Abstract:
With the development of cooled CCD detector, it has become possible to detect the spatial and temporal variation of the small-scale structure in airglow emission more accurately. Using tilting filter photometers (Full-size image (<1 K) and OH) and a CCD-based multi-channel all-sky imager, the night airglow observations were carried out from Kolhapur (16.8°N,74.2°E) and Panhala (17.0°N,74.2°E; height above mean sea level Full-size image (<1 K)), India, during the clear and moonless nights of January–February, 2001. The multi-wavelength airglow imaging enables us to study the horizontal structures of the small-scale gravity waves at various heights in the region of emissions and to investigate propagation of those waves in detail. Hydroxyl (OH) and OI Full-size image (<1 K) images on the night of February 18, 2001 showed row-like structures moving from north to south direction spanning over Full-size image (<1 K) in the sky. The observed horizontal phase speed Full-size image (<1 K), wavelength Full-size image (<1 K), wave period Full-size image (<1 K) of the atmospheric gravity waves have been determined from a set of sequential images of OI Full-size image (<1 K) (at Full-size image (<1 K)) and OH (at Full-size image (<1 K)) observed at Panhala. These are the first observation of the signature of atmospheric gravity waves using an all-sky imager in Indian region indicating perturbation in density in the mesospheric region (80–Full-size image (<1 K)). The possible sources of the waves to the extended region have been discussed.
