Earth magnetic field and geomagnetic activity effects on long-term trends in the F2 layer at mid-high latitudes

It is well known that the Earth magnetic field, as well as geomagnetic activity, presents long-term variations. Both phenomena affect the height of the F2 layer peak, hmF2, and the maximum electron concentration estimated by foF2. Experimental data of three mid-high latitude stations (Argentine Islands, Slough and Uppsala) were used to estimate foF2 long-term trends. These trends were compared with a theoretical approximation considering long-term variations in the Earth magnetic field, and also with a qualitative assessment of geomagnetic activity increasing trend effects. Although the agreement between experimental and theoretically approximated trends is not within a desired acceptance level, the ability of the Earth's magnetic field variations to produce trends in the F2 layer of the ionosphere may be an important result. Long-term trends in geomagnetic activity could possibly explain some discrepancies such as the seasonal pattern of Slough and Uppsala, with lesser negative trends in winter, and also the similarity in the trend pattern of both northern stations. (c) 2006 Elsevier Ltd. All rights reserved.