Flows in noaa ar 8210 an overview of muri progress to thru feb 04
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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!

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Flows in noaa ar 8210 an overview of muri progress to thru feb 04
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


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

Traditionally, modellers:

  • 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!


Muri drive simulations directly from data
MURI: drive simulations directly from data

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

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

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


Q how do we get velocities from magnetograms
Q: How do we get velocities from magnetograms?

24 hour MDI movie on 1 May 1998


Three velocity reconstruction methods
Three Velocity Reconstruction Methods

  • Local Correlation Tracking (LCT)

  • Minimum Energy Fitting (MEF)

  • Induction + LCT (ILCT)

  • LCT:

    • i) cross-correlate subregions between two images;

    • ii) find shift that maximizes cross-correlation;

    • iii) interpret shift as velocity? tricky!


Lct applied to mdi data
LCT applied to MDI data

  • Note shear across neutral line near (10,40) --- track (+/-) indep.

  • Note flux emergence near (50,70) --- fools LCT!


Minimum energy fitting mef
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:


Mef cont d
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.”


Ilct reinterpret lct a la demoulin berger 2003
ILCT: Reinterpret LCT, a la Demoulin & Berger (2003)

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


Ilct cont d find
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 :



Conclusions re i lct mef
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!


Amari et al initial velocity
Amari et al. Initial Velocity





Data driven zeus run
Data-driven ZEUS Run

(BACK)


Q what is the proximate cause of cmes

‘STORAGE & RELEASE’ PARADIGM

Q:What is the proximate cause of CMEs?

  • Energization: Field emerges (twisted?); flows in high-b 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


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