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1986 Vol. 3, No. 4

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A STUDY ON THE EXCITATION, ESTABLISHMENT AND TRANSITION OF MULTIPLE EQUILIBRIUM STATES PRODUCED BY NEARLY RESONANT THERMAL FORCING-PART II: THEORETICAL ANALYSIS OF THE MECHANISM OF MULTIPLE EQUILIBRIUM STATES
Qin Jianchun, Zhu Baozhen
1986, 3(4): 397-405. doi: 10.1007/BF02657930
Abstract:
Based on the results acquired in Part I of this paper, analysis is made of the theoretical mechanism of thermal forcing multiple equilibrium states (MES) and their stability. The results are as follows: 1) non-linear effect and external forcing are determinative factors for MES formation; 2) under proper “environ-mental conditions” the forcing can excite stable MES, particularly three types of solutions, two of which, with larger amplitude of resonance, are not sensitive to the change in the forcing intensity; while the other, i. e. the one of small amplitude, dependent significantly on it; 3) in general, the domain of parameter values for the MES existence increases, but the stability decreases, with increasing thermal forcing; 4) steady thermal forced waves are always unstable for the most part; 5) thermal driving and orographic effect act equally as dynamical triggers; 6) friction has significant influence upon the behavior of MES solutions.Analysis shows that the changes in the “environmental parameters”, such as the alteration of the shear of a basic current and intensity of the forcing, induce the transition between different equilibria.
THE EFFECT OF ASPECT RATIO ON THE BIFURCATION PROPERTIES OF A DOUBLE PARALLEL-CONNECTION LORENZ SYSTEM
Zou Chengzhi, Yang Peicai, Zhou Xiuji
1986, 3(4): 406-423. doi: 10.1007/BF02657931
Abstract:
A double parallel-connection (DPC) Lorenz system is developed by performing spectrum truncation of the Galerkin series expansion of the two-dimensional Rayleigh-Benard convection equation. Analyses of the equilibrium states indicate that a convective roll stems from a flow with a given wavenumber first losing its stability for a particular aspect ratio β after a stable laminar flow gets unstable; when β has the value βc able to deprive synchronously two flows with different wavenumbers of stability, occurrences of convective rolls with different wavenumbers depend entirely on the initial conditions, in good agreement with the relevant experimental results. The calculations of the unstablized rolls show that, with a smaller β (as compared with βc), the DPC Lorenz system has the same bifurcation properties as the ordinary Lorenz system; for a moderate β, the system has very complicated periodic, quasi-periodic and phase-locking motions; for a larger β, it results in intermittent chaos and causes mean flows with different numbers of vortices to occur alternately with time. All these indicate that β has substantial effect on the two Lorenz systems coupled through parallel connection in their interaction and the results.
DYNAMICS OF NONLINEAR BAROCLINIC EKMAN BOUNDARY LAYER
Liu Qinyu, Qin Zenghao
1986, 3(4): 424-431. doi: 10.1007/BF02657932
Abstract:
By the geostrophic momentum approximation, the wind structure and vertical motion within the non-linear baroclinic Ekman layer matching with the surface layer are determined. A comparison of the Ekman solution with the classical one is made. It is demonstrated that the contributions of baroclinity, stratification and nonlinear effects to the wind profile within the layer are all of definite importance.
METEOROLOGICAL AND CHEMICAL CONTROLS ON THE VERTICAL DISTRIBUTION OF BEIJING SUMMER COARSE AND FINE AEROSOLS
Wang Mingxing, John W. Winchester, Lü Weixiu, Ren Lixin, Hong Zhongxiang
1986, 3(4): 432-442. doi: 10.1007/BF02657933
Abstract:
Vertical profiles of fine and coarse aerosol particles were determined by cascade impactors at the me-teorological tower in Beijing for three days and one night, July 18-23, 1980. Coarse mode aerosols showed a maximum concentration at 47 m when there was an inversion at about 140 m height, and a rather uniform distribution when there was no inversion. This may indicate a two-component origin of coarse particles at the tower site, one being surface dust and the other being tall stack emissions. Fine mode aerosols showed more complex vertical profiles. Median particle size distributions of most metals were bimodal, indicating distinct coarse particle dispersion and fine accumulation mode processes. A chemical thermodynamic cal-culation indicates that fine mode Si can result from the reduction of silica to volatile SiO during coal combustion with limited air supply, a process which should release substantial amounts of carbon monoxide to the atmosphere.
