GNSS无线电掩星数据的电离层校正和统计优化

Ionospheric correction and statistical optimization of GNSS radio occultation data

为了消除电离层折射效应对全球卫星导航系统无线电掩星信号的影响,首先对掩星数据进行电离层订正,然后进行统计优化,最后与欧洲中期数值预报中心的数据比较,验证电离层校正和弯曲角统计优化对弯曲角廓线反演精度提高的效果。结果表明:无论是模拟仿真还是真实的掩星事件,电离层校正后,50km以上弯曲角廓线仍呈现高频振荡的形式;统计优化后,50km以上弯曲角廓线近似呈现与中性大气相同的分布规律,基本消除了电离层小扰动和接收机热噪声对高层弯曲角廓线的影响;弯曲角统计优化能有效提高弯曲角反演折射率廓线时的精度。

To eliminate the impact of ionospheric refraction effects on the global navigation satellite system （GNSS） radio occultation signal, the occultation was processed with the ionosphere correction firstly, and then with the statistical optimization and compared with the data of European Centre for Medium-Range Weather Forecasts （ECMWF） to verify the improvement of accuracy of the bending angle profiles after the ionosphere correction and statistical optimization. The results show that in both the simulation occultation event and the real occultation event, after ionospheric correction, the profiles of bending angle present high frequency oscillation above 50 km. After the statistical optimization, the profiles of bending angle show the similar regularities of distribution to the neutral atmosphere, which suggests that the impact of the dis- turbance of ionosphere and the receiver noise is eliminated. Finally, the results show that statistical opti- mization can effectively improve the accuracy of the profiles of refractivity inversed from the bending angle.