# How is the orbit plot generated?

The improved model given in Shue et al. (1998) is used to generate magnetopause locations given the z-component of the interplanetary magnetic field (Bz) and the dynamic pressure (Dp) of the solar wind.

The MMS orbit plot represents the magnetopause with a solid black line indicating the mean magnetopause and shaded regions indicating the range of probable magnetopause locations. The mean magnetopause is given by the mean Bz and mean Dp. The outer and inner boundaries of the shaded region are given by the outermost and innermost magnetopause locations returned by the model using the four following sets of parameters, where sigma represents the standard deviation of the parameter it is added to:

(Bz + sigma, Dp + sigma), (Bz - sigma, Dp - sigma), (Bz + sigma, Dp - sigma), (Bz - sigma, Dp + sigma)

Bz and Dp are given by the NASA OMNI one minute resolution data
from 2010 through 2014. Values are as follows:

Bz = 0.012695087 nT

Bz sigma = 3.2014756 nT

Dp = 1.7389104 nPa

Dp sigma = 1.4139446 nPa

Data and further documentation available here: ftp://spdf.gsfc.nasa.gov/pub/data/omni/high_res_omni/

The magnetic field lines and L-shell indicators on the Side view plot are calculated using the IDL Geopack DLM code, an IDL wrapper that provides access to the Geopack Fortran routines developed by Kolya Tsyganenko.

The Geopack model is run using the following default values:

Ram Pressure: 30

DST: -20

IMFbY: 3 nT

IMFbX: -5 nT