A fast‐propagating, large‐scale atmospheric gravity wave observed in the WAVE2004 campaign

Abstract

[1] The Waves in Airglow Campaign in 2004 (WAVE2004), which aimed to elucidate the formation process of waves in airglow structures from both dynamical and chemical perspectives, was conducted using rocket-borne and ground-based instruments in Japan on 17 January 2004. In this experiment, we observed a large-scale atmospheric gravity wave (AGW), which appeared in both the vertical profiles of sodium density obtained by a Na lidar and the horizontal distributions of airglow emission obtained by an all-sky imager (ASI). Vertical propagation of the AGW accompanied by a shortening of its vertical wavelength was clearly visualized using the Na lidar data. The horizontal wavelength, horizontal phase velocity, period, and propagation direction of the AGW were estimated from the ASI data as 673-774 km, 107-122 m/s, $1.75 hours, and north-northeastward, respectively. Using these parameters and the MF radar wind, vertical wavelengths of the wave were calculated from the dispersion relation of gravity waves. The calculated vertical wavelengths were comparable at altitudes of 85.5 km and 93.25 km to those estimated from the variation of the sodium density. Using a simple ray tracing technique, the AGW was traced back to the southern edge of the distorted jet stream near tropopause. This result strongly suggests that an unstable baroclinic wave associated with ageostrophic motions in the jet stream was the wave source of the large-scale AGW observed in the WAVE2004.

Characteristics of nighttime medium-scale traveling ionospheric disturbances observed over Alaska

“…The vertical wavelength of the gravity wave ( λ z ) can be estimated from wave period (T), zonal and meridional phase velocities ( v px and v py ) and background neutral wind using the dispersion relationship, which can be written as follows [e.g., Kubota et al , 2006; Marks and Eckermann , 1995]: where ω int is the intrinsic frequency of the gravity wave, f is the inertial frequency, N is the Brunt–Väisälä frequency, H is the scale height, and k , l , and m are zonal, meridional, and vertical wave numbers, respectively. We obtained the values of N and H by using the MSISE‐90 model [ Hedin , 1991].…”

In situ observations of instabilities in the mesopause region using foil chaff technique during the Waves in Airglow Structures Experiment (WAVE) campaigns

“…In the WAVE2004 campaign, an AGW with period of about 1.75 h was observed by both the all‐sky imager and the Na lidar. The vertical wavelength estimated from the Na lidar is 6 km at around 90 km altitude [ Kubota et al , 2006]. In order to estimate the vertical wind component of the AGW with period of about 1.75 hours, sodium density profiles obtained by the Na lidar can be used to calculate the relative perturbation of the neutral atmospheric density [ Chiu and Ching , 1978; Shelton et al , 1980; Gardner and Shelton , 1985].…”

“…The second campaign, WAVE2004, was conducted at the same place, Kagoshima, in January 2004. An overview and the initial results of the WAVE2004 campaign have been presented by Iwagami et al [2005], and Kubota et al [2006] presented the result of the detailed data analysis and discussed the source of the AGW.…”

An investigation of long-distance propagation of gravity waves under CAWSES India Phase II Programme

“…Medeiros et al (2005) compared the characteristics of gravity waves observed at four sites located between 2 and 23 • S and found that there is a preferential direction of motion of these waves from the continent towards the Atlantic Ocean. Using multi-instrument (imager, Na lidar, MF radar) observations in the range 31-32 • N latitude, Kubota et al (2006) observed a large-scale gravity wave of wavelength ∼ 673-774 km, period ∼ 1.7 h and velocity 107-122 m s −1 . Wrasse et al (2006) investigated the propagation characteristics of gravity waves using the ray-tracing technique at four different stations -Cachoeira Paulista (22.7 • S, 45 • W), Brazil, São João do Cariri (7.4 • S, 36.5 • W), Brazil, Tanjungsari (6.9 • S, 107.9 • E), Indonesia and Shigaraki (34.9 • N, 136 • E), Japan -and found that the source region of the gravity waves was located 1000 km away from the observational site on a few occasions.…”