GNSS广播电离层模型在极区的改正效果分析

ANALYSIS OF GLOBAL NAVIGATION SATELLITE SYSTEM BROADCAST IONOSPHERIC MODEL CORRECTION IN POLAR REGIONS

电离层时延为GPS测量中最棘手、最严重的误差源,而极区结构复杂波动较大,电离层延迟极大影响了GPS测量精度,故在极区选取一个简单有效的电离层模型极为重要。将GPS及BDS采用的不同Klobuchar模型以及Ne Quick模型计算的极区总电子含量,以欧洲定轨中心提供的GIM模型电离层产品作为参考标准,研究三种广播电离层模型在北极地区的均方根和模型改正率。选取了2009—2013年共计5年的时间数据进行分析。结果表明,纬度在57.5°以上地区电离层改正GPS系统采用的Klobuchar模型基本不适用,但改正效果依然优于BDS,而Ne Quick模型改正效果弱于中低纬度,改正率整体在40%左右。

Time delay in the ionosphere is a major source of error in the Global Navigation Satellite System （GNSS）. In particular, the ionosphere in polar regions is quite changeable, resulting in low precision of GNSS positioning. Therefore, an appropriate broadcast ionospheric model is needed for the polar regions. In this paper, vertical total electron content data, derived from the GIM model, are regarded as the true value, and the effects of three correction models （the GPS-Klobuchar model, the BDS-Klobuchar model and the NeQuick model） on the ionospheric delay of positioning accuracy were compared and analyzed. In the polar regions north of 57.5°N and south of 57.5°S, the GPS-Klobuchar model performed less well and even had a negative effect in some cases. The BDS-Klobuchar model is totally unusable in the polar regions. The NeQuick model is better than Klobuchar model, but performed worse at high latitudes than at middle and low latitudes, with a correction rate of about 40%.