中文摘要：

为消除LEO轨道以上的电离层影响,需采用LEO轨道以下的改正TEC进行电离层掩星反演,这必然引入近似误差。为避免其误差,提出了一种改善方法——基于非改正TEC的电离层反演方法,并将该方法应用于模拟掩星观测数据和实测掩星观测数据的反演。结果表明：1）无论是基于模拟数据还是实测数据,非改正TEC反演精度较改正TEC反演精度均有所提高,尤其对于较低LEO轨道,提高更为明显;2）在模拟和实测数据反演中,有些通过改正TEC方法反演的结果出现严重偏差,而非改正TEC反演的结果正常。

英文摘要：

In order to eliminate the effect from the topside ionosphere above LEO,it is necessary to retrieve electron density profiles based on the calibrated TEC below LEO,which introduces the approximation that the LEO and GPS orbit are close to being coplanar.In this paper,firstly an improved technique is proposed to eliminate this approximate error based on the non-calibrated TEC,and then the technique is applied in the inversion of simulated data and real observation data respectively.The results show that：1） whether the simulated data or real observation data are used,the inversion results derived from the non-calibrated TEC are better than those derived from the calibrated TEC technique,especially it is more obvious for low LEO altitudes;2） based on the above data,some serious errors occur while the electron density profiles are retrieved from the calibrated TEC,on the contrary,the inversion results derived from non-calibrated TEC are reasonable.