1- (Upper-left) Vertical Electron Content (VTEC) map at the date and time selected.

2- (Upper-right) Median of the VTEC over the past 15 days with respect to the date and time selected.

3- (Bottom-left) Difference between maps 1- and 2- (VTEC of the date and time selected - VTEC Median over the past 15 days with respect to the date and time selected).

4- (Bottom-right) The percentage of difference range between maps 1- and 2- and statistics :
     - mean of the differences,
     - standard deviation (std),
     - percentage of differences greater than 5 TECU,
     - percentage of differences gerater than 10 TECU,
     - amplitude of the differences (max-min).