Investigation of the Tidal Signatures in the Thermosphere Using the TIMED/GUVI Data

Friday, 19 December 2014: 10:50 AM
Hyosub Kil1, Larry J Paxton2, Yongliang Zhang2, Young-Sil Kwak3 and Woo Kyoung Lee3, (1)Johns Hopkins University, Baltimore, MD, United States, (2)The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (3)KASI Korea Astronomy and Space Science Institute, Daejeon, South Korea
The observations of CHAMP satellite showed the existence of longitudinal wave patterns in the neutral mass density at an altitude of 400 km. The wave pattern could be characterized by the zonal wave number 4 (wave 4), and the wave 4 pattern showed a strong dependence on the solar cycle. This phenomenon was explained by the direct penetration of non-migrating atmospheric tides into the F region height. However, the existence of the wave 4 pattern in the thermosphere has not yet been verified from other observations. In this study, we investigate the tidal characteristics (focused on the DE3 tide) in the thermosphere at an altitude range of 200–400 km by analyzing the observations of the Lyman-Birge-Hopfield (LBH) band emission by TIMED/GUVI. The radiance of LBH band is used as a proxy of the column number density of molecular nitrogen. Our preliminary results obtained from the TIMED/GUVI data in 2008 show that the wave 4 pattern does not exist in any months in the altitude range. This result contradicts the results obtained from the CHAMP observations. In addition, recent studies by model simulations showed that the thermospheric structure in low latitudes can be induced by the ion drag along the magnetic field line. We will extend our investigation of the tidal signature in the thermosphere to the period of other solar cycle. The coupling of the thermosphere with atmospheric tides will be discussed by reviewing previous studies and comparing with model simulation results.