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Table of Content

    24 December 1992, Volume 12 Issue 4 Previous Issue    Next Issue
    论文
    CHARACTERESTICS OF A SOLAR HARD X-RAY BURST
    Zhou Ai-liua
    1992, 12 (4):  241-248.  doi: 10.11728/cjss1992.04.241
    Abstract ( 1576 )   PDF (693KB) ( 883 )   Save
    In this paper,a very intense high-energy event occurred on April 27,1981 is analysed.Observations on SMM/GRS and radiometers at Purple Mountain Observatory reveales the onc-to-one correspondence of individul spikes in the time profiles of the hard X-rays (HXR),γ-rays and microwaves (MW) in the maximum phase.The main characteristics of the spikes are as follows: (1) The time profiles at Mm channnel (0.3-1.1MeV) of γ-rays is simira to that at higher frequence (35GHz) of MW;(2) Tie duration of individual spikes are in 66-168 second range,it decreases with increasing of HXR energy,but with decreasing of MW frequencies;(3) The peak of higher energy channel is later than that of lower energy channel in HXR and γ-rays In contrast with this,the peak at higher frequency preceeds one at lower frequency in MW;(4) The profiles in MW peak appear later and decay is later than in HXR.For example,the peak at 35 GHz is delaied by 17s with respect to channel X23 (54-100 keV),the everage delay at 35 GHz and at M10 channel are well marched,which agrees with expectation of the turbulence acceleration theory;(5) Delay time increases with increasing of spike duration,chnnel energy,MW wavelength,and hardness of HXR spectrum;(6) During spike bursts the spectra of HXR exhibit soft-hard-soft behavior (varying amplitude being about 1),which means these spikes result from acceleration of electrons.The power-low spectrum index and the total numbers of nonthermal electrons in the HXR burst source are estimated on the assumption of thin target model.The magnetic field strength (being about 2.6×10-3-3.0×10-2T) in the MW radiation source is also estimated.
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    NUMERICAL SIMULATION OF PROPAGATION AND OVERLAP OF INTERPLANETARY SHOCK
    Gu Hui-cheng;Wei Feng-si;Lu Jian-yong
    1992, 12 (4):  249-257.  doi: 10.11728/cjss1992.04.249
    Abstract ( 1929 )   PDF (791KB) ( 1118 )   Save
    A time dependent,two-dimensional magn:tohydrodynamic model is used to simulate the flare-associated shock waves and their subsquent disturbances in equatorial plane between 0.1 AU and 1.1 AU.It is simulated that the shocks associated with a disturbed interplanetary medium by two flares,erupted one after with a delay of several hours.The result shows that interactions between shocks depends on the time interval of the two flares.These interactions can be classified into four types,(1) strong interaction,(2) middle interaction,(3) weak interaction,(4) no interaction,according to the interval of flares.Computations are carried out in two cases,(1) the shock wave associated with a single flare,(2) the shock wave associated with two flares which belong to strong interaction.The result shows that interplanetary magnetic fields in first case are similar to those in the second case,44 hours after the introduction of disturbances.The parameters of the solar wind measured at 1.0 AU,along the flare normal also have the similar time profiles in the two cases.
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    MHD SIMULATION OF INTERACTIONS BETWEEN TWO NEIGHBORING INTERPLANETARY SHOCK WAVES——ENEGETIC EFFECTS
    Lu Jian-yong;Wei Feng-si;Gu Hui-cheng
    1992, 12 (4):  258-269.  doi: 10.11728/cjss1992.04.258
    Abstract ( 1594 )   PDF (927KB) ( 919 )   Save
    A MHD 2 1/2D,time-dependent model is used to investigate a series,individually of neighboring interplanetary shock wave interactions in the equatorial plane.For an azimuthal angular separation of 36 degree,between the centers of two disturbances,four different initial velocities,vs=500,1000 2000 and 3000 km/s are considered in this paper.The results indicate: for the case of vs=2000 and 3000 km/s,the two shock waves have already coalesced into a new shock within 1 AU,there are not any two peaks in the velocity,desity and temperature.From those parameters at 1 AU,it is difficult to identify whether this new shock wave coalesced from two shock waves,however,the magnetic field distribution in the new shock is very distinct from a single shock wave;for the case of vs=1000 km/s,the two shock waves have not completely coalesced into a new shock wave,and the peak of shock parameters of each shock wave can be identified from their distributions;for the case of vs=500 km/s,the coalescence would almost not occur,in fact,the two shock waves would decayed independently into ordinary MHD waves near 0.3 AU.
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    STORM-TIME INCREASE IN COSMIC RAY INTENSITY AND ITS CHARACTERISTICS
    Ye Zong-hai;Sun Xiao-qing
    1992, 12 (4):  270-278.  doi: 10.11728/cjss1992.04.270
    Abstract ( 1675 )   PDF (772KB) ( 1384 )   Save
    The cosmic ray increases due to considerable depressions of cosmic ray cut off rigidity during large geomagnetic storms are investigated.Data from 11 superneutron monitors in world network are analyzed for six geomagnetic storms of various type during 1984-1989.The results show that the storm-time increases are due to existence of westward equatorial ring currents developing or intensifying during geomagnetic storms.The stronger the geomagnetic storm,the larger the storm-time increase.The storm-time increases have obvious latitude effect or geomagnetic cut off rigidity dependence.Beijing station is at the obvious region for the storm-time increase,and storm-time increases are of local tune dependence.This enhancement is larger at the daytime than at the nighttime.Showing that the intensifying ring current is asymmetrical.
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    INTERACTION BETWEEN WHISTLER MODE WAVE AND THE ELECTRONS IN THE MAGNETOSPHERE
    Hu Xiong;Zhang Xun-xie
    1992, 12 (4):  279-286.  doi: 10.11728/cjss1992.04.279
    Abstract ( 1456 )   PDF (795KB) ( 902 )   Save
    Nonlinear interaction between the whistle mode wave and the electrons in the magneto-sphere reduces the electron's pitch angle and makes some electrons precipitating into the ionosphere,which enhances the local ionization and induces Trimpi Effects.In this paper the equations governing the wave-particle interaction are given and the Super Particle Mode,Long-Time-Scale-Method are used to simulate this nonlinear process.The results of the simulation are as following: (1) When the electrons meet the whistler wave,there occur the phase focus of resonance electrons and phase bunching of unresonance electrons.The resonance electron oscillate asymmetrically in he space (-4)-μ during the interaction.(2) The inhomogeneity of the earth magnetic field causes the shift of center angle of trapped region and has influences on the whistler wave trapping electrons.(3) This paper also gives the curves of energy flux of the electron precipitation with time at the altitude of 1000 km above the earth and the curves of energy distribution of the precipitating electrons.
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    A PHYSICAL MODEL OF IONOSPHERE FOR LOW LATITUDES AND ITS' APPLICATIONS IN DISCUSSIONS OF F1 VALLEY FORMATION
    Gao Ming;Xiao Zuo
    1992, 12 (4):  287-297.  doi: 10.11728/cjss1992.04.287
    Abstract ( 1701 )   PDF (827KB) ( 844 )   Save
    F1 valley has recently been one of the interesting issues in ionospheric F2 region.In this paper,a physical model of ionosphere for mid-and low-latitudes is taking into account self-consistently both the neutral wind and motions of ions.The speeds of neutral particles and ions are obtained by simultaneously solving sets of dynamic equations satisfied by those two kinds of particles,with are coupled through collisions.Four species of ions are included to represent photo-chemical reactions.With this ionospheric model and focusing on the area of China's central part,i.e.,116° and 30℃,the effects of photo-chemical and dynamical processes on the F2 region are discussed with particular emphasis put on the influence of ions' vertical motion on F1 valley.Results show that under photo-chemical equalibrium,E region always forms and a F1 ledge appears only in summer at low solar activity,but deep F1 valley and formation of F2 region can not be explained solely by photo-chemical process.Ambipolar diffusion is falally important for F2 formation.Vertical motions of ions caused by neutral wind does not affect E region much,but can produce a considerably profound valley in summer at low solar activity with a depth of 0.05-0.1.Diurnal variations of F1 valley is also examined and results show that this model can reflect some features of F1 valley for China's mid-and low-latitude area.
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    THE VERTICAL PLASMA DRIFTS NEAR THE IONOSPHERIC PEAK
    Zhang Shun-rong;Su Yuan-zhi;Huang Xin-yu
    1992, 12 (4):  298-304.  doi: 10.11728/cjss1992.04.298
    Abstract ( 1592 )   PDF (644KB) ( 998 )   Save
    On the basis of the ionosonde data,this paper deals with the diurnal morphology of the plasma vertical drifts near the ionospheric F2 peak by means of Servo Model.And corresponding variations of the drifts with season and solar activity are also discussed over a group of lower mid-latitude locations.The results indicate a roughly good consistence with the experimental ones,while some new features,mainly the "hollow-at-dawn" and "buldge-at-sun-rise" on the diurnal curves,are discovered.
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    VARIATION OF IONOSPHERIC ELECTRON DENSITY IN THE 100-200km HEIGHT REGION AT LOW LATITUDES
    Xu Xiu-juan;Chen Yao-wu
    1992, 12 (4):  305-312.  doi: 10.11728/cjss1992.04.305
    Abstract ( 1533 )   PDF (648KB) ( 927 )   Save
    Using the photochemical equilibrium daytime model,the electron density profiles in the 100-200 km region at low latitudes are calculated.The characteristics of the depth and width of E-F1 valley are also analysed.The main results obtained are: (1) the variation of electron density with height and solar zenith angle depends on solar activity levels.It is found that the correlation of electron density with solar activity indices can be both positive or negative;(2) the solar activity can affect the morphology of E-F1 valley.Under a certain solar activity level,the relation between the width and depth of valley and solar zenith angle can not be represented by a simple function at a given solar declination and geographical latitude;(3) the solar flare and geomagnetic activity influence obviously the distribution of the electron density;(4) O+(2P) and photoionization of nitre oxide may play a significant role in the 100-200 km height region.
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    IONOSPHERIC DISTURBANCES CAUSED BY SOLAR ACTIVITIES IN MARCH 1989
    Huang Qing-ming
    1992, 12 (4):  313-317.  doi: 10.11728/cjss1992.04.313
    Abstract ( 1352 )   PDF (352KB) ( 683 )   Save
    In this paper,the characteristics of major ionospheric disturbances caused by large flares is analysed by using ionospheric data from 16 vertical ionosonde stations,in China,USSR,Japan and Australia.
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    研究简讯
    SOME FEATURES OF THE VARIATION OF f0E, f0Es,fbEs IN XIZANG PLATEAU AND GUANGZHOU REGION
    Li Yu-hui
    1992, 12 (4):  318-320.  doi: 10.11728/cjss1992.04.318
    Abstract ( 1447 )   PDF (250KB) ( 563 )   Save
    In this paper,ionospheric features parameters f0E,f0Es and fbEs are statistic analyzed using pratical measuring formation in Xizang plateau and Guangzhou region during the summer of 1985 to 1988,and their variation law and characteristics are also obtained,too.
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