1990 Vol. 10, No. 4

Display Method:
PREDICTION OF GEOMAGNETIC ACTIVITY MAXIMUM AND PEAK TIME IN THE 22ND SOLAR CYCLE
Gao Mei-qing, Xiang Jing-tian, Kong Nan, Zhang Gui-qing
1990, 10(4): 241-246. doi: 10.11728/cjss1990.04.241
Abstract(1953) PDF 339KB(915)
Abstract:
This paper discusses the character and differences of the solar cycle and geomagnetic cycle from the 13th to the 22nd solar cycles. The self-excitation threshold autoregressive time series model and autoregression method using maximum entropy spectrum are used to simulate and predict that the peak time of the annual average value of geomagnetic aa index is in the spring of 1994 or the Autumn of 1993. The maximum in geomagnetic annual average aa index is 26-29. The 22nd geomagnetic cycle is expected to be a middle active cycle.
NUMERICAL SIMULATION OF THE COSMIC RAY FORBUSH DECREASE
Guo Wei-ji, Zhu Bang-yao
1990, 10(4): 247-255. doi: 10.11728/cjss1990.04.247
Abstract(1718) PDF 563KB(889)
Abstract:
Considering that the effect of shock waves on cosmic ray is simply produced by a disturbed region where the solar wind speed is raised and the diffusion coefficient is reduced. The numerical modeling on the base of solar modulation of galactic cosmic ray is performed. It is found that the decrease of diffusion coefficient is more effective than the increase of solar wind speed in producing the Forbush clecrease.The amplitude of Forbush decrease is getting smaller as it propagates outward. The Forbush decrease when two independent shock waves exist is simply the linear superposition of the two Forbush decreases produced as if the two shock waves exist separately.
TRANSITION DOMAIN'S SPECTRAL CHARACTERISTICS OF ESF
Wu Ying, Wang Jing-fang, Liang Bai-xian
1990, 10(4): 256-264. doi: 10.11728/cjss1990.04.256
Abstract(2010) PDF 572KB(604)
Abstract:
In this paper, an electrostatic model for transitional domain of ESFis derived from plasma two-fluid equations, then, its spectrum equation is obtained according to the weak coupling approximation formalism of plasma turbulence. It is shown that this model has k-5 and k-3 type spectrum for plasma density fluctuation and electric field fluctuation respectively which agree well with the ESFtransitional domain's experimental results.
NUMERICAL CALCULATIONS OF CHAPMAN'S FUNCTION IN A REALISTIC MODEL ATMOSPHERE
Chen Yao-wu, Xu Xiu-juan, R. J. Hung
1990, 10(4): 265-273. doi: 10.11728/cjss1990.04.265
Abstract(2163) PDF 563KB(1103)
Abstract:
In present paper, the Chapman's grazing incidence function varing with heights of observational point and solar zenith angle is numerically calculated. The variation of Chapman's function in a realistic model atmosphere due to high temperature gradient, molecular and eddy diffusion transport, gravity field as well as solar activity is computed and discussed for the lower thermosphere. The results obtained indicate, in a realistic model atmosphere of the earth, especially at the thermospheric heights up to 150 km, the Chapman's function differs sufficiently from those calculated by previous authors using the constant scale height and constant scale height gradient models, and the influence of the high temperature gradient in the lower thermosphere plays a leading role among the other effects. The influences of solar activity on Chapman's function appear to be efficient at large solar zenith angles(in a range of 10-40% between high and low solar conditions). These results are of obvious benefit for the studies of solar radiation-photochemistry-dynamics processes in the thermosphere.
THE INFLUENCE OF THE SOLAR WIND ON THE RETARDATION OF ROTATION OF THE SUN
Li Lin-sen
1990, 10(4): 274-279. doi: 10.11728/cjss1990.04.274
Abstract(1797) PDF 345KB(1278)
Abstract:
In this paper, the influence of the solar wind on the retardation of rotation of the sun is examined. The theoretical expressions for the relative variation rate and secular variation of angular velocity of rotation are derived. For the relative variation rate, the effect of mass loss due to solar wind is negligible; but for the secular variation, it can not be neglected The results of numerical computation are given. The relative variation rate(这里有图片19900405-274-1.GIF)/ω= -5.4× 10-10/year. The curve of secular variation in 107 year is plotted in Fig. 1.
THE CHARACTERISTICS OF GREAT COSMIC RAY STORM EVENTS IN MARCH 1989
Ye Zong-hai, Xiao Shao-yu, Xue Shun-sheng
1990, 10(4): 280-288. doi: 10.11728/cjss1990.04.280
Abstract(1776) PDF 618KB(734)
Abstract:
The characteristics of Forbush decreases of cosmic ray caused by solar flares in March 1989 are analysed in this paper. The anisotropy for μ-meson component are also analysed beside neutron component, and the relationship between the cosmic ray intensity variation and the characteristics of solar flares and geomagnetic activities are discussed. The results show-that Forbush decreases not only bear a relation to the importances, duration and angular distance from the central meridiam of solar flares, but also depend on whether the optical flares are accompanied by strong X-ray bursts and radio bursts, as well as followed by geomagnetic storms of sudden commencement type. The anisotropic analysis shows that the anisotropy of the large cosmic ray storm events in March was obviously weaker than that of the cosmic ray intensity during the quiet days. It is probably because that strong solar activity could reduce the degree of the cosmic ray anisotropy.
THE POSSIBLE INFLUENCE OF THE TOPOGRAPHY ON THE STRATOSPHERIC SUDDEN WARMING
Shen Chang-shou, Tian Jian-hua
1990, 10(4): 289-295. doi: 10.11728/cjss1990.04.289
Abstract(1822) PDF 502KB(984)
Abstract:
The temperature data from satellite Nimbus 7 SAMS are used to analyse the latitude-altitude distribution of temperature and its temporal variation during the period of stratospheric sudden warming in winter. The distribution profiles for four meridians with different topographic features are shown in this paper. The analysis inlicates significant effects of the to pographic feature.The heating of the atmosphere caused by the planetary wave and the sudden warming in the lower stratosphere over mountain, plain and ocean, are obviously different.It is generally believed that the stratospheric planetary waves are forced in the troposphere by topography and by adiabatic heating associated with land and sea thermal contract, and propagate vertically from the troposphere. The considerable sudden warmings of the lower stratosphere over high latitudes on 80°Eand 100°Emeridians shown in this study are chiefly responding to the stronger solar heating on the land aera. The topographic effect on the stratospheric sudden warming in the west of China is of importance for understanding the coupling between the troposphere and stratosphere. The sudden warming could change the local atmospheric circulation. It is often accompanied by abnormal absorption of radio waves propagating through the ionospheric Dlayer. Therefore, the influence of the topography on the behaviors of the stratosphere and ionosphere is also an important topic for study of aeronomy.The large increase of temperature in the stratopause over high latitudes on 20 °Elongitude, which covers the Europe plain, is found in this case too. No sudden warming, however, appears in the lower stratosphere. As regard to 180°Elongitude crossing mainly over the sea area, even the enhancement of temperature in the higher stratosphere is not apparent. These different features prove again the topographic effect on stratospheric behavior.