报告题目：The Ionospheric Plasma Irregularities and their Influence on the GNSS Receiver on board Low Earth Orbit satellites

报 告 人：熊超 博士 德国地学研究中心（GFZ）

报告时间：2018年4月23日上午9:00

报告地点：学院218会议室

报告主题简介

The ionosphere is the ionized part of Earth’s upper atmosphere, and is often characterized by irregularities and fluctuations in plasma density. The ionospheric irregularities can influence the propagation of trans-ionospheric radio waves and are thus of importance for any operations that rely on precise positioning with Global Navigation Satellite Systems (GNSS). Therefore, understanding the ionospheric plasma irregularities is of both scientific and practical interest.Due to the limited spatial extension of plasma irregularities, for the ground-based GNSS receiver,usually only the GNSS signals propagate through the irregularities will be affected. However, the situation for the receiver onboard Low Earth Orbit (LEO) satellites is much server. When a LEO satellite flies just inside an areaofplasma irregularities, the GNSS signals from all directionsare expected to be affected. In this report we present some characteristics of the ionospheric irregularities, such as their dependence on solar flux, season and local time, as well as their global distributions. Examples of signal outage from the Global Positioning System (GPS) onboard LEO satellites, e.g., Swarm, GRACE, CHAMP and GOCE, are provided. And the statistics show that when Swarm satellite encounters plasma irregularities with strong depletions, it experiences GPS signaloutageas high as 95% for at least one channel. Our results also indicate that the absolute depletion magnitude of plasma irregularities play a critical role in causing GPS outages for LEO satellites.

报告人简介

熊超，2007毕业于武汉大学电子信息学院，获工学学士学位；随后在武汉大学空间物理专业攻读博士学位。读博期间获德国DAAD奖学金和中国国家留学基金委资助，前往德国地学研究中心（GFZ）进行为期两年的访问学习，并与2012年6月在武汉大学获理学博士学位。博士毕业之后，获德国洪堡基金资助，继续在地学研究中心进行为期两年的博士后研究，之后一直在地学研究中心从事电离层研究工作。研究内容主要涉及电离层物理，电离层-热层耦合，电离层/热层建模，以及电离层不规则结构对导航信号的影响等。在博士后工作期间，参与并主持多项德国科学基金委（DFG）以及欧空局（ESA）项目，取得创新成果。近年来在Geophysical Research Letter, Journal of Geophysical Research, Space weather, AnnalesGeophysicae等国际权威期刊上发表SCI论文36篇（第一作者21篇）。其中两篇论文被美国地球物理协会(AGU)评为研究亮点(Research Spotlights)，并在其EOS杂志上做出了详细报道；EAS官网也以头条对其中一篇研究成果进行了新闻报道。