Drift simulations

This application invites you to experience the complexity of the North Sea hydrodynamic regime. You may release a virtual larva, an oil particle, a message in a bottle or a rubber duck at any location in the German Bight and watch its movements during a period of 20 days. Depending on both the location and the release time you choose (any hour within the years 1958-2021) the objects will behave very differently. Possibly you may prefer to release a rubber duck instead of a bottle. The duck sitting on the water will be much more affected by prevailing wind conditions. As simulations are based on realistic environmental conditions, it is possible to refer to specific events in the past like major storm surges, for instance.

The shifting wind, current and sea state behaviour in the North and Baltic Seas can be reconstructed for the past several decades with the help of numerical model data sets from the Institute of Coastal Research at the Helmholtz-Zentrum Hereon. This game is based on computer programs and data sets, which are used by scientists, government authorities and the commercial sector in real-world applications. Two different issues can essentially be investigated using these model calculations: Where do things come from? Where do things drift? Both questions play an important role in science.

Without knowing the effects of currents, the scientists cannot decipher the interaction of different processes in the North Sea.

1. Example: Higher algae concentration was measured today than yesterday. Did the algae reproduce, or have currents replaced the clear water from yesterday with turbid water?
2. Example: Larvae of particular fish species observed in one region numbered fewer than usual. Is there a disturbance in reproduction for this species (overfishing?) or have the changes in currents due to weather conditions simply driven the larvae to other regions?
3. Example: Fewer birds have been found covered in oil on the beach than the previous year: Have, in fact, fewer birds been covered in oil or have the currents carried the dead birds out to sea so that they haven’t been observed?

In all three examples, different interpretations of observations lead to entirely different conclusions and options for taking action.

What forecasts can scientists make? Currents are driven by a) the astronomical constellation (ebb and flood) and b) by the effects of changing weather conditions (e.g., storm floods). While the first component is virtually always known ahead of time, reliable weather forecasts are limited to a few days.

1. Example: In an oil spill, the oil drift is predicted for the next three days. These forecasts are important for optimizing countermeasures.
2. Example: Even if forecasts are incapable of covering longer periods, probable drift routes can always be analysed by looking at the past. What often happened in past years? And what has never happened? This helps biologists reconstruct species’ typical migration routes. What would have happened if an oil spill had occurred at particular times? Such calculations form the basis of risk assessments.
3. Example: Where will the message in a bottle wind up? Unfortunately, this question can only be answered in hindsight, after the weather and the related currents are known (the basis for this game!)