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

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.
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
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.