Gravity wave propagation and dissipation from the stratosphere to the lower thermosphere

Abstract

One‐night (28 October 2003) temperature and horizontal wind measurements by a resonance sodium (Na) wind/temperature lidar at Maui (20.7°N, 156.3°W) and temperature measurement by a Rayleigh lidar at Mauna Loa Observatory (MLO, 19.5°N, 155.6°W), Hawaii, were used to study gravity wave (GW) propagation from the lower stratosphere to the lower thermosphere. A dominant wave mode was identified from 35 to 103 km. The wave was partially dissipated and propagating upward with a scale height of temperature amplitude at ∼14 km. A damping layer was present around the stratopause where the wave amplitude was small, which also corresponded to a low static stability layer. The vertical wavelengths were larger in the mesosphere (12–13 km) than in the stratosphere (6–7 km), consistent with the decreasing static stability with altitude. Hodograph analysis of the Na lidar wind data showed that the wave was propagating northward and the horizontal wavelength was 2140 km and intrinsic period was 15 h in the region 84–103 km. The apparent period was ∼6 h and consistent with Doppler shift of the background wind. It is suggested that the convective zone over the equator to the south of Hawaii provided a constant GW source that is responsible for the observed GW throughout the night.