Editors' Highlight
Exosphere influenced by processes near Earth's surface
Can processes occurring near Earth's surface, such as evaporation and condensation, affect conditions in the exosphere, the outermost portion of the atmosphere, which reaches thousands of kilometers above the surface? To explore the issue, Forbes et al. (2009) used measurements from the Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites to determine the temperature of the exosphere as a function of local time, longitude, and latitude. They found that exosphere temperature varies significantly with longitude, and they showed that this variability in the exosphere is linked to several diurnal and semidiurnal thermal tides that begin near Earth's surface as heat is released by evaporation and condensation. These tides, which reflect variations at Earth's surface, such as the distribution of land and sea, had previously been shown to influence the thermosphere at about 110 km in altitude; the new results are the first to demonstrate that these tides extend all the way to the exosphere. The authors also suggest that similar effects could be occurring on other planets, including Mars.
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Published: 07 August 2009
(2009), Surface-exosphere coupling due to thermal tides, Geophysical Research Letters, 36, L15812; doi: 10.1029/2009GL038748.
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