空间科学学报

1994 Vol. 14, No. 1

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DELTA-SUNSPOTS AND X CLASS FLARES IN SOLAR CYCLE 22

Shi Zhong-xian, Wang Jing-xiu

1994, 14(1): 1-7. doi: 10.11728/cjss1994.01.001

Abstract(2543) PDF 583KB(1173)

Abstract:
Asample of 221 active region with magnetic configurations from 1986 to 1991 in solar cycle 22 is used to investigate the characteristics of δ-sunspots and the relationship between the δ-sunspots and Xclass X-ray flares.(1) The previous findings from Tang (1983), Zirin and Liggett (1987) are confirmed that all δ-sunspots form from penetration of leading and following sunspots from two dipolar regions, and have strong sheared transverse field on the polarity inversion line. However, unlike that concluded by Zirin (1987), examples of separation of δ-sunspots have been identified in this study. The separation is caused by individual proper motions of each dipole.(2) The δ-sunspots tend to have an imbalanced flux in opposite polarities. For 35 δ-sunspots with available sunspot data and Huairou magnetograms at hand, which produce 104 Xclase X-ray flares, the average ratio of flux in majority polarity to minority polarity is about 5.3; and in all highly flare productive regions, such as AR5395, 5629, 6555, 6659 and 6891, the a ratio is≥5.(3) There are relationship intimately between lifetime of δ-sunspots and productivety of Xclass X-ray flares.

THE SPATIAL STRUCTURE AND HEIGHT DISTRIBUTION OF HARD X-RAYS IN FLARE LOOP WITH NON-UNIFORM CROSS SECTION

Lin Hua-an

1994, 14(1): 8-14. doi: 10.11728/cjss1994.01.008

Abstract(2039) PDF 450KB(1082)

Abstract:
According to hard X-ray temporal, spectral and spatial characteristics,solar f-lares are identified as type A, B and C. In this paper, the spatial structure and he-light distribution of hard X-rays in flare loop with non-uniform cross section are an-alysed. The formation and characteristics of hard X-ray sources for the three type flares are discussed. It is shown the structure and distribution of hard X-ray sourc-es are closely related with the parameters of magnetic structure of background plasma and spectrum of non-thermal electrons.

THE MODULATIONAL INSTABILITY OF ALFVEN WAVES

Du Xiao-long, Lu Sheng-zhi

1994, 14(1): 15-22. doi: 10.11728/cjss1994.01.015

Abstract(2077) PDF 332KB(1256)

Abstract:
Considering the actions of the porderomotive force from both density variations and changes of flow speed, using Karpman's method, the modulational instability of Alfven waves has been investigated. For the two branches of left and right hand circular polarization waves, the coalitions for the existence of wave packet solitons and of anti-wavepacket solitons, the correlations between density fluctuations and wave energy densities, and the nonlinear frequency drifts have been obtained respectively.For the left hand circular polarization Alfven waves with a finite amplitude, the conditions for the occurence of instabilities and it's growth rate have been obtained also.

THE ELECTROSTATIC ION SOLITARY WAVES WITH LOW FREQUENCIES IN THE SOLAR WIND

Song Li-ting, Jao Wei-xin

1994, 14(1): 23-29. doi: 10.11728/cjss1994.01.023

Abstract(2218) PDF 413KB(1053)

Abstract:
This paper indicates that under the condition of super sonic stream of the solar wind the electrostatic ion solitary waves propagate with very different properties. The results can be campared with the electrostatic ion noises observed by Hellos 1,2. The nonlinear evolution of the ion acoustic disturbance makes the solar wind plasma fluctuating regularly in small scale. The ion acoustic wave propagates outside Mach Cone. Based on this understanding, we could predict that the density fluctuations of the solar wind are not along solar wind velocity but in the transverse direction.

A NEAR-EARTH TRIGGERING MODEL FOR THE MAGNETOSPHERIC SUBSTORM EXPANSION PHASE

Pu Zu-yin, Fu Sui-yan, Li Yao-ting, Chen Zu-xing, Liu Zhen-xin, A. Korth, G. Kermser

1994, 14(1): 30-38. doi: 10.11728/cjss1994.01.030

Abstract(2345) PDF 2783KB(1018)

Abstract:
Based on GEOS-2 observations, a new substorm expansion phase model-the Near Earth Ballooning Instability Model (NEBIM) is proposed. It is shown in this model that during the growth phase, strong earthward energetic ion gradient is build up at the inner edge of the near Earth plasmasheet (IENEP) which arrives at (6-10) R_E on the nightside; the tail current is greatly enhanced; and the magnetic field lines there are stretched out to the tail. Ballooning instability can be generated at the IENEPwhen the plasmasheet becomes very thin, and the electron precipitation and hence the conductivity in the auroral ionosphere are greatly increased, leading to the disruption and diversion of the tail current to the ionosphere, and the formation of the substorm current wedge. The substorm expansion phase is thus triggered. Further comparison with GEOS-2 data indicates that all features of the expansion phase predicted by the NEBIMare in good agreement with those observed by the spacecraft.

