surface net radiations over western Qinghai-Xizang Plateau in winter (from Nov. to Feb.)of 1961~ 1981 using the observed data of surface radiation balance over the Qinghai-Xizang Plateau in the period from August 1982 to July 1983. Base on the analyse for the surface net radiation during the winter of the year, the paper expounds the characteristics of surface heating fields in the western Plateau and discusses the relationship between the wintertime surface net radiation over the Western Plateau and precipitation in the Southwestern China in Autumn, Mid-Summer drought along the Yangtze River basin as well as the precipitation in the upper reaches of the Yellow River during the rainy season.

• THE CLIMATIC CHARACTERISTICS OF SURFACE HEATING FIELDS OVER THE QINGHAI-XIZANG PLATEAU
• Xu Guochang;Li Dongliang;Chen Liping
• 1990 Vol. 9 (1): 32-43. 
• Abstract ( ) PDF (703KB) ( )
• Using the 25 years (1961-1986) data set of 60 observation stations over the Qinghai-Xizang Plateau, the intensity of the Plateau surface heating fields is calculated according to regression eguations of Ji(1986) and their climatic characteristics are analysed. It is found that their values are only 71 percent of that given by Ye(1979) and the average departures of surface heating eguations of 2 station (Yushu and Rikaze) can represent roughly that of the whole of the Plateau by Empircal Orthogonal Function Analyses and calculations of load values. They have remarkable quasi-3 years, 5 years and 11 years periods and persistences in winter and spring.

• TELECONNETIONS OF THE ZONAL ANOMALY FIELD OF 500 hPa HEIGHT OVER THE NORTHERN HEMISPHERE IN JANUARY AND JULY
• Yi Yuhong;Pan Tao;Huang Jianping;Chou Jifan
• 1990 Vol. 9 (1): 44-53. 
• Abstract ( ) PDF (566KB) ( )
• The teleconnection structures of zonal anomaly fields of 500 hPa height over the Northern Hemisphere in January and July were studied by using a 36-year period data set (1951-1986). The results show that in January the teleconnection structures in zonal anomaly fields of monthly mean height are the same as that in their own monthly mean height field, but in July, the teleconnections in their own height fields are not so obviously, however, in zonal anomaly fields of them there exist four significant teleconnection patterns which present the zonal symmetric feature. The intercomparisons of the teleconnections of the zonal anomaly fieids of height in January with that in July show there ere seasonal variation in these phenomena.

• THE TRANSMISSION LINE MODEL AND CURRENT VELOCITY OF LIGHTNING RETURN STROKES
• Chen Mingli;Liu Xinsheng
• 1990 Vol. 9 (1): 54-63. 
• Abstract ( ) PDF (588KB) ( )
• By analyzing the character of ionized gas in lightning channel, a new idea is raised. It is inferred that the velocity of current propagation along the channel is approximately equals to the velocity of light, and the return front or the streamer front is only the initial front of electron avalache caused by collision between ions accelerated by the current, and the return stroke velocity is the same as that of initial front. Based on this new opinion, an improved transmission line model of lightning return strokes is proposed. Results computed by the model show that: (i) The wave form and it's peak value of simulated field are in good agreement with that of electric field observations. (ii)Using the approximate expression for high frequency, the relation between peak amplitude of field and current obtained from artifcial triggering lightning experiments (Fieux, 1978; Djebari, 1981) and natural lightning struck to high metal structure (Weidman, 1986) can be well explained.

• EXPERIMENT OF ARTIFICIALLY TRIGGERED LIGHTNING AND PRELIMINARY ANALYSIS OF ITS DISCHARGE CHARACTERISTIC
• Liu Xinsheng;Guo Changming;Xiao Qingfu;Zhang Cuihua
• 1990 Vol. 9 (1): 64-73. 
• Abstract ( ) PDF (1331KB) ( )
• In the summer of 1989, experiment of artificial lightning triggered with rocket-wire technique was conducted at yongdeng, Gansu and succeeded in three cases. This paper analyses the discharging characteristers of three triggered lightnings. Results show that negative streamer was initiated by rocket-wire and propagated upwards in the effect of lower positive charge of thundercloud. 6-8 kV/m was necessary for the lightning to be triggered successfully. Discharge parameters were estimated approximately by using a simple physical model. Magnitude and altitude of neutralized charge of triggered lightning were 1.2-5.3 C and 1.3-2.5 km respectively, the latter being in agreement with the altitude of lower positive charge of Gansu thunderstorms.

