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Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI goal: use data to do this! Must find (B, v). IVM & MDI tell us B. How do we get v? LCT: commonly used method, but not acceptable! MEF: developed by UCB-MURI. ILCT: modified LCT, developed by UCB-MURI. NOAA AR 8210 Results

Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

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Page 1: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04

• Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations

• MURI goal: use data to do this! Must find (B, v).• IVM & MDI tell us B. How do we get v?• LCT: commonly used method, but not acceptable!• MEF: developed by UCB-MURI.• ILCT: modified LCT, developed by UCB-MURI.• NOAA AR 8210 Results

Page 2: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Q: Can we simulate relevant CME process(es)?

Traditionally, modellers:

1. start with magnetic field configuration B(x,y,z),

2. then drive boundary with velocities v(x,y,t) to store

energy and, perhaps,

3. trigger an eruption!

Page 3: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

MURI: drive simulations directly from data

1. Start with photospheric mag’gram (IVM data just presented)…(*)

2. and best guess at initial field topology (also just presented)…(*)

3. then evolve with MHD simulations, consistent w/photospheric evolution, conserving topology along the way

Page 4: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Q: How do we get velocities from magnetograms?

24 hour MDI movie on 1 May 1998

Page 5: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Three Velocity Reconstruction Methods

1. Local Correlation Tracking (LCT)

2. Minimum Energy Fitting (MEF)

3. Induction + LCT (ILCT)

• LCT:

i) cross-correlate subregions between two images;

ii) find shift that maximizes cross-correlation;

iii) interpret shift as velocity? tricky!LCTu

Page 6: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

LCT applied to MDI data

• Note shear across neutral line near (10,40) --- track (+/-) indep.• Note flux emergence near (50,70) --- fools LCT!

Page 7: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Minimum Energy Fitting (MEF):

• LCT can’t drive codes: no vz, not consistent with

• We developed method consistent w/z-comp. of ideal induction equation:

• Represent unkown vector fields w/potentials:

tB

)vB-Bv(E)(1

t

Bzzz

z

c

)z (vB-Bv zz

Page 8: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

MEF, cont’d:

• Induction eqn. determines :

• Constrain by minimizing integrated velocity field, – this quadratic form resembles ‘energy,’ hence “MEF.”– assumes

• Solution v(x,y) is “as small as possible, consistent with the data.”

2z

t

B

)v( 2z

2vda

0Bv

Page 9: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

• Apparent horizontal motion can be either true horizontal motion, or vertical motion of a tilted field geometry.

zzzzz

vB - vB uBvB

B - v u

ILCT: Reinterpret LCT, a la Demoulin & Berger (2003)

Page 10: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

ILCT, cont’d: Find

• Similar to MEF, use scalar potentials:

• As w/MEF: indn eqn. fixes ; ass’d.

• Instead of minimizing ‘energy’ to find , ILCT uses LCT to constrain :

)uB( 2LCTz

)z (vB-BvuB- zzz

0Bv

Page 11: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

These data used in our AR 8210 simulations. (*)

Page 12: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Conclusions Re: I-LCT, MEF

• Some method of deriving from data is required to drive MHD codes.

• Method must be consistent with magnetic field evolution, . (Will use .)

• UCB-MURI team has developed two novel methods, where none existed before.

• Our methods are only consistent with --- still more work to be done!

zv,v

tB

tBz

0Bv

Page 13: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Amari et al. Initial Velocity

Page 14: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Cancellation flow in Amari et al.

(BACK)

Page 15: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Vector Field in AR 8210, c. 1 May Eruption

Page 16: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

NLFFF of AR 8210, from S.Regnier

(BACK)

Page 17: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Data-driven ZEUS Run

(BACK)

Page 18: Flows in NOAA AR 8210: An overview of MURI progress to thru Feb.’04 Modelers prescribe fields and flows (B, v) to drive eruptions in MHD simulations MURI

Q:What is the proximate cause of CMEs?

• Energization: Field emerges (twisted?); flows in high- photosphere stress ‘line-tied’ coronal field.

• Impulsive Release: Corona undergoes massive, violent restructuring: a CME

• Released Energy: is stored in currents, both those present at emergence and those induced by flows

‘STORAGE & RELEASE’ PARADIGM