The location and field strength of the magnetopause is integral to most external field models. However, it is sometimes useful to be able to estimate the magnetopause location explicitly. Some simple expressions can be used to estimate basic locations of magnetospheric boundaries for mission planning. The standoff radial distance of the magnetopause in the sunward direction is given approximately by:
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(E-2) |
where
Lmp is in units of Earthradii,
nsw, the solar wind proton number density is in units of cm-3 and
usw the solar wind bulk velocity is in units of km s-1.
Typical values for nswand usw are 8 cm-3 and 450 km s-1 respectively, leading to a standoff distance of about 10 RE.
The model of Sibeck et al. [RD.32] represents the complete magnetopause position, not just at the sub-solar point, as the function:
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(E-3) |
where
R2 = y2 + z2;
x, y, and z are GSM coordinates, in Earthradii;
A, B and C are fit parameters dependent on the solar wind pressure as given in Table E-2.