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24 March 1991, Volume 10 Issue 1
- DIAGNOSTIC ANALYSES OF A SUMMER VORTEX OVER QINGHAI-XIZANG PLATEAU FOR 29-30 JUNE 1979
- Luo Siwei;Yang Yang;Lu Shihua
- 1991 Vol. 10 (1): 1-12.
- Abstract ( ) PDF (855KB) ( )
- In this paper a case study of development mechanism of a summer vortex in Qinghai-Xizang Plateau had been made for 00 UTC 29 through 12 UTC 30 June 1979. From view point of energy, by using apparent heat source and apparent moist sink equations used by Kou and Anthes and energy equations used by T. Nitta, a detailed diagnostic analysis about it had been performed. The results show that the surface eddy flux of sensible heat and latent heat due to cumulus convection and disturbance α( Q 1- Q 2) contributed to the development of the vortex substantially in which the surface evaporation plays a little role.The rainfall of vortex is convective whose moisture comes from the convergence below 500 hPa.The analysis of energy transformation shows that in the young and mature stage of vortex its energy mainly comes from the diabatic heating α Q 1 and takes the following form as CISK in the low latitude:α Q 1→ E→K.The most of diabatic heating comes from the vertical eddy flux of surface sensible heat due to cumulus convection and disturbance.Prior to the formation of vortex and in its last stage the developing mechanism is like baroclinic instability in the atmosphere of midlatitude and takes the following energy transformation form: E→E→K. At this time the α Q 1 plays a little role.
- TEMPORARY AND SPACE STATISTIC CHARACTERISTICS OF AEROLOGICAL GEOPOTENTIAL, TEMPERATURE AND DEW-POINT TEMPERATURE FIELDS OVER QINGHAI-XIZANG PLATEAU AND THEIR APPLICATIONS
- Jiao Yanjun;Wu Shengjin;Qian Zhengan
- 1991 Vol. 10 (1): 13-25.
- Abstract ( ) PDF (844KB) ( )
- In this paper the temporary and space statistic characteristics of aerological potential, temperature and dew-point temperature(PTD) fields over Qinghai-Xizang Plateau have been analysed utilizing Summer data(June-August) during the period of Qinghai-Xizang Plateau meteorological scientific experiment in 1979 and Winter data(December-February) in 1979-1980. The results show:the correlate function distributions of the PTD fields over the Plateau have a ellipse shape with a long axis in east-west direction, but it is something different from that in east part of China due possibly to the influence of the Plateau. The correlate degree in potential fields is better than that in temperature; in dew-point temperature field, even worse. Such correlate degree in Winter is better than in Summer; on 300 hPa, better than on 400 hPa and 500 hPa. The PTD fields over the Plateau have a quite good persistence, especially the potential and temperature fields on upper troposphere level in Summer. Based on above features, the analysis formula of the variations of the correlate function in PTD fields over the Plateau with the distance were fitted, also the relation formula of the PTD fields over mid-Plateau stations to that over west-Plateau stations, as well as the antecedent PTD fields to that in real time, were already fitted. These formulas can use in diagnosis and objective analysis in PTD fields over the Plateau.
- A STUDY OF SCATTERING AND ATTENUATION PROPERTIES OF MODEL HAIL WITH DIFFERENT PHASE AT 5.6 cm WAVELENGTH
- Liu Liping;Xu Baoxiang
- 1991 Vol. 10 (1): 26-33.
- Abstract ( ) PDF (505KB) ( )
- In order to distinguish the different phases of hydrometeors by using a dual-linear polarization radar, in this work we have calculated the backscattering, extinction and absorption cross sections of oblate spheroidal and conical model hails with different phases by using the extended boundary condition method for an inhomogeneous body.We have got the ZDR and ZH values of these model hails and their extinction properties at 5.6 cm wavelength.This work has provided an operational approach to identify hail by using radar.
- COMPARISON BETWEEN NOAA-7 AND NIMBUS-7 RADIATION BUDGET OBSERVATIONS OVER THE QINGHAI-XIZANG PLATEAU
- Wang Keli;Zhong Qiang
- 1991 Vol. 10 (1): 34-42.
