2013 Vol. 33, No. 4

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Alfvén Waves in the Solar Wind
L. YANG, J. K. CHAO
2013, 33(4): 353-373. doi: 10.11728/cjss2013.04.353
Abstract(3292) PDF 251KB(1997)
Abstract:
Alfvén waves are found to be ubiquitous in the solar wind. Recent progress in observational studies of the waves is reviewed to formulate a microscopic picture for the Alfvénic fluctuations. The main aspects of the observational properties of these waves, including the wave intervals, propagation, evolution, origin and generation, are presented. Then Alfvén wave heating and acceleration of the solar wind plasma are briefly introduced. The relation of the waves to rotational and tangential discontinuities, magnetic decreases, and other relatively large-scale structures such as flux tubes/ropes, magnetic clouds and interplanetary coronal mass ejections in the solar wind is particularly investigated. Finally, some remaining open questions are also indicated due to their fundamental importance of understanding of the physical nature of Alfvén waves and the role of the waves in heating and accelerating the solar wind.
Physics of Wind-blown Sand and the Threshold Wind Speed of Dust Storms on Mars
CAI Huangbing, CHEN Chuxin
2013, 33(4): 374-380. doi: 10.11728/cjss2013.04.374
Abstract(2952) PDF 525KB(1172)
Abstract:
The planet Mars is most closely related to Earth in its size and character. From the comparative planetology point of view, what happens on the Mars is of importance to our human being on the Earth. There exist dust storms on both Earth and Mars. The dust storm on Mars is different from that on Earth in its scale. However, in some aspects, they are similar on these two planets, like the mechanism for the generation of dust storm. In this paper, a model of wind-blown sand at the surface of sanded ground is constructed, and the threshold wind speed for dust storms to start on Mars is calculated based on the wind profile of atmospheric turbulent boundary layer. It is concluded that the wind speed of 28.7 meters per second at 2 meters height is needed for a dust storm to start on Mars, and the suspended dust particles' diameter is less than 30 micron when wind speed is at the threshold value. It is also found that sands need to roll a distance of one particle's diameter before saltation.
Influence of Solar Wind Speed and Heliospheric Current Sheet on the CMEs Transit Time
LUO Tian, XIE Yanqiong
2013, 33(4): 381-386. doi: 10.11728/cjss2013.04.381
Abstract(2511) PDF 598KB(1063)
Abstract:
88 CME events that cause significant geomagnetic storms, 47 CME events and 27 Full Halo CME events, along with the ACE spacecraft observations of interplanetary solar wind and ICME at 1AU, as well as the magnetic graph on the solar photosphere assembled by Wilcox Solar Observatory (WSO), are used to analyze the effect of various conditions of both ambient solar wind speed and heliospheric current sheet on the CME transit time to the Earth. The results demonstrate that the ambient solar wind speed and the CME transit time errors show little correlation, even after taking into account of the effect of the angle between magnetic cloud flux tube and the ecliptic plane. However, the heliospheric current sheet exerts significant influences on the CME transit time. For CMEs with relatively lower initial velocity, the transit time of the opposite side events is longer than that of the same side events (if the earth and the source of CME are on the opposite side of the current sheet it is called a opposite side event, otherwise it is called a same side event). For CMEs with higher initial velocity, the transit time of the opposite side events is shorter than that of the same side events. The result is contrary to our expectations that the current sheet will impede the dissemination of ICMEs in the interplanetary space and thus extend the transit time. One possible explanation is that the interaction of CMEs with solar wind and the current sheet is not simply the convective interaction and the mechanism behind this phenomenon is very complex and requires further study.
Research on Sloar Proton Event Warning With Observation Data of ACE Satellite
XIONG Senlin, CUI Yanmei, LIU Siqing
2013, 33(4): 387-395. doi: 10.11728/cjss2013.04.387
Abstract(2797) PDF 605KB(1203)
Abstract:
Solar Proton Event (SPE) can bring significant radiation hazards to astronauts and spacecrafts in space. An accuracy SPE warning model is meaningful since some effective actions on basis of the warning results could be done to reduce the abundant radiation from which astronauts and spacecrafts would suffer. Therefore, a number of researchers try to build reliable SPE warning models, and some of the results are quite satisfactory. Five-minute- average real-time integral energetic solar protons flux data (mainly above 10MeV) from ACE satellite and GOES in Solar Proton Event periods were analyzed. Besides, correlation coefficients between two kinds of data were calculated. The optimal correlation coefficients were satisfactory, and they showed that the flux data from GOES have tens of minutes up to several hours lag time compared with that from ACE. This paper tries to use the ACE satellite data described above to build a new SPE onset warning method. Furthermore, five-minute- average real time integral energetic proton flux on GOES from Aug. 7, 2001 to Feb. 20, 2012 were utilized to check the new method's validity. This new method has low false probabilities (14.7%) and fairly good detection probabilities (76.3%) in SPE onset warning. Moreover, it has a prior time from tens of minutes up to couple hours. The results were compared with SPE warning results of SWPC, which shows this new method is superior to the latter in some extent.
