CME Propagation CSI 769 / ASTR 769 Lect. 11, April 10 Spring 2008
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, , 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, , DOI: /s , 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 Q Fe 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
IMF
The End