Estimation of the Ionosphere Critical Frequency Without Radio Sounding

The frequency parameters of the ionospheric Alfvén resonator (IAR) emission show a close connection with the critical frequency foF2 of the ionospheric F2 layer. However, the quantitative characteristics of the connection are unstable and can vary significantly from day to day. To overcome this instability, we propose to use a multiple regression analysis with additional factors that reflect the state of the ionosphere as predictors. On the basis of the training sample, we compute a set of regression equations using various combinations of regressors, of which we choose the most effective from the point of view of minimizing the estimate standard error. The efficiency of the obtained equations for the critical frequency estimation is checked using the control data sample. The results suggest that the proposed method makes it possible to estimate the value of the critical frequency with an accuracy of about 0.5 MHz. A proposal is made to use the information on the IAR frequency structure in the development of assimilation ionospheric models.