2014 Vol. 34, No. 1

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Statistical analysis of solar wind velocity from ACE and STEREO-B satellites
Song Dan, Xue Bingsen, Cheng Guosheng
2014, 34(1): 1-10. doi: 10.11728/cjss2014.01.001
Abstract(1534) PDF 7054KB(1923)
Abstract:
The wavelet analysis method was used to discuss the 27-day periodicities characteristic of the solar wind speed detected by ACE and STEREO-B satellites from the year of 2008 to 2011. Using the method of unary linear regression, the linear equation of solar wind speed is calculated. From the analysis and calculation results detected by ACE and STEREO-B, it is shown that the solar wind speed in 8～16d and 16～32d frequency domain is significant. The solar wind speed detected by the two satellites presents significant 27-day periodicities in parts of the same frequency domain. And it presents better correlation in the year when solar activity is low. As an application example, solar wind data detected by STEREO-B is applied to predict the solar wind speed of ACE from 1 to 17 in October, 2012. The results show that the trend of predicted values and measured values are consistent, although the CME has a certain influence on the predicted values. Through this research, the relationship of solar wind speed detected by ACE and STEREO-B satellites was preliminarily studied, and the solar wind speed was detected by STEREO-B a few days before it came to the Earth. This work laid the foundation to establish the medium-term forecast models for the non-recurrent geomagnetic storms.
Predicting whether an interplanetary shock will encounter the Earth by using solar and interplanetary parameters
Xie Yanqiong, Zhang Ying, Du Dan
2014, 34(1): 11-23. doi: 10.11728/cjss2014.01.011
Abstract(1234) PDF 854KB(2367)
Abstract:
Predicting whether an Interplanetary (IP) shock driven by solar eruptions will encounter the Earth is the prerequisite and foundation to predict its arrival time at the Earth and the geoeffectiveness. Using 542 IP shock events associated with solar eruptions during 1997—2006, the influence of intensity, location, initial shock speed, duration of solar eruptions and Solar Energetic Particles (SEP) flux upon the propagation of IP shocks is investigated statistically, and then key physical parameters mentioned above that obviously influence the IP shock's arrival at the Earth are chosen. Finally, an Earth-directed and Earth-away Shock Prediction Model (EdEaSPM) based on not only solar parameters but also SEP parameters is built. The results of historical prediction show that the success rate of EdEaSPM model is about 66%, which is significantly higher than that of the other prevailing models, STOA, ISPM and HAFv2. The False Alarm Ratio (FAR) of EdEaSPM is less than 50% and the situation that FAR is too high is improved. For the ratio of number of events with shock forecast to that with shock detection, bias, although the value of Bias of all of the models is greater than 1, the Bias of EdEaSPM is the smallest and most close to 1. For the other forecast skill scores, TSS, HSS and GSS, the EdEaSPM performs better than HAFv2 model. In addition, prediction test of 6 IP shock events between Jan. and Oct. 2012 shows that the forecast results are consistent with observations. The EdEaSPM model can forecast whether an IP shock will encounter the Earth about 1 to 3 days in advance, and its accuracy is comparable to that of the other prevailing models. In particular, the success rate and false alarm ratio are improved significantly.
Relationship between interplanetary magnetic field clock angle and magnetosphere open magnetic flux
Xia Zhiyang, Wang Chi, Peng Zhong, Lu Quanming
2014, 34(1): 24-28. doi: 10.11728/cjss2014.01.024
Abstract(1407) PDF 469KB(2250)
Abstract:
The open magnetic flux (Fpc) is a key parameter to study magnetospheric dynamical process, which is closely related to magnetic reconnections in the dayside magnetopause and magnetotail. The dayside reconnection rate controls the amount of the open magnetic flux, which is affected by various solar wind parameters, among which the clock angle θc of the interplanetary magnetic field (IMF) is an important factor that influence the dayside reconnection rate. Using global MHD simulations, we analyze the relationship between θc and Fpc. The results show that the open flux Fpc increases as the clock angle θc approaches 180°(due southward), and the open flux Fpc is proportional to sin3/2 (θc/2). This reflects the physical connection between them, since θc describes the magnitude of the shear between IMF and terrestrial magnetic field, and affects the dayside reconnection rate, thus controlling the open flux Fpc.
