空间科学学报

1996 Vol. 16, No. 1

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A CME EXPANDING IN BOTH THE RADIAL AND LATERAL DIRECTIONS

Zhang Gong-liang

1996, 16(1): 1-6. doi: 10.11728/cjss1996.01.001

Abstract(2166) PDF 464KB(1279)

Abstract:
The angular expansion of the 5 May 1980 event is large in the outer loop,but insignificant in the inner loop; the expansion made the outer front flattering,and the streamer moving and bending. In comparison with the event in successionoccurring in the same solar region on the next day, the characteristics of theradial motion are different in the time domain, but similar in the space domain.Physical implications of above features are discussed in the paper.

KINETIC ALFVEN WAVE DAMPING AND POWER SPECTRUM OF TURBULENCE IN THE SOLAR WIND(a)

Song Li-ting

1996, 16(1): 7-16. doi: 10.11728/cjss1996.01.007

Abstract(2468) PDF 601KB(1112)

Abstract:
A new model is presented that Alfvenic turbulence in the solar wind is formedby kinetic Alfven waves assembly.bThe kinetic kAlfven wave is a coupling mode ofAlfyen wave and ion acoustic wave. The kinetic Alfren wave dispersion andLandau damping are derived, and the power spectrum of interplanetary Alfrenicfluctuations is given. When kinetic AlfVen waves with different wave length arepropagating outward from the sun the nonlinear interaction in the waves assemblyevolves the turbulence fluctuations. It is derived that the power spectrum of kinetic Alfrenic turbulence P_k∝k^-3/2, with the nonlinear interaction of waves assembly far away from the Alfvenic radius (≈ 0.3AU ). In the inner of Alfvenic pointthe power spectrum P_k changes from P_k∝k^{-1^{near the sun gradually to P_k∝k^-3/2with the competition between wave energy cascading and Landau damping. TheLandau damping of the kinetic Alfvenic fluctuations occurs only in the inner ofAlfvenic point and disappears out of Alfvenic radius. This model can overcomethe difficulties of previous theoretical models.}}

THE RAREFACTIVE SOLITON SOLUTION OF NONLINEAR MAGNETOSONIC WAVE AND KINETIC ALFVEN WAVE,AND THEIR APPLICATION IN THE LOWER CUSP REGIONS

Wang De-yu, Huang Guang-li, Dominique Le Queau, Chen Yan-ping

1996, 16(1): 17-23. doi: 10.11728/cjss1996.01.017

Abstract(2158) PDF 2574KB(1071)

Abstract:
The properties of the rarefactive soliton solution of nonlinear magnetosonicwave and kinetic Alfven wave have been studied in detail. It is found that the electric and magnetic fields, induced by different nonlinear wave are apprantly different in directions and patterns. These results are compared with the observationdata from Freja satellite in the lower cusp region. It is shown that the low frsquency events with density depression are most possibly due to nonlinear kineticAlfven wave.

THREE DIMENSIONAL NONLINEAR COUPLING OF TEARING MODES AND FAST MAGNETIC RECONNECTION

Deng Xiao-hua, Wang Shui, Wang Jing-fang

1996, 16(1): 24-35. doi: 10.11728/cjss1996.01.024

Abstract(2061) PDF 778KB(798)

Abstract:
In this paper, magnetic reconnection caused by the tearing-mode instability ina long and thin cylindrical geometry is numerically studied in the framework ofthree-dimentional incompresible resistive MHD theory. The results show that thenonlinear coupling of tearing modes with low ploidal mode numbers leads to therapid destabilization of the modes with higher ploidal mode numbers and to fastmagnetic reconnection. Furthermore, tearing mode turbulence is generated and theanomalies will be produced. The anomalous resistivity can quicken the growth ofthe tearing-mode instability and accopanying reconnection process. It is suggestedthat fast magnetic reconnection as a mechanism for the solar flares may be associated with this self-excited process caused by the nonlinear coupling of tearingmode instabilities in the solar corona.

DOPPLER SPECTRUM OF IONOSPHERIC IRREGULARITIES

Ning Bat-qi, Li Jun

1996, 16(1): 36-42. doi: 10.11728/cjss1996.01.036

Abstract(2164) PDF 498KB(1075)

Abstract:
The doppler spectra of ionospheric irregularities have been analyzed by usingfive years HF doppler records at Wuhan Ionospheric Observatory. Usually, thedoppler spectra of spread F are always diffusive, while the spectra of Es showsmooth straight line daytime, and become diffusive in the night. The meandoppler spread of scattering echoes is 2 or 3 times more than that of normalechoes. Moreover, one type of slant striated doppler spectrum associated with thedrift of ionized clouds in Es or spread F is also discussed in this paper.

