Wave Coupling between the Lower and Middle Thermosphere from TIMED and GOCE
Friday, 19 December 2014
Vertical coupling between the lower and middle thermosphere due to solar tides and the Ultra-Fast Kelvin Wave (UFKW) with 3-day period is investigated using simultaneous measurements from TIMED-SABER (near 110 Km) and the GOCE accelerometers (near 260 Km). The analysis is performed during 2011 at low and middle latitudes using SABER temperatures and GOCE accelerometer-derived neutral densities and zonal winds. Evidence is found for vertical propagation of the UFKW and several tidal components (DE3, DE2, DE1, SE1, SE2) from the lower to the middle thermosphere. Separation of the raw data into the symmetric and anti-symmetric in longitude space allowed for clearer the extraction of the diurnal and semidiurnal tides (i.e., DE3 from SE2 for wave-4). All of the wave components exhibit significant variability throughout the year. Spectral and temporal analyses of the SABER and GOCE data also reveal the presence of secondary waves due to the modulation of tides by the UFKW. Contribution of secondary waves to the overall thermospheric variability and their role in defining longitude structures is explained and quantified.