Fitting Flux Ropes to a Global MHD solution: A comparison of - - PowerPoint PPT Presentation

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Fitting Flux Ropes to a Global MHD solution: A comparison of - - PowerPoint PPT Presentation

Dec 29, 2022 96 likes •263 views

Fitting Flux Ropes to a Global MHD solution: A comparison of techniques Pete Riley, J. A. Linker, R. Lionello, and Z. Mikic Science Applications International Corporation, San Diego. CA D. Odstrcil Center for Integrated Research in

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SLIDE 1

Fitting Flux Ropes to a Global MHD solution: A comparison of techniques

Pete Riley, J. A. Linker, R. Lionello, and Z. Mikic

Science Applications International Corporation, San Diego. CA

  • D. Odstrcil

Center for Integrated Research in Environmental Sciences, University of Colorado and SEC, NOAA, Boulder, CO

  • M. A. Hidalgo, C. Cid

Departamento de Fisica, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain

  • Q. Hu

Bartol Research Institute, University of Delaware, Newark, DE now at IGPP University of California, Riverside, CA

  • R. P. Lepping

Laboratory for Extraterrestrial Physics, NASA-Goddard Space Flight Center, Greenbelt, MD

  • B. J. Lynch

Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI

  • A. Rees

The Blackett Laboratory, Imperial College London, London SW7 2BW, UK

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SLIDE 2

The Motivation

  • Flux rope fitting models are a useful tool for

recovering intrinsic and global properties of Magnetic clouds

  • Difficult, if not impossible, to assess accuracy
  • f fits as underlying global structure cannot

be independently determined

  • MHD models, on the other hand can provide

both a global view as well as localized time series at specific points in space

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SLIDE 3

The Teams

  • Riley, Linker, Mikic at SAIC and Odstrcil at

NOAA/SEC (MHD Model)

  • Hidalgo and Cid at U. de Alcalá, Madrid

(Elliptical Cross Section Model)

  • Hu at UC Irvine (GSR Model)
  • Lepping at NASA/GSFC (Force Free Model)
  • Lynch at U. Michigan (Force Free Model)
  • Rees at Imperial College, London (Force

Free Model)

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SLIDE 4

The Techniques

  • MHD Simulation
  • Force Free Model
  • Elliptical Cross Section Model
  • Grad-Shafranov Reconstruction

Technique

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SLIDE 5

The MHD Simulation

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SLIDE 6

Simulated Time Series

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SLIDE 7

Lepping Force Free Fit

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SLIDE 8

Lynch Force Free Fit

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SLIDE 9

Rees Force Free Fit

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SLIDE 10

Hidalgo Elliptical CS Fit

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SLIDE 11

7 8 9 10 11 12 13 14 15 16 17

0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.02 0.01 0.01 0.02 0.03 x (AU)

5 nT

nT

Bz

Case A: Hu

2 4 6 8 10 12 14

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.1 0.08 0.06 0.04 0.02 0.02 x (AU) y (AU)

5 nT

nT

Bz

Case B: Hu

HU GSR Fit

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SLIDE 12

Comparison of Results: Case A

  • ฀
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SLIDE 13

Comparison of Results: Case B

  • ฀
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SLIDE 14

Conclusions

  • All fitting techniques are, and will continue

to be useful tools for describing magnetic clouds

  • Some limitations to note:
  • Boundary identification is a critical issue
  • Minimum variance analysis is poor technique for identifying orientation of

axis

  • Results from models that reproduce global shape must be treated with

caution

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SLIDE 15

Future Directions

  • We need to make progress in identifying the

boundaries (GSR Technique)

  • We need to assess which, if any, of the

models provides the best fits, and under what conditions?

  • What are the improvements from multi-

spacecraft techniques?