A coordinated investigation of the gravity wave breaking and the associated dynamical instability by a Na lidar and an Advanced Mesosphere Temperature Mapper over Logan, UT (41.7°N, 111.8°W)
| Autor: | Xuguang Cai, Yucheng Zhao, Michael J. Taylor, William R. Pendleton, Pierre-Dominique Pautet, Tao Yuan |
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| Přispěvatelé: | American Geophysical Union |
| Rok vydání: | 2014 |
| Předmět: |
010504 meteorology & atmospheric sciences
Geophysics Atmospheric sciences 01 natural sciences Instability Mesosphere Atmospheric Sciences Lidar 13. Climate action Space and Planetary Science Diurnal cycle Wind shear 0103 physical sciences Mesopause Gravity wave Thermosphere 010303 astronomy & astrophysics Geology 0105 earth and related environmental sciences |
| Zdroj: | Publications |
| Popis: | The impacts of gravity wave (GW) on the thermal and dynamic characteristics within the mesosphere/lower thermosphere, especially on the atmospheric instabilities, are still not fully understood. In this paper, we conduct a comprehensive and detailed investigation on one GW breaking event during a collaborative campaign between the Utah State University Na lidar and the Advanced Mesospheric Temperature Mapper (AMTM) on 9 September 2012. The AMTM provides direct evidence of the GW breaking as well as the horizontal parameters of the GWs involved, while the Na lidar's full diurnal cycle observations are utilized to uncover the roles of tide and GWs in generating a dynamical instability layer. By studying the changes of the OH layer peak altitude, we located the wave breaking altitude as well as the significance of a 2 h wave that are essential to this instability formation. By reconstructing the mean fields, tidal and GW variations during the wave breaking event, we find that the large-amplitude GWs significantly changed the Brunt–Vaisala frequency square and the horizontal wind shear when superimposed on the tidal wind, producing a transient dynamic unstable region between 84 km and 87 km around 11:00 UT that caused a subsequent small-scale GW breaking. |
| Databáze: | OpenAIRE |
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