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Abstract
Regular and systematic measurements of mesospheric temperatures have been carried out during March and April 2007 to determine planetary-scale wave activities in the tropical region, utilizing ground-based Rayleigh Light Detection and Ranging (LiDAR) and satellite-based Microwave Limb Sounder (MLS) data from Gadanki, India (13.5° N, 79.2° E) and MLS data over a site in North America (23.5° N, 100° W). A dominant component of the 3–5 day period wave is revealed at four altitudes (80, 70, 60 and 50 km) over the two observation stations. The estimated vertical wavelength (∼40 km), zonal phase speed (∼140 m s−1), longitudinal and latitudinal extensions have suggested the wave to be an ultra-fast Kelvin (UFK) wave with zonal wave number 1. In addition to the UFK wave, a probable quasi 2 day Rossby gravity wave is also found to be present most of the time. Another 5–7 day wave component, observed at some altitudes with significant prominence, is surmised to be a manifestation of a 6.5 day wave.
Acknowledgements
The authors are grateful to the National Atmospheric Research Laboratory (NARL), Tirupati, India and the Microwave Limb Sounder (MLS) team for providing excellent quality data. The authors are grateful to anonymous reviewers for their constructive comments and suggestions.