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Numerical simulation of multiple CME‐driven shocks in the month of 2011 September
Author(s) -
Wu ChinChun,
Liou Kan,
Vourlidas Angelos,
Plunkett Simon,
Dryer Murray,
Wu S. T.,
Socker Dennis,
Wood Brian E.,
Hutting Lynn,
Howard Russell A.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2015ja021843
Subject(s) - coronal mass ejection , interplanetary spaceflight , physics , geomagnetic storm , solar wind , solar cycle 23 , magnetic cloud , shock (circulatory) , space weather , earth's magnetic field , solar cycle 24 , meteorology , geophysics , astrophysics , magnetic field , medicine , quantum mechanics
A global, three‐dimensional (3‐D) numerical simulation model has been employed to study the Sun‐to‐Earth propagation of multiple (12) coronal mass ejections (CMEs) and their associated shocks in September 2011. The inputs to the simulation are based on actual solar observations, which include the CME speeds, source locations, and photospheric magnetic fields. The simulation result is fine tuned with in situ solar wind data observations at 1 AU by matching the arrival time of CME‐driven shocks. During this period three CME‐driven interplanetary (IP) shocks induced three sizable geomagnetic storms on 9, 17, and 26 September, with Dst values reaching −69, −70, and −101 nT, respectively. These storm events signify the commencement of geomagnetic activity in the solar cycle 24. The CME propagation speed near the Sun (e.g., < 30 R S ) has been widely used to estimate the interplanetary CME (ICME)/Shock arrival time at 1 AU. Our simulation indicates that the background solar wind speed, as expected, is an important controlling parameter in the propagation of IP shocks and CMEs. Prediction of the ICME/shock arrival time at 1 AU can be more problematic for slow (e.g., < 500 km s −1 ) than fast CMEs (>1000 km s −1 ). This is because the effect of the background solar wind is more pronounced for slow CMEs. Here we demonstrate this difficulty with a slow (400 km s −1 ) CME event that arrived at the Earth in 3 days instead of the predicted 4.3 days. Our results also demonstrate that a long period (a month in this case) of simulation may be necessary to make meaningful solar source geomagnetic storm associations.