Improved critical frequency prediction for F-region

Abstract

A new method for improved prediction of critical frequency of the F-region (<i>f</i>₀F2) using the critical frequency immediately preceding a particular season, time, and location is described. The deviation of quadratic least squares fit <i>f</i>₀F2 approximation from the corresponding observed <i>f</i>₀F2 value is found to strongly affect the subsequent monthly median values. A correlation is seen to exist between the monthly changes in quadratic fit values and corresponding observed values, which holds good also for linear dependence of <i>f</i>₀F2 on running average sunspot number (RASSN). Assuming quadratic dependence of <i>f</i>₀F2 on RASSN as first approximation, the maximum and minimum improvements in predicted values are found to be 72% and 48.5%; and these are 82% and 55% for linear approximation.