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Monitoring of the German Bight with a HF-Radar Network J. Horstmann, J. Seemann, K.-W. Gurgel, T. Schlick, S. Maresca, and P. Braca HF-Radar Network of German Bight The HF-Radar network in the German Bight consist of three Wellen Radar (WERA) Systems, which are located on Sylt, Büsum and Wangerooge. All Systems transmit via a rectangular array of four antennae with an average power of 32 W. The Systems on Sylt and Büsum operate at 10.8 MHz with a linear receive array consisting of 12 antennae, while the Wangerooge radar operates at 12.1 MHz with a 16 antennae array. Each radar covers a 120°field of view with a 3°azimuth and 1.5 km range resolution. All systems are operated continuously with a hourly program, where 58 minutes are for measurements and the remaining 2 minutes are utilized to find the best suited frequency around the selected frequency band. The acquired data are preprocessed at each radar site and than forwarded to the main server at HZG in Geesthacht were the final products are generated and uploaded to the COSYNA data base. HF-Radar Current Fields The radial component of the ocean surface current with respect to the radar look direction is retrieved at each radar site utilizing 20 minutes of data. These components typically cover a range distance of 100 km within the azimuth of 120°covered by the radar. The surface current components are forwarded to the main server at HZG were the data are subject to quality control and fused to a surface current vector field. The radar network resolves surface currents every 20 minutes, which are made available on the COSYNA web portal within 30 minutes of acquisition (http://codm.hzg.de/codm/). In an additional pro- cessing step the radial components of each radar site are assimilated into a numerical simulation model (Stanev et al., 2014) this output is also available on the COSYNA web portal. HF-Radar Ship Detection and Tracking Since mid of 2013 the HF-radar network is also exploited with regards to ship detection, tracking and fusion. Ship detection is performed at each HF-radar station every 33 s and forwarded to the main server at HZG. The tracking and fusion of the ship detects is performed as a post processing task utilizing state-of-the-art algorithms (Bruno et al. 2013, Maresca et al. 2014, Vivone et al., 2014). Since the HF-radar systems were setup for oceanographic parameters, their configurations are not optimal for ship detection, which leads to degradation of the detection performance. In addition the poor resolution, significant false alarm rate, as well as crowding of the HF-spectrum have to be tackled. Within the next steps the system will be setup to operate in near real time and an in depth validation of the ship detects and tracks in particular with respect to geophysical dependencies will be carried out. A example of ship tracks resulting from 30 minutes of HF-radar data collected on 1. August 2013 is shown on the right hand side. AIS reports HF tracks Büsum Transmitter Receiver Sylt Transmitter Wangerooge Transmitter Receiver Receiver Wangerooge Sylt Büsum Availability of current vector Coverage of the HF-radar Network References: L. Bruno, P. Braca, J. Horstmann, and M. Vespe,” Experimental Evaluation of the Range-Doppler Coupling on HF Surface Wave Radar,” IEEE Geosci. Remote Sens. Lett., Vol. 10, No. 4, pp. 850–854, 2013. S. Maresca, P. Braca, J. Horstmann, and R. Grasso, “Maritime surveillance using multiple high- frequency surface-wave radars,” IEEE Trans. Geosci. Remote Sens., Vol. 52, No. 8, pp. 5056–5071, 2014. E.V. Stanev, F. Ziemer, J. Schulz-Stellenfleth, J. Seemann, J. Staneva and K.W. Gurgel, “Blending Surface Currents from HF Radar Observations and Numerical Modelling: Tidal Hindcasts and Forecasts,” J. Atmos. Ocean Techn., accepted 2014. G. Vivone, P. Braca, and J. Horstmann, Knowledge-Based Multi-Target Ship Tracking for HF Surface Wave Radar Systems, IEEE Trans. Geosci. Remote Sensing, in revision 2014. Dr. Jochen Horstmann, Radar Hydrography, Institute of Coastal Research, Tel. 04136 87 1530, [email protected]
