Advanced Search

1989 Vol. 6, No. 1

Display Method:
Non-Acceleration Theorem in a Primitive Equation System: I. Acceleration of Zonal Mean Flow
Wu Guoxiong, Chen Biao
1989, 6(1): 1-20. doi: 10.1007/BF02656914
Non-acceleration theorem in a primitive equation system is developed to investigate the influences of waves on the mean flow variation against external forcing. Numerical results show that mechanical forcing overwhelms thermal forcing in maintaining the mean flow in which the internal mechanical forcing associated with horizontal eddy flux of momentum plays the most important roles. Both internal forcing and external forcing are shown to be active and at the first place for the mean flow variations, whereas the forcing-induced mean meridional circulation is passive and secondary. It is also shown that the effects on mean flow of external mechanical forcing are concentrated in the lower troposphere, whereas those due to wave-mean flow interaction are more important in the upper troposphere. These act together and result in the vertically easterly shear in low latitudes and westerly shear in mid-latitudes. This verti-cal shear of mean flow is to some extent weakened by thermal forcing.
The Influence of ENSO on the Summer Climate Change in China and Its Mechanism
Huang Ronghui, Wu Yifang
1989, 6(1): 21-32. doi: 10.1007/BF02656915
The influence of ENSO on the summer climate change in China and its mechanism from the observed data is discussed, It is discovered that in the developing stage of ENSO, the SST in the western tropical Pacific is colder in summer, the convective activities may be weak around the South China Sea and the Philippines. As a consequence, the subtropical high shifted southward. Therefore, a drought may be caused in the Indo-China peninsula and in the South China. Moreover, in midsummer the subtropical high is weak over the Yangtze River valley and Huaihe River valley, and the flood may be caused in the area from the Yangtze River valley to Huaihe River valley. On the contrary, in the decaying stage of ENSO, the convective activities may be strong around the Philippines, and the subtropical high shifted northward, a drought may be caused in the Yangtze River valley and Huaihe River valley.
Sensitivity of the Multiple Equilibria to Gorverning System, Mode Chosen and Parameter
Zhao Jingxia, Zhu Baozhen
1989, 6(1): 33-43. doi: 10.1007/BF02656916
A Numerical World Ocean General Circulation Model
Zhang Xuehong, Liang Xinzhong
1989, 6(1): 44-61. doi: 10.1007/BF02656917
This paper describes a numerical model of the world ocean based on the fully primitive equations. A “Standard” ocean state is introduced into the equations of the model and the perturbed thermodynamic variables are used in the modle’s calculations. Both a free upper surface and a bottom topography are included in the model and a sigma coordinate is used to normalize the model’s vertical component. The model has four unevenly-spaced layers and 4 × 5 horizontal resolution based on C-grid system. The finite-difference scheme of the model is designed to conserve the gross available energy in order to avoid fictitious energy generation or decay.The model has been tested in response to the annual mean surface wind stress, sea level air pressure and sea level air temperature as a preliminary step to its further improvement and its coupling with a global atmospheric general circulation model. Some of results, including currents, temperature and sea surface elevation simulated by the model are presented.
Conditions for Producing and Maintaining Plasma Ball Lightning in the Atmosphere
Zou Yousuo
1989, 6(1): 62-74. doi: 10.1007/BF02656918
Based on the results of plasma experiments and research work done by Dawson and Jones, Trubnikov, Endean, and other researchers, three requirements for producing and maintaining plasma ball lightning have been found: 1) rotation of plasma, 2) the density of charged particles nc > 3.15 × 10-10ω2,3) a stable confinement of plasma. In this model, the energy density of ball lightning ranged from 10-2 J / cm3 to 104 J/ cm3, the formation, shape, stability, energy, maintaining processes and other properties of ball lightning were explained reasonably.
