Using the location of equatorial ionization anomaly (EIA) crest derived from GPS observations in China and Brazilian sector, we investigated the longitudinal dependence of periodic meridional movement of EIA crest during sudden stratospheric warming events in 2003, 2006, and 2009. The solar activity was from high to low for the three events. Results show that the locations of EIA crests in both China and Brazilian sectors exhibit obvious and constant 14‐ to 15‐day periodic oscillation being in‐phase in two sectors, which coincide with the half of the lunar revolution period (29.53 days) and the lunar phase. The temporal extent of wave power at 14–15 days is consistent with the temporal extent of stratospheric zonal wind, indicating that 14‐ to 15‐day periodic meridional movement of EIA crest is due to enhanced lunar tide modulated by zonal wind. In addition, it is also found that the amplitude of 14‐ to 15‐day periodic oscillation of EIA crest in China sector is larger than that in Brazilian sector, which may be caused by the longitudinal variation of tides and neutral wind pattern.
Using the location of equatorial ionization anomaly (EIA) crest derived from GPS observations and CHAllenging Minisatellite Payload (CHAMP) satellite measurement, along with the F2 layer peak height (hmF2), critical frequency (foF2), and the equatorial electrojet (EEJ) in India and China longitudinal sectors, we found the obvious 6-day oscillation in these ionospheric parameters during 16 April to 31 May 2003 and 21 September to 26 October 2004. The tidal amplitudes of EEJ are enhanced during the positive phase of the 6-day waves and are weakened during its negative phase. Since the strong 6-day planetary wave activities in mesosphere and lower thermosphere (MLT) region during these two events have been reported by earlier studies, this 6-day oscillation in EIA region can be due to the interaction of enhanced planetary waves with the tidal wind. Moreover, the temporal variations of this 6-day wave are consistent and in phase in these ionospheric parameters, indicating that the 6-day planetary wave modulates electric fields via E region wind dynamo, thereby altering the vertical height and horizontal distribution of electron densities through upward E × B drift, which results in the periodical variations in these ionospheric parameters in F region. These observation results provide insight into how the 6-day planetary waves modulate the ionospheric morphological structure.
According to the characteristics of highway network for sustainable development and make clear the purpose and content of evaluation. On the basis of that this paper from network capacity, network traffic environmental carrying capacity, social benefit continuity and management system and policy this four aspects to set up the evaluation index system for the degree of highway network sustainable development, and illustrate the quantitative method of the attribute value of quantitative and qualitative indicators. This paper put forward the comprehensive evaluation method which is based on the Fuzzy AHP. Finally take the trunk road network of Zhang Jiakou city for instance to study.
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