Statistical study of magnetic holes in the upstream region of Mercury’s bow shock  

作　　者：GuoQiang Wang SuDong Xiao MingYu Wu YuanQiang Chen TieLong Zhang 

机构地区：[1]Institute of Space Science and Applied Technology,Harbin Institute of Technology,Shenzhen 518055,China [2]Shenzhen Key Laboratory of Numerical Prediction for Space Storm,Harbin Institute of Technology,Shenzhen 518055,China [3]Mengcheng National Geophysical Observatory,University of Science and Technology of China,Hefei 230026,China [4]Chinese Academy of Sciences Center for Excellence in Comparative Planetology,Hefei 230026,China [5]Space Research Institute,Austrian Academy of Sciences,Graz,Austria

出　　处：《Earth and Planetary Physics》2024年第2期326-337,共12页地球与行星物理（英文版）

基　　金：the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2022041);the National Natural Science Foundation of China(Grant Nos.42241155,41974205,42130204,and 42241133);the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A1515011698,2023A1515030132,and 2022A1515010257);the Shenzhen Science and Technology Research Program(Grant Nos.JCYJ20210324121412034 and JCYJ20210324121403009);the Shenzhen Key Laboratory Launching Project(Grant No.ZDSYS20210702140800001);the Joint Open Fund of Mengcheng National Geophysical Observatory(Grant No.MENGO-202315);the Macao Foundation,the pre-research Project on Civil Aerospace Technologies(Grant No.D020103)funded by the China National Space Administration,and the Chinese Academy of Sciences Center for Excellence in Comparative Planetology。

摘　　要：Magnetic holes are magnetic depression structures that exist widely in many plasma environments.The magnetic holes with durations of>1 s in the solar wind at Mercury’s orbit have drawn much attention,but the properties of the magnetic holes with shorter durations are still unclear.Here,we investigate the magnetic holes with durations of 0.1-100 s in the upstream region of Mercury’s bow shock based on observations by the MESSENGER(MErcury Surface,Space ENvironment,GEochemistry,and Ranging)spacecraft.They can be divided into two groups according to the distribution of their duration:small-duration magnetic holes(SDMHs,<0.6 s)and large-duration magnetic holes(LDMHs,>0.6 s).The duration of each group approximately obeys a log-normal distribution with a median of~0.25 s and 3 s,respectively.Approximately 1.7%(32.6%)of the SDMHs(LDMHs)reduce the magnetic field strength by more than 50%.For both groups,some structures have a linear or quasi-linear polarization,whereas others have an elliptical polarization.The magnetic hole events in both groups tend to have a higher rate of occurrence when the interplanetary magnetic field strength is weaker.Their occurrence rates are also affected by Mercury’s foreshock,which can increase(decrease)the occurrence rate of the SDMHs(LDMHs).This finding suggests that Mercury’s foreshock might be one source of the SDMHs and that the foreshock can destroy some LDMHs.These observations suggest that a new group of magnetic holes with durations of<0.6 s exist in the upstream region of Mercury’s bow shock.

关 键 词：magnetic hole solar wind MERCURY FORESHOCK 

分 类 号：P185.1[天文地球—天文学]