Ionosphere response to recurrent geomagnetic activity during 2008 and 2009
Liu Xiaoju, Chen Yanhong, Gong Jiancun
2014, 34(1): 29-37. doi: 10.11728/cjss2014.01.029
Abstract(1482) PDF 4882KB(2598)
Abstract:
GPS TEC data are used to analyze ionospheric response to recurrent geomagnetic activity in 2008 and 2009. Periodic analysis indicates that the significant periodicities of 9 and 13.5 days exist in in global mean Total Electron Content (TEC), ap index and solar wind speed but not in solar F10.7 index. This shows that the short period variations in TEC are mainly related to recurrent geomagnetic activity caused by solar high-speed stream. The local time and latitudinal analysis indicates that the positive and negative perturbations always occur at high-latitude of northern and southern hemisphere at nighttime. At middle to low latitudes, there is mainly positive perturbation at night. The amplitude of the nighttime disturbance in high latitude is larger than middle to low latitudes at night. The daytime TEC response at middle to low latitude is generally in-phase with ap's perturbation. There is a time delay between TEC disturbance and ap variations at high-latitude of southern hemisphere. The amplitude of 9-day, 13.5-day periodicities in 2008 are larger than those in 2009.
Sporadic E morphology of East Asia
Zhao Haisheng, Xu Zhengwen, Wu Zhensen, Wu Jian
2014, 34(1): 38-45. doi: 10.11728/cjss2014.01.038
Abstract(1075) PDF 7870KB(1957)
Abstract:
Sporadic E (Es) is the irregular structure of ionosphere occurred in the layer E sporadically, and the highest electron density can exceed the background by more than 100 times. In East Asia, the Es is of frequent occurrence, and the Es morphological characteristics research in this region has the uniqueness and typicality, which is of great significance to explore the cause and reveal the essence of Es. Based on more than fifty years' data from Chinese ionospheric vertical sounders, and combining with the Japanese vertical sounders data, the strength characteristics, spatial distribution characteristics, daily variations, seasonal changes and long-term trends of the Es over East Asia were studied, and conclusions are obtained.
Monitoring of Ionospheric Anomaly Using COSMIC Occultation Measurementsormalsize
WANG Hu, LIU Zhiqiang, BAI Guixia, DANG Yamin
2014, 34(1): 46-52. doi: 10.11728/cjss2014.01.046
Abstract(1130) PDF 3049KB(1982)
Abstract:
The paper introduces the method of electron density inversion using COSMIC occultation data, and advantages of the inversion method are analyzed using practical calculation. Meanwhile, electron density profiles obtained from ISR (Incoherent Scattering Radar) are compared and analyzed with those from COSMIC occultation. Finally, electron density profiles over the SHAO (IGS station) which is located in Yangtze river region, are reversed using COSMIC occultation measurements during the total solar eclipse and the solar storm, and are compared with electron density profiles during the quite day. Ionospheric anomaly caused by the total solar eclipse and the solar storm are analyzed. The advantages of the inversion method from COSMIC occultation data have been found by using inversion method to monitor the ionosphere anomaly.
Investigations of low latitude E region field-aligned irregularities with Hainan VHF radar
Shang Sheping, Shi Jiankui, Yan Jingye, Yang Guotao, Wang Xiao, Yan Chunxiao, Wang Jihong, Wu Qiongzhi, Nan Fang
2014, 34(1): 53-62. doi: 10.11728/cjss2014.01.053
Abstract(1327) PDF 5275KB(2345)
Abstract:
Using the continuous observation data of Hainan VHF radar (19.5°N, 109.1°E; dip latitude 8.1°N) on July 15—22, 2011, the characteristics of 3m scale Field-Aligned ionospheric Irregularities (FAI) in Eastern Asia low latitude are analyzed. The main results show the E region FAI echoes almost occur everyday during the whole observation period. They can occur both in day and night and have different complicated structures. According to their occurrence time and structure, the E region FAI echoes can be classified into the following three cases. First is the lower continuous echoes, which mainly occur from the later afternoon to pre-midnight (17:30LT—23:00LT) with evident enhanced echo intensity and negative (downward/southward) Doppler velocities. The second is the upper descend layer structures, which mainly appear from nearly midnight to pre-sunrise (23:00LT°05:00LT) with more enhanced echo intensity and both positive and negative Doppler velocities, where the positive Doppler velocities (upward/northward) dominate in the upper E region echoes. The third is the daytime continuous echoes, which mainly occur from morning to nearly noontime (07:00LT—11:30LT) with reduced echo intensity and both positive and negative Doppler velocities. These low latitude E region echoes mainly are type-I!I, which is similar to that of the Equatorial Electrojet (EEJ) and mid-latitude regions, but their temporal behavior is evidently different from that of the latter two latitudes and also has some differences with that of the other low latitudes.
