基于Chapman函数的电离层TEC同化模型构建

Construction of Ionospheric TEC Assimilation Model Based on Chapman Function

电离层总电子含量TEC(total electron content)是影响卫星导航定位的主要误差源之一。为了构建精确的电离层TEC模型,基于Chapman函数建立了基于物理机制的电离层TEC同化模型背景场,并着重以IGS发布的2008年4个时段低纬度、中纬度和高纬度地区的电离层TEC数据为样本,同化稀疏点上的已知电离层TEC值,分析模型计算值的残差和相对精度分布,利用模型对电离层TEC进行了2h短期预报和1d预报,并将1d的预报值和IGS发布值进行对比。实验结果表明:(1)由同化模型计算得到的TEC残差值超过92%分布在±2TECU以内,并且除边缘区域外,同化模型TEC计算值的相对精度均在90%以上;(2)2h和1d预报残差小于±3TECU的比例分别为81.8%和81.5%。

The TEC（total electron content）of ionosphere is one of the major error resources for the accuracy of satellite navigation positioning.To construct a precise ionospheric model,a background field for an ionospheric TEC assimilation model,which is on basis of physical mechanism,was constructed based on the Chapman function.Residual and relative accuracy analyses of model were based on the IGS（international GNSS service）TEC data sample（low latitude,mid-latitude and high latitude within four periods of time,2008）,when the ionosphere IGS TEC value for sparse points were known and assimilated.Also,2hshort-term prediction and one day predictions are presented.The one-day prediction results were compared with the IGS TEC.The results showed that：1）92% of TEC calculation residuals in the assimilation model were less than±2TECU,while the relative accuracy of TEC computed by the proposed model was above 90%in addition to the edge of the areas;2）the percentage of 2hshort-term and 1day predicted residuals,less than±3TECU,were 81.8% and81.5%,respectively.