Surface-exosphere coupling due to thermal tides

Using densities measured by accelerometers on the CHAMP and GRACE satellites, and taking advantage of the local time precession characteristics of these near-polar orbiting satellites, exosphere temperatures are derived as a function of local time, longitude and latitude. Significant longitude variability (e. g., +/- 25K maximum to minimum over the equator) in geomagnetically-quiet exosphere temperatures is shown to exist, and is attributed to a spectrum of diurnal and semidiurnal thermal tides that are excited in the troposphere and strongly influenced by the global land-sea distribution. Since exosphere temperatures are independent of height, this discovery constitutes evidence that exosphere variability is linked to surface variability. Recent evidence suggests that analogous effects exist at Mars. Citation: Forbes, J. M., S. L. Bruinsma, X. Zhang, and J. Oberheide (2009), Surface-exosphere coupling due to thermal tides, Geophys. Res. Lett., 36, L15812, doi: 10.1029/2009GL038748.