Numerical Simulation on the Rainout-Removal of Sulfur Dioxide and Acidification of Precipitation from Stratiform Clouds
Qin Yu
1989, 6(1): 75-88. doi: 10.1007/BF02656919
The rainout-removal of SO2 and the acidification of precipitation from stratiform clouds are simulated using a one-dimensional, time-dependent model, parameterized microphysically in which dissolution and dissociation of gaseous SO2 and H2O2, and oxidation reaction in aqueous phase are taken into account. The effects of dynamic fac-tors, including updraft flow and turbulent transport, and the concentration of gaseous SO2 and H2O2 being transported into the clouds on pH value of the precipitation, the conversion rate S(IV)-S (VI) and the wet deposition rate of SO2 are discussed.
Role of Ozone in the Sodium and Hydroxyl Nightglow
L.S. Hingane
1989, 6(1): 89-98. doi: 10.1007/BF02656920
One-dimensional photochemical diffusion model which includes oxygen-hydrogen-sodium atmosphere has been used to examine the relation between sodium and hydroxyl nightglow and the role of ozone in it. It is found that both emissions can be obtained on the basis of photochemistry. The following reactionsNa + O3→NaO + O2 and H + O3 → OH* + O2 play key role in sodium and hydroxyl emission respectively. Further it is found that variations in both emissions are controlled by the variation in the concentration of ozone.
Correlations of the Evolution of a CCOPE Squall Line with Surface Thermodynamics and Kinematic Fields
Xu Yumao, J.C. Fankhauser
1989, 6(1): 99-112. doi: 10.1007/BF02656921
A midlatitude squall line passed over the array of the Cooperative Convective Precipitation Experiment (CCOPE) on 1 August 1981. The structure and evolution of the squall line, and the correlations of the storm with sur-face thermodynamics and kinematic fields are investigated, mainly by using radar and surface mesonet data in CCOPE. The storm-wide precipitation efficiency is also estimated.The squall line was of an obvious process of metabolism. Thirty-four cells formed successively in front of the primary storm und eventually merged into it during the period 1700-2010 MDT. The newest cells formed near sur-face equivalent potential temperature maxima, and near surface moisture flux convergence zones or / and the “tem-perature break lines”. The thunderstorm rainfall, with the precipitation efficiency of 54%, lags 25-30 min behind the moisture flux convergence on the average.
Analysis of Indian Monsoon and Associated Low-Level Circulation in 1980 and 1981
Tao Zuyu
1989, 6(1): 113-119. doi: 10.1007/BF02656922
In this paper, Indian monsoon of 1980 and 1981 is analysed based on the seasonal and half-month averaged data of 850 hPa of ECMWF analysis. The results show that Indian monsoon is related to Somali jet, the low-latitude easterlies and the mid-latitude westerlies over southern Indian Ocean, which are associated with the stationary wave of Southern Hemisphere. The forces affecting on the low-level flow are diagnosed, which display the relationship between Indian monsoon and the associated low-level flow.
Sensitivity Experiments on Summer Monsoon Circulation Cell in East Asia
He Jinhai, Li Jun, Zhu Qiangen
1989, 6(1): 120-132. doi: 10.1007/BF02656923
The East-Asian summer monsoon meridional circulation (SMMC) cell is simulated together with two vigorous rainbands in terms of a primitive-equation model including in itself a variety of diabatic heating, frictional dissipation and moist processes under the condition of mountains available. Results are comparable to observations. Also, performed are experiments with the reduction of water content, and exclusion of the cumulus convective process and mountain effect. Contrast analyses indicate that the cell is strongly sensitive to the condition of the humidity field in the atmosphere, more intensely at 120o than at 100oE, and the presence (absence) of the cumulus convection has considerable effect on the intensification (weakening) of the cell, with the mountain ranges exhibiting more influence upon the cell at 100o than 120oE. This may suggest that a great difference lies in the cause of the cell for the two meridions.
A Numerical Experiment of Mesolow on the Eastern Side of the Taihang Mountains
Xu Yuantai, Li Hongzhou
1989, 6(1): 133-136. doi: 10.1007/BF02656924
A numerical experiment on the formation and decay process of a mesolow on the plain east to the Taihang Mountains has been conducted. The dynamical effect of the special topography of the Taihang Mountains and the Yanshan Mountains on the formation of the mesolow is very important. Namely, the difference of the heating be-tween the Taihang Mountains and the North China plain plays an important role in the formation and decay of the mesolow.