电离层对GPS测距的影响

利用单层电离层改正模型就GPS卫星高度角对测距的影响作了探讨。研究表明，通常采用的单层电离层改正模型中电离层高取均值对低高度角卫星测距的改正是不适应的，利用单层电离层模型改正时应顾及电离层高的变化。最后利用1986年武汉地区实测TEC数据进行了计算并将结果和IRI－90模型计算结果作了分析比较。

Ionospheric Effects on GPS Ranging

The single ionospheric layer correction model is used to delete the effects(L) on GPSranging, and the average ionospheric height is generally used in the calculation. In fact,the variations of ionospheric height (H) is re1ated to the hour angle (T) of the sun, theseasons as well as the solar activities, and it must be taken in to account in the calculationof the effects especia1ly for the satellites which are at low altitudes(E). The different effects caused by the different ionospheric heights are discussed in this paper and the resultsare shown in Fig. 2 and Fig. 3 respectively. In addition, the effects obtained with theTEC data of 1986 measured in Wuhan are compared with those calculated according to theIRI-90 model. The results (Fig. 4) show the correspondence between them. And it isconcluded that the theory of IRI- 90 can be used as a primary correction for the ionospheric effects at the places of intermediate latitude, such as Wuhan, for the years when theionospheric activities are at a low level.