Current Issue

• AN ALTERED KUO-TYPE CUMULUS PARAMETERIZATION SCHEME SUITABLE FOR THE QINGHAI-XIZANG PLATEAU AREA
• Chen Bomin;Qian Zhengan
• 1992 Vol. 11 (1): 1-11. 
• Abstract ( ) PDF (654KB) ( )
• In this paper, utilizing a limited area model with full physical processes and the complex terrain, and the FGGE level-Ⅲb data for June to July 1979, firstly, the performances of originally modified Kuo-type parameterization scheme (hereafter the original scheme) over the Qinghai-Xizang Plateau (hereafter the Plateau) have been examined. Then according to its deficiencies and considering the characteristics of cumulus activities over the Plateau, an altered Krishnamurti multiple regression approach is adopted to include the mesoscale source of moisture supply and to fit the moistening coefficient b and mesoscale convergence parameter η through the observed divergence as well as the stratification stability over the Plateau ( hereafter the new scheme). Finally, using the new scheme a set of nine case 24-h forecasts and their diagnoses are carried out. The results show: the original scheme tends to obviously overforecast the precipitation over the Plateau; the new one makes a considerable improvement in forecasts of the rainfall and circulation both over the Plateau and east of China; besides, the values of moistening coefficient b and the vertical profiles of heating and moistening over the Plateau calculated by the new scheme get more reasonable.

• NUMERICAL STUDY ON THE INTERACTION BETWEEN LOCAL CIRCULATIONS AND TURBULENCE IN THE ATMOSPHERIC BOUNDARY LAYER
• Qi Ying;Fu Baopu
• 1992 Vol. 11 (1): 12-22. 
• Abstract ( ) PDF (616KB) ( )
• A two-dimensional steady atmospheric mesoscale numerical model is developed in this paper. And the model is applied to study the interaction between the turbulence in the atmospheric boundary Layer and the local atmospheric circulations induced by the non-uniform surface roughness(local dynamic reinforcement) and temperature(local thermodynamic reinforcement). The conclusions as following are obtained. When the surface temperature is non-uniform, the turbulent mixing term in the equation of motion can cause local thermodynamic circulations as the horizontal pressure gradient term in the equation of motion. The nonlinear interaction between the local circulations induced by the non-uniform surface roughness and the local thermodynamic circulations induced by the non-uniform surface temperature is realized by the turbulent mixing.

• A NUMERICAL EXPERIMENT OF THE ROLE OF WESTERLY JET IN FORCED DISTURBANCE
• You Xingtian;Xiong Tingnan;Zhu He;Liu Shixiang
• 1992 Vol. 11 (1): 23-30. 
• Abstract ( ) PDF (528KB) ( )
• By using a global spectral model with nonlinear barotropic primitive equations, the forced responses of different initial basic flows on vortex sources in the low-latitudes and in the middle-latitudes are simulated. The role of the westerly jet in forced disturbance in largescale flow field is discussed. It shows that the westerly jet intensifies and blockes the wave of disturbance from low-latitudes, and changes the number of forced waves. The responses of basic flow to the disturbance source in low-latitudes are much more intensive than that in middle-latitudes when the westerly jet exists.

• THE CHARACTERISTIC ANALYSIS OF EKMAN LAYER'S STREAMLINE FIELDS OF SOUTHWEST VORTEX
• Xie Mingen;Ju Jianhua;Bu Yukang
• 1992 Vol. 11 (1): 31-38. 
• Abstract ( ) PDF (479KB) ( )
• In this paper, Ekman layer's streamline fields of a Southwest Vortex from 24 to 25 July 1979 are analysised by using a atmosphere boundary layer model. Based on the theoretical calculation, dynamical adjustment has been done by adding limited practical pibal data. The characteristics of cyclone circulation in high layers (850 hPa, 700 hPa) in Ekman layer are well simulated, and the meso-scale disturbance characteristics in planetary boundary layer in Southwest Vortex are found. There is a part of anticyclone in the whole cyclone. All above can't be obtained in the weather map of 850 hPa and 700 hPa, and these are in correspondence with diagnostic analysis.

