Abstract
The trends in the F2-layer critical frequency foF2 are analyzed based on the observations at Juliusruh station to 2022. Five solar activity indexes (proxies): Ly-a, MgII, Rz, F10.7mon, and F30 are used to remove the SA effects. It is found that the conclusions obtained earlier on the diurnal (in the daytime stronger than at night) and seasonal (in winter stronger than in summer) variations in the amplitude of negative trends in foF2, k(foF2) are confirmed using all five proxies. The maximal negative values of k(foF2) are 0.03–0.04 MHz per year. Use of the “Delta” method confirms these conclusions. Indications are found that the negative trends in foF2 are stronger during the recent decade than during the entire considered period 1996–2022.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
