Gravity-wave-induced oscillations have been characterized over Kolhapur (16.8°N and 74.2°E), India, using the adiabatic variations in OH airglow intensity and temperature data. The results show that there exist large deviations from one investigation to the other. We also use a full-wave model to simulate the response of OH emission to the wave motion and compare the results with observed values. This report discusses the observed wave characteristics and cause of the noted difference.

The small-scale gravity waves are the least understood processes in the middle-atmospheric variability. Using airglow imaging, we provide new measurements of gravity wave propagation over equatorial latitudes in India. We find that propagation of waves is often in the opposite direction to the tropospheric convective regions. These waves are found to have horizontal wavelengths ranging from 12 to 42 km, with the phase velocities in the 20 to 90 km range.

This study investigates the long-distance propagation (~ 1200–2000km) of gravity waves in the Indian subcontinent using coordinated nightglow measurements at Allahabad and Gadanki (separated by ~ 12º latitude). On few occasions, an identical wave (period in range ~ 2.2–4.5h) was seen at both sites that shared a common source. Waves had large horizontal wavelength (~ 1194–2746km) and phase speed (77–331m/s). The m2 profile analysis suggests the ducted propagation of the common waves.

Sources and propagation characteristics of high-frequency gravity waves observed in the mesosphere using airglow emissions from Gadanki and Hyderabad, India, are investigated using reverse ray tracing. Wave amplitudes are also traced back, including both radiative and diffusive damping. Interestingly, large vertical shears in the horizontal wind are noticed near the ray terminal points (at 10-12km altitude) and are thus identified to be the source for generating the observed gravity waves.