The Optimum Solar Activity Proxy for Ionospheric Climatology and Long-Term Trend Studies
Abstract
Selection of the optimum solar activity proxy is important for long-term trend and climatological studies of ionospheric parameters as well as for modeling. Here I focus on ionospheric parameter foF2 at middle latitudes. Yearly average values based on monthly medians at 1100-1300 LT (local noon) are analyzed for stations Juliusruh, Pruhonice and Roma (Europe), Boulder (US), Kokubunji (Japan) and Canberra (Australia) over 1976-2014 divided into sub-periods 1976-1995 and 1996-2014. Solar indices F10.7, F30, Mg II, He II, sunspot number R and H Lyman-alpha flux F are used as solar activity proxies. Mg II and F30 are found to be the optimum solar proxies for all six stations, so we can expect that they are the optimum proxies for foF2 in middle latitudes in general. Both optimum proxies describe 99% of total variance of yearly values foF2 even with a simple linear regression equation foF2 = A + B * solar proxy, which means among others that the dependence of foF2 on solar activity is highly linear. The results for the three European stations show that Mg II and F30 are the optimum solar activity proxies also for monthly medians of foF2 as well as for years of deep solar minima 2008/2009 and 2018/2019.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMSA23A..09L