Effect of Lower Atmospheric Waves on the Ionosphere and Thermosphere 
 
R.W. Schunk, L. Gardner, L. Scherliess, D.C. Thompson and J.J. Sojka 
 
Center for Atmospheric & Space Sciences, Utah State University, Logan, Utah 
84322-4405 
 
We are developing a thermosphere-ionosphere-plasmasphere data assimilation model 
that will be used as an upper atmospheric component for an ocean-atmosphere 
model. The ionosphere - plasmasphere data assimilation model was developed as 
part the Global Assimilation of Ionosphere Measurements (GAIM) program. This 
data assimilation model is based on a physics-based model of the 
ionosphere-plasmasphere system that covers the E-region, F-region, topside 
ionosphere, and plasmasphere (90  – 30,000 km). The model is capable of 
assimilating data from a variety of sources, including bottomside Ne profiles 
from ionosondes, slant GPS/TEC from a network of stations, in situ Ne from DMSP 
satellites, line-of-sight UV emissions measured by satellites, and occultation 
data. The data are assimilated via an ensemble Kalman filter technique. In 
addition to the global N e distribution, the data assimilation model also 
provides global distributions of the self-consistent drivers (neutral winds & 
composition, electric fields, and particle precipitation). The thermosphere data 
assimilation model has been constructed from a physics-based, global, 
thermosphere model using an ensemble Kalman filter technique. This model will 
eventually be able to assimilate UV radiances from the SSUSI and SSULI 
instruments, is situ winds and densities along satellite tracks, and satellite 
drag data. The goal is to couple the thermosphere-ionosphere-plasmasphere data 
assimilation model to the Navy’s troposphere-mesosphere weather model 
(NOGAPS-ALPHA) at 90 km, which will allow for studies of the effect that 
tropospheric weather disturbances have on the upper atmosphere. Preliminary 
simulations have been conducted of the effect that upward propagating tides 
(diurnal, semi-diurnal, terdiurnal), sound waves, and gravity waves have on the 
ionosphere –thermosphere system. The status of this modeling effort will be 
reviewed. The wave effects will also be compared with thermosphere disturbances 
generated by the ionosphere.