AGU: Geophysical Research Letters

 

Editors' Highlight

Nightglow on Venus: Requirements for upper atmospheric circulation

When atoms combine to form molecules in the upper atmosphere, energy may be released in the form of photons, causing the atmosphere to weakly glow. Called "dayglow" over the dayside and "nightglow" over the nightside, such emissions of light are seen over Earth, Mars, and Venus. Noting that nightglow emissions are important tracers of upper atmospheric transport, Gérard et al. (2008) studied Venus's nightglow using data from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board the European Space Agency's Venus Express spacecraft. Past research has shown that solar ultraviolet light splits CO₂ molecules on Venus's dayside, releasing oxygen atoms; these atoms are transported to the nightside where they combine to form oxygen molecules, releasing energy and producing nightglow. Through VIRTIS images, the authors characterized the distribution of excited oxygen molecules over most of the southern hemisphere and found that the nightglow observed requires that approximately 50% of the oxygen atoms produced in the dayside be carried to the nightside by global circulation. This requirement will be important to refine circulation models of Venus's atmosphere.

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