GPS/LEO掩星方法中的电离层延迟量对太阳射电辐射流量的响应

对无线电信号在电离层中的传播路径进行了数值模拟;针对掩星观测中的五组实际卫星轨道数据(包括GPS和LEO卫星),给出了在太阳射电辐射流量(FLUX)分别为0,70,160和240等几种情况下的电离层延迟量对10.7cm波长的太阳辐射流量的响应结果;这分别对应着无太阳辐射、太阳射电辐射处于活动低谷、平静期和高峰期等几种情形。从中可以发现,掩星观测中电离层延迟量对10.7cm波长的太阳射电辐射流量的响应表现为如下特性:电离层延迟同参数FLUX的大小有明显的对应关系,即FLUX越大,则掩星观测中的电离层延迟越大;对于上升掩星情况而言,掩星观测中电离层延迟量起先逐渐增加,然后达到某一峰值,其后逐渐下降;在掩星观测的初期和中期,太阳射电辐射处于活动低谷、平静期和高峰期等几种情形之间的电离层延迟量差异都较为显著,而在掩星观测的后期,几种情形相互间电离层延迟量的差异都比较小。

Impact of Solar Radio Flux on Ionospheric Phase Delay in GPS/LEO Occultation Methodology

The propagation of radio signal in the ionosphere is simulated based on the previous mathematical model. Given five data sets of real satellite state vectors from radio occultation measurements, the phase delays are respectively calculated with four different flux, i.e., flux=0, 70, 160 and 240. It corresponds to four representative conditions,i.e. no solar activity, low solar activity, average solar activity and peak solar activity. The simulation has shown such features as follows:the ionospheric phase delay is obviously correlated with solar radio flux, and the greater solar radio flux, the greater ionospheric phase delay; as for a rising occultation event, at the beginning, the phase delay increases, then it reaches a peak, finally it decreases till the end of occultation event. The phase delay differences among three different solar radio flux conditions tend to enlarge in the first most part of occultation event, however, they tend to narrow in the rest of the occultation event. Considering the strong correlation between the ionospheric phase delay and the solar radio flux, GPS radio occultation methodology is expected to contribute much to the study of solar and terrestrial relationship.