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Data Source: Radar Measurements

Surface current data from three high-frequency (HF) radar stations at Wangerooge, Büsum, and Sylt is continuously measured and transmitted in "real time" to the Helmholtz-Zentrum Geesthacht. After automated quality control, current vectors are calculated.

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Surface current data from three high-frequency (HF) radar stations at Wangerooge, Büsum, and Sylt is continuously measured.

COSYNA Product: Surface Current Fields in the German Bight

Every hour, the measured radar data are linked to and assimilated into a 3D hydrodynamic model (General Estuarine Transport Model, GETM). The advantages of the modeled and assimilated current fields compared to the measured data are obvious: Current fields are calculated for the entire German Bight. Forecasts can be provided for the next 6 to 12 hours. Time series of current maps are publicly available for download from the COSYNA data portal. They can be utilized, for instance, for ship trafic safety, for the spreading of pollutants, or for rescue operations.

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COSYNA Product: Currents in the German Bight, snapshots from 16 April 2016.

Improvement by Assimilation

Due to the data assimilation, the model results are closer to reality thus reducing forecast errors. In particular, the dominant tidal signal is well represented. The deviation from the measured HF radar current data is typically about 0.1 m/s, with large spatial variations. Examplary, the figure shows the improvement in the calculation of drifter positions by assimilating real time data compared to model runs without assimilation (shown is the monthly mean, 24h-drift time).

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Improvement in the calculation of drifter positions by assimilation: Two trajectories provide an example of the drifter path with (red) and without (black) data assimilation).

Use of Products

The COSYNA products, data and metadata, are disseminated over the internet for further use by different end-users. COSYNA cooperates with government agencies, which, at some stage of the product development, could convert the pre-operational to operational products – a process that has been pioneered for the pre-operational analysis system for current fields in the German Bight based on real-time HF radar data.

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