- Abstract ( ) PDF (673KB) ( )
- In this paper, the basic characteristics of both NOAA-7 and Nimbus-7 radiation budget observations over the Qinghai-Xizang Plateau during August 1982-July 1983 are compared. The differences and ralations of them are analysed. The results show that the differences are obvious over the Qinghai-Xizang Plateau region. The Nimbus-7 observations show the latitudinal variation tendency and the NOAA-7 observations show the higher resolution to indicate the effect of the Plateau. For the Plateau climate studies, NOAA-7 data set seems to be more suitable.
- A STOCHASTIC CLIMATE MODEL ON THE QUASI-PERIODIC OSCILLATION OF LAND-AIR SYSTEM
- Ma Zhuguo;Tang Maocang
- 1991 Vol. 10 (1): 43-51.
- Abstract ( ) PDF (589KB) ( )
- In this paper, considering stochastic forcing action in land-air system, the second order stochastic fluctuation climate model of land-air interaction is derived by using the thermodynamic equilibrium equation. It is found that there are two kinds of quasi-periodic oscillations in subsurface temperature departure, one is the oscillation of quasi-six months ranging from four to nine-months; the other, from two to three-years, and that there is a minimum period with the changes of some climate parameters. It is also found that the relative importance of both the interaction and self-feedback action in, land-air system for above-mentioned two periodic oscillations is different.
- EFFECT OF PRECIPITATION ON THE CONCENTRATIONS OF BOTH THE AEROSOL AND THE ION OF RAINWATER IN CHONGQING AREA
- Wu Yuxia;Shen Zhilai;Huang Meiyuan
- 1991 Vol. 10 (1): 52-60.
- Abstract ( ) PDF (565KB) ( )
- In this paper, based on the samples obtained in Chongqing area, during the period of from September to October 1985, the aerosol size spectra, their daily variations, and the influences of precipitation on the concentrations of both the aerosol and the ion in rainater are discussed.The data analyses show that the washout of rain water causes aerosol concentrations decrease, moreover in the following period of precipitation, processes ion concentration and conductivity of rainwater descend correspondingly. The washout rate is related to rainfall intensity.For aerosol with 0.5-2μm in diameter it is 1.92×10 -5/s when the rain intensity is less than 1 mm/h, but it increases up to 2.13×10 -5/s when rain intensity is more than 1 mm/h.Under the same rain intensity, the aerosol with larger size is easily removed by rainwater.
- RELATIONSHIPS BETWEEN THE ATMOSPHERIC LOW-FREQUENCY OSCILLATION AND THE VARIATION OF THE SOUTH ASIAN HIGH
- Liu Fuming;Lin Hai
- 1991 Vol. 10 (1): 61-69.
- Abstract ( ) PDF (601KB) ( )
- In this paper, the relations between the quasi-40 day and quasi-15 day oscillations of zonal winds on 200 hPa and the intraseasonal movements as well as the medium-range south-north and eastwest oscillations of the South Asian High are discussed. These two types of oscillation have the similar geographical distributions. The intraseasonal variation of the South Asian High is mainly correlated to the quasi-40 day oscillation and the quasi-15 day oscillation is mainly related to its east-west movement.It provides a clue for the long-and medium-range forecast of the variations of the South Asian High according to the phase transitions of the two oscillations of ucomponent on 200 hPa in typical regions.
- THE ENVIRONMENT FIELD AND THE Q-VECTOR ANALYSES FOR HEAVY RAIN OF VORTEX OVER NORTHEAST SICHUAN BASIN
- Yu Shuhua;Luo Hong
- 1991 Vol. 10 (1): 70-77.
- Abstract ( ) PDF (483KB) ( )
- The vortex over northeast Sichuan Basin is one of the main heavy rain-producing systems over San Xia region, especially, the vortex with 700 hPa shear line. The analyses of 500 hPa height fields and 700 hPa wind fields with the vortex from May to September of 1973-1985, show the favorable situations for formation of the vortex are:(1) the ridge line of the subtropical High is in the vicinity of 25°N, and 500 hPa. northwest and southwest currents meet over the northeast of the Sichuan Basin.(2) 700 hPa shear line is also over the Sichuan Basin. After the Q-Vector fields of one case of heavy rain by the vortex were analysed, it is found that a convergent zone of 500 hPa Q-Vector existed over the Sichuan Basin in advance of 12-24 hours in which the vortex was generated, and when Q-Vector convergent areas of middle and lower troposphere were overlapped, a vortex would be formed in the overlap area during the period of 24 hours. It is a good clue for forecasting formation of the vortex.
