基于ROTI和AATR的测地型GNSS接收机监测北半球高纬度区域电离层闪烁准确性分析

Accuracy assessment of ionospheric scintillation monitoring in high-latitude regions of the northern hemisphere utilizing geodetic GNSS receivers based on ROTI and AATR

当前,第25个太阳周期已进入强活跃时期,能引发大量电离层不规则体,进而对使得穿行其中的GNSS信号产生电离层闪烁。这已成为影响GNSS全球稳定导航定位服务的重要干扰源。对全球电离层闪烁进行广泛且全面的监测是消除闪烁对GNSS干扰的重要前提,然而传统电离层闪烁监测接收机(ISMR)分布有限,无法满足闪烁全球监测需求;测地型接收机分布广泛,但从其低采样数据中提取的闪烁因子缺乏新太阳周期长时序监测数据验证,导致其闪烁监测可靠性存疑。为此,本文基于近3 a新太阳周期测地型接收机数据,以ISMR提供的闪烁因子为参考,从代表性空间天气事件闪烁响应、日闪烁发生率、闪烁持续时间概率分布、闪烁日发生规律及其随极昼、极夜、地磁指数的特征变化等方面,对比研究了两种测地型接收机电离层闪烁因子(即电离层总电子含量变化率指数ROTI和沿弧段电子含量变化率指数AATR)监测北极高纬度区域电离层闪烁的准确性,并给出了ROTI和AATR在高纬度区域判断闪烁发生的经验阈值。结果表明,ROTI和AATR均能较为准确探测到地磁扰动、太阳活动等因素驱动的区域电离层闪烁,并能有效表征电离层闪烁统计学上的日变化规律,但两种闪烁因子不能准确区分闪烁和电离层电子密度梯度变化,导致在电子密度梯度变化剧烈期间存在较高虚警。该研究成果可为准确选择区域电离层闪烁监测因子提供指导。

Currently,the 25th solar cycle has entered a period of high activity that can trigger numerous ionospheric irregularities,which in turn lead to ionospheric scintillation on the signals of GNSS.This has become a significant source of interference affecting the stable positioning navigation and timing services of GNSS.It is crucial to conduct extensive and comprehensive monitoring of global ionospheric scintillation to mitigate its adverse effect on GNSS.However,the limited distribution of traditional ionospheric scintillation monitoring receivers(ISMR)cannot meet the requirement of global scintillation monitoring.Geodetic receivers are widely deployed,but the reliability of their scintillation monitoring is questionable due to the lack of validation with long-term and low-sampling data from the new solar cycle.To address this issue,this study compares the accuracy of two ionospheric scintillation indices,i.e.Rate of total electron content change index(ROTI)and along arc total electron content rate index(AATR)in monitoring ionospheric scintillation in the high-latitude Arctic region,based on geodetic receiver data from the past three years and the scintillation factors provided by ISMR as a reference.The study assesses their performance in terms of the following aspects,e.g.the scintillation response to representative space weather events,daily scintillation occurrence rates,probability distribution of scintillation duration,daily occurrence patterns of scintillation,and characteristic variations with polar day,polar night,and geomagnetic indices.Additionally,empirical thresholds for ROTI and AATR are provided to determine the occurrence of scintillation in high-latitude regions.The results indicate that both ROTI and AATR can accurately detect regional ionospheric scintillation driven by geomagnetic disturbances and solar activity.They effectively characterize the daily variations in ionospheric scintillation statistically.However,these two scintillation indices cannot accurately differentiate between scintillation and changes in ionospheric electron density gradients,leading to higher false alarms during periods of drastic changes in electron density gradients.The findings of this study provide guidance for accurately selecting ionospheric scintillation monitoring factors in specific regions.