Validation of the Thermospheric Vector Spherical Harmonic (VSH) Computer Model
Abstract
A semi-empirical computer model of the lower thermosphere has been developed that provides a description of the composition and dynamics of the thermosphere (Killeen et al., 1992). Input variables needed to run the VSH model include time, space and geophysical conditions. One of the output variables the model provides, neutral density, is of particular interest to the U.S. Air Force. Neutral densities vary both as a result of change in solar flux (eg. the solar cycle) and as a result of changes in the magnetosphere (eg. large changes occur in neutral density during geomagnetic storms). Satellites in earth orbit experience aerodynamic drag due to the atmospheric density of the thermosphere. Variability in the neutral density described above affects the drag a satellite experiences and as a result can change the orbital characteristics of the satellite. These changes make it difficult to track the satellite's position. Therefore, it is particularly important to insure that the accuracy of the model's neutral density is optimized for all input parameters. To accomplish this, a validation program was developed to evaluate the strengths and weaknesses of the model's density output by comparing it to SETA-2 (satellite electrostatic accelerometer) total mass density measurements.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA267784
Entities
People
- Jerry L. Davis Jr
Organizations
- Air Force Institute of Technology