37
Storm Impact on the Coastal Geomorphology and Current Field
in the area for more than a decade. In the following paragraphs, details about the
instrumentation for all the analyzed data are presented.
3.1.2.1 Radar Data
The monitoring station was mounted near the lighthouse List West on the island of
Sylt. The radar radius covered the Lister Landtief and part of the Lister Tief. The
instrument used for acquisition of the sea surface is a software–hardware combination described in many publications (e.g., Borge et al. 1999), as part of the Wave
Monitoring System (WaMoS), consisting of a Furuno FR 1201 nautical radar, a
WaMoS II analog–digital converter, and a WaMoS II software package for the acquisition of the radar images. The instrument used for observation is a ground-based
nautical X-band radar with horizontal polarization, mounted 25 m above the Normal
Zero reference level, which is considered a common reference level in Germany. The
grazing incidence angle (the angle between the horizon and the radar view direction)
varies between 1º and 5º, depending on the distance from the radar; therefore, the
radar measurement is considered as a low-grazing-angle measurement.
Sequences of radar data are acquired on an hourly basis. The sequences consisted
of 256 individual images with an interval of 1.8 s between successive images, which
are determined by the antenna rotation time. The antenna period may be impacted
by the wind; therefore, the total duration of the sampling varies, but it is approximately 8 min. The polar images cover a radius of a nautical mile and are interpolated
to a Cartesian grid with a cell size of 7 m × 7 m, corresponding to the spatial resolution of the radar. The size of one image is 576 pixels × 576 pixels.
3.1.2.2 Meteorological and Oceanographic Measurements
The rest of the in situ instrumentation covers the experimental and operational needs
for the monitoring of the coastal environment. The wave heave and direction were
measured in the vicinity (5.5-m depth) of the radar range by a directional wave-rider
Mark II, which is operated by HZG. The offshore wave conditions (13-m depth)
are monitored operationally by the Federal Maritime and Hydrographic Agency of
Germany (Bundesamt für Seeschifffahrt und Hydrographie; BSH) 16 km south. At
a nearby position, the tide-level data were acquired by a gauge. A second gauge was
recorded at the Port of List, approximately 10 km inside the tidal basin. The time
shift for the two measuring points from the area of investigation is known from the
tidal calendar. The weather parameters were measured by an automatic meteorological weather station, manufactured by Siggelkow Geraetebau GmbH, mounted on
the radar mast, approximately 3 m below the radar antenna and extrapolated at a
10-m height by assuming a logarithmic profile. In addition, the wind speed, wind
direction, and air pressure data are available at the Port of List by the Seewetteramt
Hamburg part of the Meteorological Service for Germany and were used for the
cross validation of the meteorological measurements and for filling gaps in the time
series.
3.1.2.3 Multibeam Echosounder Data
For the validation of the DiSC bathymetry, bathymetric data from the multibeam
echosounder EM 3000 from Simrad-Kongsberg have been acquired. The bed relief
Storm Impact on the Coastal Geomorphology and Current Field
in the area for more than a decade. In the following paragraphs, details about the
instrumentation for all the analyzed data are presented.
3.1.2.1 Radar Data
The monitoring station was mounted near the lighthouse List West on the island of
Sylt. The radar radius covered the Lister Landtief and part of the Lister Tief. The
instrument used for acquisition of the sea surface is a software–hardware combination described in many publications (e.g., Borge et al. 1999), as part of the Wave
Monitoring System (WaMoS), consisting of a Furuno FR 1201 nautical radar, a
WaMoS II analog–digital converter, and a WaMoS II software package for the acquisition of the radar images. The instrument used for observation is a ground-based
nautical X-band radar with horizontal polarization, mounted 25 m above the Normal
Zero reference level, which is considered a common reference level in Germany. The
grazing incidence angle (the angle between the horizon and the radar view direction)
varies between 1º and 5º, depending on the distance from the radar; therefore, the
radar measurement is considered as a low-grazing-angle measurement.
Sequences of radar data are acquired on an hourly basis. The sequences consisted
of 256 individual images with an interval of 1.8 s between successive images, which
are determined by the antenna rotation time. The antenna period may be impacted
by the wind; therefore, the total duration of the sampling varies, but it is approximately 8 min. The polar images cover a radius of a nautical mile and are interpolated
to a Cartesian grid with a cell size of 7 m × 7 m, corresponding to the spatial resolution of the radar. The size of one image is 576 pixels × 576 pixels.
3.1.2.2 Meteorological and Oceanographic Measurements
The rest of the in situ instrumentation covers the experimental and operational needs
for the monitoring of the coastal environment. The wave heave and direction were
measured in the vicinity (5.5-m depth) of the radar range by a directional wave-rider
Mark II, which is operated by HZG. The offshore wave conditions (13-m depth)
are monitored operationally by the Federal Maritime and Hydrographic Agency of
Germany (Bundesamt für Seeschifffahrt und Hydrographie; BSH) 16 km south. At
a nearby position, the tide-level data were acquired by a gauge. A second gauge was
recorded at the Port of List, approximately 10 km inside the tidal basin. The time
shift for the two measuring points from the area of investigation is known from the
tidal calendar. The weather parameters were measured by an automatic meteorological weather station, manufactured by Siggelkow Geraetebau GmbH, mounted on
the radar mast, approximately 3 m below the radar antenna and extrapolated at a
10-m height by assuming a logarithmic profile. In addition, the wind speed, wind
direction, and air pressure data are available at the Port of List by the Seewetteramt
Hamburg part of the Meteorological Service for Germany and were used for the
cross validation of the meteorological measurements and for filling gaps in the time
series.
3.1.2.3 Multibeam Echosounder Data
For the validation of the DiSC bathymetry, bathymetric data from the multibeam
echosounder EM 3000 from Simrad-Kongsberg have been acquired. The bed relief