Brief Description:
The Global Plasmasphere Ionosphere Density (GPID) model uses a simplified theoretical approach based in part on
diffusive equilibriumto describe the
density of the main ions (O+, H+) and the electron temperature in the plasmasphere along a magnetic flux tube.
GPID assumes an ionosphere=plasmasphere composition
of O+ and H+, and includes chemical processes and simple diffusive transport. Comparisons between GPID and the refilling
fluxes obtained from whistler observations
generally show good agreement, both in diurnal variations and during prolonged refilling of empty flux tubes. Comparisons
to seasonal variations during solar maximum at L=2.5 show good agreement with observations, but at solar minimum there
is variable agreement. The model uses the IRI model for its
base point of 350 km and below.
A weighting function is used that allows the H+ profiles to be smoothly converted
from diffusive control to chemical control in the upper ionosphere.This approach avoids the problem
of hemispherical density mismatch, which normally occurs
at the field line apex when diffusive equilibrium calculations
are used to extrapolate ion densities up the field line from
the two hemispheres.
Availability: Please contact model authors.
References:
P.A. Webb and E.A. Essex, A dynamic diffusive equilibrium model of the ion densities
along plasmaspheric magnetic flux tubes, J. Atmos. Solar-Terr. Phys. 63, 1249-1260,
2001
P.A. Webb and E.A. Essex, Modifications to the Titheridge upper ionosphere and plasmasphere temperature model, J. Geophys. Res. 108, A10, 1359, doi:10.1029/2002JA009754, 2003
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