A SIMPLIFIED MODEL STUDY ON THE SHORT-TERM CLIMATIC EFFECT OF SNOWFALL ANOMALY IN MID-HIGH LATITUDES
Ji Jinjun
1986, 3(4): 443-453. doi: 10.1007/BF02657934
Abstract:
A simulation of the annual variation of temperature and moisture in the atmosphere and sublayer of soil in mid-high latitudes has been performed with a one-dimensional atmosphere-land coupled model, in which snowmelt process is included. The computed temperature variations in each latitudinal belt are con-sistent with the seasonal change of snowextent over continents in the Northern Hemisphere.To analyse the short-term climatic effect of snowfall anomaly, two sets of experiments have carried out by using the above simplified model, i. e. 1) the snowmelt period is earlier than the climatic mean and 2) snowdepth is less than the climatic mean. The results are shown in the present paper. In the first ex-periment, snow melts earlier, and comparing with the normal annual variation, the absorption of solar radia-tion increases significantly due to the earlier decrease of albedo. Thus the surface temperature is higher, and latent and sensible heat fluxes are enhanced. This process is characterized by thermal anomaly. In less snow-depth experiment, the soil is drier after snowmelting, and thus evaporation and precipitation are reduced. The hydrological anomaly constitutes its main character which will continue till August. In summary, the snowfall anomaly is an important factor in the formation of dry-warm or cold-wet climate in spring and summer.
CALCULATIONS OF ABSORPTION, ATTENUATION, AND BACKSCATTERING OF HAILSTONES AND THEIR POSSIBLE APPLICATIONS
Liu Jinli
1986, 3(4): 454-465. doi: 10.1007/BF02657935
Abstract:
The absorption, attenuation, and backscattering of hailstones with various structures are investigated by the model calculations of four kinds of spherical hailstones: pure ice spheres, liquid water-coated ice spheres, spongy ice-coated ice spheres, and all spongy ice spheres. All the results for the wavelength 5.56 cm, including the radar reflectivity factor, absorption factor, and attenuation factor of hailstones with different size distributions are given and discussed in this paper. The possible applications of these character-istics in radar monitoring of hailstones are also discussed. It is shown that in certain conditions, a micro-wave radiometer simultaneously operating with a radar will be helpful to the identification of the hail-bearing area. Finally, the possible influence of hailfall area on the accuracy of the measurements of the rainfall distribution by using a radar-radiometer is simply discussed.
A STUDY OF CIRCULATION DIFFERENCES BETWEEN EAST-ASIAN AND INDIAN SUMMER MONSOONS WITH THEIR INTERACTION
Zhu Qiangen, He Jinhai, Wang Panxing
1986, 3(4): 466-477. doi: 10.1007/BF02657936
Abstract:
Primarily based on the 1979 FGGE data an analysis is made of the circulation differences between the East-Asian and Indian summer monsoons together with their oscillation features and also the interplay be-tween various monsoon systems originating from the fact that the Asian monsoon area is divided into the East-Asian and Indian regions, of which the former is demarcated into the Nanhai (the South China Sea) and the Mainland subregions.
THE NONLINEAR INTERACTION BETWEEN DIFFERENT WAVE COMPONENTS AND THE PROCESS OF INDEX CYCLE OF GENERAL CIRCULATION
Xu Youfeng
1986, 3(4): 478-488. doi: 10.1007/BF02657937
Abstract:
By using a two-level quasi-geostrophic truncated spectral model taking account of the nonlinear in-teraction between different wave components (i. e. basic current, ultra-long waves and long waves), the index cycle of general circulation is investigated. The calculated results show that the circulation index has a, quasi-periodic vacillation with a period of 8 to 16 days, which can be created by the nonlinear interaction and that the nonlinear interaction between different wave components may cause the tilted-trough vacillation, amplitude vacillation of wave pattern and quasi-periodic change of wave number of flow pattern.