A new GNSS signal carrier tracking algorithm for ionospheric TEC monitoring
Liu Wenxue, Yuan Hong, Wei Dongyan, Xu Ying
2014, 34(1): 63-72. doi: 10.11728/cjss2014.01.063
Abstract(1364) PDF 1570KB(1895)
Abstract:
Currently, GNSS (Global Navigation Satellite System) is widely used in ionospheric TEC monitoring. The traditional method of GNSS monitoring ionospheric TEC is based on the original output measurements of navigation receiver, and then we obtain the ionospheric TEC information through the data conversion. The signal processing algorithm is also the navigation receiver algorithm which is used for navigating. The purpose of this work is to design a new GNSS dual-frequency signals tracking algorithm for the GNSS ionospheric TEC monitoring application, which is called sum-diff joint tracking algorithm. Compared with the traditional method, the algorithm is directly tracking the ionospheric TEC changes, and can improve the sensitivity of dual-frequency tracking and the TEC observation precision, so that it can improve the performance of GNSS monitoring ionospheric TEC.
Correlations between solar activity and thermospheric density
Niu Jun, Fang Hanxian, Weng Libin
2014, 34(1): 73-80. doi: 10.11728/cjss2014.01.073
Abstract(1270) PDF 3616KB(1862)
Abstract:
The periodic characteristics of solar F10.7 index and the thermospheric density at 250km, 400km and 550km altitude have been investigated. The results show that the thermospheric density correlates well with the solar activities, and both of them have significant period of 27 days and 11 years. Besides, the thermospheric density also has 7～11 days' period, semiannual and annual variations. The response of thermospheric density lags the solar activity for three days. No matter what the level of geomagnetic activity is, the correlation between solar activity and thermospheric density at 400km is larger than 250km, minimum at 550km. The relationships between the neutral density and solar activity show linear, saturation and amplification features. The thermospheric density in higher altitude is more sensitive to the solar activities.
Comparison and analysis of the thermospheric density between TIEGCM and CHAMP during a severe geomagnetic storm
Wu Yuan, Li Jiawei, Zhang Xiaoxin, Wang Wenbin, ZHOU Lü, Li Chuanqi
2014, 34(1): 81-88. doi: 10.11728/cjss2014.01.081
Abstract(1401) PDF 2101KB(2296)
Abstract:
The thermospheric densities at the altitude of 410km during the geomagnetic storm on Nov. 20—21, 2003 are calculated by NCAR-TIEGCM model, and the results are compared and analyzed with the observational data from CHAMP/STAR. The results show that the model can exactly represent the distribution and variation of the density during geomagnetic storm, and the model results have a good consistency with the CHAMP data in trends and orders. But some differences do exist in detailed structure and magnitude. The model underestimated the increases of the density during geomagnetic storm with the values of 100%～125%, instead of the 250%～400% observed by CHAMP. The deviations between the model and CHAMP at high latitude are bigger than those of low latitude, and dayside bigger than nightside. It is also found that the density disturbance during geomagnetic storm presents day-night asymmetry and Southern-Northern hemisphere asymmetry. The model can exactly represent the propagation of the density disturbance from high latitude to low latitude, and the time delay in response of the density to geomagnetic storm.
Ballistic coefficient estimation of satellite in low Earth orbit and atmosphere model error analysis
Qi Yalong, Li Huijun, Xiang Jie, Man Haijun
2014, 34(1): 89-94. doi: 10.11728/cjss2014.01.089
Abstract(1462) PDF 587KB(2068)
Abstract:
An inversion method is introduced to study the variations of the ballistic coefficient for orbital satellites with different geometrical characteristic. Using satellite tracking data and NRLMSISE00 empirical model of the atmosphere, ballistic coefficients B of the selected satellites are compiled out with this new method. The "true" values of B (Bt) were computed by averaging the 31 years of B values obtained for each satellite. These true B values were validated by comparing the Bt values of two spheres and by comparing the Bt values obtained for a pair of satellites having very similar size, shape and mass. The estimated ballistic coefficients B' variations for a number of selected satellites were then averaged over each year, and compared with solar indices. Some interesting results are found. Firstly, there does not appear to be a bias in the Bt values computed using the 31 years' time period. Secondly, the large similarity between the time series of B ratios is apparent and solar activity related variations in the thermosphere increase in amplitude with increasing height, as do the errors in the NRLMSISE00 model. Thirdly, the anti-correlations of B' variations with the F10.7 variations were found in short periods. Finally, the NRLMSISE00 model has failed to produce the low thermospheric density during the 2008 solar minimum. The variations in B' point out that the scaling factor is required to correctly predict the true densities from empirical atmosphere models, especially in solar maxima and minima. It is also shown that changes in B ratios during some major geomagnetic storms cannot be explained by atmosphere model.
