重力波在从低层大气向中高层大气垂直传播过程中，通过耗散和破碎将其携带的动量和能量传输到背景大气中，从而在驱动中高层大气环流的过程中起到了重要作用。已有研究表明低纬度低层大气剧烈变化（如ENSO）会显著影响极区大气及重力波活动，因此对极区重力波的研究有助于理解低层大气和高层大气耦合的机制。然而极区中高层大气及重力波（特别是小尺度重力波）的观测数据很少。本项目拟利用北极OH全天空气辉成像仪、法布里-珀罗干涉仪（FPI）、卫星微波探测仪（MLS）等长期观测数据并结合ECMWF再分析数据和WACCM模式，对北极冬季中间层顶小尺度重力波的特性及变化进行研究；利用射线追踪模型对小尺度重力波进行溯源分析，研究其形成及传播机制；结合低纬度低层大气剧烈变化期间极区中高层大气背景和重力波的变化，探究极区高层大气对低层大气变化的响应机制。本项研究对理解极区中高层大气和低纬度低层大气的耦合机理具有重要的科学意义。

Gravity waves play an important role in driving the global atmospheric circulation in the middle/upper atmosphere through their momentum and energy deposition into the mean flow. Previous studies have suggested that abrupt change (eg. El Niño–Southern Oscillation, ENSO) in the lower atmosphere of the low latitudes has significant impact on the middle/upper atmosphere, so studies on gravity waves in polar regions can improve our understandings of the coupling mechanisms between lower atmosphere and middle/upper atmosphere. However, there are few observational data available in the polar middle/upper atmosphere, especially for small-scale gravity waves. In this project, using the long-term dataset observed by the OH all-sky imager, Fabry-Perot Interferometer (FPI) and Microwave Limb Sounder (MLS) onboard the Aura satellite, as well as the ECMWF reanalysis data in the Arctic and WACCM, we will study the characteristics and variations of gravity waves in the Arctic winter mesopause. In addition, we will also study the generation and propagation mechanisms of small-scale gravity waves, which will be traced back to their sources using the ray-tracing model. Finally, with considerations of the changes of background flow and gravity waves in the polar middle/upper atmosphere during anomalous disturbances in the lower atmosphere, we will study the response of the middle/upper atmosphere to the lower atmosphere in the polar region. The expected findings of this project will greatly enhance our understandings of the coupling mechanisms between the middle/upper atmosphere in the polar region and the lower atmosphere at low latitudes.