European Space Agency

European Space Agency

Royal Belgian Institute for Aeronomy

Royal Belgian Institute for Aeronomy

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uf410 - search the geographic position of a magnetic field line

subroutine  uf410(flm, fbm, glon, guess, mpos, falt, ifail)
Parameters:

  • flm [real8,in] :: McIlwain’s shell parameter

  • fbm [real8,in] :: Magnetic field intesity at the mirror points

  • glon [real8,in] :: Equatorial Longitude

  • guess [real8,in/out] :: Equatorial radius

  • mpos [zgeo,in] :: Equatorial location

  • falt [real8,in] :: Boundary condition on the altitude

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

Description

The subroutine uf410() searches iteratively a magnetic field line segment for which the shell parameter L, the magnetic field intensity Bm at the mirror points and the longitude of the point with the lowest magnetic field intensity are fixed. The values of L, Bm and longitude are passed through the arguments flm, fbm and glon, respectively. The argument guess can be used to guess the geocentric radius of the point with the lowest magnetic field intensity. As a result, the magnetic field line segment is returned in the common block uc170, the argument guess is set to the current geocentric radius and the argument mpos contains the geographic location of the local magnetic equator. Note that the argument falt can be used such that the subroutine traces the field line till the foot points.

Diagnostics

  • -41001, field line segment not found, probably the value of Bm is less than B0

  • -41002, field line segment not found

  • -41003, too many iterations

  • -41004, field line found, but problem with the altitude boundary

  • -41005, invalid value of flm or fbm argument

Common Blocks

Dependencies

Called by

Calls

See also

None

Reported Bugs

  • 26-Aug-97 (v1.05), Anomalously return of subroutine ud310() with error code -41108

Examples

None

UNILIB/tags/v3.02