Statistical Comparison of Various Dayside Magnetopause Reconnection X-line Prediction Models

Ramiz A. Qudsi,

Brian Walsh, J. Broll, Emil Atz, Stein Haaland

Boston University,   Los Alamos National Lab, Max-Planck Institute

*(qudsira@bu.edu)

(https://qudsiramiz.github.io)

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1, *

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Qudsi (qudsira@bu.edu)

https://sites.bu.edu/bwalsh

Center for Space Physics

Space Physics and Technology Lab

Outline:

  • Magnetic Reconnection
    • X-lines
  • Region of interest
  • Location of x-line
    • Different models
  • Data
  • Results
  • Discussions

Qudsi (qudsira@bu.edu)

The BASICS

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Source: NASA

Qudsi (qudsira@bu.edu)

[Broll et al., 2017]

Source: wikipedia

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Inflow

Inflow

Region of interest:

Qudsi (qudsira@bu.edu)

Qudsi (qudsira@bu.edu)

Why Magnetic Reconnection?

Need to work on something!

Why not?

Ubiquitous nature of reconnection

Energy dynamics

Dynamo effect

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Reconnection models

Qudsi (qudsira@bu.edu)

Questions regarding reconnection:

  • Where?

 

  • When?

 

  • How fast?

 

  • How long?

Qudsi (qudsira@bu.edu)

Classical picture:

  • Anti-parallel reconnection
    • Crooker-1979
  • Component reconnection
    • Uniform, out of plane guide field
      • Sonnerup-1974, Gonzalez and Mozer-1974
    • Equal and opposite component of reconnecting fields
      • Cowley-1976

[Dungey-1961, Trattner-2021]

A slightly more modern picture

Local field bisection [Moore et al., 2002]

Maximum exhaust speed  [Swisdak and Drake, 2007]

Maximum magnetic shear [Trattner et al., 2007]

Maximum reconnecting field energy [Hesse et al., 2013]

Qudsi (qudsira@bu.edu)

Reconnection occurs where some parameter is maximized

Maximum Current Density [Alexeev et al., 1998]

Magnetic shear [Trattner et al., 2007]:

\cos(\theta) = \left(\textbf{B}_{\rm sh} \cdot \textbf{B}_{\rm msp}\right)/ \left(|\textbf{B}_{\rm sh}| |\textbf{B}_{\rm msp}|\right)
B_{\rm rec} = |\textbf{B}_{\rm msp} \cdot \textbf{i}_{\rm xn}|

Local field bisection [Moore et al., 2002]:

Reconnection field energy [Hesse et al., 2013]:

E \propto \left(B_{\rm sh}^2 \times B_{\rm msp}^2\right)

Exhaust speed [Swisdak and Drake, 2007]:

V_{\rm A} = \left[\frac{B_{\rm sh} B_{\rm msp} \left(B_{\rm sh} + B_{\rm msp}\right)}{\left(n_{\rm p,msp}B_{\rm sh} + n_{\rm p,sh}B_{\rm msp}\right)} \right]^{1/2}

sh: magnetosheath

msp: magnetosphere

Location of x-line: Models

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\textbf{i}_{\rm xn}

         : unit vector normal to X-line

DATA

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Data:

Solar

Wind

OMNI

Cooling-2001

Magnetosheath

Magnetopause

Shue-1998

T-96 + IGRF

Magnetospheric Fields

Qudsi (qudsira@bu.edu)

Data

Solar Wind data: OMNI (propagated to the magnetopause)

Magnetosheath data: MMS (FPI and FGM)

Magnetospheric magnetic field: Models (T96 and IGRF)

Magnetosheath magnetic field: Models (Cooling model)

Qudsi                                                                Center for Space Physics, BU                                                 qudsira@bu.edu

GSM coordinate system

y

z

x

Methodology

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Methodology

  • Look at the instances when MMS observed a jet reversal while crossing the magnetopause.

Qudsi (qudsira@bu.edu)

Methodology

  • Look at the instances when MMS observed a jet reversal while crossing the magnetopause.

Qudsi (qudsira@bu.edu)

V_{\rm p}
t
+ \Delta V
- \Delta V

[Broll et al., 2017]

Qudsi (qudsira@bu.edu)

Magnetosheath

Magnetosphere

MMS data (FPI & FGM)

Jet Center

[Qudsi et al., 2023, in Prep]

Methodology

  • For the observed parameters of IMF, Magnetosheath and Magnetosphere and Magnetopause find the model predicted x-line locations.
  • Find the distance of x-line from MMS, along the magnetopause, for different models.
  • Look at the statistical distribution of distances (histogram etc.) for different models.

Qudsi (qudsira@bu.edu)

  • Look at the instances when MMS observed a jet reversal while crossing the magnetopause.
\left< \Delta V_{L} \right> = \pm 70 km/s

RESULTS

Qudsi (qudsira@bu.edu)

The maximum shear model:

[Qudsi et al., 2023, in Prep]

The maximum exhaust velocity model

[Qudsi et al., 2023, in Prep]

[Qudsi et al., 2023, in Prep]

[Qudsi et al., 2023, in Prep]

B_z \gt 0
B_z \lt 0

[Qudsi et al., 2023, in Prep]

[Qudsi et al., 2023, in Prep]

[Qudsi et al., 2023, in Prep]

[Qudsi et al., 2023, in Prep]

DISCUSSIONS

Qudsi (qudsira@bu.edu)

Discussions:

For negative z-component of IMF, reconnection energy and bisection field models both give very similar statistics.

Maximum Exhaust velocity appears to perform worse than other models. Can be because of poor assumption of ion-density in the magnetosphere.

Statistically, bisection field model seem to perform better than other models for different IMF and magnetopause conditions.

Qudsi (qudsira@bu.edu)

Overall result of the study largely agrees with observations made elsewhere in the literature.

Bisection model is least affected by the direction of IMF as well the dominance of y-component.

Qudsi (qudsira@bu.edu)

Thank You!

Link to the presentation

Questions?

Thank You!