磁暴期间中国中低纬电离层不规则体与扰动分析

2017年9月8日发生了一次强磁暴，Kp指数最大值达到8.利用区域电离层格网模型（Regional Ionosphere Map，RIM）和区域ROTI（Rate of TEC Index）地图，分析了磁暴期间中国及其周边地区电离层TEC扰动特征和低纬地区电离层不规则体的产生与发展情况，同时利用不同纬度IGS（International GNSS Service）测站BJFS（39.6°N，115.9°E），JFNG（30.5°N，114.5°E）和HKWS（22.4°N，114.3°E）的GPS双频观测值，获取各测站的ROTI和DROT（Standard Deviation of Differential ROT）指数变化趋势.结果表明:此次磁暴发生期间电离层扰动先以正相扰动为主，主要发生在中低纬区域，dTEC（differential TEC）最大值达到14.9TECU，随后电离层正相扰动逐渐衰减，在低纬区域发生电离层负相扰动，dTEC最小值达到-7.2TECU；在12:30UT-13:30UT时段，中国南部低纬地区发生明显的电离层不规则体事件；相比BJFS和JFNG两个测站，位于低纬的HKWS测站的ROTI和DROT指数变化更为剧烈，这表明电离层不规则体结构存在纬度差异. 

Analysis of Ionospheric Irregularities and Disturbances at Middle and Low Latitudes in China during the Magnetic Storm

A strong magnetic storm occurred on 8 September 2017 with the Kp index reaching its maximum of 8. The Regional Ionosphere Maps (RIM) were utilized to analyze the ionospheric TEC (Total Electron Content) disturbances over China and its adjacent areas, and the ROTI (Rate of TEC Index) maps were utilized to analyze the ionospheric irregularities in the low-latitude areas of China during the magnetic storm. Furthermore, the dual-frequency GPS observations of three IGS stations at BJFS (39.6°N, 115.9°E), JFNG (30.5°N, 114.5°E) and HKWS (22.4°N, 114.3°E) were used to obtain the trends of ROTI and DROT (standard deviation of differential ROT) indexes for each station. The results showed that during this magnetic storm, the ionospheric positive phase disturbances dominated in the beginning and mainly occurred at middle-and-low latitudes of China, and the dTEC (differential TEC) reached its maximum of 14.9TECU at about 04:00UT. Then the ionospheric positive phase disturbances gradually declined, the ionospheric negative phase disturbances began to occur at low latitudes of China with the dTEC reaching its minimum of -7.2TECU at about 12:00UT. There were obvious ionospheric irregularities observed at lower latitudes in southern China during 12:30UT-13:30UT. Compared with the BJFS and JFNG stations, the ROTI and DROT indexes of HKWS station at low latitude exhibited instability, indicating the latitudinal differences of ionospheric irregularities.