17:15 〜 19:15
[PEM12-P02] Initial analysis of mesospheric gravity waves observed in Tromsø, Norway, on December 17, 2014, using an OH-airglow imager and a sodium lidar.
キーワード：大気重力波、大気光画像
Studies of small-scale (20-100 km) mesospheric gravity waves have been conducted using airglow imagers. Airglow imagers can observe the small-scale gravity waves, which are hard to observe with radars. S. Suzuki et al. (2007) estimated the momentum flux of small-scale gravity waves in the upper mesosphere using an OH-airglow imager at Shigaraki, Japan. They reported that waves with horizontal wavelengths of 60–90 km and apparent phase speeds of 40–80 m/s carry upward momentum fluxes of 1-15 m2/s2, which is significant and possibly controls the mean winds in the mesopause region. Nevertheless, the calculation of momentum flux, which is directly related to the squared temperature variation, has remained ambiguous. This ambiguity stems from the necessity of transforming airglow intensity fluctuations into spatial and temporal temperature variations. Here we report an initial analysis of mesospheric small-scale gravity waves observed by an OH-airglow imager and a sodium lidar in Tromsø, Norway, on December 17, 2014. Sodium lidar at Tromsø provides spatial and temporal variations of temperature, which have previously lacked observational information for estimation of gravity wave momentum flux. From ~18:00 UT to 20:00 UT, mesospheric gravity waves, propagating toward the southwest with horizontal wavelengths of ~20-50 km, were observed. As part of the initial analysis to estimate the momentum flux, we attempted to correlate these airglow images of gravity waves with mesospheric temperature profiles obtained from the sodium lidar to confirm that the identical gravity waves are observed with both instruments.