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Karen's Homepage
Introduction to the Sun-Earth Relationship
Introduction to Research
Finding Averages
Fitting Clouds
The Magic Bullet (Results)
Where We Go From Here
Without Whom
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Do two guns really produce two different bullets?
This image is a sample fit. One can clearly see the rise in magnetic field
magnitude as well as the smooth rotation of the cloud through 180 degrees of
latitude.
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We also ran the data through a program called cloud_fit, developed by Dr. Robert
Leamon and Brian Lundberg (2002 REU participant). This program fit the data to a
magnetic cloud model using the following six parameters:
- θ0
- initial latitude (deg)
- φ0
- initial longitude (deg)
- t0
- 'center time,' time from initial cloud contact to the
- spacecraft's closest approach to the center of the
- cloud (hrs)
- B0
- magnetic field magnitude along the cloud axis (nT)
- R0
- cloud radius (km)
- Y0
- distance of closest approach as a fraction of the cloud radius
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It then called the program AMOEBA to minimize the error (chi-squared) between
model and actual
data. A value of 0.02 or less for this chi-squared is considered a good fit. The
program then gave us the actual values of the six parameters for the model, as
well as values for the current and flux. A more detailed description of the
program and how it works can be found on Brian's webpage.
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