Flows in noaa ar 8210 an overview of muri progress to thru feb 04
Sponsored Links
This presentation is the property of its rightful owner.
1 / 18

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

  • Uploaded on
  • Presentation posted in: General

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!

Download Presentation

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

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

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)?

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

  • 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?

24 hour MDI movie on 1 May 1998

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

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

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

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:

  • 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)

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

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 :

These data used in our AR 8210 simulations.


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

Cancellation flow in Amari et al.


Vector Field in AR 8210, c. 1 May Eruption

NLFFF of AR 8210, from S.Regnier


Data-driven ZEUS Run



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

  • Login