Abstract
A low-frequency inertial atmospheric gravity wave (AGW) event was studied with lidar (40.5° N, 116° E), meteor radar (40.3° N, 116.2° E), and TIMED/SABER at Beijing on 30 May 2012. Lidar measurements showed that the atmospheric temperature structure was persistently perturbed by AGWs propagating upward from the stratosphere into the mesosphere (35–86 km). The dominant contribution was from the waves with vertical wavelengths λ z = 8 − 10 km and wave periods T ob = 6.6 ± 0.7 h . Simultaneous observations from a meteor radar illustrated that MLT horizontal winds were perturbed by waves propagating upward with an azimuth angle of θ = 247 ° , and the vertical wavelength ( λ z = 10 km ) and intrinsic period ( T in = 7.4 h ) of the dominant waves were inferred with the hodograph method. TIMED/SABER measurements illustrated that the vertical temperature profiles were also perturbed by waves with dominant vertical wavelength λ z = 6 − 9 km . Observations from three different instruments were compared, and it was found that signatures in the temperature perturbations and horizontal winds were induced by identical AGWs. According to these coordinated observation results, the horizontal wavelength and intrinsic phase speed were inferred to be ~560 km and ~21 m/s, respectively. Analyses of the Brunt-Väisälä frequency and potential energy illustrated that this persistent wave propagation had good static stability.
Highlights
It is widely recognized that atmospheric gravity wave (AGW) activity has a profound effect on general circulation patterns, temperature structure, and the spatial distributions of atmospheric gas mixing ratios by transporting energy and momentum from the troposphere into the middle and upper atmosphere [1]
By using lidar (40.5◦ N, 116◦ E), meteor radar (40.3◦ N,116.2◦ E), and TIMED/SABER, a lowfrequency inertial AGW propagating obliquely from the stratosphere into the upper mesosphere and persisted for an entire night was observed over Beijing on 30 May 2012
mesosphere and lower thermosphere (MLT) winds were simultaneously measured by meteor radar, and hodograph analysis of wind perturbation shows that the waves propagated upward at an azimuth of θ = 247◦
Summary
It is widely recognized that atmospheric gravity wave (AGW) activity has a profound effect on general circulation patterns, temperature structure, and the spatial distributions of atmospheric gas mixing ratios by transporting energy and momentum from the troposphere into the middle and upper atmosphere [1]. Because the horizontal wave-field of AGW is often inhomogeneous, it is generally difficult for those ground-based instruments to monitor the spatial variations of AGW activities In this respect, satellite observations can be a valuable complement to conventional ground-based and in situ observations of AGWs. By using a temperature lidar and two meteor radars, gravity waves observed by airglow imagers were investigated by Nielsen et al [17] during the MaCWAVE winter campaign. After the background conditions of temperature and winds were respectively measured with lidar and meteor radar, AGWs that were simultaneously observed with airglow imagers were studied by Ejiri et al [18]. With support from the Chinese Meridian Project, coordinated observations and studies of AGW activities in the middle and upper atmosphere over China can be realized by conducting simultaneous observations from lidar, airglow imager, and radar at different observation stations. This work attempts to give a comprehensive picture of this special mesoscale AGW propagation from the stratosphere into the mesosphere (35–86 km), regarding vertical and horizontal wavelengths, intrinsic period, phase speed, propagation directions, and static stability
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