1 Correction to: Surv Geophys https://doi.org/10.1007/s10712-017-9438-y

In the original publication of the article, under Section 2.1, the sentence in the eighth paragraph that reads as “It has been demonstrated…very disturbed periods.” should read as “It has been demonstrated (Mirò Amarante et al. 2007) that the ionosphere shows small scale variations that global or regional empirical models describe hardly, especially for very disturbed periods.”

In the eleventh paragraph under Section 3.2, the sentence that reads as “In formulas (3)–(4),…respectively.” should read as “In formulas (3)–(4), \( U_{2j,k}^{\text{low}} \) and \( U_{2j,k}^{\text{high}} \) (similarly for 2j − 1 terms) are the coefficient values calculated for \( IG_{12} \) or \( R_{12} \) equal to 0 (low solar activity) and equal to 100 (high solar activity), respectively.”

Finally, under Section 3.3.2, the sentence in the third paragraph that reads as “In this case, the… or small values of h.” should read as “In this case, the experimental variogram has a parabolic behavior near the origin, that is, it is proportional to h 2 for small values of h.”