Case studies of the propagation characteristics of auroral TIDS with EISCAT CP2 data using maximum entropy cross-spectral analysis
1*Max-Planck-Institut für Aeronomie, Germany. On leave from Department of Space Physics, Wuhan University, China
1Max-Plank-Institut für Aeronomie, D-37189 Katlenburg-Lindau, Germany
2Dept. of Space Physics, Wuhan University, Wuhan 430072, China
Abstract. In this paper case studies of propagation characteristics of two TIDs are presented which are induced by atmospheric gravity waves in the auroral F-region on a magnetic quiet day. By means of maximum entropy cross-spectral analysis of EISCAT CP2 data, apparent full wave-number vectors of the TIDs are obtained as a function of height. The analysis results show that the two events considered can be classified as moderately large-scale TID and medium-scale TID, respectively. One exhibits a dominant period of about 72 min, a mean horizontal phase speed of about 180 m/s (corresponding to a horizontal wavelength of about 780 km) directed south-eastwards and a vertical phase speed of 55 m/s for a height of about 300 km. The other example shows a dominant period of 44 min, a mean horizontal phase velocity of about 160 m/s (corresponding to a horizontal wavelength of about 420 km) directed southwestwards, and a vertical phase velocity of about 50 m/s at 250 km altitude.
Key words. Ionosphere · Auroral ionosphere · Ionosphere-atmosphere interactions · Wave propagation)
Ma, S. Y., Schlegel, K., and Xu, J. S.: Case studies of the propagation characteristics of auroral TIDS with EISCAT CP2 data using maximum entropy cross-spectral analysis, Ann. Geophys., 16, 161-167, doi:10.1007/s00585-998-0161-3, 1998.