Explanations

left top: value of characteristic number for a single event.
left bottom: mean value of the characteristic number within the period of data analysis.
right top: maximum value of the characteristic number within the period of data analysis.
right bottom: minimum value of the characteristic number within the period of data analysis.

Examples

mean ebb water level	mean ebb water level (maximum)

mean ebb water level (mean value)	mean ebb water level (minimum)