A Multi-Instrument Measurement of a Mesospheric Front-Like at the Equator Structure

[摘要] We have made a comprehensive measurement of a front-like structure in the mesosphere at the equator at Kototabang, Indonesia (0.2°S, 100.3°E), using an airglow imager, an airglow temperature photometer, a meteor radar, and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. The event was detected in airglow images of both OH-band (peak emission altitude: 87 km) and 557.7-nm (96-km) emissions, as an east-west front-like structure propagating northward with a velocity of 52-58 m/s. Wave trains with a horizontal wavelength of 30-70 km were observed after the passage of the front. The airglow intensity decreased for all the mesospheric emissions of OI (557.7 nm), OH-band, O2-band (altitude: 94 km), and Na (589.3 nm) (90 km) after the front passage. The rotational temperatures of both the OH-band and the O2-band also decreased ∼10 K. An intense shear in northward wind velocity of 80 m/s/6 km was observed at altitudes of 84-90 km by the meteor radar. The kinetic temperature profile at altitudes of 20-120 km was observed near Kototabang by TIMED/SABER. The front-like structure and trailing waves were similar to those of the mesospheric tidal bore. However, we found that the ducting condition, which is necessary to form a bore, was not satisfied for the observed wave parameters. We speculate that the intense wind shear may play some role for the generation of the front-like structure.

[学科分类] 大气科学