2002 Vol. 22, No. 1

Display Method:
MICROWAVE SOLAR RADIO EVENTS
LIU Yuying, FU Qijun, NING Zongjun
2002, 22(1): 1-5.
Abstract(1997) PDF 451KB(928)
Abstract:
The two solar radio spectrometers on the bands of 1.0-2.0GHz and 2.63.8 GHz respectively have put into operation at National Astronomical Observatory of China (NAOC) from January 1994 and September 1996. There have been 297 and 316 solar radio events recorded up to April 10, 2000 by these two spectrometers. High sensitivity as well as high frequency and time resolution is characterized by these records. They provide a rich and valuable information for studying the evolution process of solar flare with the various time periods. A typical solar radio event of them on April l5, 1998 shows a variety of the morphological features and fine structures on this frequency range.
A NEW APPROACH TO DETERMINE LOCAL MRAMETERS OF INTERPLANETARY SIMULATED MHD SHOCKS
XIANG Zhangqing, WANG Jingfang, WEI Fengsi, HUANG Weimin, XIONG Donghui
2002, 22(1): 6-12.
Abstract(1811) PDF 628KB(792)
Abstract:
Firstly it is accounted for the validity of the hypothesis that interplanetary MHD shocks can be treated as locally planar with no thicklless when analyzing their Iocal properties, and the fact is demoastrated that the variatious of the physical quantities can be ignored in the area where no shock perturbs (in the upper reach of the shock) within a few hours. Then making use of the method to analyze planar MHD shocks. In doing so, a new approach is deveoped to detedrie local parameters of interplanetary simmulated MHD shocks. The proposed approach includes defining the location of the shock, selecting the state parameters in the upper and lower reaches of the shock, computing the shock’s local parameters, and classifying the shock according to its upstream and downstream Alfevn Mach numbers. Finally, the proposed method is used to deal with the result of a two-dimensional MHD simulation. The analyses confirm the linkage law of hybrid MHD shocks’ spatial connection and temporal evolution in the past reference and reveal that the slow and intermediate shocks near the solar equator finally evolve into fast shocks during their outward propagation.
THE INTENSE IONOSPHERIC ABSORPTIONS ASSOCIAfED WITH R9O77
HU Hongqiao, LIU Ruiyuan, LIU Yonghua, LIU Shunlin, YANG Huigen, XU Zhonghua, N Sato, H Yamagishi
2002, 22(1): 13-20.
Abstract(2136) PDF 753KB(900)
Abstract:
Using the ground observation data at Zhongshan Station of Antarctica during July 13 to 17, 2000, the intense absorption events associated with the activities of the solar active region R9077 are analyzed. It was shown that an intense polar cap absorption event lasted more than 3 days, which was caused by the solar proton event accompanying the X5/3B major flare at 1024UT on 13 July The polar cap event started at about 1040 UT on July 14, and lased to bo 1940UT on July 17, with a typical day-night variation. At the same time, the intense solar activities extremely disturbed the magnetosphere, therefore aurora substorms occurred frequently. The energetic particle precipitation from the magnetotail caused several absorption spikes superimposing on the background of polar cap absorption. The distinct event is an absorption enhancement that started at about 0300 UT on 15th, reached its peak of 26dB around 0645 UT and recovered at about 1110 UT on the same day, which was the strongest absorption event observed at Zhongshan Station since the imaging riometer installed in February, 1997. Another outstanding absorption spike with pulsation occurred at around 1753 UT on 14th, its peak reached 6 dB.
SOLAR DIURNAL AND SEMIDIURNAL VARIATION CHARACTERISTICS OF COSMIC RAYS OBSERVED AT BEIJING NEUTRON MONITOR DURING MAGNETIC QUIET DAYS FROM SOLAR CYCLE 22 TO SOLAR CYCLE 23
LE Guiming, YE Zonghai, GONG Juhong, HUANG Wengeng, LU Hong
2002, 22(1): 21-26.
Abstract(2431) PDF 508KB(924)
Abstract:
Data of cosmic rays observed at Beijing Neutron Monitor Station during magnotic quiet days from solar cycle 22 to solar cycle 23 are analysed to show the diurnal and semidurnal variation characteristics by using Fast Fourier Transformation and power spectrum estimation. The days for data analysis are so selected that not only these days be at least in a successive 6 days’ period of very low magntic activities, but also the previous five days with geomagntic index Ap lower than 15. The computational results show that the periodical features of diurnal and senmidiurnal of the cosmic rays disappeared during the period from one solar cycle to the next solar cycle. When solar activity gradually increased from Solar Minimum to Solar Maximum, the diurnal vartation appeared earlier than semidiurnal variation. The solar diurnal variation’s magnatitude is bigger than that of semidiurnal’s. Diurnal variation of cosmic rays during Solar Meximum of solar cycle 22 is not clearly seen, while on the contrary it is very distinct during solar maximum for solar cycle 23.
