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Focus Area VIII: Satellite Drag in the Re-Entry Region: Tidal and Longitude Variations in Density Jeff Forbes (CU) and Jens Oberheide (Univ. of Wuppertal)

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Presentation on theme: "Focus Area VIII: Satellite Drag in the Re-Entry Region: Tidal and Longitude Variations in Density Jeff Forbes (CU) and Jens Oberheide (Univ. of Wuppertal)"— Presentation transcript:

1 Focus Area VIII: Satellite Drag in the Re-Entry Region: Tidal and Longitude Variations in Density Jeff Forbes (CU) and Jens Oberheide (Univ. of Wuppertal) Motivation Re-entry prediction an important problem. Few density measurements exist at re- entry altitudes (ca. 80-200 km) Strong longitude variations in tides known to exist in temperature and wind measurements Reconstructed Density Diurnal Amplitudes 110 km, September 2005 Questions to be Addressed: Q1: What are the tidal density variations 80-200 km including longitude dependences? Q2: What are the corresponding wind variations? Q3: What are the solar cycle dependencies of the above?

2 Methodology: A fitting scheme using “Hough Mode Extensions (HMEs)” will be applied to TIMED/SABER and TIMED/TIDI measurements of temperatures and winds over 80-120 km and -50 o to +50 o latitude during 2002-2006. 1.SABER and TIDI are analyzed for diurnal and semidiurnal tidal components of various zonal (longitudinal) wavenumbers (i.e., SW2, SW1, SE2; DW1, DE3, etc.). 2.Each tidal component is fit with several HMEs; winds and temperatures are fit simultaneously. 3.Internal consistency of the HMEs yields the corresponding tidal density perturbations. 4.The HME methodology and the above internal consistency between winds, temperatures and densities has been tested using GCM output. Methodology: Hough Mode Extensions as Basis Functions

3 Recent Progress: Validation 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. Oberheide J., J. M. Forbes (2008), Thermospheric nitric oxide variability induced by nonmigrating tides, Geophys. Res. Lett., 35, L16814, doi:10.1029/2008GL034825.

4 Recent Progress: Validation Cross-calibrate CHAMP & GRACE data Derive Texos from NRLMSISE00 Utilize time periods when local time distribution was good Fit diurnal curves at all longitudes; then perform zonal wavenumber decomposition

5 Recent Progress: Validation


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