空间科学学报

1995 Vol. 15, No. 1

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SPONTANEOUS RECONNECTION OF CURRENT SHEETS AND FORCE-FREE FIELD──FORMATION OF MAGNETIC ISLANDS

Li Xing, Hu You-qiu

1995, 15(1): 1-7. doi: 10.11728/cjss1995.01.001

Abstract(2540) PDF 427KB(817)

Abstract:
Using the multistep implicit scheme,a numerical study was made to reveal the influence of linear force-free field to the spontaneous reconnection of current sheets.It is found that the background field (force-free field)of current sheets can strongly affect the topology of the reconnection.When the force-free factor a reaches a critical value,a big area of magnetic island forms in the simulation domain,and the thickness of the island is an increasing function of times.But if the force-free factor is smaller,than the critical value, no islands can be formed.When a is zero,it turns to the common single Xline reconnection of potential field.The reconnection topology of the potential field agrees to that of Scholar.

THE OCCURRENCE OF COUNTER ELECTROJET AND THE QBO

Chen Pei-ren, Ma Jun

1995, 15(1): 8-13. doi: 10.11728/cjss1995.01.008

Abstract(2296) PDF 416KB(914)

Abstract:
The hourly value of horizontal component of geomagnetic field measured in Trivandrum, India has been analysed.The data length covers about two sunspot cycles.After reducing the variations of solar cycle and one year periodity in the data set,a quasi-biennial variation in the occurrence of Counter Electrojet(CEJ) is revealed:the occurrence of CEJ is increased in the easterly phase of QBO and decreased in the westerly phase of QBO. Based on this discovery,the causative mechanism of CEJ is discussed.It is suggested that, the interaction between the upward propagating planetary waves and solar and lunar semidinal tides,may causes the semidinal tides enlarging in amplitude and shifting in phase, and finally results in the occurrence of CEJ.

THE EFFECTS OF NITRIC OXIDE ON ELECTRON DENSITY

Xu Xiu-juan

1995, 15(1): 14-18. doi: 10.11728/cjss1995.01.014

Abstract(3135) PDF 257KB(1181)

Abstract:
In this paper,The effects of Nitric Oxide on electron density content in the 100-200km region at mid-low latitudes is studied by using the model of ionospheric electron density. It is found that the correlation of Nitric Oxide with electron density can be either negative or positive.The positive correlation occurs as the NO + hv → NO⁺ + e is the dominant production source of NO⁺.

ATTITUDE STABILITY OF LIQUID-FILLED SATELLITE IN GRAVITATIONAL FIELD

Liu Yan-zhu, Cheng gong

1995, 15(1): 19-23. doi: 10.11728/cjss1995.01.019

Abstract(2033) PDF 294KB(727)

Abstract:
The attitude stability of an asymmetrical liquid-filled satellite relative the orbital coordinate system in a circular orbit under application of the gravitational torque is discussed in present paper.A sufficient and necessary condition of stability of relative equilibrium is obtained by use of the Liapunov's direct method and the firstapproximation theory.

EMERGENT MAGNETIC FLUX AND FILAMENT ACTIVATION IN ACTIVE REGIONS

Yin Chun-lin, Tang Yu-hua

1995, 15(1): 24-32. doi: 10.11728/cjss1995.01.024

Abstract(2369) PDF 517KB(686)

Abstract:
In this paper,the basic regularity of filament motion driven by emerging magnetic flux is first explored numerically.The results show that the emerging flux in the active region is an effective mechanism for driving filament motion and causing ilament activation.This process can be realized by the interaction between the filament current and background magnetic field in the active region. With different emerging flux intensities,the periodic oscillation,activation rising and "twinkle" can occur in the filament.Moreover,if the polarity of emerging flux is the same with that of the filament,the filament would drop down at the beginning of its evolution when the emerging flux is strong enough.

THE GEOMAGNETIC DISTURBANCES CAUSED BY SOLAR ACTIVITY IN MARCH 1991

Gao Yu-fen, Zhang Gong-liang, Zhou Rong-mao

1995, 15(1): 33-41. doi: 10.11728/cjss1995.01.033

Abstract(2476) PDF 570KB(718)

Abstract:
Using the geomagnetic data of Baijiatuan and Madaoyu observatories in Beijing,the magnetic storms of March 24-27 caused by solar activity during the last ten days of March 1991 are analysed. From the records of mid-latitude, one could find the storms have some specific morphological features: the amplitude of the sudden commencement is very large, the most severe activity of the storms is produced by the substorm beginning immediately after the sudden commencement; there appear some pulsations in many intervals during the storms, in particular, the pulsations with T = 650s are outstanding.It is polarization direction displays mainly left-handed,but,it mixed up with right-handed ones without any obvious regularities. The results of spectra analysis indicate that power spectrum p(f) of the whole storm follows the form P(f) = f^-2.0. In addition, the interplantary disturbances are discussed,which may cause the storms.

THE CURRENT COLLECTION BY HIGH VOLTAGE SOLAR ARRAY FROM THE SPACE PLASMA

Gu Shi-fen, Shi Li-qing, Song Li, Tian Bao-ning

1995, 15(1): 42-46. doi: 10.11728/cjss1995.01.042

Abstract(2299) PDF 323KB(1280)

Abstract:
In this paper,a theoretic model of current collection is developed.the model makes it easier to calculate the current collected by high voltage solar array (HVSA)from the space plasma.Through analysis of the physical process we suggest that plasma coupling power loss for HVSAdesigning should not be neglected.

THE MAGNETOSPHERE-IONOSPHERE COUPLING AND THE VARIATION OF THE MID-LATITUDE GEOMAGNETIC INDEX

Zi Min-yun, Shen Chang-shou

1995, 15(1): 47-52. doi: 10.11728/cjss1995.01.047

Abstract(2585) PDF 302KB(1088)

Abstract:
Features of the mid-latitude geomagnetic index ASY-Hduring periods of the magnetosphere-ionosphere coupling are analysed. They are compared with feature of the auroral electrojet(AE) index and that of the equatorial electrojet.Both the results of the courrelation analysis and the superposed epoch analysis can be brought into a self consistent physical picture.It is also shown that the diurnal variation of the equatorial electrojet during the main phase of a geomagnetic storm with Revent is different from that on disturbed days when no energy injects into the ring current.All these results prove that it is'important to distinguishs.the effect of magnetospheric disturbance penetrating directly to mid- and lowffetitude from that generated in the ionosphere by dynamic processes.

P-D TRANSFER WITH TILTED IONOSPHERE AND PREDICTION OF MUF

Si Jia-cai

1995, 15(1): 53-58. doi: 10.11728/cjss1995.01.053

Abstract(2163) PDF 375KB(922)

Abstract:
This paper presents a method to transfer the minimum time-delay on backscatter ionogram into the earth's distance with ionospheric tilt considered;and discusses MUF prediction by use of backscatter ionogram.Under D>1000km,the maximum error of the P-D transfer is ≤ 3.5%; the difference between CCIR and the result of this paper are±1.5 MHz.

THE APPLICATION OF ARTIFICIAL NEURAL NETWORKS TO THE PREDICTION OF GEOMAGNETIC INDEX

Gu Zuo-wen, Gao Yu-fen, Fan Guo-hua

1995, 15(1): 59-65. doi: 10.11728/cjss1995.01.059

Abstract(2116) PDF 2664KB(1040)

Abstract:
The application of Artificial Neural Networks to the prediction of Geomagnetic Index is introduced in this paper.The topology of one of such Networks-Multi-Layer perceptron,which is applied to the prediction of C₉ Index, the efficiency of prediction and the features and problems in the practice of prediction are discussed.

CHANGABLE PULSE WIDTH LIDAR SIMULATION AND RECORDED DATA ANALYSIS

Wu Feng, Liang Zhen-mei, Luo Fu-shan

1995, 15(1): 66-72. doi: 10.11728/cjss1995.01.066

Abstract(2579) PDF 426KB(1284)

Abstract:
Conception of ideal LIDAR received power P_m and real received power are suggested. By numerical calculation,relations of P_r/P_m with height under different laser pulse width,various background,β layer and receiving gate width are obtained.The results are applied in observational data analysis and results which show the feature of aerosol and molecule scattering up to 50km in Beijing.

THE INFLUENCE OF SOLAR FLARE ON THE TEMPERATURE OF THE MIDDLE ATMOSPHERE

Yu Hai-ren, Ma Rui-ping

1995, 15(1): 73-76. doi: 10.11728/cjss1995.01.073

Abstract(2507) PDF 271KB(2193)

Abstract:
Using the NIMBUS-7 SAMS GRID-T data,the variations of the middle atmosphere temperature induced by solar flare events classed larger than 3.5 during 1979-1982 is discussed. The results show that the temperature of the upper mesosphere is obviously decreased and that, of the lower mesosphere is obviously increased,while the stratospheric temperature does not varies obviously,within sevaral days around the Ha flare bursts day.

SCINTILLATION CHARACTERISTICS OF SPORADIC IRREGULARITIES OVER XINXIANG

Long Qi-li

1995, 15(1): 77-82. doi: 10.11728/cjss1995.01.077

Abstract(1799) PDF 2484KB(1021)

Abstract:
According to the results of the 136MHz signal amplitude scintillation from ETS-IIsatellite observed at Xinxiang in the summers during 1989-1990,a statistical relation between scintillation occurrence and f₀E_s is given with the help of digital ionosond observations. The quasi-periodic scintillation properties are shown.The probabilities of scintillation intensity and of the duration, as well as the features of scintillation spectrum are obtained from the statistical study.Physical characteristics of irregularities, such as the size and the drift speed are deduced from the observations.