[P-CG38_1PO1] Planetary atmosphere, ionosphere and magnetosphere

[PCG38-P05] Temporal variations of Venus O2 night airglow using IRTF/CSHELL

*Shoko OHTSUKI¹, Naomoto IWAGAMI², Severine ROBERT³, Hideo SAGAWA⁴, Toru KOUYAMA⁵, Takao M. SATO⁶ (1.Senshu University, 2.University of Tokyo, 3.Belgian Institute for Space Aeronomy, 4.National Institute of Information and Communications Technology, 5.Information Technology Research Institute, 6.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)

Venus 1.27-micron O₂ night airglow is the indicator of the general circulation at about 95 km in Venus. Recent observations reported that the airglow emission showed the temporal variations with a period of a few hours and days [e.g. Ohtsuki et al., 2008; Gerard et al., 2008]. Such variations may be caused by the upward momentum transport and fluctuations by atmospheric waves. In recent years, the importance of planetary-scale waves on the general circulation of the Venus atmosphere has been recognized. Forbes and Konopliv [2007] suggested the propagation of planetary-scale waves originated in the cloud deck into the upper atmosphere. However, effects of planetary-scale waves on the Venus upper atmosphere have not been investigated yet. We conducted 5-days monitoring observation of the airglow to detect the planetary-scale waves with IRTF/CSHELL from 11-15 July 2012, 3 and 5 February 2014. The 1.27-micron O₂ night airglow in the Venus atmosphere can pass through the Earth's atmosphere with a help of the Doppler shift. We obtained spectral image cubes at the wavelength of R-branch of the airglow band, which includes several rotational lines. In order to cover spectral information continuously, a slit drifted across Venus' nightside disk. The spatial resolution of the image is governed by seeing. The typical seeing was 0.6" to 1.5" in our observing run and corresponds to 200-450km at the center of Venus' disk. Under such conduction, we may detect airglow structures of small scales due to atmospheric waves; this is smaller than the region of enhanced airglow having a horizontal scale of ~3000km. We can also derive the hemispherical distribution of the rotational temperature. To coincide with our observations, SOIR/Venus Express stellar occultations were conducted. We can try to compare our horizontal temperature map and vertical temperature profile from SOIR data.In this presentation, we will show temporal variation of the airglow distributions in July 2012 and report a preliminary result of our new observations in February 2014.