MODEL STUDY OF MID-LATITUDE IONOSPHERIC DENSITY PROFILE VARIATION DURING GEOMAGNETIC STORMS

Zhang Qi-wei, Guo Jian-shan, Zhang Gong-liang

1994, 14(1): 39-47. doi: 10.11728/cjss1994.01.039

Abstract(2109) PDF 758KB(1099)

Abstract:
Atheoretical ionospheric model is developed in order to study the variation of ionospheric density profile during geomagnetic storms, considering the disturbances of thermospheric temperature, composition, wind and electric field. The results show that the increase of N₂/O is the most efficient way to decrease the electron density as well as the peak density N_mF₂, but the up and down movement of peak height (h_mF₂) is mainly caused by neutral wind or electric field disturbance. The temperature change has little effect on the profile variation. It is possible to distinguish these different physical processes using f₀F₂ and h_mmF₂ parameters in practical measurement.

MECHANISM OF EFFECTS OF ATMOSPHERIC PLANETARY WAVES ON ABSORPTION VARIATION AT LF BAND

Ruan Xue-qing, Zhang Xun-jie, Huang Ze-rong

1994, 14(1): 48-53. doi: 10.11728/cjss1994.01.048

Abstract(2621) PDF 421KB(914)

Abstract:
On the basis of observed facts that disturbance of amplitude at LFobtained in mid and low latitudes related with activity of the planetary waves in high latitudes during the winter warming, a mechanism which can better explain the above observed phenomena is given. The planetary wave is a main reason in producing absorption variation of the radio wave at LF. The atmospheric ionization rate can be changed by the planetary wave through two ways, Therefore, the disturbances of the electron density in the lower ionosphere occur when there are planetary waves and lead to variation of absorption at LFradio wave band. As a result, we observed the amplitudese at LF changes with the planetary waves at high latitudes. In this paper. we give the computing formula and results.

THE INFLUENCE OF QUASI-BIENNIAL OSCILLATION ON THE EQUATORIAL PLANETARY WAVES

Ma Jun, Chen Pei-ren

1994, 14(1): 54-62. doi: 10.11728/cjss1994.01.054

Abstract(2201) PDF 562KB(1254)

Abstract:
From the theory of the occurrence of Quasi-Biennial Oscillation (QBO), we conclude that Kelvin wave and Rossby-gravity wave should propagate upward alternately during the different phase of the QBO. With the results of the numerical simulation, we conform this conclusion. Further more, we reasonably apply this effect on some other planetary waves, and try to find out the association between the QBO and the solar-terrestrial coupling.

A MONTE CARLO SIMULATION OF SOLAR X-RAY TRANSPORTION IN EARTH'S ATMOSPHERE

Zong Qiu-gang, Ye Zong-hai

1994, 14(1): 63-69. doi: 10.11728/cjss1994.01.063

Abstract(2274) PDF 435KB(691)

Abstract:
The Monte Carlo method is applied to simulate solar X-ray bursts (1-8 Å, 0.5-4 Å) transportation in earth's atmosphere. And the electron production rate due to solar X-ray bursts penetrating in ionospheric D-layer is calculated. From that, we can get the value of cosmic noise absorption. Aexample result of solar X-ray bursts is compared with the value of Riometer absorption observed in antarctic Zhong-Shan station, showing very good correlation.

THE INFLUENCE OF SOLAR MASS-LOSS ON PLANETARY ORBITS

Yu Li-zhong, Zheng Xue-tang, Li Lin-sen

1994, 14(1): 70-75. doi: 10.11728/cjss1994.01.070

Abstract(2281) PDF 355KB(1697)

Abstract:
Using Gylder-Meshcherckii equation and Eddington-Jeans law, the influence of solar mass-loss on planetary orbits is discussed in this paper. It is shown that solar mass-loss will cause the first-order secular and periodic terms in the semimajor axis a, the first-order periodic and secon-order mixed terms in the eccentricity, and the first-order periodic, second-order secular and mixed terms in the argument of perihelion of planetary orbits. The secular variation of the semimajor axis of planetary orbits should influence the stability of solar system.

ON THE SOLAR WIND-MAGNETOSPHERE COUPLING WHEN IMF IS NORTHWARD AND B_z>10 nT

Shen Chang-shou, Zi Min-yun

1994, 14(1): 76-80. doi: 10.11728/cjss1994.01.076

Abstract(2179) PDF 365KB(970)

Abstract:
Relationship between the solar wind-magnetosphere energy coupling function and the energy consumption in the magnetospheric system is tested by the samples during period of northward B_z(>10 nT) of IMF. It is shown that the energy function which can well describe the solar wind-magnetosphere coupling when B_z>0 is no more applicable for B_z>10 nT, but the coupling still exists, the effects of which are mainly found at the polar cap. Dst often turns to positive when B_z> 10 nTand the coupling mechanism is different from that when B_z<0. New coupling function has to be introduced to describe the solar wind-magnetosphere coupling for the case of B_z> 10 nT.

OBSERVATIONS AND ANALYSIS OF THE TRAVELLING IONOSPHERIC DISTURBANCES AT LANZHOU IN APRIL 1984

Zhang Xiu-ju

1994, 14(1): 81-84. doi: 10.11728/cjss1994.01.081

Abstract(1774) PDF 2328KB(895)

Abstract:
This paper presents the experimental results about the travelling ionospheric disturbances (TIDs) during 20-22 April 1984. by backscattering of a phase-controlled pulse doppler radar signals. Some characteristic parameters of the typical TIDare calculated with those results and they are generally in agreement with the variation of virtual heights of vertical sounding.