HR: 11:30h
AN: SA52A-05 INVITED     [Abstracts]
TI: Global Distribution and Inter-annual Variations of Mesospheric and Lower Thermospheric Neutral Wind Diurnal Tide
AU: * Wu, Q
EM: qwu@ucar.edu
AF: HAO/NCAR, P.O.Box 3000, Boulder, Co 80307-3000, United States
AU: * Wu, Q
EM: qwu@ucar.edu
AF: Key Laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences, P.O.Box 8701, Beijing, 100080, China
AU: Ortland, D A
EM: ortland@nwra.com
AF: Northwest Research Associates, P.O.Box 3027, Bellevue, Wa 98009-3027, United States
AU: Killeen, T L
EM: killeen@ucar.edu
AF: HAO/NCAR, P.O.Box 3000, Boulder, Co 80307-3000, United States
AU: Roble, R G
EM: roble@ucar.edu
AF: HAO/NCAR, P.O.Box 3000, Boulder, Co 80307-3000, United States
AU: Solomon, S C
EM: stans@ucar.edu
AF: HAO/NCAR, P.O.Box 3000, Boulder, Co 80307-3000, United States
AU: Xu, J
EM: xujy@center.cssar.ac.cn
AF: Key Laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences, P.O.Box 8701, Beijing, 100080, China
AU: Skinner, W R
EM: niciejew@engin.umich.edu
AF: SPRL/Univ. of Michigan, 2455 Hayward St., Ann Arbor, Mi 48109-2143, United States
AU: Niciejewski, R J
EM: niciejew@engin.umich.edu
AF: SPRL/Univ. of Michigan, 2455 Hayward St., Ann Arbor, Mi 48109-2143, United States
AB: Using the TIMED Doppler interferometer (TIDI) mesospheric and lower thermospheric neutral wind multiyear data set (2002 - 2005) and NCAR TIME-GCM 1.2 annual run results at the TIDI sampling points, we study the migrating diurnal tide global distribution, interannual, and seasonal variations in connection with the mean zonal wind interannual and seasonal variations. Strong quasi-biennial oscillation (QBO) effect on the diurnal tide was observed in the TIDI data and reproduced to a less degree in the TIME-GCM run. The migrating diurnal tide amplitude is larger during the eastward phase of the stratosphere QBO and weaker during the westward phase. Westward mesosphere mean zonal winds appeared during the eastward phase of the stratosphere QBO (2002 and 2004). The strongest QBO effect on both the migrating diurnal tide and mean zonal winds were observed during the northern spring equinox. We believe that is because both the stratosphere winds and diurnal tide amplitude reach their maximum magnitudes during northern spring equinox. The stratospheric QBO winds apply the maximum filtering effect on the gravity waves, which in turn strongly modulate the diurnal and mean zonal winds. The TIDI data also exhibit large inter-hemispheric asymmetry. While in most cases, westward mean zonal winds in the mesosphere are associated with the enhanced diurnal tide, but not always. The results seem to imply that mean zonal wind is not the only factor controlling the diurnal tide amplitude. The TIME-GCM 1.2 diurnal tide amplitudes are in general smaller than that observed by TIDI. Limited vertical spatial resolution for the TIME-CGM 1.2 is suggested as the cause. Future improvements are expected with higher spatial resolution in the model. QBO effects on nonmigrating tides will also be examined.
DE: 3332 Mesospheric dynamics
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3360 Remote sensing
DE: 3369 Thermospheric dynamics (0358)
DE: 3389 Tides and planetary waves
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly