HR: 0800h
AN: SA51B-1138    [Abstracts]
TI: Toward Absolute Thermospheric Densities
AU: * Moe, K
EM: kmmoe@att.net
AF: Science and Technology Corporation, 23 Purple Sage , Irvine, CA 92603 United States
AU: Moe, M M
EM: kmmoe@att.net
AF: Science and Technology Corporation, 23 Purple Sage , Irvine, CA 92603 United States
AB: New spectroscopic methods are being developed to monitor the density and composition of the thermosphere. These new measurements on GUVI and DMSP require validation by comparison with other kinds of absolute density measurements. Recent advances in our understanding of gas-surface interactions on satellite surfaces has led to the determination of improved physical drag coefficients of satellites, placing us on the threshold of deriving absolute densities. This progress provides two avenues of validation: The densities derived from the spectrometers can be compared with absolute densities inferred from (1) the drag on a satellite near the same time and place as the spectrometric measurements, or (2) the density of a model atmosphere corrected to remove the bias introduced by using inappropriate drag coefficients in the original development of the model. The advances in satellite drag coefficients have proceeded from improved knowledge of the parameters which determine the momentum transfer to the satellite: the energy accommodation coefficients and angular distributions of molecules reemitted from satellite surfaces. These parameters depend on the amount of atomic oxygen adsorbed on the satellite surface as well as on the altitude and local atmospheric temperature. We present the parameters as a function of satellite altitude and time in the sunspot cycle. An example of the removal of a bias in a thermospheric model is given in the case of the Jacchia model.
DE: 3369 Thermospheric dynamics (0358)
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005