Investigation of a “Wall” Wave Event

A bright airglow event was observed at Maui, Hawaii, on the night of 11–12 August 2004 with multiple instruments including a Na wind/temperature lidar, an airglow imager, and a mesospheric temperature mapper. The characteristics of this event were investigated with measurements from these instruments. Analysis showed that this event was caused by a large-amplitude, upward-propagating gravity wave with a period of about 4–5 hours and a vertical wavelength of about 20 km, i.e., a “wall” wave. This wall wave induced dramatic changes in temperature (60 K), airglow intensity (doubled in the OH and tripled in the O ₂ emissions), and Na abundance (tripled). It experienced strong dissipation and induced large downward heat flux with values about an order of magnitude larger than the annual mean. The wave also carried large momentum flux (~70 m ² s ^-2 ).