Corrected Geomagnetic Co-ordinates

Corrected geomagnetic co-ordinates were introduced by B.Hultquist and Gustafsson [1960].

According to K. Stasiewicz [1991] the classical algorithm of the corrected co-ordinates calculation looks as follows:

• Step 1: The magnetic field line tracing from the satellite position up to magnetic equatorial plane using IGRF magnetic field model.
• Step 2: Tracing back from the point (produced on the Step 1) to the Ionosphere (by using only dipole magnetic field)
• The CORLAT, CORLON, and CORMLT of the original point are equal to the dipole latitude, longitude and local time of the point, produced on the step 2.
• Corrected geomagnetic co-latitude is the difference: (90 deg - CORLAT).

But this algorithm can be used only for the points belonging to the Earth's surface or to the near Earth space limited by 6 RE, where influence of the extraterrestrial magnetic field is not sufficiently.

For the long-distance Earth environment the following algorithm of the corrected co-ordinates calculation proposed by V. Sergeev and N. Thsyganenko [1980] is used:

• The magnetic field line tracing from the satellite position up to the Ionosphere (the stop trace altitude 110 km) using Main (dipole)+Extraterrestrial magnetic field model (for example, Tsyganenko [1987], or [1989], or [1990])
• The CORLAT, CORLON, and CORMLT of the original point are equal to the dipole latitude, longitude and local time of the produced footprint.
• Corrected geomagnetic co-latitude is the difference: (90 deg - CORLAT).

References

• Hultquist, B. M, and G.Gustafsson, On the magnetic time dependence of auroral zone currents, J.Atmos. Terr., Phys., 19, 246, 1960.
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• Stasiewicz K. Polar Cusp Topology and Position as a Function of Interplanetary Magnetic Field and Magnetic Activity: Comparison of a Model with Viking and other Observations, J. Geophys. Res., 96, 15789-15800, September 1, 1991.
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• The main magnetic field IGRF WWW site http://fdd.gsfc.nasa.gov/IGRF.html
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• Sergeev, V.A., and Tsyganenko N.A. Magnetosphere of the Earth // M.: Nauka. 1980 (In Russian)
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• Tsyganenko N.A., Global quantitative models of the geomagnetic field in the cislunar magnetosphere for different disturbance levels, Planet. Space Sci., 35, 1347-1358, 1987.
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• Tsyganenko N.A., Magnetospheric magnetic fields model with a warped tail current sheet. Planet. Space Sci. 1989. 37. 5-20.
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• Tsyganenko N.A. Quantitative models of the magnetospheric magnetic field: Methods and results. Space Sci. 1990. Rev. 54. 75.
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Dr. Victoria Prokhorenko
Last modified 11 January 1999