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Non-Migrating Tides, with Zonally Symmetric Component, Generated in the MesosphereFor comparison with measurements from the TIMED satellite and coordinated ground based observations, we discuss results from our Numerical Spectral Model (NSM) that incorporates the Doppler Spread Parameterization (Hines, 1997) for small-scale gravity waves (GWs). The NSM extends from the ground into the thermosphere and describes the major dynamical features of the atmosphere including the wave driven equatorial oscillations (QBO and SAO), and the seasonal variations of tides and planetary waves. With emphasis on the non-migrating tides, having periods of 24 and 12 hours, we discuss our modeling results that account for the classical migrating solar excitation sources only. As reported earlier, the NSM reproduces the observed seasonal variations and in particular the large equinoctial maxima in the amplitude of the migrating diurnal tide at altitudes around 90 km. Filtering of the tide by the zonal circulation and GW momentum deposition was identified as the cause. The GWs were also shown to produce a strong non-linear interaction between the diurnal and semi-diurnal tides. Confined largely to the mesosphere, the NSM produces through dynamical interactions a relatively large contribution of non-migrating tides. A striking feature is seen in the diurnal and semi-diurnal oscillations of the zonal mean (m = 0). Eastward propagating tides are also generated for zonal wave numbers m = 1 to 4. When the NSM is run without GWs, the amplitudes for the non-migrating tides, including m = 0, are generally small. Planetary wave interaction and non-linear coupling that involves the filtering of GWs and related height integration of dynamical features are discussed as possible mechanisms for generating these non-migrating tides in the NSM. As is the case for the solar migrating tides, the non-migrating tides reveal persistent seasonal variations. Under the influence of the QBO and SAO, interannual variations are produced.
Document ID
20030113045
Document Type
Conference Paper
Authors
Mayr, H. G. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mengel, J. G. (Science Systems and Applications, Inc. Lanham, MD, United States)
Talaat, E. R. (Johns Hopkins Univ. Laurel, MD, United States)
Porter, H. S. (Furman Univ. Greenville, SC, United States)
Hines, C. O. (Arecibo Ionospheric Observatory Arecibo, Puerto Rico)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Meteorology and Climatology
Meeting Information
EGS-AGU-EUG Joint Assembly 2003(Nice)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.