A Statistical Study of Gravity Waves in the Troposphere and Lower Stratosphere in the Antarctic Based on the PANSY Radar Observations

Using observational data from the Program of the Antarctic Syowa Mesosphere-Stratosphere-Troposphere/ Incoherent Scatter radar (PANSY radar) at Syowa Station (69.0 degrees S, 39.6 degrees E) over seven years, the climatology of gravity wave (GW) characteristics in the troposphere and lower stratosphere in the Antarctic were examined. Our analysis shows that the GW kinetic energy in the lower stratosphere is consistent with previous studies using operational radiosonde observations in the Antarctic, including an enhancement during austral spring. We derive a theoretical formula relating horizontal and vertical wind contributions to the GW kinetic energy with the GW intrinsic frequency and the aspect ratio. The vertical variation of the intrinsic frequency suggests the presence of GW sources near the tropopause in addition to those in the troposphere and near the ground. The GW momentum fluxes estimated from radar data indicate that net GW forcing is eastward in the lower stratosphere in seasons except for summer, which acts to accelerate the lower part of the polar night jet. Furthermore, we present the climatology of Eulerian-mean vertical winds elucidated from the long-term radar observations.