- A PRELIMINARY ANALYSIS OF PRECIPITATION CHARACTERISTICS OF CHINA IN THE YEARS OF ENSO PHENOMENA AND THEIR FOLLOWING YEARS
- Li Cunqiang
- 1991 Vol. 10 (1): 78-82.
- Abstract ( ) PDF (300KB) ( )
- THE HEAT ISLAND EFFECT OF LANZHOU
- Chen Zhenmei
- 1991 Vol. 10 (1): 83-87.
- Abstract ( ) PDF (330KB) ( )
- In this paper, the heat island effect over Lanzhou City is analysed by using(l)U.S.A. TS-2A detection system,(2) satellite diagnosis and(3) conventional meteorological data. The research result point out that the Chengguan, Langang and Xigu districts are three different region for heat island intensity, and the heat island effect will be step up increased with the development of Lanzhou City.
- A ESTIMATION METHOD OF THE DISTRIBUTION OF OROGRAPHIC PRECIPITATION OVER THE HIMALAYAS
- Lin Xianchao;Lin Zhenyao
- 1991 Vol. 10 (1): 88-93.
- Abstract ( ) PDF (384KB) ( )
- In this paper, after changing Alpert' s method estimating mountain precipitation rate into the method estimating the mountain yearly mean rainfall, the method was utilized to estimate the yearly rainfall variation with height along 87°and 95°longitudes over Himalayas. The results show that the calculated precipitation have good agreement with the observed values along 87°E over the Himalayas.There are two maximums of preciptation along the longitude on the southern slope of the mountain:one situating at the heights between 1000 to 1500 m above sea level, with yearly rainfall of about 2800 mm; The another, at the heights between 3000 to 3500 m, with yearly rainfall of about 2000 mm. While there are three maximums of precipitation along the 95°E meridian on the southern slope of the Himalayas. They are located at heights of about 1000, 2000 and 3500 m, respectively. The corresponding rainfall are about 4100, 2700 and 2100 mm, respectively.
- A MICROCOMPUTER NUMERICAL MODEL SYSTEM AND ITS FEASIBILITY EXPERIMENT OF PREDICTION
- Chen Yuchun;Lu Shihua
- 1991 Vol. 10 (1): 94-98.
- Abstract ( ) PDF (360KB) ( )
- In order to establish the microcomputer operational numerical prediction system, a real time data processing system including objective analysis and a nested fine-mesh model under complex topography have already been transplanted from VAX-computer to SUN-386 microcomputer with somewhat modifications. The actual case prediction results shows that it is available for microcomputer to carry out realtime operational numerical prediction if equipped with speeder and made full use of the main memory of the microcomputer.
- VERIFICATION OF THE MOS FORECAST OF THE MAXIMUM AND MINIMUM AIR TEMPERATURE IN THE QINGHAI-XIZANG PLATEAU REGION
- Wang Xijuan
- 1991 Vol. 10 (1): 99-104.
- Abstract ( ) PDF (384KB) ( )
- According to the Mos forecasting data of 48-h maximum and 36-and 60-h minimum of the atmospheric temperature forecasted by Central Meteorological Observatory from November 1987 to September 1988, the verification of them were made for 19 meteorological stations over Qinghai-Xizang Plateau region.The results show that some of them, like the stations of Xining, Lhasa etc., give a valuable estimation of their maximum and minimum air temperature, but there exist systematic forecast bias higher or lower than the observed, some, like the station Gantze, have a poor skill.
- ADVANCES IN RESEARCH OF CUMULUS CONVECTION PARAMETERIZATION SCHEME
- Xu Xihua
- 1991 Vol. 10 (1): 105-110.
- Abstract ( ) PDF (498KB) ( )
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