Atmospheric gravity waves excited by a fireball meteor: Observations and modeling

In a companion paper, Suzuki et al. (2013) studied an expanding circular train observed in the Na airglow for 9 min above Syowa Station, Antarctica, on 7 June 2008. This train was created by a southwestward moving fireball meteor. Here we report on “V”-shaped faint gravity waves (GWs) partially visible in many of the Na airglow images 8 to 43 min after the meteor. The GW phase lines appear to originate from the horizontal projection of the meteor path, with angles −42 to −52° south and 10 to 20° north of the path. The GWs south of the path propagated southwestward with a horizontal phase speed of cH∼80–100m/s, while those north of the path propagated northwestward with cH∼20–40m/s. Those south (north) of the path had horizontal wavelengths λH∼25–35km (λH∼18 km) and periods τr∼5–6 min (τr∼7–15 min). We then model the GWs excited by idealized horizontal and slanted heatings and body forces. We show that the GW phase lines form Vs when the heat/force is slanted vertically. If the central altitude of the heat/force is z0>92 km, the open ends of the Vs are mainly directed away from the meteor trajectory. If the heat/force is long enough, two oppositely directed Vs are created, forming an “X” at the center of the structure. We find that λH depends sensitively on the width of the heating. We obtain heating parameters which compare reasonably well with the Na observations: z0∼120 km, half-length half maximum of ∼25–35km, and half width half maximum of ∼2–3km.