Fig. 2From: PCA and vTEC climatology at midnight over mid-latitude regionsAverage values of vTECGNSS for each region at 22 LT (panels a, e, i and m); at 00 LT (panels c, g, k and o). Average values of V HWM07 for each region at 22 LT (panels b, f, j and n); at 00 LT (panels d, h, l and p)Back to article page