New image measurements of the gravity wave propagation characteristics from a low latitude Indian station.

The image observations of mesospheric O(1S) 558nm have been performed from a low latitude Indian station, Gadanki (13.5° N; 79.2°E) using a CCD based all sky camera system. Based on three years (from year 2012 to the year 2014) of image data during March-April, we characterize the small scale gravity wave properties. We noted 50 strong gravity wave event and 19 ripple events to occur. The horizontal wavelengths of the gravity waves are found to vary from 12 to 42 km with the phase velocity ranging from 20 to 90 km. In most cases, these waves were propagating towards north with only a few occasions of southward propagation. The outgoing longwave radiation data suggest that lower atmospheric convection was most possible reason for the generation of the waves observed in the airglow data. [ABSTRACT FROM AUTHOR]