The graph below demonstrates the differences between the instantaneous, the instantaneousToMean and the MeanToMean methods when aggregating data.
The blue line (first column in the table) shows the original 15 minute data. The red line (second column) is the result of the instantaneous aggregation. The next two columns show the results of the meanToMean (light green line) and the instantaneousToMean (dark green line) method.
The default behaviour of all these aggregations is to save the result at the end of the time interval that is being investigated. This explains the apparent shift in the hydrograph. Although this is very useful for many operational environments (it ensures you have data NOW) it may not always be wanted. In that case it is easy to combine these aggregations with a delay. |