[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-P32] Development of gravity-wave propagation diagnostic diagram to represent transient background field.

*Masaru Kogure^1,2,3, Takuji Nakamura^4,5, Damian J. Murphy⁶, Michael J. Taylor⁷, Yucheng Zhao⁷, Pierre Dominique Pautet⁷, Masaki Tsutsumi^4,3, Yoshihiro Tomikawa^4,5,8, Mitsumu K. Ejiri^4,3, Takanori Nishiyama^4,5 (1.Kyushu University, 2.NASA/GSFC, 3.Department of Physics, Catholic University of America, 4.National Institute of Polar Research, 5.Department of Polar Science, SOKENDAI, 6.Australian Antarctic Division, Department of Agriculture, Water and the Environment, 7.Center for Atmospheric and Space Sciences/Physics Department, Utah State University, 8.Polar Environment Data Science Center, Research Organization of Information and Systems)

Keywords:Gravity wave

Gravity waves are well-known as carriers of vertical momentum and energy from the troposphere to the upper atmosphere. An airglow imaging technique is a powerful gravity wave observation instrument and gives us spectra of ground-based frequencies and horizontal wavenumbers. Matsuda et al. [2014] developed the method, well-known as the M-transform, to calculate ground-based phase velocity spectra from the period and wavelength spectra. The phase velocity spectra diagnostic has an advantage of easy comparison with the transmission (or blocking) diagram, allowing us to estimate vertical propagation processes of observed gravity waves. Nowadays, many papers have compared both spectra and diagrams and revealed the impacts of the background wind and temperature on the gravity wave propagation. However, the transmission diagram does not represent a temporal variation of the background[DM1] . This assumption can be valid in the short term with a stable background but invalid in long term and transient background.
This study develops a new diagram (probability diagram) to represent the temporal variation of the background. This presentation will introduce to the method used to calculate the new diagram and will show an example for comparison with phase velocity spectra over two Antarctic stations (Syowa and Davis). We will show that our new diagram is much more consistent with the mean spectrum during austral spring than the transmission diagram calculated from the mean background field.