Central axial field direction in magnetic clouds and its relation to southward interplanetary magnetic field events and dependence on disappearing solar filaments

Extended periods of strong southward interplanetary magnetic field Bs are the primary cause of intense geomagnetic storms. Most such intervals are associated with magnetic clouds in the solar wind. We define a magnetic cloud Bs event as the interval of southward interplanetary magnetic field observed as a magnetic cloud passes by the Earth. For the 26 well-characterized events studied here, we find that (1) magnetic cloud central axial field directions are almost evenly distributed between −90° and 90° ecliptic latitude, the longitudinal distribution is slightly peaked around the east and west, (2) the duration and intensity of magnetic cloud Bs events correlate linearly with the direction of the cloud's central axial field, and (3) cloud central axial field directions are correlated with the central axial field directions of the associated disappearing filament on the Sun. These findings are useful in predicting from solar observations the duration and intensity of those magnetic cloud Bs events that hit Earth.

[1]  F. Mariani,et al.  Magnetic loop behind an interplanetary shock: Voyager, Helios and IMP-8 observations , 1981 .

[2]  L. Burlaga,et al.  Interplanetary magnetic clouds at 1 AU , 1982 .

[3]  H. Goldstein.  On the field configuration in magnetic clouds , 1983 .

[4]  H. Rosenbauer,et al.  Coronal mass ejections and interplanetary shocks , 1985 .

[5]  R. Wilson,et al.  On the association of magnetic clouds with disappearing filaments. [interplanetary phenomena associated with coronal mass ejection , 1986 .

[6]  K. Marubashi.  Structure of the interplanetary magnetic clouds and their solar origins , 1986 .

[7]  L. Burlaga,et al.  Compound streams, magnetic clouds, and major geomagnetic storms , 1987 .

[8]  L. Burlaga,et al.  Magnetic clouds and force‐free fields with constant alpha , 1988 .

[9]  B. Tsurutani,et al.  Origin of interplanetary southward magnetic fields responsible for major magnetic storms near solar maximum (1978–1979) , 1988 .

[10]  D. Webb.  Erupting prominences and the geometry of coronal mass ejections , 1988 .

[11]  L. Burlaga,et al.  Magnetic field structure of interplanetary magnetic clouds at 1 AU , 1990 .

[12]  Catalogue of solar filament disappearances 1964-1980 , 1991 .

[13]  B. Tsurutani,et al.  Great magnetic storms , 1992 .

[14]  Xuepu Zhao.  Interaction of fast steady flow with slow transient flow: A new cause of shock pair and interplanetary Bz event , 1992 .

[15]  M. Freeman,et al.  A study of an expanding interplanetary magnetic cloud and its interaction with the Earth's magnetosphere: The interplanetary aspect , 1993 .

[16]  D. Rust.  Spawning and Shedding Helical Magnetic Fields in the Solar Atmosphere , 1994 .

[17]  V. Bothmer,et al.  Eruptive prominences as sources of magnetic clouds in the solar wind , 1994 .