Coordinated Ground and Space Based Observations of the Quasi Two-Day Wave in January 2004

The quasi two-day wave is a predominant feature of the mesosphere and lower thermosphere during January and early February each year with horizontal wind speeds exceeding 50 m/s and temperature perturbations on the order of 14K. Theoretical and modeling results indicate the quasi two-day wave is initiated through a baroclinic instability of the summer westward mesospheric jet. The global quasi two-day wave response is repeatable from year to year and is the result of the 3,0 Rossby normal mode being forced by the instability. Observations from the TIMED spacecraft in January 2004 have provided the first opportunity to study the global structure and evolution of the quasi two-day with measurements of both the temperature and horizontal wind field. These measurements from the mesosphere into the lower-thermosphere are provided from the SABER and TIDI instruments on TIMED. These observations will be combined with observations from the global network of ground-based meteor and medium frequency radars to provide a comprehensive view of the quasi two-day wave observed during January 2004.