Geomagnetic Storms as a Dominant Component of Space Weather: Classic Picture and Recent Issues

摘要: It was in the mid-1800s that extraordinary, worldwide disturbances Earth's magnetic field were coined “geomagnetic storms.” would not be too much of an exaggeration to state space weather predictions originated early studies geomagnetic storms. The effects storms surrounding Earth result from a chain processes involving flow/transformation solar wind energy, and electrodynamic coupling among interplanetary medium, magnetosphere, ionosphere, upper atmosphere. importance predicting lies only its “academic” purposes understanding physical solarterrestrial environment, but also practical aspects, influencing societal problems such as on communications satellite anomalies. This chapter discusses characteristic signatures storms, obtained number statistical studies, addresses recent major issues which impact directly our fundamental magnetospheric ionospheric processes, i.e., control storm/substorm relationships, ring current constituents, cycle seasonal dependence following are main points discussion: (1) Most Dst variance during intense can reproduced by knowledge about changes large-scale electric fields wind. A continuing controversy exists, however, whether successive occurrence substorms plays direct role energization storm-time particles. (2) increase 50% largest goes through two steps at phase. causes this double enhancement must identified. (3) CMEs (coronal mass ejections) CIRs (corotating interaction regions) appear primary sources leading These dominant near maximum phase declining cycle, respectively. 22-year activity quantitatively evaluated terms CIRs. (4) Recent observations inner magnetosphere have shown abundance origin ions is high correlated well with substorm relative wind-origin ionosphere-origin constituting particles currently critical unsolved question.