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AGU: Geophysical Research Letters

 

Keywords

  • nonmigrating tides
  • thermosphere
  • EIA

Index Terms

  • Atmospheric Processes: Tides and planetary waves
  • Atmospheric Processes: Mesospheric dynamics
  • Atmospheric Processes: Thermospheric dynamics
  • Ionosphere: Ionosphere/atmosphere interactions
  • Ionosphere: Equatorial ionosphere

Abstract

Tidal propagation of deep tropical cloud signatures into the thermosphere from TIMED observations

J. Oberheide

Physics Department, University of Wuppertal, Wuppertal, Germany

J. M. Forbes

Department of Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado, USA

The diurnal eastward zonal wavenumber-3 (DE3) tide is excited in the tropical troposphere by latent heat release in deep convective clouds. Its direct propagation into the thermosphere is explored using Hough Mode Extension (HME) analysis of temperature T, and zonal and meridional wind (u, v) measurements from SABER and TIDI on board the TIMED satellite. HMEs provide observation-based tidal information about parameters not measured (vertical wind w, density ρ) and at latitudes and altitudes not covered by the two instruments. DE3 in (u, v, T, ρ) maximizes around 100 km. The thermospheric (180 km) signal is negligible for (v, ρ) but still considerable for (u, w, T). Maximum amplitudes are 6 m/s (u), 0.12 m/s (w), and 8 K (T). The HME analysis also shows the quantitative consistency of the DE3 tides from SABER and TIDI in the mesosphere/lower thermosphere region. This allows one to interpret the seasonal DE3 variation in terms of symmetric vs. antisymmetric modes.

Received 18 October 2007; accepted 25 January 2008; published 28 February 2008.

Citation: Oberheide, J., and J. M. Forbes (2008), Tidal propagation of deep tropical cloud signatures into the thermosphere from TIMED observations, Geophys. Res. Lett., 35, L04816, doi:10.1029/2007GL032397.

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