The method of determination of the long-term trends in the F2 region independent of geomagnetic activity

A. D. Danilov (1)

1 Institute of Applied Geophysics

A detailed analysis of the f oF2 data at the Sverdlovsk station is performed to answer the question: whether the long-term trends of the F2-layer parameter detected recently are mainly due to the long-term changes in geomagnetic activity during the recent decades. Two methods to derive trends independent of geomagnetic activity are developed. It is found that both methods agree well and give a relative nongeomagnetic trend of about - 0.0015 per year (or an absolute nongeomagnetic trend of about - 0.015 MHz per year). The close relation of foF2 to Ap found by several authors is mainly due to a high correlation between the foF2 deviations from the regression line and year-to-year changes in the Ap index rather than to systematic long-term changes of Ap as has been suggested earlier.

Domaines: Océan, Atmosphère; Sciences de la Terre

A. D. Danilov. The method of determination of the long-term trends in the F2 region independent of geomagnetic activity. Annales Geophysicae, 2002, 20 (4), pp.511-521. ⟨hal-00316973⟩