A Review on the Acquisition and Analysis Methods of Spectral Characteristics of Space Debris
JIN Xiaolong, TANG Yijun, SUI Chenghua
2014, 34(1): 95-103. doi: 10.11728/cjss2014.01.095
Abstract(1360) PDF 1988KB(2322)
Abstract:
The reflectance spectrum of space debris is the interactive result of the space debris material and the solar spectrum, which can reflect the material nature of space debris and provide the basis for studying the optical properties of space debris. In this paper, we preprocess the observed space debris images, extract debris spectral curves, correct spectral data of atmospheric turbulence and then compare the actually observed reflectance spectra of space debris with the known space material reflectance spectra. The optical properties differences between them, such as peak, slope, shape, narrow band characteristics, absorption lines in the continuous reflectance spectrum curve and imaging differences, color indices, characteristic temperature in multiband can be analyzed. Then the space debris can be distinguished from others by its surface materials finally.
Orbit requirements for detecting the upflow ion source region
Liu Yong, Wang Chi, Xu Jiyao, Li Xiaoyu
2014, 34(1): 104-108. doi: 10.11728/cjss2014.01.104
Abstract(1078) PDF 712KB(1964)
Abstract:
Polar upflow ions from ionosphere to magnetosphere are crucial for space weather modeling. The origin and the acceleration of the upflow ions are the main scientific objectives for the Magnetosphere-Ionosphere-Thermosphere Coupling Constellation Mission. The constellation is composed of two magnetosphere satellites and two ionosphere/thermosphere satellites to monitor the polar region at different altitude jointly. The in-situ measurement on the source region of the upflow ions is vital for investigating the magnetosphere/ionosphere coupling, and it is also the requirement for designing orbit of the ionosphere/thermosphere satellite. We compared the circular and elliptical orbits based on the observations of other missions, and then choose the orbit of ionosphere/thermosphere satellites to be elliptical.
Finite-time Control of Satellites Formation[-1.5mm] Based on Terminal Sliding Mode
HUANG Yong, LI Xiaojiang, WANG Zhiheng, LI Zhaoming
2014, 34(1): 109-115. doi: 10.11728/cjss2014.01.109
Abstract(1546) PDF 2116KB(3347)
Abstract:
Aiming at the relative control problem of reference satellite maneuver-considered formation flying, a finite-time control method based on terminal sliding mode (TSM) is given. Based on the dynamic model of formation satellites relative motion, a finite-time terminal sliding controller is designed, and it is proven that the system state error can converge in finite time under the controller. Lastly, the formation reconfiguration and the formation keeping considering reference satellite maneuver are simulated and analyzed with the control method. The results show that the finite-time control method based on terminal sliding mode has higher formation control precision as well as faster error convergence speed compared with the traditional linear sliding mode.
Algorithm of astronomy autonomous navigation based on multi-sensors and the analysis of observability
Pan Xiaogang, Jiao Yuanyuan, Zhou Haiyin
2014, 34(1): 116-126. doi: 10.11728/cjss2014.01.116
Abstract(939) PDF 3915KB(2003)
Abstract:
The technology of autonomous navigation is an inevitable trend in the development of spacecraft in the future. Based on the integrative platform of multi-sensors composed of sun sensor, moon sensor and the infrared Earth sensor, the observation model of multi-sensors were proposed. In order to construct the autonomous navigation system, the observability of navigation system was analyzed. Then the algorithm of astronomy autonomous navigation was built up based on two modes. One is based on the original astronomy multi-sensors data. The other is based on the analytical single position data calculated by the original astronomy multi-sensors data. Simulation results showed that the navigation precision of the mode based on original astronomy multi-sensors data was higher than that of the mode based on analytical single position data. And the navigation error was approximately within 200m when the observation data contains no system error. The precision of navigation with constant observation error is equal with that of the navigation with only random observation error when the system error estimation method is used.
Design of a 1553B IP core based on ASIC technology
Zhou Li, An Junshe, Xie Yan, Li Xianqiang, Cao Song
2014, 34(1): 127-136. doi: 10.11728/cjss2014.01.127
Abstract(1909) PDF 721KB(2079)
Abstract:
It is a problem to miniaturize space avionics when we use traditional 1553B bus interface chips. To solve this problem, design of an ASIC chip for spacecraft integrated avionics is proposed. The design of a 1553B IP core with independent intellectual property in this chip is described in detail. The 1553B IP core includes the bus controller module, the remote terminal module, the Manchester decode and encode module, the shared RAM, the RAM arbitration module, the AXI bus slave interface module, the channel select module and the timer module. Each module is introduced. The top-down designing method is used and the program is described by Verilog hardware description language. The 1553B IP core design is tested and verified by the functional simulation, the ASIC system simulation and FPGA test. DDC's 1553B test board is used to test the IP core. The test results indicate that the 1553B IP core design is reasonable. The design of 1553B IP core has good performance in reliability, portability, real-time and less resource occupancy.

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