Quality-controlled, science-based, near real-time environmental information derived from observations and model results can assist governmental and local authorities as well as other stakeholders to manage routine tasks, emergency situations and evaluate trends. An operational system in the heavily used North Sea may serve as a role model for many coastal areas worldwide.
One of the first COSYNA products is the pre-operational analysis system for current fields in the German Bight based on real-time HF radar data.
Surface Current Fields in the German Bight
COSYNA Product: Currents in the German Bight, snapshots from 23 April 2012.
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. Every hour, these data are linked to and assimilated into a 3D hydrodynamic model (General Estuarine Transport Model, GETM). Due to this data assimilation, the model results are closer to reality thus reducing forecast errors. In particular, the dominant (M2-) tidal signal is well represented.
The deviation from the measured HF radar current data is typically about 0.1 m/s, with large spatial variantions. Time series of current maps are publicly available for download from the COSYNA data portal. They can be utilized, for instance, for ship traffic safety, for the spreading of pollutants, or for rescue operations.
The pre-operational COSYNA wave forecast model system runs twice a day at 0 and 12 UTC and provides a 24 hour forecast on the regional scale for the North Sea and on the local scale for the German Bight. With boundary information from the regional wave model EWAM of the German Weather Service (DWD a number of wave parameters such as significant wave height, period, and total wave direction are calculated. Wave rider buoys serve for validation of the model outputs.
Temperature & Salinity
COSYNA Product: Temperature and Salinity. Skill of the SST data assimilation (in best case skill =1). The red line indicates the area beyond which the influence of FerryBox observations was reduced with a filter to avoid unrealistic SST fields.
Automated FerryBox systems provide valuable information on the spatial distribution of sea surface temperature (SST) and salinity (SSS) in the North Sea. In order to obtain a two dimensional picture of SST and SSS the observations taken along ship tracks are extrapolated to larger areas using additional information from numerical models. For example, data from the route Cuxhaven-Immingham are assimilated into a three-dimensional circulation model. An assimilation step is performed every 24 h. The output is validated against an independent data set (the MARNET Deutsche Bucht station). Misfits of SST and SSS in the free run are corrected almost completely after data assimilation. FerryBox data can locally enhance SST fields of the German Bight (up to ± 40 km apart from the track).
One of the main characteristics of COSYNA is the development of pre-operational (i.e., routine provision of) ‘products’ that improve present routinely applied observational and modelling techniques. These products comprise hourly updated maps, model results, and 6 hour-forecasts of ocean currents, salinity, temperature, and waves. Future products will include wind fields, ship detection, and biogeochemical parameters. A COSYNA focus is on information derived from an optimized synthesis of observations and model data (see COSYNA product “current”).
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.