11:00 〜 13:00
[PEM12-P14] Observational evaluation of temperature/wind perturbations associated with small-scale AGWs : Momentum flux estimation
キーワード：大気重力波、ライダー観測、大気光イメージング観測
The Tromsoe Na lidar operated by the Institute for Space-Earth Environmental Research, Nagoya University has monitored wind and temperature structures associated with auroral activity in the high latitude upper atmosphere since 2010. Although the observations are limited in the winter night, the lidar detected atmospheric wave signatures with an oscillation period of several hours and temperature change related to the wave propagation with high precision (less than 1K). Furthermore, this lidar started five-direction observation in 2012: two elevation angles, 30 and 12.5 degrees, of the oblique beams have been employed, which corresponds to horizontal distances of 58 and 22 km, respectively, between a pair of the two beams at a height of 100 km and the observational setup can detect small-scale perturbations.
In this study, we tried to identify small-scale (less than 100 km) and short-period (less than 1 h) gravity waves by using the Tromsoe Na lidar. Gravity waves contribute significantly to the wind field and thermal balance in the mesosphere and lower thermosphere (MLT) region because they vertically transport horizontal momentum from the lower atmosphere. It is also pointed out that, in particular, smaller-scale and shorter-period waves tend to transport larger momentum. Small-scale gravity waves in the MLT region are mainly studied with airglow imaging measurements. The airglow measurements, however, cannot observe temperature and wind perturbations directly, which are necessary for the estimation of the wave’s momentum flux. Based on temperature and wind perturbations with the five-direction lidar, we evaluate the dynamical effect of small-scale gravity waves propagating in the upper atmosphere quantitatively.
On the simultaneous measurement of the lidar and airglow imaging on 20 January 2018, we identified the gravity wave with a horizontal wavelength of 37 km, a phase speed of 85 m s-1, and a wave period of 7.2 min. In this presentation, we will discuss its momentum flux estimation by comparing the wave parameters calculated by both measurements.
In this study, we tried to identify small-scale (less than 100 km) and short-period (less than 1 h) gravity waves by using the Tromsoe Na lidar. Gravity waves contribute significantly to the wind field and thermal balance in the mesosphere and lower thermosphere (MLT) region because they vertically transport horizontal momentum from the lower atmosphere. It is also pointed out that, in particular, smaller-scale and shorter-period waves tend to transport larger momentum. Small-scale gravity waves in the MLT region are mainly studied with airglow imaging measurements. The airglow measurements, however, cannot observe temperature and wind perturbations directly, which are necessary for the estimation of the wave’s momentum flux. Based on temperature and wind perturbations with the five-direction lidar, we evaluate the dynamical effect of small-scale gravity waves propagating in the upper atmosphere quantitatively.
On the simultaneous measurement of the lidar and airglow imaging on 20 January 2018, we identified the gravity wave with a horizontal wavelength of 37 km, a phase speed of 85 m s-1, and a wave period of 7.2 min. In this presentation, we will discuss its momentum flux estimation by comparing the wave parameters calculated by both measurements.