HR: 09:45h
AN: SA31A-07    [Abstracts]
TI: Inter-annual and long-term variations observed in the ITM system
AU: * Talaat, E R
EM: elsayed.talaat@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: Yee, J
EM: sam.yee@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: Ruohoniemi, J M
EM: michael.ruohoniemi@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: Zhu, X
EM: xun.zhu@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: DeMajistre, R
EM: Robert.DeMajistre@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: Russell, J
EM: james.russell@hamptonu.edu
AF: Hampton University, 23 Tyler Street, Hampton, VA 23668, United States
AU: Mlynczak, M
EM: m.g.mlynczak@larc.nasa.gov
AF: Hampton University, 23 Tyler Street, Hampton, VA 23668, United States
AU: Mlynczak, M
EM: m.g.mlynczak@larc.nasa.gov
AF: NASA Langley Research Center, Mail Stop 420 Atmospheric Sciences Research, Hampton, VA 23681, United States
AU: Paxton, L
EM: larry.paxton@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: Christensen, A
EM: Andrew.B.Christensen@aero.org
AF: The Aerospace Corporation, PO Box 92957, Los Angeles, CA 90009, United States
AB: The Ionosphere-Thermosphere-Mesosphere (ITM) region is highly variable and has a complex system of drivers including variable solar radiation, geomagnetic activity, and forcing from the lower atmosphere. Waves that originate in the troposphere grow in amplitude as they travel upwards into decreasing density at higher altitudes where they become the most prominent dynamical features of the ITM. Planetary and gravity waves modify the zonal mean temperature and winds through dissipation and momentum deposition. The effects of these waves on the ITM are expected to depend on the level of solar activity. For all types of waves, how high they penetrate into the thermosphere depends on the temperature, wind, and viscosity profiles. Current observations have shown signatures of both gravity waves and planetary waves in upper atmospheric measurements of winds, temperature, and ion density. The momentum deposition from upward propagating waves is thought to generate the quasi-biennial oscillation (QBO) and semiannual oscillation (SAO) in the zonal circulation of the stratosphere and mesosphere. These zonal wind oscillations, in turn, modulate the waves as they propagate upwards, including the migrating and nonmigrating tides. Understanding the behavior of the tides is not only crucial to characterizing mesopause variability but also transport in the region. Momentum deposition by the diurnal tide at low latitudes in the lower thermosphere produces indirect circulations that will transport neutral and ionized constituents both vertically and horizontally to higher latitudes. Six years of measurements by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite and longer time series from the Super Dual Auroral Radar Network (SuperDARN) HF radars are analyzed to examine the seasonal and inter-annual variations of the diurnal, semidiurnal and terdiurnal tides in the mesosphere and lower thermosphere. We present estimates of both the migrating and nonmigrating of these tides from the lower stratosphere to the lower thermosphere and discuss evidence of nonlinear interaction between the tides and other wave modes. We also examine the inter-relationship the tides may have with lower and middle atmosphere variability (e.g., QBO, SAO, and stratospheric warmings) and tidal impacts on the zonal mean structure of the upper atmosphere and ionosphere using additional data from TIMED/GUVI and TOPEX/Jason data.
DE: 2437 Ionospheric dynamics
DE: 3332 Mesospheric dynamics
DE: 3369 Thermospheric dynamics (0358)
DE: 3389 Tides and planetary waves
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting