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利用国际IGS网和美国CORS网提供的GPS TEC观测资料,构建了北美地区的二维TEC扰动图像,分析研究了2012年7月14日一次强磁暴期间大尺度电离层行进式扰动在北美地区的二维结构以及扰动沿着70°W左右的子午线在南北半球的分布与传播特性.研究结果表明,磁暴急始开始90分钟后,伴随着一次亚暴的膨胀相,在北半球发生了一次大尺度电离层行进式扰动事件.该扰动在北美地区形成幅度1.2~2.2 TECU,宽度达4000 km的等相面,以190°的传播方位角,西南向传播了2000 km,扰动的周期和水平相速度分别为40~60 min,500 m/s.通过台链观测发现,该扰动向西南方向一直传播到约30°N,在传播过程中,扰动的绝对振幅在55°N至42°N之间逐渐增强并达到最大值2.2 TECU,在42°N以南逐渐衰减.通过对相关时间段内北美亚极光带地磁观测数据的分析发现,在65°N至85°N、100°W至150°W之间,地磁场水平分量在LSTID发生前出现明显变化,显示极光电集流增强,这一区域是北美地区观测到的LSTID事件最可能的源区.北半球的电离层扰动消失之后约1小时,通过南半球GPS台链观测到南向电离层扰动,该扰动的绝对振幅为1.8 TECU,相速度为400 m/s左右,传播范围局限在16°S至20°S.在南北半球的低纬赤道区,台链观测没有发现与北美LSTID关联的电离层扰动.根据台链上扰动传播的中断,我们认为,南半球台链观测到的电离层扰动并不是北半球LSTID直接跨赤道传播到南半球的结果,而是北半球电离层扰动在赤道地区的耗散过程中形成的二次扰动引起的.
Based on the GPS TEC observations provided by the international IGS network and CORS network in the United States, two-dimensional TEC perturbation images in North America are constructed and analyzed. The large-scale ionospheric marching perturbations during a strong magnetic storm on July 14, 2012 in North America Dimensional structure and the distribution and propagation characteristics of the meridional perturbation in the northern and southern hemispheres around 70 ° W. The results show that a large scale occurs in the northern hemisphere Ionospheric marching event.The perturbation formed isosceles of 1.2 ~ 2.2 TECU in width and 4000 km width in North America, propagating 2000 km in the southwest at 190 ° azimuth, the period of disturbance and the horizontal phase velocity 40 ~ 60 min and 500 m / s, respectively.According to the observation of the station chain, the disturbance propagates to about 30 ° N in the southwest direction and the absolute amplitude of the disturbance during the propagation is between 55 ° N and 42 ° N Gradually increased and reached the maximum value of 2.2 TECU, which gradually attenuated to the south of 42 ° N. By analyzing the geomagnetic data from the North American sub-aura in the relevant time period, it was found that at 65 ° N to 85 ° N, 100 ° W to 150 ° W, the horizontal component of geomagnetic field in the LSTID hair A significant change before that shows an increase in polar opto-electric current, which is the most likely source region for the LSTID events observed in North America.About 1 hour after the ionospheric disturbances disappeared in the Northern Hemisphere, Southern Ionization The perturbation has an absolute amplitude of 1.8 TECU and a phase velocity of about 400 m / s, and its propagation range is limited to 16 ° S to 20 ° S. In the low latitude equatorial regions of the northern and southern hemispheres, no correlation was observed with the North American LSTID Related ionospheric disturbances.According to the interruption of the disturbance propagation on the chain, we believe that the observed ionospheric disturbances in the southern hemisphere chain are not the result of the Northern Hemisphere LSTID transmitting directly to the southern hemisphere across the equator, but rather the result of the northern hemisphere ionospheric disturbance in the equatorial region Dissipation caused by the formation of secondary disturbances.