汪毓明
行星际动力学和空间天气学
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- 姓名:汪毓明
- 目前身份:
- 担任导师情况:
- 学位:
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学术头衔:
博士生导师, 教育部“新世纪优秀人才支持计划”入选者
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学科领域:
空间物理学
- 研究兴趣:行星际动力学和空间天气学
汪毓明博士,2003 年毕业于中国科学技术大学地球和空间科学学院,获理学博士学位。2004 年起在中国科学技术大学任教。先后获得2003 年度中国科学院院长特别奖和2004 年度首届中国科学院优秀博士学位论文奖,并入选2004 年度教育部新世纪优秀人才支持计划。主持和参与多项国家自然科学基金项目、中国科学院创新工程重要方向项目和973 重大项目。主要研究方向为行星际动力学和空间天气学。至今已完成论文20 余篇,其中SCI 收录近20 篇。取得的创新成果主要有:l )首次在国际上提出了多重磁云概念,总结出观测特征及其强烈的地磁效应,并通过数值模拟,研究了双重磁云的形成和演化过程;2 )首次报导了强激波穿入压缩磁云,并造成特大地磁暴的事件,建立简单模型,得出了激波穿入深度对磁云地磁效应的影响规律;3 )统计研究了强磁暴的行星际成因,建立了一个反映地磁指数Dst 与行星际参数一VBz 和△t 之间关系的经验公式;4 )统计得到了日冕物质抛射( CME )的日面初发位置的东西不对称性,进一步提出了CME 在行星际介质中偏转的观点,并建立了与实际相吻合的理论模型。
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【期刊论文】THEORETICAL ANALYSIS ON THE GEOEFFECTIVENESSOF A SHOCK OVERTAKING A PRECEDING MAGNETIC CLOUD
汪毓明, Y.M. WANG, P.Z. YE, S. WANG and M. XIONG
Solar Physics 216: 295~310, 2003.,-0001,():
-1年11月30日
The shock compression of the preexisting southward directed magnetic field can enhance a geomagnetic disturbance. A simple theoretical model is proposed to study the geoeffectiveness of a shock overtaking a preceding magnetic cloud. Our aim is to answer theoretically the question how deep the shock enters into the cloud when the event just reaches the maximum geoeffectiveness. The results suggest that the minimum value of Dst* decreases initially, then increases again while the shock propagates from the border to the center of the cloud. There is a position where the shock compression of the preceding cloud obtains the maximum geoeffectiveness. In different situations, the position is different. The higher the overtaking shock speed is, the deeper is this position, and the smaller is the corresponding Dst∗min. Some shortcomings of this theoretical model are also discussed.
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汪毓明, Y.M. Wang, P.Z. Ye and S. Wang, G.P. Zhou and J.X. Wang
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO.A11, 1340, 2002,-0001,():
-1年11月30日
CME,, geomagnetic storm
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【期刊论文】MULTIPLE MAGNETIC CLOUDS IN INTERPLANETARY SPACE
汪毓明, Y.M. WANG, S. WANG and P.Z. YE
Solar Physics 211: 333~344, 2002.,-0001,():
-1年11月30日
An interplanetary magnetic cloud (MC) is usually considered the byproduct of a coronal mass ejection (CME). Due to the frequent occurrence of CMEs, multiple magnetic clouds (multi-MCs), in which one MC catches up with another, should be a relatively common phenomenon. A simple flux rope model is used to get the primary magnetic field features of multi-MCs. Results indicate that the magnetic field configuration of multi-MCs mainly depends on the magnetic field characteristics of each member of multi-MCs. It may be entirely different in another situation. Moreover, we fit the data from the Wind spacecraft by using this model. Comparing the model with the observations, we verify the existence of multi-MCs, and propose some suggestions for further work.
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汪毓明, Yuming Wang, C.L. Shen, S. Wang, and P.Z. Ye
GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO.20, 2039, 2003,-0001,():
-1年11月30日
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汪毓明, Y.M. Wang, P.Z. Ye, S. Wang, and X.H. Xue
GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO.13, 1700, 2003,-0001,():
-1年11月30日
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【期刊论文】Periodicities in Solar Coronal Mass Ejections
汪毓明, Yu-Qing Lou, , Yu-Ming Wang, Zuhui Fan, Shui Wang, JingXiu Wang
Mon. Not. R. Astron. Soc. 000, 1~11 (2003),-0001,():
-1年11月30日
d in daily averages of Ap index for geomagnetic disturbances from the World Data Center (WDC) at the International Association for Geomagnetism and Aeronomy (IAGA) are also examined for the same four-year time span. By Fourier power spectral analyses, the CME data appears to contain significant power peaks at periods of ~358±38, ~272±26, ~196±13 days and so forth, while except for the ~259±24-day period, X-ray solar flares of class>~M5.0 show the familiar Rieger-type quasi-periods at ~157±11, ~122±5, ~98±3 days and shorter ones until ~34±0:5 days. In the data of daily averages of Ap index, the two significant peaks at periods ~273±26 and ~187±12 days (the latter is most prominent) could imply that CMEs (periods at ~272±26 and ~196±13 days) may be proportionally correlated with quasi-periodic geomagnetic storm disturbances; at the speculative level, the ~138 ±6-day period might imply that X-ray flares of class>M5.0 (period at ~157±11 days) may drive certain types of geomagnetic disturbances; and the ~28±0:2-day periodicity is most likely caused by recurrent high-speed solar winds at the Earth's magnetosphere. For the same three data sets, we further perform Morlet wavelet analysis to derive period-time contours and identify wavelet power peaks and timescales at the 99 percent confidence level for comparisons. Several conceptual aspects of possible equatorially trapped Rossby-type waves at and beneath the solar photosphere are discussed.
