European Space Agency

Royal Belgian Institute for Aeronomy

ut998 - evaluate the magnetic field vector and the normal to the field line

subroutine  ut998(mgp, rc, mnr, mb, ifail)

Parameters:

• mgp [zgeo,in] :: Geographic location.

• rc [real8,out] :: Radius of curvature.

• mnr [zvec,out] :: Vector normal to the magnetic field line.

• mb [zvec,out] :: Magnetic field vector.

• ifail [integer4,out] :: error flag (see Diagnostics)

Description

The subroutine ut998() evaluates for a given geographic location the magnetic field vector and the vector normal to the magnetic field line passing through the point. Note that the subroutine makes use of the common block uc170 without corrupting the data already present in the common block. The norm of the normal vector is inversely proportional to the radius of curvature.

The magnetic field vector mb is correctly returned by the subroutine, even when the value of the error flag ifail is equal to -99801 or -99802. When the error flag ifail is equal to -99804, only an approximated value of the normal vector mnr is returned.

History

• The error flags -99802 to -99804 where not generated in version 2.02 and earlier.

Diagnostics

• -99801, not enough place in common uc170

• -99802, not able to evaluate the normal vector mnr

• -99803, not able to compute the magnetic field vector mb

• -99804, uncertainties occured in the evaluation of the normal vector mnr

Common Blocks

• uc160 - general constants

• uc170 - temporary magnetic field line

Dependencies

Called by

None

Calls

• uf423 - Runge Kutta step

• uf425 - evaluate the curvature of the field lines

• um530 - evaluate the magnetic field vector

• ut999 - radius of curvature in a dipolar magnetic field

See also

None

Reported Bugs

None

Examples

None

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UNILIB/tags/v3.02