Mesospheric Bore Evolution And Instability Dynamics Observed In Pmc Turbo Imaging And Rayleigh Lidar Profiling Over Northeastern Canada On 13 July 2018

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES(2020)

引用 16|浏览88
暂无评分
摘要
Two successive mesospheric bores were observed over northeastern Canada on 13 July 2018 in high-resolution imaging and Rayleigh lidar profiling of polar mesospheric clouds (PMCs) performed aboard the PMC Turbo long-duration balloon experiment. Four wide field-of-view cameras spanning an area of similar to 75 x 150 km at PMC altitudes captured the two evolutions occurring over similar to 2 hr and resolved bore and associated instability features as small as similar to 100 m. The Rayleigh lidar provided PMC backscatter profiling that revealed vertical displacements, evolving brightness distributions, evidence of instability character and depths, and insights into bore formation, ducting, and dissipation. Both bores exhibited variable structure along their phases, suggesting variable gravity wave (GW) source and bore propagation conditions. Both bores also exhibited small-scale instability dynamics at their leading and trailing edges. Those at the leading edges comprised apparent Kelvin-Helmholtz instabilities that were advected downward and rearward beneath the bore descending phases extending into an apparently intensified shear layer. Instabilities at the trailing edges exhibited alignments approximately orthogonal to the bore phases that resembled those seen to accompany GW breaking or intrusions arising in high-resolution modeling of GW instability dynamics. Collectively, PMC Turbo bore imaging and lidar profiling enabled enhanced definition of bore dynamics relative to what has been possible by previous ground-based observations, and a potential to guide new, three-dimensional modeling of bore dynamics. The observed bore evolutions suggest potentially important roles for bores in the deposition of energy and momentum transported into the mesosphere and to higher altitudes by high-frequency GWs achieving large amplitudes.
更多
查看译文
关键词
mesospheric bores,gravity wave breaking,gravity wave self-acceleration,bore propagation,bore instabilities,mesospheric turbulence
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要