利用多GNSS掩星任务资料研究全球平流层重力波活动及其气候特征

重力波活动影响中层大气环流的基本性质，利用各类观测资料获取大气重力波信息并认识其时空变化特征有助于在全球大气模式中构建准确的重力波参数化方案，对全球气候变化研究具有重要意义。GNSS掩星资料具有高精度、高垂直分辨率、全球分布、长期稳定的特点，对于全球平流层重力波活动研究有其独特优势。本项目旨在利用多项GNSS掩星任务的数据，结合模式再分析温度、风场、地表辐射资料与地形、降雨等数据，研究全球平流层重力波活动情况，分析其气候特征。主要内容包括：研究基于掩星的重力波温度扰动提取和水平波长计算的优化方法；以重力波势能、垂直波长、水平波长和动量通量等参数为表征，研究平流层重力波时空分布；对热点区域的波源进行分析，对重力波产生和传播的物理机制进行探讨；在对重力波参数的年际、季节、季节内等不同时间尺度的变化规律进行深入讨论的基础上，研究重力波活动与QBO、ENSO及MJO的响应关系，并对其进行物理解释。

The gravity wave activities have great impacts on the properties of the middle atmospheric circulation. To acquire the information about gravity waves and to analyze the characteristics of their temporal and spatial variations from different types of observations has great significances for the establishment of precise gravity wave parameterization schemes and for the global climate related research. GNSS radio occultation observations which are of high precision, high vertical resolution, global coverage and long stability are of special advantages for the study of global gravity wave activities. Data from multiple Global Navigation Satellite System (GNSS) Radio Occultation (RO) missions, together with temperature, wind field and surface sensible heat flux from model reanalysis, topographic data and precipitation data, will be used in this project to study the global stratospheric gravity wave activities and to analyze their climatological characteristics. Firstly, the methods to extract the gravity wave-induced temperature perturbations and to calculate the horizontal wavelength from RO temperature profiles will be refined, based on which the temporal and spatial distributions of stratospheric gravity wave parameters, including potential energy, vertical wavelength, horizontal wavelength and momentum flux (MF) absolute value, will be studied. The sources of the gravity waves will be analyzed for hot spots and the principals for the occurrence and propagation of gravity waves will be discussed. Based on the analysis about the inter-annual, inter-seasonal, intra-seasonal variations of gravity wave parameters, the responses of stratospheric gravity wave activities to three large scale atmospheric patterns, QBO, ENSO and MJO, will be studied and the interpretations will be given.