Predictors based on best available predictions
Each calculation is done with help of predictors. These components are constructed to estimate the water levels, water direction, water speed and swell at any location and time at the two channels. These predictors are constructed automatically with use of the best available information possible. This means that data settings with lower data classifications are preferred above higher data classifications.
Construction routine
For each different unit (water level, water speed, water direction and swell) there are different sources that fill the PROTIDE predictions database. Water level typically is described most and swell the least accurate. PROTIDE uses a construction routine that automatically detects the number of available points that predictions are available and then uses a one or two location predictor to base its predictions on. With a one location prediction the predictions for that location are assumed to be accurate for the whole channel. With a two location predictor, the estimations of both locations are used, which are inter- or extrapolated to the desired kilometer position. A compound predictor is created, that is a composite of predictors with varying data classifications, when more data settings are needed to cover the time span the predictions are needed for. The compound predictor makes sure that for each kilometer position the predictor with the lowest available data classification is used. The figure below demonstrates the construction of a compound predictor.
Constant value predictors
Some prediction units, like swell and wave height, have a short prediction span of 48 hours or less. To be able to calculate (indicative) tidal windows beyond these 48 hours, a constant value predictor is introduced. The constant value predictor will infinitely extend the prediction data with a fixed mean value of the prediction unit over multiple years. To compensate the uncertainty of this prediction data, a higher standard deviation will be used.
The current constant value predictors are:
| Unit | Constant value | Standard deviation |
|---|---|---|
| Swell: | 20cm | 30cm |
| Wave height: | 150cm | 40cm |
