NeQuick Model Algorithm Research and Performance Assessment

NeQuick is an empirical model which has been selected as the GALILEO single frequency receivers' ionospheric delay correction model. The current baseline versionis the NeQuick1(ITU-R) since 2001. Based on that, the NeQuick2 version improvement and implementation method has been studied, and also the performance compare has been done in China.Firstly, the TEC accuracy has been retrieved in one solar year cycle and compared in Chinese mid-high latitude area in high/low solar activityusing NeQuick1/NeQuik2 versions. Compared with GIM, it indicates the NeQuick2 average TEC bias and RMS has been improved significantly especially in high solar activity level. In China mid-high latitude area, yearly TEC bias has been reduced 76%, 38% and yearly TEC RMS has been reduced 72%, 13% in low(2008) and high(2014) solar activity year respectively.The TEC accuracy in mid-high latitude area is 11% to 13% superior than low-latitude area. Secondly, the F₂ top layer electron density profile of height has been reconstructed using the two versions, compared with ISIS2 profile data, the result showed the top layer electron density accuracy improved about 40%. Finally, the electron density at height of 100 km, 150 km, 200 km of mid-high latitude area in China has been represented, it showes that the strong gradients and strange structures appeared in E and F₁ layer has disappeared in NeQuick2 version.