A STATISTICAL TEC MODEL BASED ON THE OBSERVATION AT WUHAN IONOSPHERIC OBSERVATORY
CHEN Yanhong, WAN Weixing, LIU Libo, LI Libin
2002, 22(1): 27-35.
Abstract(1838) PDF 644KB(898)
Abstract:
In this paper, an empirical model of ionospheric total electron content(TEC) is obtained by analyzing the TEC data observed at Wuhan Ionospheric Observatory for a solar cycle (from 1980 to 1990). In the model, a linear function was applied to describe the relationship between TEC and solar 10.7cm flux index, and took Fourier series analysis to investigate the diurnal and semidiurnal variations of TEC over Wuhan. The agreement between the prediction by this TEC model and the observed TEC data at Wuhan is quite satisfactoryr: the basic trends and the diurnal variations are well reproduced. The overall model prediction error is smaller in the years with low solar activity than in those with high solar activity, smaller in winter and summer than in spring and autumn. and in the morning and at night than in the day time and in the evening. The semiannual of TEC and seasonal anomaly (winter maximum) are also well represented in our TEC model. With the decrease of solar activity, the anomaly is gradually disappeared. In addition, this model is more accurate than International Reference Ionosphere (IRI) model in predicting TEC over Wuhan.
A NUMERICAL STUDY ON THE PROPAGATION CHARACTERISTICS OF GRAVITY-WAVE PACKETS IN REAL ATMOSPHERE
ZHANG Shaodong, YI Fan, XIONG Donghui
2002, 22(1): 36-43.
Abstract(1819) PDF 818KB(987)
Abstract:
By using a two-dimensional full-implicit-continuous-Euleri (FICE) scheme, the nonlinear propagation and evolution of gravity-wave packets in real atmosphere is simulated. The numerical results show that when an upgoing gravity-wave packet is generated in low mesosphere, it can propagate along its ray path before arriving at the height of mesopause, the nonlinearity and background atmospliere have little influence on its energy propagation path. However, when the wave packet arrives at low thermosphere, the wave packet and wave associated energy propagate almost horizontally, and its vertical propagation is halted. which departs obviously from the prediction of linear gravity-wave theory under WKB approximation in nondissipative case. A further discussion indicates that it is the vertical inhomogeneity of molecular viscosity that causes the restriction of upward energy propagation of the gravity-wave packet. Moreover, during the whole propagation, affected by the joint actions of nonlinearity, background temperaturc and dissipation, the dominant vertical wavelength of the wave packet decreases obviously with time. These indicate that the molecular viscosity especially the vertical inhomogeneity of molecular viscosity plays an important role in the nonlinear propagation of gravity-wave packets.
THE INFLUENCE OF BACKGROUND WINDS ON THE PROPAGATION OF MEDIUM-SCALE DUCTED GRAVITY WAVES
DING Feng, WAN Weixing, YUAN Hong
2002, 22(1): 44-51.
Abstract(1726) PDF 725KB(1022)
Abstract:
The full-wave solution method in a horizontally stratified atmosphere is adopted in the analysis of the propagation features of medium-scale atmospheric gravity waves, and the effect of background winds on gravity waves is considered. The dispersion and attenuation distance curves of ducted waves are calculated. The numerical results show that, the existence of strong background winds blowing against the propagating direction of gratrity waves can considerably prolong the attenuation distance of various ducted modes, within which mode W1 and W4 have the longest attenuation distance in short period area. Thus strong winds blowing against the propagating direction of gravity waves can support the propagation of mediumscale gravity waves. The attenuation distance decreases rapidly with the increasing of wave period, which shows that the ducted mechanism vanishes in long period range, and that the support of winds on the long-distance propagating of ducted waves is valid only in medium-scale range. The distribution in periods of Travelling Ionospheric Disturbances observed at Millstone Hill and Wuhan is statistically analyzed. The result shows that the superior distribution of TIDs both in Wuhan and Millstone Hill are mainly the mode W1 and mode W4, thus the experimental results confirm the existence of these superior distributions of ducted gravity wave modes.
EFFECTS OF SPACE ENVIROMENT ON SOLAR DIFFUSER
WANG Yingjian
2002, 22(1): 52-57.
Abstract(1787) PDF 564KB(978)
Abstract:
The degradation of optical system in space environment has an important effect on the measuring precision of satellite-borne remote sensing instruments. The solar diffuser is an important tool of radiation intensity scaling for satellite-borne optical remote sensing instrument. In this paper a comparison of the decay of solar diffusers in ADEOS/TOMS and Earth Probe/TOMS, and analyses the effects of atomic oxygen and solar UV radiation on solar diffuser is given. The results show that the decay coefficients of solar diffuser in the wavelength of 360 nm due to solar UV radiation exposures and atomic oxygen erodes are 0.00049/h and 1.2 × 10-17cm2 respectively. So the effect of atomic oxygen erodes is about 5 times of solar UV radiation exposures in the altitude of 800km during the solar activity minimum. For the solar activity maximum, the effect of atomic oxygen will greatly increase. In the early days of satellite orbit, however, the effect of solar UV radiation exposures on solar diffuser may increaise about 4 times. It may be due to the contamination. But our analyses havn’t find the interaction between atomic oxygen erodes and contamination effect.
