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CSI 769 / ASTR 769 Lect. 11, April 10 Spring 2008. CME Propagation. CME Flux Rope Model. Lepping, R.P., Jones, J.A., Burlaga. “Magnetic Field Structure of Interplanetary Magnetic Clouds at 1 AU” JGR, Vol. 95, No. A8, 11957-11965, 1990. CME MSOE Model.
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CSI 769 / ASTR 769 Lect. 11, April 10 Spring 2008 CME Propagation
CME Flux Rope Model Lepping, R.P., Jones, J.A., Burlaga. “Magnetic Field Structure of Interplanetary Magnetic Clouds at 1 AU” JGR, Vol. 95, No. A8, 11957-11965, 1990
CME MSOE Model Siscoe, G.L., Crooker, N.U., Elliott, H.A., “Initial-Condition Influences on CME Expansion and Propagation” Solar Physics, Vol. 239, 293-316, DOI: 10.1007/s11207-006-0302-3, 2006 MSOE: Melon-Seed-Overpressure-Expansion Model
Interplanetary CME (ICME) • CME propagates into the interplanetary space, plowing through the ambient solar wind • The magnetic structure of ICME at 1 AU is similar to that in its solar origin, which is highly helical (called flux rope) • At 1 AU, it is called magnetic cloud • highly organized magnetic field is observed, e.g., smooth rotation • Large scale, crossing the Earth for ~ 24 hours Magnetic Cloud
ICME Identification Dst B/Bz Vel Np Tp Texp β Sun 2004/07/27 storm (-182 nT) Shock Front: discontinuity • ICME (ejecta): • B enhance • Bz rotation • Low Plasma β • Low Tp • High QFe • ----- SH (Shock Sheath) Solar Sources
Fast and Slow Wind Solar Wind: Bimodal Fast wind originates from coronal hole, Slow wind originates from regions close to streamer belts or heliospheric current sheet SW heliographic latitudinal Distribution (Ulysses observation)
Corotating Interaction Region (CIR) • When a low latitude coronal hole appears (across the heliographic equator), fast wind exists in the ecliptic plane.
Corotating Interaction Region (CIR) • The jetline of fast wind is less curved than that of slow wind • Fast streams “catching up” with slow streams, compressing the preceding stream and produce a high pressure region. • The interaction region is at the leading edge of the fast stream • Since low-latitude coronal holes can live over several solar rotations, this structure can recur several times • This is commonly called “corotating interaction region” or CIR • A pair of forward and reverse shocks forms
CIR Corotating Interaction Region: Caused by the interaction of fast SW originated from coronal hole with preceding slow SW CIR/SI