The Effect of Ionospheric Models on Electromagnetic Pulse Locations

Fenimore, Edward E.¹  Triplett, Laurie A.¹ 

[1] Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

关键词: IONOSPHERE;   

DOI  :  10.2172/1136094
RP-ID  :  LA-UR-14-24917
PID  :  OSTI ID: 1136094

学科分类：地球科学(综合)

美国|英语

来源: SciTech Connect

【 摘 要 】

Locations of electromagnetic pulses (EMPs) determined by time-of-arrival (TOA) often have outliers with significantly larger errors than expected. In the past, these errors were thought to arise from high order terms in the Appleton-Hartree equation. We simulated 1000 events randomly spread around the Earth into a constellation of 22 GPS satellites. We used four different ionospheres: ???simple??? where the time delay goes as the inverse of the frequency-squared, ???full Appleton-Hartree???, the ???BobRD integrals??? and a full raytracing code. The simple and full Appleton-Hartree ionospheres do not show outliers whereas the BobRD and raytracing do. This strongly suggests that the cause of the outliers is not additional terms in the Appleton-Hartree equation, but rather is due to the additional path length due to refraction. A method to fix the outliers is suggested based on fitting a time to the delays calculated at the 5 GPS frequencies with BobRD and simple ionospheres. The difference in time is used as a correction to the TOAs.