THE LATEST ADVANCES ON E REGION IRREGULATIES STUDY BY COHERENT RADAR

Chen Pei-ren

1996, 16(1): 43-50. doi: 10.11728/cjss1996.01.043

Abstract(2049) PDF 434KB(1062)

Abstract:
The paper begins with the introduction of the ionospheric E region which is aspecial plasma space environment, then the six aspects of the latest advances ofthe investigation of the E region irregularities carried by VHF coherent radar arereviewed. Finally the fine prospect of this investigation carried in China is given.

STUDY OF THE VELOCITY FIELD OF THE POST-FLARE LOOP ON FEBRUARY 18,1984

Li Ke-jun

1996, 16(1): 51-55. doi: 10.11728/cjss1996.01.051

Abstract(1813) PDF 322KB(861)

Abstract:
The downward motion of materials within the post-flare loop of February 18,1984 under the joint action of solar gravity and the both gravity and the both gradients of the magnetic field pressure and atmospheric pressure is studied. Thevelocity distribution along the loop is calculated in the case that the temperaturechanges within the loop but the shape of the loop changes less with time. The results obtained show that the downward motion at both the top and the middle ofthe loop can be regarded as free d.ownward motion due to solar gravity, but atthe bottom of the loop, the motion is obviously affeCted by material density andthe magnetic field strength within the loop.

THE EVOLUTION OF THE FILAMENT IF THE REGION AR2522 AND THE ERUPTION OF THE FLARE

Wu Gui-ping, Xu Ao-ao

1996, 16(1): 56-61. doi: 10.11728/cjss1996.01.056

Abstract(2031) PDF 470KB(1164)

Abstract:
With observational data in several bands in region AR2522, the relationshipbetween the evolution of the filament and the eruption of 1B/M4 two-ribbon flareis analysed. It is shown that: (1) the shearing movement of the filament footpointleads to the increase of the current intensity and the stored energy for the flareeruption; (2) the ascending motion and twisting of the filament are the results ofthe increasing current intensity and the stored energy of the flare, (3 ) Martens Kuin model is applicable to illustrate eruptive phenomena of the two-ribbon flarerelated to the filament with rapid motion.

THE VLF FIELD ON THE SURFACE OF THE SEA GENERATED BY THE SPACEBORNE TRANSMITTER AND ANTENNA

Pan Wei-yan

1996, 16(1): 62-70. doi: 10.11728/cjss1996.01.062

Abstract(2264) PDF 379KB(1107)

Abstract:
The recent space technology is capable to design a spaceborne VLF/ELFtransmitter and antenna for the communications to submarines, in this.case, the antenna is a vertical wire in the F-layer of the ionosphere at a height of 400km. Forsimplicity, the antenna is idealized as a dipole, the ionosphere is idealized as ahomogeneous anisotropic plasma with sharp boundaries, the VLF magnetic fieldon the sea surface is analyzed and calculated.

EFFECT OF ANTHROPOGENIC PERTURBATIONS ON THE UPPER STRATOSPHERE AND MESOSPHERE

Wang Ying-jian

1996, 16(1): 71-77. doi: 10.11728/cjss1996.01.071

Abstract(2356) PDF 446KB(692)

Abstract:
In this paper, the effeCts of increased CH₄, N₂O and CO₂ due to human activities on the upper stratosphere and mesosphere are investigated using a coupledchemical-radiative one-dimensional model. The results indicate that a doubling inthese gases leads to an obvious variation of water vapour and ozone concentrationsand temperature in the middle atmosphere. The temperature in the upper part ofmiddle atmosphere will decrease about 10K due to a doubling in troposphericCO₂. And a doubling CH₄concentration in the troposphere not only lead to anincrease in water vapour concentration of more than 50% in the mesopause region, but also decrease its temperature obviously. It could be in favour of the formation of nocticlucent cloud.

SOLAR RADIO EMITTING CHARACTERISTICS OFX-RAY EVENTS GENERATED FROM AR5395 AND AR5629

Wu Hong-ao, Sun Jiu-zhen

1996, 16(1): 78-84. doi: 10.11728/cjss1996.01.078

Abstract(1974) PDF 512KB(644)

Abstract:
In this paper the solar soft X-ray events with importance X, proton eventsand the corresponding radio alow varying component (SVC) as well as radioevents generated from AR5395 and AR5629 in March and August, 1989, are analysed respectively comprehensively. The main results are as follows:1. The X-ray events with importance X occurred basically on the backgroundlevel C2 of X-ray emission, which are well correlated with spectra index α_s at highfrequency side of SVC spectrum, for example, level C2 corresponds to-2 < α_s< 0 for AR5395.2. The importance of X-ray event is proportional to the harder spectral indexand the ratio of peak flux density at high frequency to that at low frequency ofdouble peak spectrum, and inversely proportional to the spectral index between8.8GHz and 4.995 GHz of mono tonicaly rising spectrum.3. Proton event may also be related with the spectral depth T≤0. 5 at 2. 695GHz, except type U spectrum of radio event.