Effect of Interplanetary Magnetic Field on the Field-aligned Currents Occurrence in the Magnetotail
CHENG Zhengwei, SHI Jiankui, ZHANG Ziying, LIU Zhenxing
2013, 33(4): 396-402. doi: 10.11728/cjss2013.04.396
Abstract(2495) PDF 836KB(1197)
Abstract:
Using the magnetic field and plasma data from Cluster spacecraft, the effect of Interplanetary Magnetic Field (IMF) clock angle Φ and cone angle θ on the Field-Aligned Currents (FAC) occurrence rate at the Plasma Sheet Boundary layer (PSBL) in the magnetotail is investigated. There were more FAC cases occurred when IMF was within the 0°< Φ< 180° clock angle range comparing with the range of -180°< Φ<0°. It indicated that FAC occurrences were associated with duskward IMF (IMF By>0). Also, there were more FAC cases occurred when the IMF was within the 90° < |Φ|< 180° clock angle range. It supported that FAC occurrences were associated with southward IMF (IMF Bz<0). Most of the FAC cases occurred when IMF was within the θ>30° cone angle. In addition, A few of FAC cases occurred when the IMF clock angle was in the θ<30° range regardless of the value of Φ. The occurrence rate of FAC was the largest when θ> 30° and 140°< Φ<160°.
Use Double Channel Solar Irradiance Flux to Compute the E10.7 Index
FAN Lei, WEI Fei, FU Yang, ZHAO Wei, FEI Zengping
2013, 33(4): 403-409. doi: 10.11728/cjss2013.04.403
Abstract(2141) PDF 714KB(1299)
Abstract:
Solar Extreme Ultraviolet (EUV) plays an important role in space weather research and forecasting. The E10.7 index is the integrated EUV energy flux at the top of the atmosphere. Solar 2000 model combines the best of empirical and physics-based models to provide a wide variety of solar irradiance products for science and engineering applications, including E10.7 integrated EUV flux etc. In this paper, the physics significance of the E10.7 index is described, and a new computation method of E10.7 index is also described in details. Double channel solar irradiance flux were used to compute the E10.7 index. At first the experiential coefficients were obtained based on the empirical expression and historical solar irradiance data picked up from the Solar2000 model. Then the new method was applied to solar irradiance flux data from the year of 2000 to 2005, and successfully yields the E10.7 index. The differences between the compute result and the result from Solar 2000 model were achieved. The comparison results show that the mean relative deviation is within 10% with a maximum deviation less than 20%.
Observation of the double sodium layer over Haikou, China by Lidar
ZHANG Tiemin, WANG Jihong, FU Jun, YANG Dali, YANG Xianchang, WU Wei, YANG Guotao
2013, 33(4): 410-412. doi: 10.11728/cjss2013.04.410
Abstract(2804) PDF 137KB(1056)
Abstract:
A Double Sodium Layer (DSL) structure was observed during the night of August 22, 2011 over Haikou, China (20°N, 110°E) by Na lidar. This DSL comprised a typical sodium layer at altitudes of 80~105km and a higher sodium layer at altitudes of 105~115km in about 0.5 h. A wavelength of 589nm dye laser pumped by a Nd: YAG laser was used to make the measurement. The backscattered fluorescence photons from the sodium layer were collected by a telescope with a primary mirror of 1000mm in diameter. The sodium density of these layers during the nighttime observation in the Mesosphere and Lower-Thermosphere (MLT) was studied.
Effect of ion dynamics on the evolution of electron phase-space holes
WANG Peiran, LU Quanming, WU Mingyu, WANG Shui
2013, 33(4): 413-417. doi: 10.11728/cjss2013.04.413
Abstract(2201) PDF 504KB(1317)
Abstract:
The evolution of two-dimensional (2D) electron phase-space holes (electron holes) has been previously investigated with electrostatic Particle-in-Cell (PIC) simulations, which neglect ion dynamics. The electron holes are found to be unstable to the transverse instability, and their evolution is determined by the combined action between the transverse instability and the stabilization by the background magnetic field. In this paper, the effect of ion dynamics on the evolution of an electron hole is studied. In weakly magnetized plasma (Ωe < ωpe, where Ωe and ωpe are electron gyrofrequency and plasma frequency, respectively), the electron hole is still unstable to the transverse instability. However, it evolves a little faster and is destroyed in a shorter time when ion dynamics is considered. In strongly magnetized plasma (Ωe > ωpe), the electron hole is broken due to the lower hybrid waves, and its evolution is much faster.
