Abstract
Distribution of the O2 infrared nightglow observed with VIRTIS on board Venus Express
Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liege, Belgium
Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liege, Belgium
Istituto Nazionale di Astrofisica and Istituto di Astrofisica Spaziale e Fisica Cosmica, Rome, Italy
Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, Meudon, France
Laboratoire de Physique Atmosphérique et Planétaire, Université de Liège, Liege, Belgium
Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, Meudon, France
Escuela Superior Ingeniería, Universidad del País Vasco, Bilbao, Spain
Escuela Superior Ingeniería, Universidad del País Vasco, Bilbao, Spain
We present characteristics of the statistical horizontal distribution of the O2 infrared nightglow over most of the southern hemisphere observed with the VIRTIS instrument over a period spanning nearly 11 months of low solar activity. We show that the distribution is inhomogeneous with the regions of brightest emission reaching ∼3 MegaRayleighs (MR) located at low latitude near and dawnward of the midnight meridian. The hemispherically averaged nadir brightness is 1.3 MR, in very good agreement with earlier ground based observations. We show that the dayside supply of O atoms is sufficient to produce the observed global O2 nightglow if approximately 50% of the dayside O production is carried to the nightside by the subsolar to antisolar global circulation. Limb profiles observed at northern mid-latitudes exhibit large intensity variations over short time periods. Calculations with a one-dimensional chemical diffusive model produce an airglow peak at 96 km, in agreement with the limb observations. The atomic oxygen density derived from the best fits to O2 airglow limb profiles reaches a maximum of 1.8–3.5 × 1011 cm−3 at 104 km.
Received 13 September 2007; accepted 21 November 2007; published 30 January 2008.
Citation: (2008), Distribution of the O2 infrared nightglow observed with VIRTIS on board Venus Express, Geophys. Res. Lett., 35, L02207, doi:10.1029/2007GL032021.
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