中间层和低热层大气季节内振荡(ISO)及其对对流层ISO/MJO的响应

MLT intra-seasonal oscillation (MLT-ISO), which is essential component of the MLT general circulation, widely exists from the low latitudes to the poles in both the northern and southern hemispheres. Accurate knowledge of MLT-ISO is crucial to understand climate and middle atmospheric dynamics. Therefore, this work will be focused on the temporal and spatial variability of MLT-ISO in neutral wind and temperature, as well as its mechanism, based on ground-based meteor radars measurements and SABER/TIMED satellite observations. The studies proceed as following: (1). Using the wind profiles from four meteor radars near 120°E in China, we are going to analyze the meridional features of MLT-ISO in different seasons. Then the roles of tides, gravity waves (GWs), and planetary waves (PWs) in maintaining the intra-seasonal dynamic will be examined. In addition, the response of MLT-ISO to the tropospheric ISO and Madden-Julian Oscillation (MJO) and Tibet Plateau will be investigated by the combination of the radar and sounding data that from the troposphere to the MLT region. (2). We will utilize the SABER/TIMED temperature observations to study the global (altitude and latitude) structure and seasonal and inter-seasonal variations of MLT-ISO. Moreover, the possible modulation of MLT-ISO by different waves (i.e. tides, GWs, and PWs), which are excited in the lower atmosphere and affect the MLT through non-linear wave-mean interaction, will be discussed. This work is a crossed study of the space physics and the atmospheric science. The result will help to improve model-measurement comparisons, the studies of intra-seasonal dynamic process in MLT region, and both the climate and the middle-and-upper-atmosphere models.

MLT大气季节内振荡(MLT-ISO) 是MLT大气环流的重要组成成分，在低纬到高纬地区均显著存在。本项工作将综合利用我国120°E子午面附近的流星雷达链与气象探空廓线，对我国MLT风场及其波动（潮汐波、重力波、行星波等）中的季节内振荡进行研究，分析其经向分布和季节变化，探讨MLT-ISO对热带MJO、青藏高原大地形的响应特征及响应机制。此外，还将利用SABER/TIMED数据对温度场及其波动的MLT-ISO的全球时空变率进行分析，同时结合对流层ISO/MJO指数，研究MLT-ISO对季节内尺度的气候变化的响应，并以此为切入点探讨对流层-MLT的耦合过程。本项工作属于空间物理学（中高层大气）与大气科学交叉研究，期望在观测数据基础上建立对MLT季节内尺度物理过程及其机制的清晰认识，得到对流层-MLT耦合的关键作用要素，为中高层大气模式的优化以及我国中高层大气模式的建立提供数据基础和理论依据。

大气季节内振荡（ISO）具有30-100天的宽频带振荡周期，是中间层和低热层（MLT）大气环流的重要成分之一。本项工作利用120°E子午线附近四台流星雷达纬向风数据，统计分析了中低纬MLT-ISO的变化特征及其与讨论了热带MJO和高纬平流层对MLT-ISO的可能调制。结果表明：（1）.MLT-ISO信号在低纬到中纬均存在，主要发生在冬季，具有显著的年际变化；不同高度和纬度MLT-ISO的主要周期和年际变化不同。（3）2012/2013年冬季（2012年10月至2013年4月），三亚、武汉和漠河上空强的MLT-ISO信号出现在热带海洋大陆MJO活跃期间，主要周期均在45天左右；当高纬平流层环流出现了短周期变化后，MLT-ISO主要周期也随之改变，不同高度的变化趋势不同；100 km处MLT-ISO的变化特征与其他高度不同，似乎与平流层准定常行星波的变化有较强的相关。我们推测，中低纬MLT-ISO可能受到热带MJO和高纬平流层大气的同时调制。本研究属于空间物理学和大气科学两个学科的交叉性研究课题，在观测数据基础上对MLT区域大气季节内尺度物理过程进行了统计分析，有助于更深入地理解高低层大气的耦合过程中的关键要素，为中高层大气模式的优化提供一定的理论支持。