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For each peak, a value is selected to be used for the calculation of the correction factor. So for peak N = -6, a value of the astro timeseries is selected, a value for the observed water level and (within 2 hours)nd a value of the surge forecast. THe The value of the surge forecast is selected at the time of the observed peak from the nearest surge forecast in time. This is best illustrated with the following example:
A surge forecast is run daily every 6 hours, e.g. at 00:00, 06:00, 12:00. 18:00. The -6 peak occures at 7:15, it will use the surge forecast at 06:00, which is the closest forecast and use the value at 7:15 in the tidal correction transformation.
- Peak 8 is first astro peak after T0 (index 7)
- Peak 7 is first astro peak before T0 (index 6) - Peak nummer -1
- Peak 6 ---
- Input Peak selection variable is astro water level
- Input time selection variable is observed water level
- Find peak -2 from Astro
- Find peak -2 from observed closest to astro peak
- Check if time difference is less than 2 hours, then take time of observed peak
- If no closest observed peak found, then return missing and do not calculate peak correction.
The tidal correction transformation, the XML configuration is also attached to this page. The output of the transformation is a single value, which has the timestamp of the first next peak.
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