Characteristics of Ionospheric Multiparameter Changes in Qujing Area

The Qujing ionospheric vertical sounders 11 years data in network of radio environment observatories are processed. The correlations between ionosphere parameters and solar activity month local time are analyzed including f_min, f₀E_s, h'E_s, f₀E, f₀F₁, f₀F₂, h'F, MUF(3000)F₂. Several interesting results are achieved. Firstly, the relationships between f_min, f₀E_s, h'E_s and solar activity are not obvious, but f₀E, f₀F₁, f₀F₂, h'F, MUF(3000)F₂ have good correlation with solar activity. Secondly, the value of f₀F₂ parameter often enlarged on sunset, and both are independent. The f₀F₂, h'F, MUF(3000)F₂ parameters variation trend of Lhasa and Urumqi are compared, it is found that the variation trend of local time and month are similar, but extreme values appeared in different positions. This phenomenon may have a relationship with topography and latitude and longitude. Thirdly, the daytime value of h'F is smaller than night, and rise abruptly at sunrise and sunset, and the winter h'F value is smaller than other seasons. Fourthly, the change trend of MUF(3000)F₂ is similar with f₀F₂, the daytime value is higher than night, the equinox value is higher than summer and winter, and the MUF(3000)F₂ value in high solar activity year is high till 03:00－04:00 LT on the morning.