Antarctic polar stratospheric clouds under temperature perturbation by nonorographic inertia gravity waves observed by micropulse lidar at Syowa Station

Abstract

Type II Polar Stratospheric Clouds (PSCs) were observed by micropulse lidar (MPL) at Syowa Station in the Antarctic on 30 June and on 1 July 2001. The vertical profiles of the PSCs had a wavy structure that was synchronized with the temperature fluctuations. A wave analysis using radiosonde data shows that the wavy fluctuations were associated with an inertia gravity wave that was not forced by ground topography, but probably by spontaneous adjustment in association with synoptic-scale wave-breaking processes in the upper troposphere. It is suggested that the observed PSCs were generated under the low-temperature conditions induced by these waves and that such gravity waves generated by spontaneous adjustment of large-scale fields can be more important to the formation of PSC particles, in both the Antarctic and Arctic stratospheres, than topographically forced gravity waves, because the former are not fixed to the ground topography.