Data sources
Every source, and the licence it is used under. Attribution is a condition of most of these, and it is the right thing to do regardless.
| What | Source | Licence |
|---|---|---|
| Tide predictions | Derived from Environment Agency tide gauge observations | Open Government Licence v3.0 |
| Live sea level | Environment Agency real-time tide gauge API | Open Government Licence v3.0 |
| Water quality | Environment Agency Bathing Water Quality | Open Government Licence v3.0 |
| Wind, temperature, UV | MET Norway Locationforecast 2.0 | CC BY 4.0 |
| Sun and moon | Calculated on device | , |
Tide prediction is a sum of sine waves. Given a set of harmonic constants for a place, an amplitude and a phase for each constituent that makes up the tide, you can compute the water level for any moment.
Strandline does not licence those constants from a commercial provider. They were derived by least-squares harmonic analysis of 29 days of real fifteen-minute observations from each of 38 Environment Agency tide gauges, using data published under the Open Government Licence.
Fifteen constituents are used. That number was chosen by testing rather than preference: the model was fitted on 22 days and then asked to predict the 7 days it had never seen. Adding long-period constituents fitted the training data better while predicting worse, so they were left out.
This app contains public sector information licensed under the Open Government Licence v3.0.
It uses Environment Agency tide gauge data from the real-time data API (Beta).
Weather data is provided by MET Norway and licensed under CC BY 4.0. It has been processed for display: units converted and values sampled to the times shown.
England only, for now. Bathing waters are an Environment Agency dataset; Wales, Scotland and Northern Ireland publish equivalents through Natural Resources Wales, SEPA and NIEA.