Studies are available in the literature for evaluating local time variations of the density of the atmosphere imparted by tidal effects. Methods are reported here for incorporating the results of these analyses into easily computed formulations of the dependence on local time of the temperature and density. The Jacchia-Bass density model was modified to simplify calculations by excluding from consideration those minor constituents whose total contribution to the mass density is less than 1%. Software was developed to support studies of atmospheric density variations based on data collected by satellite-borne accelerometers. Modifications were made to several standard satellite ephemeris codes. The changes include: (1) adaptation of the imbedded atmospheric density model to extend its validity to cases of extremely high solar activity; and (2) improvement in the accuracy of conversion between mean Keplerian elements and position/velocity vectors. An HF ducted mode of propagation is to be supported using artificial ionospheric irregularities. One terminal is to be ground-based; the other, satellite-borne.