• A CASE STUDY ON NUMERICAL SIMULATION OF SUMMER VORTEX OVER QINGHAI-XIZANG(TIBETAN) PLATEAU
• Luo Siwei;Yang Yang
• 1992 Vol. 11 (1): 39-48. 
• Abstract ( ) PDF (718KB) ( )
• In this paper using mesoscale model MM ₄ of NCAR USA, the genesis and development process of a Plateau vortex on 500 hPa had been studied by numerical experiments, and simulations in 00 UTC 29-30 June 1979. After comparing analysis of these 6 experiments and simulations with adiabatic and diabatic processes, with and without surface heat flux(sensible heat and evaporation) and with whole orography and half orography, the following preliminary results are obtained:(1) The 24h forecast of vortex center position at 500 hPa nearly coincides well with synoptical map; the 24h forecast of the mean intensity near vortex center approaches to the actual situation and that of rainfall approaches to the observation too with exception of less intensity and some differences in position. So we think that the forecast is fundamentally reasonable.(2) The most contribution of vorticity to the vortex(22.6×10 ^-5 s ^-1) is caused by the diabatic process and only 6.0×10 ^-5 s ^-1 belongs to contribution of dynamical process. In the total vorticity 22.6×10 ^-5 s ^-1 caused by diabatic process the contribution(8.0×10 ^-5 s ^-1) of latent heat is much less than that(14.6×10 ^-5 s ^-1) of surface heat flux which is caused by convection of cumulus cloud and turbulence. In the contribution of surface heat flux the most part of vorticity(13.4×10 ^-5 s ^-1) is due to the surface sensible heat and the surface evaporation plays a little role(1.2×10 ^-5 s ^-1). These are the same as the results of diagnostic analysis obtained in the first part ^[6] of this case study.(3)When the orography is raised from half height to the whole the dynamical contribution to vortex intencity is strengthened from 2.0 to 6.0×10 ^-5 s ^-1 and the diabatic contribution from 7.2 to 22.6×10 ^-5 s ^-1. From this we know that it is very important how to correctly treat topographical height in the model. Although only one case is studied here the result(2) is supported by the statistical one of diagnosticaljanalyses for 81 vortices.

• THE QUASI-PERIODIC FEATURE AND JUMP PHENOMENON FOR THE INTERANNUAL VARIATION OF NORTHERN HEMISPHERE MONTHLY MEAN GENERAL CIRCULATION ANOMALIES
• Jin Liya;Wang Yuxi;Zhang Banglin
• 1992 Vol. 11 (1): 49-55. 
• Abstract ( ) PDF (402KB) ( )
• In this paper, the joint-space and time EOF method is used to analyse 100, 500 and 700 hPa geopotential height anomaly fields in January and July. The eigenvectors indicate not only the distribution features in three dimension structure but also the organic relationship between them. The interannual variation features of time-coefficient are discussed using power spectrum and maximum entropy spectrum method as well as "climate jump" conception. The results show: there are the quasi-periodic features and unsuccessive jump phenomena in the interannual variation processes of Northern Hemisphere monthly mean general circulation anomalies.

• THE STATISTICAL CHARACTERISTICS OF THE 500 hPa HIGH OVER THE QINGHAI-XIZANG PLATEAU
• Duan Tingyang;Ma Lanxiang;Lu Jianzhuang
• 1992 Vol. 11 (1): 56-65. 
• Abstract ( ) PDF (648KB) ( )
• In this paper, the 500 hPa high duration, moving tracks, seasonal variation, high frequency areas are analysed by statistical analysis 336 cases, and their structure and the influence on weather are also studied by 18 cases over the Qinghai-Xizang Plateau during the 1978-1987.

• THE ANALYSES OF THE INPUT AND OUTPUT OF STATIC ENERGY OVER THE WEST PACIFIC DURING THE LATTER PERIOD OF EI Nino EVENT(SEPT.-NOV.) IN 1987
• Ma Zhuguo;Yao Lanchang
• 1992 Vol. 11 (1): 66-72. 
• Abstract ( ) PDF (433KB) ( )
• By using the data observed by Chinese Academy of Sciences on West Pacific in 1987 and the data of National Bureau on the Pacific and Atlantic. A method for computing atmospheric humidity from atmospheric temperature and height has been obtained. Utilizing this method and the data of atmospheric temperature and height (the data was from NMC, 5°N×5° S mesh scale), the change and transfer of atmospheric static energy was analysed over the West Pacific (0°-30°N, 20°-170°E) from September to November 1987. The result indicates that there was a resource of atmospheric static energy, and the atmospheric static energy was released from this area during this period.

• THE RESEARCH OF RECENT CLIMATIC CHANGE TENDENCY IN SPRING IN THE MAO WU SU SAND REGION
• Sun Anjian;Liu Desong;Qu Jianhe
• 1992 Vol. 11 (1): 73-82. 
• Abstract ( ) PDF (593KB) ( )
• By using the meteorological data at five stations(Etoke, Dongsheng, Yanchi, Yulin, Ushenqi)in the Mao Wu Su sand region in spring during recent 40-years, we have discussed in detail climatic evolution tendencies of the factors related to desertification processes. These factors include aridity coefficients, cloud cover, precipitation, humidity, wind speed and wind sand days. The results show that it was wetter in the 1960's and became drier in the 1970's and wetter in 1980's in spring. If it is true to exist a quasi-ten years oscillation, it would be drier in spring of 1990's. The power spectrums have been analysed for time series(1955-1988) of precipitation and aridity coefficient in spring at the five stations, respectively. The pronounced period throgh significance test at significance level of 0.05 are two to three and eight to nine years for both precipitation and aridity coefficient each station. The oscillation of 2-3 years may be associated with SST of tropical oceans, the subtropical high over the western Pacific and cold air activity in the northern hemisphere that all have the same periodic oscillation. The regression prediction models have been set up for both precipitation and aridity coefficient in spring each station, respectively. Based on theses models, we can predict the precipitation and aridity coefficients in spring in this region for three months or half a year in advance. Finally, we discuss the impact of human activity on desertification. We point out that different human intervention on nature will bring about various climatic effects in the same climatic environment.

