Earth magnetic field variation effects on long-term trends in the F2 layer

ANA G. ELIAS; NIEVES ORTIZ DE ADLER

Sodankyla

Workshop; 4th Workshop on Long-Term Changes and Trends in the Atmosphere; 2006

IAGA - ICMA - CAWSES, Sodankyla Geophysical Observatory

The intrinsic Earth magnetic field presents long-term variations, which could affect the ionosphere maximum electron concentration. Using experimental data, long-term trends in foF2 (a measure of the maximum electron concentration) of several worldwide ionospheric stations are estimated in the present work. Data was arranged according to the different months and hours, which amount to 288 trend values for each station. A daily and seasonal pattern is observed. This pattern and the trend magnitude are not compatible with the greenhouse effect over the ionosphere. Through theoretical approximations and empirical models, foF2 trends due to long-term variations in the Earth magnetic field are assessed. Theoretical and experimental foF2 trend values are compared. The Earth magnetic field would produce trends similar in magnitude to those observed and can also explain some seasonal and daily variation patterns observed in foF2 trend values.