RELATIONSHIP BETWEEN THE INCREASE TEMPERATURE AND VARIATION OF OZONE LEVEL OVER THE ANTARCTICA AND TIBETAN PLATEAU IN SPRING
Gao Dengyi, Sadao Kawagochi
1986, 3(4): 489-498. doi: 10.1007/BF02657938
Abstract:
Based on the ozone and aerological sounding data at Syowa Station (69o 00'S, 39o35'E), Antarctica during 1966-1979 and Lhasa Station (39o40'N, 91o08'E), Tibetan Plateau during 1979-1983, the processes of temperature increase in spring over the Tibetan Plateau and the Antarctica are compared in this paper, and the relationship between the increase of air temperature and variation of total ozone and ozone partial pressure is analyzed. It is found that: (1) The process of temperature increase over the Tibetan Plateau is quite different from that over the Antarctica in spring. This is a proof that the heating effects of their ground surface on the atmosphere are of great difference; (2) Sudden increase of total ozone is always associated with sudden warming in the stratosphere over the Antarctica, but sudden decrease of total ozone is associated with sudden warming in the troposphere over the Tibetan Plateau in spring; and (3) There is a good positive correlation, with a correlation coefficient of about 0.85, between the temperature increase and variation of ozone partial pressure in the stratosphere over the Antarctica in spring.
A NUMERICAL EXPERIMENT OF CYCLOGENESIS AND THE DEVELOPMENT OF DISTURBANCES
Liu Ruizhi
1986, 3(4): 499-504. doi: 10.1007/BF02657939
Abstract:
A numerical experiment has been carried out to study the mechanism of cyclogenesis and the develop-ment of disturbances. First, an idealized field of temperature and pressure is designed, which is very similar to the actual synoptic situation, consisting of the jet-like zonal circulation with some nonzonal waves superim-posed on it. Prediction is made by using a six-level splitting primitive model with the idealized field as an initial one. The results show that if a disturbance like a frontal zone in the lower troposphere is superim-posed on the zonal circulation, a frontal cyclone will quickly develop and then gradually become an oc-cluded one. Its life cycle is similar to that of the actual frontal cyclone on the synoptic map. However, if there is a disturbance superimposed on the zonal circulation in the middle troposphere, the cyclone with weaker intensity will be slowly formed near the surface. Finally, if the initial disturbance is located at the high-level, a situation like a cut-off low rather than a frontal cyclone will develop.
DIVISION AND EVOLUTION OF DROUGHT AND FLOOD PHASES DURING THE LATEST 200 YEARS IN EASTERN CHINA
Lu Wenfang, Wang Qiang
1986, 3(4): 505-513. doi: 10.1007/BF02657940
Abstract:
Based on the past 200-year graded data of dryness/wetness in eastern China (24 stations), five phases to show the floods and droughts have been objectively divided by using the approach of cluster analysis of a sequential sample. The characteristics of flood/drought evolution have been described and explained. It is concluded that the floods or droughts occurred more often for the past two centuries, and the normal phase was seldom seen in eastern China. The transitions between floods and droughts are frequently of jumping feature. The extent and the frequency of serious drought or heavy flood in eastern China tended to expand and increase significantly in the last 50 years. Finally, by using the Walsh power spectrum, the periodicity of dryness/wetness graded series has been analysed. It is found that there exist the 2-9 year high-frequency fluctuations in eastern China.
THE BURST OF INDIAN SUMMER MONSOON AS REVEALED BY GOES SATELLITE DURING MONEX 1979
P. N. Mahajan, V. R. Mujumdar, S. P. Ghanekar
1986, 3(4): 514-519. doi: 10.1007/BF02657941
Abstract:
During FGGE year 1979, low-level air flow over the western Indian Ocean was determined from the analysis of GOES images (5-20 June). The wind pattern shows sudden change in low-level air circulation over western Indian Ocean during the initial burst of summer monsoon. The burst of monsoon is characte-rized by sudden establishment of low-level jet and strong cross-equatorial flow. This abrupt change signals the beginning of southwest monsoon over India and it is associated with the first monsoon rainfall over the southern part of western coast of India. Sudden change in low-level air flow is followed by the burst of monsoon within 3-5 days.