SpatialHomogeneityCheck

Contents of check for SpatialHomogeneityCheck

The purpose of this check is to update the flags of the output timeseries whenever the error exceeds the specified threshold. The error is defined by the difference between the value and the estimation which is the average of the values from the selected neighbouring locations weighted for distance. Note that the check suppports non-equidistant comparison where timesteps should be within the same fixed range +/- 500 milliseconds.

During the check, the threshold criteria for the check are first sorted. Unreliability before doubtful and absolute before relative. The first worst case result will be applied and logged. This means that when exceedances for all four checks need to be logged then it is required to specify the four checks individually. In the latter case, the state of the flags result will not always be the same, since the result also depends on the flags, e.g. if the first test alters the flag, the next check has different input.

The estimation formula used:

where:
is the estimated value at the test station at time
is the measured value at neighbour station at time
is the distance between the test station and the neighbour station
is the number of neighbour stations taken into account
is the power of distance , (default = 2)

Test criteria

The test criterion with an absolute threshold is exceeded when the following condition fails:

The test criterion with relative threshold is exceeded when the following condition fails:

with:
the admissable absolute difference
the multiplier of the standard deviation
the standard deviation of neighbouring values

Configuration

• id: identifier of the check.
• variableDefinition: embedded variable definition (see above).
• inputVariableId: One or more identifiers for variables of which the flags have to be used.
• outputVariableId: One or more identifiers for variables for which the flags have to be modified.
• searchRadius: The maximum radius for selecting reference locations in meters.
• numberOfPoints: The maximum number of neighbouring locations to base the estimation on. The neighbouring locations are established once per check. Missings are ignored.
• distancePower: Power of distance, default is 2.

For each threshold,

• absolute or relative Compares theshold with absolute value, or relative factor times the standard deviation.
• unreliable or doubtful Output flag for values of output variables that exceed the specified threshold.
• outputMode: When this option is set to logs_only, the flags will not be updated but the log events will be generated.
• logLevel: Log level for the log message that is logged if a time series does not pass the check. Can be DEBUG, INFO, WARN, ERROR or FATAL. If level is error or fatal, then the module will stop running after logging the first log message. Fatal should never be used actually.
• logEventCode: Event code for the log message that is logged if a time series does not pass the check. This event code has to contain a dot, e.g. "TimeSeries.Check", because the log message is only visible to the master controller if the event code contains a dot.
• logMessage: Log message that is logged if a time series does not pass the check. Some more options are available than in the other checks:

Rules for updating the flags

For each timestep, the most unreliable flag in the inputVariables is determined, e.g. unreliable > doubtful > reliable.
If the most unreliable flag in the inputVariables is unreliable, and the corresponding flag in the outputVariable is reliable or doubtful, it is made unreliable as well.
If the most unreliable flag in the inputVariables is doubtful, and the corresponding flag in the outputVariable is reliable, it is made doubtful as well.

Configuration examples for spatialHomogeneityCheck

A configuration example for the spatialHomogeneityCheck is given below: