Magnitude characteristic

A magnitude characteristic compares each flow observation with a threshold or inclusive range. It is useful for identifying observations above, below, or between specified flow levels. Moving-average startup values can be unknown until the averaging interval is available; see unknown outcomes.

Configuration

magnitude = [">", 1]
# Alternatives:
# magnitude = [">", 1, 7]
# magnitude = [0.5, 5.0]
# magnitude = [0.5, 5.0, 7]

Parameter	Type	Valid values	Meaning
operator	string	<, <=, >, >=, =, !=	Comparison with one threshold.
threshold	number	0 or greater	Flow value used in a one-threshold comparison.
minimum, maximum	numbers	0 or greater; minimum less than maximum	Inclusive flow range.
ma_periods	integer	1 or greater; default 1	Number of timesteps used in the trailing moving average.

When ma_periods = k is greater than one, the mean is calculated from the current observation and the preceding observations in that window:

average[t] = mean(flow[t-k+1], ..., flow[t])

Its unit is the same as the input flow unit. The calculation is unavailable for the first k - 1 observations because the full window is not yet available; this statement concerns the moving-average value, not how an outcome is classified. A value of one compares the original observation.

Worked example

With the condition flow >= 1, each observation is assessed separately:

Flow	Magnitude outcome	Component outcome
0	0	0
1	1	1
2	1	1
1	1	1
0	0	0

Expected diagnostic: [0, 1, 1, 1, 0]

Expected component outcome: [0, 1, 1, 1, 0]

For how this characteristic combines with duration or frequency, see evaluation order. When a moving-average value is unavailable during startup, its comparison outcome is unknown. This fully known example does not illustrate those startup outcomes.