利用多GNSS掩星任务资料研究全球电离层偶发E层形态及其对低层大气气候现象的响应

偶发E层（Es层）是一种广受关注的非稳定电离层现象，利用各类观测资料获取Es信息并认识其时空形态特征有助于电离层建模中Es参数的精化，对保障通讯导航服务质量、提高空间天气和气候预报精度有重要意义。GNSS掩星资料具有全球分布、高精度、高垂直分辨率、长期稳定的特点，对Es研究有独特优势。本项目旨在利用多掩星任务的多类型产品，结合模式、全球垂测仪、太阳活动、地磁活动等数据，研究全球Es形态及其对低层大气气候现象的响应。主要内容为：研究利用多类型掩星产品确定Es参数的优化方法，并对单层与多层Es的区分准则进行精化；联合利用以COSMIC和FY-3C为代表的多掩星任务数据，以Es发生率、高度、厚度和强度为表征，研究全球Es时空分布及其与MLT风场、地磁场、太阳活动和地磁活动关系的形态特征；在对不同时间尺度Es形态变化规律进行讨论的基础上，分析其对ENSO和QBO的响应，并进行相应物理解释。

Sporadic E (Es) layer is an unstable phenomenon occurring in the ionosphere, which has been paid much attention. To extract Es information and to understand its time and space morphology based on different types of observations would benefit the refinement of the Es parameters in the modelling of the ionosphere, which is also of great importance for the ensurance of the quality of radio communication and navigation and for the improvement of the precision of space weather and climate forcast. Global Navigation Satellite System (GNSS) radio occultation (RO) observations, which are of high precision, high vertical resolution, global coverage and long stability, are of special advantages for the study of Es morphology over the globe. Different types of data products derived from multiple GNSS RO missions, together with model data, global ionosonde observations, solar activity and geomagnetic data, will be used in this project to study the global Es morphology and its response to the climatological phenomena of lower troposphere. Firstly, the methods to derive the Es parameters from multiple types of RO products will be refined, taking into consideration the difference between single-layer-type and multiple-layer-type Es. Then the temporal and spatial distributions of Es parameters, including the occurrence rate, the height, the thickness, and the intensity of Es, will be studied using data from multiple GNSS RO missions of multi organizations, including Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), Fengyun-3C (FY-3C) and so on. The relationship between the temporal and spatial distributions of Es and the wind field of mesosphere/lower thermosphere (MLT), the solar activity and the geomagnetic activity will be studied. Based on the analysis about the variations of Es morphology of different time scales, the responses of Es activities to two large scale atmospheric patterns, Quasi-Biennial Oscillation (QBO) and ElNiño –Southern Oscillation (ENSO), will be studied and the interpretations will be given.