• ANALYSES AND STUDIES ON THE FORMATiONS AND VARIATIONS OF THE ANTARCTIC OZONE HOLE
• Qu Shaohou
• 1992 Vol. 11 (1): 83-89. 
• Abstract ( ) PDF (459KB) ( )
• The Antarctic ozone hole which was discovered in the mid 1980's has attracted the scientists and politicians throughout the world much attention. For the formation of the Antarctic ozone hole, most scientists believe that the man-made chemical materials such as CFCs etc. are main cause. On the other hand the electrochemistry-dynamics theory presented by Wei two years ago has also attracted some attention. In the paper the data of ozone, solar activity and meteorological elements over Antarctica have been used for statistical analyses and studies. Our results present some new evidence to support the Wei theory. The results show that combination of the quasi-11-years period variation of changed particle current caured by solar activity and special atmosphere general circulation over Antactica is important cause of forming Antractic ozone hole. However the influence of the human activities can never be slighted.

• THE PRELIMINARY STUDY OF FLASH HEAVY RAIN IN THE FRONT OF QINGZANG HIGH
• Chen Zhongming;Rong Jinhai
• 1992 Vol. 11 (1): 90-95. 
• Abstract ( ) PDF (386KB) ( )
• In this paper, the diagnostic analyses on a case of flash heavy rain in front of Qingzang High are conducted. Results show:(1) Ambient fields to generate this heavy rain are very different as compared with last research results.(2) Using technic of band-pass filter, mesoscale system related to this heavy rain can be dissociated from baseline fields.(3) Positive feedback process between disturbance and non-thermal wind adjustment is a mechanism of evolution of mesocale cyclone.

• ENVELOPE SOLITARY ROSSBY WAVESIN THE ATMOSPHERE——THE EFFECT OF LATITUDE
• Luo Dehai
• 1992 Vol. 11 (1): 96-101. 
• Abstract ( ) PDF (386KB) ( )
• This paper is the second part of the author's papers, in the present paper, envelope solitary Rossby waves in the rotating barotropic atmosphere were deeply investigated, it is found that when Rossby wavenumber m( m is the zonal wavenumber) satisfies 1< m<2 the envelope solitary Rossby waves exist in the rotating barotropic atmosphere, and only when m=2, the envelope solitary Rossby wave exhibits blocking high structure. Furthermore, the persistent time of envelope solitary Rossby wave with latitude for m=2 is also computed , and some results are obtained.

• SPECTRA ANALYSIS OF SURFACE HEAT SOURCE DURING 1982-1983 WINTER OVER QINGHAI-XIZANG PLATEAU
• Li Dinghua;Lan Jilong
• 1992 Vol. 11 (1): 102-106. 
• Abstract ( ) PDF (277KB) ( )
• Maximum entropy spectra method(MEM) has been used to study the surface heat source intensity( B- H), latent heat flux( LE), surface heat fiux( H) and sensible heat flux by using the data observed at Gêrzê, Lhasa, Nagqu, Garzê stations of Qinghai-Xizang Plateau duing the period form 1 Nov. 1982 to 28. Feb. 1983. The results as follows: There are the cyeles of quasi-two weeks and quasi-week for each components of heat flux, the cycle bcomes longer from Summer to Winter.

• THE RESEARCH ON RELATIONSHIP BETWEEN LOW FREQUENCY OSCILLATION OVER QINGHAI-XIZANG PLATEAU AND RICH OR POOR WATER IN UPPER REACHES OF YELLOW RIVER
• Sun Guowu;Chen Baode;Liu Xiaodong
• 1992 Vol. 11 (1): 107-112. 
• Abstract ( ) PDF (368KB) ( )
• It is indicated that low frequency systems with 30-50 days period over Qinghai-Xizang Plateau appear two kinds of phases during oscillating process: cyclone phase and anticyclone phase. The period of cyclone phase is responded to rich water time in upper reaches of Yellow River, anticyclone is responded to poor water time. The possible cause of this relationship is analyzed. The results show it is related to low frequency disturbance kinetic energy to be strong or weak and low votices to be active or inactive. This paper have explored the prediction of water rich or poor in upper reaches of Yellow River by using the characteristics of low frequency oscillation.