Figure 1From: Filtering ionosphere parameters to detect trends linked to anthropogenic effectsfoF2 measured at Sodankyla. Twelve-month running mean of (a) monthly median foF2 (MHz) and (b) NmF2 (cm-3), measured at Sodankyla (67.3°N, 26.3°E) at 12 LT, in terms of Rz. Least squares regression line (red dashed line). The green dashed line in (a) corresponds to the least squares regression line considering only years around the maximum of solar cycle 19.Back to article page