基于全球卫星导航系统观测网的全球总电子含量快速反演方法

将全球按照地理经纬度进行网格划分,每网格选取一个接收机,基于全球卫星导航系统(GNSS)观测网的全球定位系统(GPS)双频观测数据,在电离层薄层假设条件下,提出了一种基于球谐函数拟合的高时间分辨率总电子含量(TEC)快速反演方法.利用2006年四季中16个地磁平静日的GPS双频观测数据,针对15种不同的网格选站情况考察其TEC的反演效果与解算时间.结果表明,当网格选站间隔小于15°×30°(纬度×经度)时,数据拟合度约为2TECU,并都能较好地反演TEC.综合考虑穿刺点分布与解算时间,在10°×20°(纬度×经度)选站条件下,约在3min内即可反演出有效的TEC、卫星硬件偏差和接收机硬件偏差,从而提高了反演速度,10°×20°(纬度×经度)选站的快速反演TEC能够为全球电离层TEC现报提供一种有效方法.

A Fast Totel Electron Content Derivation Based on GNSS Observation

This paper proposes to divide the globe into meshes and select one GNSS receiver from each mesh. With the observation of these receivers, it develops a TEC derivation algorithm based on the spherical harmonic function. For different mesh sizes from 2.5°×2.5° (latitude×longitude) to 30°×30° (latitude×longitude), the performance is examined by applying it to the data selected from 16 geomagnetically quiet days in four seasons in 2006. The result shows that the data can be generally well fitted, with the goodness of fit being about 2 TECU. By comparing the derived TEC and instrumental biases with those of CODE (Center for Orbit Determination in Europe), it can be found that the algorithm can give reasonable TEC and biases for those meshes smaller than 15°×30°(latitude×longitude). Considering the Ionospheric puncture point distribution and calculating time, it can be concluded that the mesh of 10°×20° (latitude×longitude) is appropriate to derive TEC and instrumental biases rapidly. This paper provides a fast and effective method for nowcasting the global ionospheric TEC.