基于Swarm卫星GPS/TEC观测的顶部电离层三维电子密度分布的层析法研究

Computerized ionospheric tomography study of three-dimensional electron density distribution in the top ionosphere based on Swarm satellites GPS/TEC observations

利用两颗伴飞的Swarm A/C卫星搭载的双频GPS接收机获取的TEC数据,在两个卫星轨道平面同时对顶部电离层电子密度进行层析成像,实现对顶部电离层电子密度的三维观测.为了能够重现扰动期间电离层电子密度的空间变化特征,在正则化求解过程中,我们引入了水平矩阵H和垂直矩阵V刻画电子密度的空间变化特征,引入整体约束矩阵C以调节不同空间对电子密度相对变化的权重.数值验证结果表明我们的算法对常见的观测误差具有较强的包容性,反演计算出的电子密度平均偏差优于10%.在不同地磁活动条件下,与第三方观测数据的对比,验证了本文反演算法的可靠性.实测数据反演结果表明我们的算法不仅能够较好地重现顶部电离层子午向百公里级别的不规则结构,还能有效分辨纬向相隔~150 km的两个卫星轨道平面的电子密度差异.

Local measurements of three-dimension electron density in topside ionosphere were achieved by means of computer tomography based on TEC observations from the Swarm A/C satellites.The computerized ionospheric tomography were carried out simultaneously in the two spacecraft orbit panels.Tikhonov regularization was employed in the inversion,during which constraints of spatial density relative variations and their weights were applied with help of empirical model.Numerical validations indicate strong tolerance to usually observation errors of our method,with an average density deviation better than 10%.Comparisons with in-situ observations under various geomagnetic conditions were carried out.It was verified that our method is capable of well reproducing the characteristics of field-aligned irregularities with scale of several hundred kilometers in the top ionosphere,as well as the density discrepancy between the two spacecraft orbit panels.