Approach for Predicting the Energetic Electron Flux in Geosynchronous Earth Orbit
GUO Ce, XUE Bingsen, LIN Zhaoxiang
2013, 33(4): 418-426. doi: 10.11728/cjss2013.04.418
Abstract(2629) PDF 648KB(1301)
Abstract:
Geosynchronous Earth Orbit (GEO) is in the earth's outer radiation belts, where energetic electrons are enriched. The flux of energetic electron will surge after the geomagnetic disturbance, which is one of the causes for the failure of satellites. So, it is important to predict the electron flux on the geosynchronous orbit in order to prevent the satellite from harming. As the enhancement of electron flux is controlled by many conditions and its temporal and spatial evolution is complex, it needs to analyze various data to make the prediction model. In this work, energetic flux data from GOES-12 was statistically analyzed together with geomagnetic Ap index and solar wind velocity and combination of input parameters was determined. An artificial neural network based model was built and trained with the data mentioned above. The prediction of electron flux of E >2MeV one day ahead has been made and the result was good that the prediction efficiencies were 0.766, 0.808 and 0.882 for the year of 2008, 2009 and 2010, which is a little better than other models. The prediction for electron flux of FY-2D satellite was made applying the GOES-12 prediction result by analyzing the flux related characteristics. The statistics showed that the E >2MeV electron flux measurement of the two kinds of satellite become similar when the flux was above 108 cm-2·d-1·sr-1. Because the deep charge effect become significant when E >2MeV electron flux exceed 108 cm-2·d-1·sr-1, the energetic electron alert for FY-2D satellite was made with the result by GOES prediction and got good result.
Influence of Ionospheric Variability in Solar Maximum and Solar Minimum Period on the Stability of Estimated GPS Instrumental Biases
JIN Yaqi, ZHANG Donghe, LIU Yumei, HAO Yongqiang, XIAO Zuo
2013, 33(4): 427-435. doi: 10.11728/cjss2013.04.427
Abstract(2508) PDF 629KB(1135)
Abstract:
It is an important step to estimate the GPS instrumental biases in the process of calculating the ionospheric Total Electron Content (TEC) from GPS data, and the estimation of GPS instrumental biases is the main source of errors in the GPS observed TEC. Therefore, study of the estimated instrumental biases is helpful for understanding the accuracy of ionospheric TEC derived from GPS observation. In this paper, data from two mid-latitude GPS stations was used to derive the instrumental biases of GPS satellites in solar maximum and minimum periods. The stability and statistical characteristics of estimated instrumental biases observed at BJFS and URUM stations in 2001, 2007 and 2009 are given. The influence of ionospheric morphology on the estimation of GPS instrumental biases was studied by analyzing the ionospheric data in the same periods. By comparing the estimated GPS instrumental biases under different ionospheric condition, the accuracy and usability of GPS observed ionospheric TEC were analyzed. Results show that the stability of estimated instrumental biases using GPS data from solar maximum period (in 2001) is poorer than that from solar minimum period (in 2007 and 2009). The yearly RMS value of estimated instrumental biases in 2001 is about 1TECU, and the yearly RMS value is about 0.8TECU in 2007 and 2009. In view of hypothesis in the process of calculating the ionospheric TEC, combining with the analysis of variability of ionospheric critical frequency observed at Beijing station, it is believed that the connection between stability of estimated instrumental biases and the solar cycle phase is related with the differences of ionospheric variability in solar maximum and minimum. Study on the stability of estimated instrumental biases indicates that the accuracy of ionospheric TEC derived from GPS observation is different in different solar cycle phase, and the error of ionospheric TEC caused by instrumental biases of the satellites is about 1TECU.
Effect of Acoustic Gravity Waves Excited by Anomalous Electric Field on Ionosphere Before Strong Earthquakes
XU Tong, HU Yanli, WANG Min, WU Jian, WU Zhensen, SUO Yucheng
2013, 33(4): 436-440. doi: 10.11728/cjss2013.04.436
Abstract(2934) PDF 439KB(1202)
Abstract:
The study of the ionospheric disturbances prior to the occurrence of large earthquakes has attracted much attention for many years. However, until recently, the physical mechanism of seismo-ionospheric coupling is not fully understood. A strong perturbation of vertical electric field may take place within the epicentral zone a few days before strong earthquakes, which can penetrate into ionosphere through atmospheric conductivity. Acoustic gravity waves may be resulted from the non-stationary Joule heating of a local region above the epicentral zone of an imminent earthquake due to the anomalous electric field. Based on this mechanism and one-dimensional time physical model of ionosphere, the effect of acoustic gravity waves on ionosphere was calculated, which showed that the disturbance of horizontal neutral speed was too weak to have obvious effect on the ionosphere. This mechanism can not well interpret the ionospheric phenomena prior to strong earthquakes. Nevertheless, the electric field might modify ionospheric dynamic and electron density distribution through the effect of E×B.
