NDLI: HF radar based current observation system in the German Bight

Content Provider	IEEE Xplore Digital Library
Author	Seemann, J. Ziemer, F. Cysewski, M. Flampouris, S. Gurgel, K.-W. Schlick, T.
Copyright Year	2011
Description	Author affiliation: Institute of Oceanography, University of Hamburg, Bundesstrassee 53, D-20146 Hamburg, Germany (Gurgel, K.-W.; Schlick, T.) \|\| Institute of Coastal Research, Helmholtz Center Geesthacht, Max-Planck Strasse 1, D-21502 Geesthacht, Germany (Seemann, J.; Ziemer, F.; Cysewski, M.; Flampouris, S.)
Abstract	In the South-Eastern part of the North Sea, known as the German Bight, the Helmholz-Zentrum Geesthacht (HZG, former GKSS Research Center) is currently realizing the experimental observation Network COSYNA for: Coastal Observing System for Northern and Arctic Seas. The observation area underlies extensive industrial use like oil and gas production, wind farming, transportation of all kind of goods, fishery, tourism but waste disposal as well, and many other industrial activities. Additionally the observation area of COSYNA covers one of the world wide hot spots in ship traffic that lies within that part of the coastal sea. The synoptic control near real time of the complex ecology inside the COSYNA water body is one of the leading objectives. The main physical dynamic is governed by tidal forces overlaid by episodic storm events, which may double the tidal heave within the observation area. All these conditions long for a synoptic, near real time survey of the current system what is achieved by a network of three HF radar stations at well chosen positions on the coasts of the German Bight. This network of High-Frequency over-the-horizon (HF) radars is currently consisting of three WERA (WEllen RAdar) systems installed on the islands of Wangerooge and Sylt, and close to the harbour of Buesum (Fig. 1). As WERA uses FMCW modulation for range resolution, there is no blind range in the vicinity to the antennas and data are available very close to the coast. Azimuthal and range resolutions are: 3 degrees and 1.5 km, respectively with a maximum range of 120 km. Ocean current maps are measured three times an hour. Operation of the COSYNA HF radar systems started during summer 2010. The three radial components of the current field as measured by the WERA radars are each transferred to a server at HZG, where they are quality checked and combined to give area-covering 2D maps. Radial components and 2D maps are archived in a data base and provided to the numerical model system. COSYNA provides a web-based interface to make the 2D maps, as well as the model now- and forecasts available to the public. This paper describes details of the HF radar network including the procedures to reduce the impact of Radio Frequency Interference (RFI) on the measured ocean current maps and to control the quality of the data. The radar processing described here may not remove all RFI and target echoes in all cases. An additional quality check of the ocean current data is implemented to identify and flag these situations. This procedure checks the past temporal variability between measurements. If the variability exceeds a threshold, the data is flagged as ”probably bad”. The radial components and the 2D current vectors are neither removed nor interpolated to avoid providing ”manipulated data” to the model / data assimilation system, which can handle these situations in a better way, as the flagged measureme
Starting Page	1
Ending Page	7
File Size	2061516
Page Count	7
File Format	PDF
ISBN	9781457700866
e-ISBN	9781457700880
DOI	10.1109/Oceans-Spain.2011.6003628
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2011-06-06
Publisher Place	Spain
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Sea measurements Radar Current measurement Hafnium Oceans Doppler effect Surface waves
Content Type	Text
Resource Type	Article

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