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Abstract: We utilize simultaneous Rayleigh lidar and mesospheric OH and O2 airglow measurements to identify the dominant and propagating waves within 40–95km altitude regions over a low latitude station Gadanki (13.8°N, 79.2°E). It is found that waves with 0.4–0.6h periodicity are common throughout the altitude range of 40–95km with significant amplitudes. The ground based temperature measurements with lidar and airglow monitoring are found to compare well with SABER data. With simultaneous Rayleigh lidar (temperature) and mesospheric airglow (emission intensity and temperature) measurements, we estimate the amplitude growth and Krassovsky parameters to characterize the propagation and dissipation of these upward propagating waves. [Copyright &y& Elsevier]

Abstract: We summarize two years of Mesosphere Lower Thermosphere Photometer (MLTP) operation of mesospheric OH and O2 emission monitoring. The deduced mesospheric OH and O2 temperatures show large variability. Nightly temperature variations over Gadanki (13.5°N, 79.2°E) are dominated by the short period wave features, while tidal amplitudes are relatively small. Our measurements are the first to report a long period seasonal variation at two upper mesospheric altitudes simultaneously over the Indian sector. Our observations reveal the presence of a dominant semi-annual oscillation (∼6months periodicity) together with a shorter period (∼2.5 months periodicity) oscillation in both OH and O2 data. [Copyright &y& Elsevier]

Abstract: An airglow imager which monitors mesospheric OH and O(1S) emissions together with thermospheric O(1D) emission with a capability to map the sky at 150° field of view has been installed at Gadanki (13.5°N, 79.2°E). First measurements with the imager have been made with 90° field of view. We note large amplitudes of mesospheric waves traveling from South to North direction with horizontal wavelengths 10–50km. The thermospheric measurements, at the same time, show occurrence of North–South aligned plasma depletions which were found moving to the East. We present these results to showcase the capability of imager and initial results on the mesospheric wave structures and their linkage to the F-region plasma depletion. [Copyright &y& Elsevier]