Ionosonde data from the WestPac 1999 campaign is assimilated into
a sector model of the ionosphere to produce a background ionosphere
spectification and forecast for the Western Pacific sector. The
comparison of results with and without assimiated data demonstrates
significant improvement may be provided for the magnetic meridian. The
improved meridian specification and forecast should help in forecasting
electrodynamics effects and instability effects in the low-latitude
Ionosondes within 5 deg of the dip equator can be used to estimate the vertical plasma drift near sunset. Ionosondes greater than 5 deg can be used to estimate the meridional neutral wind. The model ionosphere is used provide a full sector description of the ionospheric parameters. Instability conditions are examined using linear, flux-tube-integrated Rayleigh-Taylor growth rates and a non-linear model of plasma plumes.