中低纬电离层不同季节地磁暴响应的事例分析

利用中国中低纬台站漠河（53.5°N，122.3°E）、北京（40.3°N，116.2°E）、武汉（30.5°N，114.2°E）和三亚（18.3°N，109.6°E）的电离层观测数据，对比分析了4个台站电离层参数在2015年不同季节4个地磁扰动事件期间的变化特征.结果表明，4个磁暴事件期间电离层的响应特征并不完全一致，有着明显的季节特征，春季、夏季和秋季电离层以负相扰动为主，冬季以正相扰动为主.分析发现，中性成分O/N₂的降低与电离层负相扰动有关，但三亚地区的负相扰动还与扰动发电机电场相关.正相扰动的机制在不同事件中并不相同，穿透电场可能是引起春季磁暴事件期间电离层短时正暴效应的原因，而冬季长时间的正暴效应则是扰动电场和中性风共同作用的结果. 

Ionosphere Responses to Geomagnetic Storms at Middle to Low Latitude Region in Different Seasons

Knowledge of ionospheric responses to geomagnetic storms is important for knowing about the physical process of ionosphere, and useful for ionospheric application research as well. This paper analyzed and compared the ionospheric responses to four geomagnetic storms in four seasons in 2015, based on the ionospheric observations from Mohe (53.5°N, 122.3°E), Beijing (40.3°N, 116.2°E), Wuhan (30.5°N, 114.2°E), Sanya (18.3°N, 109.6°E) in China. The responses of ionosphere to four geomagnetic storms are different and have significant seasonal dependence. There are prominent negative responses during storms in spring, summer or autumn, and significant positive responses in winter. It is shown that neutral composition (O/N₂) is related to the negative phase storm, while westward Disturbance Dynamo Electric Field (DDEF) is responsible for the negative storm in Sanya. The reason of ionospheric positive response is different in different events. The Penetration of Electric Field (PEF) may cause a short-time positive response during the geomagnetic storm in spring, whereas neutral wind and PEFs are jointly responsible for the long-duration positive response during the storm in winter.