HR: 11:15h
AN: A12A-04    [Abstracts]
TI: Observational Evidence of Critical-Level Filtering of Mountain Waves
AU: * Wang, L
EM: lwang@cora.nwra.com
AF: Colorado Research Associates/NWRA, 3380 Mitchell Lane, Boulder, CO 80301
AU: Fritts, D C
EM: dave@cora.nwra.com
AF: Colorado Research Associates/NWRA, 3380 Mitchell Lane, Boulder, CO 80301
AU: Williams, B
EM: biffw@lamar.colostate.edu
AF: Colorado Research Associates/NWRA, 3380 Mitchell Lane, Boulder, CO 80301
AB: Falling sphere wind and temperature data from the winter campaign (January 2003) of NASA's MaCWAVE (Mountain and Convective Waves Ascending Vertically) project are analyzed to investigate gravity wave characteristics in the stratosphereand mesosphere. We focus on the data from two salvos of rockets launched over Kiruna, Sweden (67.9 N, 21.1 E), which is located at the lee side of the major mountain ranges in the Scandinavia Peninsula. It is found that gravity wave amplitudes maximize at about 48-50 km and 60 km for salvo 1 and salvo 2, respectively, whereas the waves' vertical scales minimize at the above mentioned altitudes, respectively. Also, the altitudes of the wave amplitude maxima and verticalscale minima correspond roughly to where the background winds are close to zero for both salvos. Such a coherence of the locations of wave amplitude maxima, wave vertical scale minima and zero background winds agrees with the theoretical expectation of the behavior of a mountain wave approaching its critical level(i.e., the altitude at which the background winds are zero), suggesting that the waves are most likely mountain waves. Also, the wave's horizontal propagation directions are analyzed using the S-transform method in this study. Compared to the conventional Stokes method, the new approach is found to give better estimate of gravity wave propagation directions, especially when there is a mixture of waves.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0342 Middle atmosphere--energy deposition
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly