Calculate the mean of all values in a time series. This can be done in multiple ways: 1. At ETime = 0 days, push all the values into a vector then calculate the mean of the vector ("Vector_Mean"), 2. At ETime = 0 days, iterate over the Time Series records using the Time Series function capability (doesn't require the use of an Array Label Set), 3. Use an Integrator with the moving average option enabled and the averaging period set to the duration of the simulation ("Integrated_Mean").
The first and second methods calculate the answer at the beginning of the simulation as long as the time series is already defined at the beginning of the simulation (not a recording time series). Note that the "Mean_NonZero" is a script that will only account for non-zero values and skips over values that are <= 0 m3/d.
The third method will provide the mean only at the end of the simulation. This method is not just limited to a Time Series. It can be used for any model output.