oscillations-space weather-Sun: activities-corona-coronal mass ejections-magnetic fields
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【期刊论文】DEFLECTION OF CORONALMASS EJECTION IN THE INTERPLANETARYMEDIUM
汪毓明, YUMING WANG, CHENGLONG SHEN, S. WANG and PINZHONG YE
Solar Physics 222: 329~343, 2004.,-0001,():
-1年11月30日
y than fast ones. This is consistent with the observational results obtained by Zhang et al. (2003), that all four Earth-encountered limb CMEs originated from the east. On the other hand, since the most of the EFHCMEs are fast events, the range of the longitude distribution given by the theoretical model is E40◦, W70◦, which is well consistent with the observational results (E40◦, W75◦)
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【期刊论文】MHD simulation of the formation and propagation of multiple magnetic clouds in the heliosphere
汪毓明, Y. Wang, H. Zheng, S. Wang, and P. Ye
A&A 434, 309~316 (2005),-0001,():
-1年11月30日
A multiple-magnetic-cloud (Multi-MC) structure formed by the overtaking of two successive coronal mass ejections(CMEs) in the heliosphere is studied by using a 2.5-D MHD simulation. This simulation illustrates the process of the formationand propagation of two identical CMEs, which are ejected with speeds of 400km s−1 and 600 km s−1 respectively and initiallyseparated by 12h. The results show that it takes ~18h for the fast cloud to catch up with the preceding slow one, thenthe two clouds form a Multi-MC structure that arrives at 1 AU three days later. The fast cloud is slowed down significantlybecause of the blocking by the preceding slow one. This implies that the travel time of a Multi-MC structure is dominatedby the preceding slow cloud. Moreover, most primary observational characteristics of Multi-MC at 1 AU are well representedby the simulation. In addition, by combining observations, theoretical model and the simulation results, differences betweenMulti-MC and other types of in-situ observed double-flux-rope structure are addressed. A comparison of Multi-MC to coronalmass-ejection cannibalization near Sun is also given.
magnetohydrodynamics (, MHD), -methods: numerical-Sun: coronal mass ejections (, CMEs), -interplanetary medium-standards
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【期刊论文】THE INTERPLANETARY RESPONSES TO THE GREAT SOLAR ACTIVITIES IN LATE OCTOBER 2003
汪毓明, YUMING WANG, PINZHONG YE, GUIPING ZHOU, SHUJUAN WANG, S. WANG, YIHUA YAN and JINGXIU WANG
Solar Physics (2005) 226: 337~357,-0001,():
-1年11月30日
Based on the observations of the Sun and the interplanetary medium, a series of solaractivities in late October 2003 and their consequences are studied comprehensively. Thirteen X-rayflares with importance greater than M-class, six frontside halo coronal mass ejections (CMEs) withspan angle larger than 100◦ and three associated eruptions of filament materials are identified byexamining lots of solar observations from October 26 to 29. All these flares were associated with typeIII radio bursts, all the frontside halo CMEs were accompanied by type II or type II-like radio bursts.Particularly, among these activities, two major solar events caused two extraordinary enhancements(exceeding 1000 particles/(cm2 s−1 ster−1 Mev−1) of solar energetic particle (SEP) flux intensity nearthe Earth, two large ejecta with fast shocks preceding, and two great geomagnetic storms with Dstpeak value of −363 and −401 nT, respectively. By using a cross correlation technique and a forcefreecylindrical flux rope model, the October 29 magnetic cloud associated with the largest CME areanalyzed, including its orientation and the sign of its helicity. It is found that the helicity of the cloudis negative, contrary to the regular statistical pattern that negative- and positive-helical interplanetarymagnetic clouds would be expected to come from northern and southern solar hemisphere. Moreover, the relationship between the orientation of magnetic cloud and associated filament is discussed. Inaddition, some discussion concerning multiple-magnetic-cloud structures and SEP events is alsogiven.
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【期刊论文】Multiple magnetic clouds: Several examplesduring March-April 2001
汪毓明, Y.M. Wang, P.Z. Ye, and S. Wang
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO.A10, 1370, 2003,-0001,():
-1年11月30日
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