钠层密度翻转现象的激光雷达观测与研究

基于国家子午工程项目钠激光雷达的长期观测数据,统计分析了北京和海南两地出现的钠层密度翻转现象,发现这种现象往往出现在钠层的下部,宽度在2~7 km范围,持续时间约为2~8 h。观测结果显示,钠层密度翻转结构的出现常伴随着大尺度重力波的传播活动,且钠层密度翻转结构的消失过程也和较大尺度重力波的破碎过程有较好的对应关系.这表明,除风剪切和自身动力学不稳定因素外,大尺度和小尺度重力波相互作用引起的垂直对流不稳定效应可能是大尺度重力波破碎的另一个重要原因.

Lidar Observations and Investigation on Density Overturning in Sodium Layer

Based on the long-term observations from Meridian Project lidars, the density overturning phenomena in the sodium layer above Beijing and Hainan are statistically analyzed. It is found that the density overturning structures generally occur in the bottomside of the sodium layer and typically last for 2~8 h with a width of 2~7 km. The observation results reveal that, the occurrence of those overturning structures are always accompanied with the propagations of large-scale gravity waves, and the disappearance are also related to the breaking process of large-scale gravity waves. These observations indicate that the convective instabilities arising from the interaction of large- and small-scale waves are probably another main reason for the breaking of large-scale gravity wave, except for the dynamic instability and the shear.