Study on Loading Techniques of Protein Species into Space Crystallization Chamber
LI Na, ZHANG Heqiao, SHANG Guijun, NIE Rongxin, MA Jianhua, CANG Huaixing
2013, 33(4): 441-447. doi: 10.11728/cjss2013.04.441
Abstract(2549) PDF 958KB(965)
Abstract:
The prerequisite of using X-ray diffracting technique to study the relation between protein molecular structure and its function is to obtain the protein crystals of high quality. The microgravity environment of space is an ideal place for culturing such protein crystals. The experimental yield of the space protein crystallization is affected heavily by the loading techniques of the protein species into the crystallization chamber. The loading technique of protein species into the new-designed crystallization chamber for protein crystallization experiment aboard Shenzhou-8 spaceship is studied systematically. It is deduced that the needle shape of the pipette, the protein loading tool, the holding manner of the glass capillary tube, the qualities of sealing and siliconization of the tube have remarkable influences on the experimental results of protein crystallization, which were proved to result in the inclusion of gas bubbles. The corresponding measures such as improving sealing technique and protein loading pipette, constructing a tube-holding tool, are adopted to optimize loading technique and eliminate the gas bubbles. The new techniques have been implemented successfully to the final space experiment of protein crystallization aboard Shenzhou-8 spaceship.
Numerical Research on Satellite Avoidance Strategy
ZHANG Yao, YANG Xu, LIU Jing, CHENG Haowen, LI Dawei, JIANG Hai, HU Jingjing
2013, 33(4): 448-452. doi: 10.11728/cjss2013.04.448
Abstract(2851) PDF 479KB(1239)
Abstract:
With the increasing number of space debris, space environment becomes more worsening. Space collisions between two objects take place more frequently which leads to more debris in space. The "active" satellites which carry out their routine tasks will face more collision threat. It's important to establish satellite avoidance strategy in order to prevent satellite from collision. Three contents are researched in this paper. First, foreign process of satellite avoidance is studied. Second, factors including orbital maneuver, orbital propagation and computation of collision probability that affect the estimation of satellite avoidance strategy is analyzed. The third, numerical estimation process of satellite avoidance strategy is established which can be used to provide suggestions for department of satellite management.
Observation of OSCAR-3 Satellite Radar Cross Section Using the Tristatic Radar
JIN Wang, WU Jian, WU Zhensen, LIU Yongjun, SUN Mingguo, LI Hui
2013, 33(4): 453-457. doi: 10.11728/cjss2013.04.453
Abstract(2531) PDF 471KB(1173)
Abstract:
This is the first space debris observation experiment using 930MHz Europe Incoherent Scatter (EISCAT) UHF Radar in China. For the purpose of analyzing the discrepancy of tristatic RCS (Radar Cross Section), taking observation satellite named OSCAR-3 as an example, the standard European Incoherent Scatter (EISCAT) ionospheric radar experiment model is used. The results showed that the RCS precision from Sodanky radar is five times higher than that from Tromso radar; according to the forecast debris model of National Astronomical Observatories of Chinese Academy of Sciences and the theoretical antenna pattern, the revised RCS is referential when the U.S. Space Surveillance Network does not provide RCS results. Results of the present work confirm that the tristatic radar could provide higher precision RCS than monostatic.
Dynamics and Control of Displaced Orbits for Solar Sail Spacecraft
QIAN Hang, ZHENG Jianhua, YU Xizheng, GAO Dong
2013, 33(4): 458-464. doi: 10.11728/cjss2013.04.458
Abstract(2620) PDF 619KB(1836)
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Based on the linear dynamics model and nonlinear dynamics model, the sun-centred displaced orbits keeping control problem is studied. Firstly, the solar sail dynamics model in cylindrical coordinate form is derived and orbit controllability of the state equation by linearizing the model along the nominal orbit is investigated. Then, by choosing the control weighted matrix R reasonably, a control law for the linear model is designed using the Linear-Quadratic Regulation (LQR) approach. The numerical simulations which are obtained by taking the control law into the nonlinear model indicate that the designed controller which has asymptotic stability and high control accuracy is capable.

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