THE EFFECT ANALYSIS OF SOLAR PROTON EVENT ON SPACE RADIATION ENVIRONMENT AT SOLAR SYNCHRONOUS ORBIT
ZHU Guangwu, LI Baoquan, WANG Shijin, LIANG Jinbao, ZHANG Wei, HUANG Hongjin, SHEN Sizhong, ZHAI Yingying, SUN Yueqiang, YE Zonghai
2002, 22(1): 58-64.
Abstract(2179) PDF 655KB(834)
Abstract:
According to detected results of Space Particle Composition Detector on board the FY-1C meteorology satellite, the paper presents radiation environmot and its distribution characteristics in the South Atlatic Anomalous during quiet days without solar proton events and magnetostorms. The effect analysis of solar proton event on July 14, 2000 on solar synchronous orbit space radiation environment has been discussed in detail. Space environment near Earth was disturbed intensively during the solar proton event. High energy electrons, protons and heavy ious possess high flux over both polar regions. The distributions of disturbances for different particles over both polar regions are different.
MESOSPHERIC MF RADAR IN WUHAN AND ITS PRELIMINARY OBSERVATION RESULTS
LI Fengqin, HU Xiong, ZHANG Dongya, ZHANG Xunxie, HUANG Zerong, XIONG Jiangang, CENG Zhen
2002, 22(1): 65-71.
Abstract(2123) PDF 616KB(981)
Abstract:
The MF radar was installed and firstly used to observe the mesospheric electron wind and ionospheric density over Wuhan. In this paper, the principle and configurations of the radar and its preliminary observations are presented. Providing the measurements of wind field and the electron density at height ranges from 60 to 100 km, the radar is configured with Spaced Antenna Mode. The method of Full Correlation Analysis is applied to estimate the wind field, while the Differential Absorption or Differential Phase Experiment technique is used to measure the electron density. The preliminarily observation results show that (1) the zonal wind usually is in west wind at Feb. 9, 200l, its value about 30-50m/s, while the meridional wind is about 10-20 m/s and vertical wind is weak with a speed is less than about 5m/s at 60-100km height over Wuhan. (2) There’s obviously diurnal variation of wind field and electron density at 60-100 km, and a wind shear is occasionally observed. (3) there’s obvious disturbance of the wind field in the mesosphere, which could be connected with the atmospheric waves.
THE GROUND-BASED MIMICKING OF SPACE CONTINUOUS-FLOW ELECTROP HORESIS ELECTROHYDROMECHANICS
TAO Zulai, JIAN Laicheng, LI Tao, GAO Yuxin
2002, 22(1): 72-81.
Abstract(1810) PDF 664KB(683)
Abstract:
Principle of similarity between the electrohydromechanic process of continuousflow electrophoresis carried out in space and that of ground-based mimicking was established by similitude analysis. Numerical simulation demonstrated the effectiveness (approximate) of this treatment. Based on these theoretical works, groundbased experimental system mimicking the electrohydromechanic process of continuous-flow electrophoresis in space was developed and used for separation of biological samples, and of course, final test of the principle of similarity depends on space experiments.
COMPOSITE ADAPTIVE AND ROBUST CONTROL OF COORDINATED MOTION OF SPACE MANIPULATOR WITH PRISMATIC JOINT
CHEN Li
2002, 22(1): 82-90.
Abstract(1833) PDF 723KB(966)
Abstract:
In this paper, the coordinated control of the base attitude of space manipulator system with prismatic joint and its arms is studied. With the momentum conservation of system, the kinematics and dynamics of system are analyzed. It is shown that the generalized Jacobi matrix and dynamic equations of the system can be linearly dependent on a group of inertial parameters. Based on the results proposed above, the composite adaptive and robust control scheme of coordinated motion for both the base and manipulator to track the desired trajectory is developed. The control scheme proposed above possesses the advantages that need no measuring or controlling the position, velocity and acceleration of the base with respect to the orbit due to an effective use of the particular property of the system dynamics. Besides it is computationally simple because an approach is chosen to make the controller robust to the uncertain inertial parameters rather than explicitly estimating them online. A two-link planar space manipulator system is simulated to verify the proposed controlling scheme.
THE DESIGN AND REALIZATION OF THE LUNAR RESOURCE DATABASE BASED ON 3-LAYER B/S STRUCTURE
ZUO Wei, LI Chunlai
2002, 22(1): 91-96.
Abstract(1775) PDF 535KB(983)
Abstract:
Based on the 3-layer B/S structure, the lunar resource database is successfully designed and constructed under Intranet environment by using Web techniques. It has been realized to efficiently manage lunar resource information collected at present. The system’s features include significantly improved runtime efficiency, a good scalability and mailltainability. It is easily and expediently visited by guests.