First results of convectively generated long-period Kelvin waves in the low-latitude mesosphere during Indian summer monsoon

Spectral analysis of Tirunelveli (8.7°N, 77.8°E) MF radar winds for the year 2007 indicate the presence of long-period Kelvin waves with periods ∼23 and ∼16 days in the low-latitude mesosphere during Indian summer monsoon months. The dominant presence of these slow-phase speed waves at mesospheric altitudes motivated us to investigate their origin and vertical propagation characteristics. Space-time Fourier analysis of NCEP winds and OLR show the presence of these periodicities with zonal wavenumber 1 indicating that tropical convection is the potential source for these waves and westward phase of stratospheric QBO winds might have favoured these waves to reach the mesosphere.