Rayleigh lidar observations of quasi‐sinusoidal waves in the tropical middle atmosphere

Rayleigh lidar observations of temperature for ∼2–7 hours on 38 nights during the period of 18 January–5 March 1999 and for ∼3 hours on 29 nights during 29 February–2 April 2000 in the altitude region of 27–60 km over Gadanki (13.5°N, 85°E) clearly show the dominance of the quasi‐sinusoidal waves of periods in the range of ∼6–13 hours in temperature in the tropical middle atmosphere. During 1999, the vertical wavelength of these waves ranges from 7.1 to 17 km with a mean value of 12.0 ± 2.4 km while during 2000 it ranges from 5.5 to 17 km with a mean value of 11.4 ± 3.5 km. The wave periods estimated from the observations during 1999 are generally greater than the observation period on each night and are estimated to be in the range of 6.5–13.1 hours with an average period of 9.7 ± 1.8 hours, which is significantly smaller than the inertial period of 53 hours. The amplitudes of these waves are in the range of 1 to 8 K. Such sinusoidal wave modes are clearly discernible in the temperature profiles for ∼50% nights of observation. Another striking feature is that the quasi‐sinusoidal structure is clearly observed in the “equivalent day” analysis also, indicating only small day‐to‐day variability in phase, a property that is characteristic of atmospheric tides.

Rayleigh lidar observations of quasi‐sinusoidal waves in the tropical middle atmosphere Journal Articles