Professor Graham Bailey


Dipolar approximation to the Earth's magnetic field

SUPIM is a physics-based model that describes the distribution of ionization within the Earth's mid to equatorial-latitude ionosphere and plasmasphere. In the model, time-dependent equations of continuity, momentum, and energy balance for the O+, H+, He+, N2+, O2+ and NO+ ions, and the electrons, are solved along closed magnetic field lines for the ion and electron concentrations, field-aligned velocities, and temperatures. The magnetic field is taken to be an eccentric-dipole representation of the Earth's magnetic field, the offset between the magnetic and geographic poles being determined from the usual spherical harmonic expansion of the geomagnetic scalar potential used in the International Geomagnetic Reference Field (IGRF). Particularly cases of the eccentric dipole are the tilted-centered dipole and the axial-centered dipole.

Included in the model are numerous physical and chemical processes. The principal processes include ion production due to solar EUV radiation, ion production and loss due to chemical reactions between the constituent ions and neutral gases, ambipolar and thermal diffusion, ion-ion and ion-neutral collisions, thermospheric meridional and zonal winds, E×B drift, thermal conduction, photoelectron heating, frictional heating, and a host of local heating and cooling mechanisms. The concentrations and temperatures of the neutral gases are taken from the MSIS86 thermosphere model [Hedin, J. Geophys. Res., 92, 4649, 1987]. The neutral wind velocities are taken from either the HWM90 thermosphere wind model [Hedin et al., J. Geophys. Res., 96, 7657, 1991] or values input by the user. The vertical E×B drift velocity is taken from either the model developed by Scherliess and Fejer [J. Geophys. Res., 104, 6829, 1999], from the observations of Fejer et al. [J. Geophys. Res., 96, 13,901, 1991], or from values input by the user.

Depending upon the inputs the model can describe different solar cycle, seasonal, daily, and magnetic activity variations. It can also provide descriptions of the diurnal, altitude, latitude, and longitudinal variations.

From time to time enhancements are made to the model and the model parameters are updated. Modifications are made to the model for specific studies.

History of SUPIM

The current versions of SUPIM have resulted from over twenty years of development by Professor Graham Bailey and coworkers. They started in the late 1970's with the development of a model that only included the O+ and H+ ions [Bailey et al., Planet. Space Sci., 26, 753, 1978]. The model was enhanced in the early 1980's to include a vertical plasma drift [Bailey, Planet. Space Sci., 31, 389, 1983]. The model was then enhanced to include the He+ ion and the molecular ions N2+, O2+ and NO+ [Bailey and Sellek, Ann. Geophys., 8, 171, 1990]. More recently, the numerical and computational procedures have been revised [unpublished]. The model codes are written in FORTRAN. Further information on the model and its application can be obtained from research overview, publications, and homepage.

Related web pages:
Research Overview
Sun-Earth Environment
Coronal Mass Ejections
The Aurora
The Ionosphere
The Topside Ionosphere
The Plasmasphere

Satellite Navigation

Every effort is made to keep the information on these pages accurate, but this is not a guarantee that it is correct. Pages last modified on 12 November 2010. These pages created and maintained by Professor Graham Bailey.

Copyright 2005 The Department of Applied Mathematics, University of Sheffield, UK.

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