HR: 0800h
AN: SA21A-0268    [Abstracts]
TI: Seasonal variations of stratospheric gravity waves in Antarctica and correlations to polar mesospheric cloud brightness in summer
AU: * Yamashita, C
EM: yamashic@colorado.edu
AF: Cooperative Institute for Research in Environmental Sciences and Department of Aerospace Engineering Sciences, University of Colorado at Boulder, 216 UCB, CIRES, Boulder, CO 80301, United States
AU: Chu, X
EM: Xinzhao.Chu@Colorado.EDU
AF: Cooperative Institute for Research in Environmental Sciences and Department of Aerospace Engineering Sciences, University of Colorado at Boulder, 216 UCB, CIRES, Boulder, CO 80301, United States
AU: Huang, W
EM: Wentao.Huang@Colorado.EDU
AF: Cooperative Institute for Research in Environmental Sciences and Department of Aerospace Engineering Sciences, University of Colorado at Boulder, 216 UCB, CIRES, Boulder, CO 80301, United States
AU: Nott, G J
AF: Department of Physics and Atmospheric Science, Dalhousie University, Dalhousie University, Halifax, NS B3H 3J5, Canada
AU: Espy, P J
AF: Physical Sciences Division, British Antractic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AB: Gravity waves (GWs) play an important role in the dynamics of global middle and upper atmosphere. However, quantitative characterization of GWs in the upper stratosphere is still rare in Antarctica. Here we present a study of stratospheric GW parameters and seasonal variations using the data obtained with the University of Illinois Fe Boltzmann/Rayleigh lidar at the South Pole (90°S) from December 1999 to January 2001 and at Rothera (67.5°S, 68.0°W) from December 2002 to March 2005. Through analyzing the Rayleigh lidar density data in 30-60 km, GW parameters are derived for the South Pole and Rothera, and the results are comparable. The annual mean GW vertical wavelength is 4.3 +/- 1.5 km, vertical phase speed is 0.33 +/- 0.15 m/s, and the period is 245 +/- 110 min. We characterize the stratospheric GW strength with the root- mean-square (RMS) relative density perturbation. The seasonal variation of GW strength is clear at Rothera, with the maximum in winter and the minimum in summer. No significant seasonal variations are observed at the South Pole. The data also show that the GW period is shorter in summer than in winter at Rothera. In addition, the stratospheric GW strength is negatively correlated with PMC brightness at Rothera but no significant correlation at the South Pole. Two important factors, i.e., the wind filtering effect and topographical GW source difference, are investigated in order to explain the GW seasonal variations. We then apply a GW ray-tracing model to analyze the GW source and propagation. The correlation between GW strength and PMC brightness also provides a clue of GW propagation from the stratosphere to the mesosphere.
DE: 3332 Mesospheric dynamics
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3360 Remote sensing
DE: 3384 Acoustic-gravity waves
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting