Abstract—By comparing the moving 12-month averaged values of the F107 solar radiation flux at a wavelength of 10.7 cm and ionospheric solar activity index T, we established the effective solar activity index T_F, which is defined as a second-degree polynomial from F107 with coefficients independent of time; it is intended for use in problems of forecasting the median of the critical frequency of the F2 layer, foF2, using well-known ionospheric models instead of T and F107 indices or international sunspot numbers Ri. T_F is applicable for any solar activity level and the entire F107 measurement period. By definition, T_F is independent of geomagnetic activity. The T index may depend on geomagnetic activity due to the dependence of the median of foF2 on this activity. It was found that the moving 12-month averaged index of geomagnetic activity Ap₁₂ and the difference ΔT = T – T_F decreased over time in 1954–2019, but for ΔT, this trend was likely qualitative. As a result, a linear dependence of ΔT on Ap₁₂ is virtually absent for this interval: their correlation coefficient was less than 0.1.

摘要—通过比较波长为10.7 cm的F 107太阳辐射通量的移动的12个月平均值和电离层太阳活动指数T，我们建立了有效太阳活动指数T _F，其被定义为二次多项式从F 107开始，系数与时间无关；它旨在用于使用众所周知的电离层模型而不是T和F 107指数或国际黑子数Ri来预测F 2层的临界频率foF 2的中值的问题。Ť _˚F适用于任何太阳活动水平和整个F 107测量期间。根据定义，牛逼_˚F是独立的地磁活动。由于foF 2的中位数对此活动的依赖性，因此T指数可能取决于地磁活动。研究发现，在1954年至2019年期间，地磁活动Ap ₁₂的移动12个月平均指数和差ΔT = T – T _F随着时间的推移而减小，但是对于ΔT来说，这种趋势可能是定性的。结果，ΔT对Ap ₁₂的线性依赖性 该间隔实际上不存在：它们的相关系数小于0.1。