Acceleration and Deceleration of Flare/Coronal Mass Ejection Induced Shocks S.T. Wu1, C.-C. Wu2, Aihua Wang1, and K. Liou3 CSPAR, University of Alabama, Huntsville, USA 2 Naval Research Laboratory, Washington, DC, USA 3 Applied Physics Laboratory, Laurel, Maryland, USA 1 STEREO-SWG21, Dublin, Ireland, March 22-26, 2010 1 Motivation To investigate flare/coronal mass ejection induced shock acceleration and decelleration from the corona/surface of the Sun to the inner heliosphere (2 AU) using a 1.5D MHD simulation with drag force.

The simulation results have compared with observation of ACE data. Drag force has compared with Cargill drag force. 2 Governing Equations D V 0 Dt DV 1 GM (r )

p (B) B r F Dt r2 Conservation of mass Conservation of momentum 1 | B |2 1 B ( V B) GM ( r ) [ e V |2 ] [V{e V |2 p} ] v r F t

2 2 2 r2 B ( V B) t Conservation of energy* Induction equation In the equations, D/Dt denotes the total derivative, is the mass density, V is the velocity of the flow, p is the gas pressure, B is the magnetic field, e is the internal energy per unit mass (e = p/(-1)), GM(r) is solar gravitational force, and is the specific heat ratio. For this research, we applied an adiabatic gas assumption (i.e., =5/3). ). F and F are a dissipative force and Rayleigh dissipation function, respectively. The former as a frictional force which is proportional to the velocity of the particle, and the latter as onehalf the rate of energy dissipation due to friction. 3

Observations Halloween 2003 Event LDE M1.7/SF flare at N00W15 0522 UT, October 25, 2003 LDE X1.2/3N flare at S18E33 0617 UT, October 26, 2003 X17/4B flare at S15E44 with a Halo CME 1102 UT, October 28, 2003 X10/2B flare at S15W02 with a Halo CME

2042 UT, October 29, 2003 DD Shock 1 Shock 2 0150 28/10/2003 0600 29/10/2003 Shock 3 1620 30/10/2003 4 Simulation Procedure A one-dimensional MHD simulation model with adaptive grids was

employed to study this event in Sun-Earth direction. We construct the back ground solar wind structure from the surface of Sun to the heliospher for study the propagation of the shock events during the Halloween epoch. To initiate the simulation, we introduce four pressure pulses corresponding to 4 observed flares. These four pressure pulses were introduced at the lower boundary (1 solar radius, Rs) at the time = 0, 24, 77, 110 hours which correspond to time = 298.24 (DOY), 299.26, 301.45, 302.86 of year 2003 according to observations, respectively. Six simulated parameters (i.e., density (Np), T, Vr, V, Br and B) are presented. 5 Simulation Inputs at lower boundary (1 Rs) LDE M1.7/SF X17/4B LDE X1.2/3N

DOY 2003). X10/2B 6 Steady state solar wind condition 1 AU 7 Vr . ACE ______Simulation T 1 AU

B Br V Simulation Results Vr Np 8 COMPARISON: Simulation Results vs. Observation .. ACE ___Simulation V = Vy -Vr = Vx Vp = Vtotal =sqrt(Vx2+Vy2+Vz2) =sqrt(Vr2+V2) 9

Oct. 26 27 S3 DD FF SF F2 FF S1 FFS 4

FF F + S1 2 S F RS Histogram of grids and waves location 28 RS 29

RS 30 31 Nov. 1 2003 10 du/dt = u/(2F ) dF/dt F = ku2 Friction force (Wu et al.,1975)b Drag force (Cargill, 2004)a dVi/dt = FD/M* = -CD (Vi Ve)/|Vi Ve| DISCUSSION F = ku2

k = 3 x 10-3(R/r)6 k: a constant depend on the physical process. REFERENCE: a Cargill, Solar Physics, 221, 135-149, 2004. b Wu et al., Solar Physics, 44, 117-133, 1975. 11 Conclusion Acceleration and Deceleration of Flare/Coronal Mass Ejection induced shocks have been simulated by 1.5D MHD model. Cause of deceleration due to drag force can be estimated from the numerical simulation. Our drag force deduced from simulation are similar to the Cargill results (2005).

We plan to use this simple model to track the STEREO observed shocks. 12 The End 13 CS,CA,Cf (km/s) CS,CA,Cf Reverse Wave Speed Solar wind speed (km/s) Location of Shocks(Rs)

Mach no. Forward Wave Speed 0 20 40 60 80 Time (Hours) 100 120 140

Characteristic wave speeds, magnetosonic Mach Number solar wind speeds, and locations of forward and reverse shock waves as a function of time after the first flare-generating CME and shock. (a) Cf (fast wave speed), Cs (sound wave speed), and CA (Alfven wave speed) for fat reverse shocks (for example, Cf1R is the fast wave speed on the sunward side of RFS1); (b) Cf, Cs, and CA for the fast forward shocks (for example, Cf1 is the fast wave speed on the anti-sunward side of FFS1); (c) magnetosonic Mach Number of both forward and reverse fast shocks; (d) solar wind plasma speed; and (e) locations (or trajectories) of various forward and reverse shocks as well as the reverse fast compression wave, RFW1, that becomes RFS1 after it is

overtaken by FFS2 at t 40 hours. The solid vertical lines (orange/red, black, blue, and yellow) are the points of two shocks collision (Wu et al., JGR, 2006). 14 Velocity profile from 1.5D MHD model with adaptive grids (Wu et al., JGR, 2005) V spike Simulation (solid line) and observed (dotted line) solar wind plasma speed. Excellent agreement with the observations is shown for the simulated shock times of arrival at ACE as well as the V spike, following Shock 4, is a reverse shock. (Wu et al., JGR, 111, A09S17, 2005) 15 16

17 18 19 No Wind/WAVES Type II or III available for LDE M1.7/SF on October 25, 2003 The M1.7/SF and X1.2/3N flares caused a geomagnetic storm with Dstmin= -48 nT Oct. 28 29 The X17/4B flare caused a geomagnetic storm with

The X10/2B flare caused a geomagnetic storm Dst min= -363 nT With Dstmin = -401 nT 30 31 Nov. 1 2003 20 Fourth pressure pulse launched 4th PP Third pressure

pulse launched Time (Hours) 3). rd PP First pressure pulse launched Vr (km/s) Second pressure pulse launched 2nd PP 100 3). 00 200 Heliocentric, Radius (R/Rs)

400 1st PP 21