Fig. 6From: Statistical analysis of ionospheric total electron content (TEC): long-term estimation of extreme TEC in JapanDistribution of slab thickness during May, June, and July from 1997 to 2018. The red curve represents an original normal distribution as in Fig. 5. The blue curves represent inflated normal distributions with the mean and the inflated sigma. The inflated sigma is derived by multiplying inflation factor to the original standard deviation. Inflated normal distributions with inflation factors of 2.0 and 3.8 are shown with the blue dashed and solid lines, respectivelyBack to article page