comparisons between magnetic field perturbations and model dipole moments at europa n.
Download
Skip this Video
Download Presentation
Comparisons between Magnetic field Perturbations and model dipole moments at Europa

Loading in 2 Seconds...

play fullscreen
1 / 10

Comparisons between Magnetic field Perturbations and model dipole moments at Europa - PowerPoint PPT Presentation


  • 100 Views
  • Uploaded on

Comparisons between Magnetic field Perturbations and model dipole moments at Europa. Derek Podowitz EAS 4480 4/28/2011. Background. Europa has an induced dipole magnetic field Orientation of magnetic field measurements x: In direction of rotation and plasma flow

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Comparisons between Magnetic field Perturbations and model dipole moments at Europa' - steel-rivas


Download Now 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
comparisons between magnetic field perturbations and model dipole moments at europa

Comparisons between Magnetic field Perturbations and model dipole moments at Europa

Derek Podowitz

EAS 4480

4/28/2011

background
Background
  • Europa has an induced dipole magnetic field
  • Orientation of magnetic field measurements
    • x: In direction of rotation and plasma flow
    • y: In direction of Jupiter
    • z: Opposite direction of the magnetic field

C. Paty 2006

procedure and data
Procedure and Data
  • Galileo magnetometer measurements from Planetary Data System:
    • Europa pass E12,Time increment: 1/3 seconds
  • Periodogram: sampling frequency = 3 Hz
  • Butterworth filter: Low Pass
    • Cut-off Frequency: 0.015
    • Nyquist Frequency: 3/0.5 = 1.5
procedure and data1
Procedure and Data
  • Background Magnetic fields
    • Linear regression
  • Magnetic field Perturbations
    • Residual Analysis
  • Calculated Dipole vs. Perturbation
    • Distribution: Chi-squared analysis, student’s t-test
      • Equation:
      • Dipole moment = 2*m
magnetic field perturbations
Magnetic field Perturbations
  • Residual calculation
    • Bperturbation = Bt – Bt-fit
observed vs modeled magnetic field
Observed vs. Modeled magnetic field
  • Chi-squared analysis was done to fit the dipole to the observed filtered perturbation data
    • moment = 9.6900e+018, n = 8176 points, dof = 997
    • theoretical chi-squared value = 1071.6
conclusion
Conclusion
  • Low pass filter is a better choice to filter the data
  • Testing for permanent Dipole moment
    • Chi-squared test showed that Europa’s magnetic field signature is not a normal distribution: B_chi2 = 16153
    • The student’s t test: The means are not equivalent
    • mean_difference = 37.1531
    • Bt_mean = 36.8775
    • 95% confidence interval = 34.2281 - 40.0780
    • Dipole_mean 74.0306
  • Other factors at play to produce signatures
  • Possible corrections: Using more strict parameters when analyzing background magnetic field to obtain better approximation of perturbations
references
References
  • Kivelson M.G., et al. Galileo Magnetometer Measurements: Stronger Case for a Subsurface Ocean at Europa, Science289, 1340 (2000).
  • Paty, C. 'Ganymede’s Magnetosphere: Unraveling the Ganymede-Jupiter Interaction through Combining Multi-fluid Simulations and Observations.' PhD thesis. University of Washington, Seattle, WA. (2006).
  • PDS: The Planetary Data System. JPL/NASA. 2/2011. http://pds.jpl.nasa.gov/index.shtml.
  • Hand, Kevin P. and Christopher F. Chyba. Empirical constraints on the salinity of the europan ocean and implications for a thin ice shell. Icarus Volume 189, Issue 2, August 2007, Pages 424-438
references1
References
  • Project4480