• ON SOME ASPECTS OF THE OBSERVATIONS OF TURBULENT FLUXES IN SURFACE LAYER
• Hu Yinqiao
• 1990 Vol. 9 (1): 74-87. 
• Abstract ( ) PDF (902KB) ( )
• The present methods of observing turbulent fluxes are reviewed and summarized in this paper. In the review paper the conditions to which every observation method can be applied are pointed out,their observation errors, their merits and demerits are compared with each other. Other relevant problems aer also discussed.
  The paper may be of interest to those who need to select observation methods in surface layer to evaluate and to correct the results of their observation.

• THE ANALOGOUS RHYTHMS PHENOMENA OF MONTHLY MEAN CIRCULATION OVER THE NORTHERN HEMISPHERE
• Huang Jianping;Gao Jidong;Chou Jifan
• 1990 Vol. 9 (1): 88-92. 
• Abstract ( ) PDF (334KB) ( )
• The amdogous evolution of monthly mean circulation over the Northern Hemisphere have been, overall and in detail, analysed by utilizing strict statistical method and observation data for long-time sequence.The results show that the analogue of the monthly mean anomalous fields between two different years gets gradually worse from a certain starting analogous month onwards, but about 6 months afterwards the analogue again occurs. This is the so-called analogous rhythms phenomenon for about six months in the evolution processes of long-term weather anomaly.

• LIGHTNING RADIATION AT 20 MHz AND DISCHARGE PROCESS
• Qie Xiushu;Liu Xinsheng;Wang Huaibin
• 1990 Vol. 9 (1): 93-97. 
• Abstract ( ) PDF (380KB) ( )
• Simultaneous measurements of lightning radiation at 20 MHz and electric field change due to a lightning discharge were obtained by using a narrow bandwidth receiver and a slow antenna. The discharge processes, such as stepped leader, return stroke, etc., of ground discharge were identified. The radiation intensity and the duration for both cloud discharge and return strokes of ground discharge are presented. It was found that the K change of cloud discharge and the frist return stroke of ground discharge have the strongest radiation at 20 MHz. The radiation becomes weaker and weaker for subsequent strokes.

• THE CLIMATIC CHARACTERISTICS OF OLR FIELD OVER QINGHAI-XIZANG PLATEAU
• Kang Shanfu;Wu Junming
• 1990 Vol. 9 (1): 98-103. 
• Abstract ( ) PDF (363KB) ( )
• The seasonal changing characteristics of OLR field over Qinghai-Xizang Plateau increases unceasingly from Janurary to May, and increases rapidly in March to May.It increases constantly in the Northern Plateau from May to August. Because of influences of the Indian monsoon in the Southern Plateau, the convection activity becomes stronger and a low-value zone of the OLR field appears. The low-value zone of May is in the southeast, and then spreads toward the northwest from the southeast crossing the Himalayas, and reaches the proximity of the northern latitude 31 in July. The low-value zone begins to withdraw to the southeast from the northwest in August, and to the southern side of the Himalayas in September. Because of the influences of the northwest currents at the outset of October, the OLR field value begins to drop from the northwest Plateau quickly and the southeast slowly. The characteristics of the annual variation curve are: it is a single-front type in the northern Plateau for the OLR with the highest value in August. It is a double-front type in the southern Plateau with the highest value in May and October respectively. It reaches the lowest-value in July.

• THE MEAN CIRCULATION CHARACTERISTICS DURING THE PRE-WARMING-AND POST-STAGES OF THE SUDDEN STRATOSPHERIC WARMING
• Wang Qiang;Zheng Guang;Zhang Haijun;Wu Tongwen;Qu Zhang
• 1990 Vol. 9 (1): 104-109. 
• Abstract ( ) PDF (367KB) ( )
• In this paper, the mean circulation characteristics during the period of pre-, warming-and post-stages for 5 strongest sudden stratospheric wanning cases selected from 14 cases have been analysed.
  The results show:
  (1) The temperature anomaly at the North Pole at 30 hPa level is 17.1℃ in the warming-stage; -4.7℃, pre-stage; and-8.9℃, post-stage, respectively.
  (2) The wave number of the height fields at 500-and 50-hPa level during the warming-stage are less than the pre-and post-stage, the meridionality of the wave is larger.
  The development of the meridional circulation and the splitting of the Polar Vortex occured at the 500 hPa level firstly.
  (3) All of the 5 cases were North Pacific warmings and occured in the years of late seasonal transformation from Winter to Summer in stratosphere.

• THE CONNECTIONS BETWEEN THE ABRUPT CHANGES OF GROUND HEAT SOURCE INTENSITY OVER TIBETAN PLATEAU AND THE ABRUPT CHANGES OF EAST ASIAN WEATHER
• Wu Jingzhi;Li Dinghua
• 1990 Vol. 9 (1): 110-112. 
• Abstract ( ) PDF (208KB) ( )