Advisory and Research group on Geo Observation Systems and Services (ARGOSS)

WP2: Experimental Monitoring and Validation
1. Insitu data and SAR data has been made available over the Western Scheldt area to assess the bathymetry assessment, to monitor the Western Scheldt area in time and for further additional analysis.
2. New interfaces have been made available to process multi temporal ERS SAR data simultaneously for bathymetry mapping purposes. This method has been implemented to geocode ERS data fully automated out of the image corner information.

There is some examples with images...An example of a SAR image recorded 13 May 1996 is shown in Figure 1. Soundings for calibration for the same area were obtained too (see Figure 2).
Figure 1. ERS-2 SAR image recorded 13 May 1996.
Figure 2. Sounding areas.

WP3. Radar remote sensing: A map production line is in development to produce maps for the Western Scheldt area and results are expected the coming months.

WP4 Optical Remote Sensing For software development and testing SeaWiFS images of the OROMA test sites have been used (http://www.argoss.nl/sediment). As an example a sediment map is shown in Figure 2. Furthermore, the SeaWiFS image of 4 June 2000 covering Gulf of Gdansk was processed into a chlorophyll map. On the same day chlorophyll measurements were performed in the Gulf of Gdansk (Cruise no. 1a by IMWG). Both techniques yield a chlorophyll concentration of approximately 5 mg/m3.
Figure 3. Suspended sediment concentration in Gulf of Gdansk, 20 April 2000


BMT Maritime Consultants (BMTMC)
For the Gulf of Gdansk, there is a lack of bathymetry data comprising nearshore zone of the depths 0-10 m, where significant changes of water depth in time and space occur. Frequently, there is a demand for the shallow water and beach (plus dune/cliff) data. Places where dynamic changes of bathymetry in time and space take place require high resolution data (grid of 2-5 meters). Acquiring such data is very expensive. For the purpose of optimizing survey campaigns additional data obtained from remote sensing would be useful.

GEOMAR
The sea bed morphology of the Lister Tief, consisting of a complex configuration of different bedforms, which is four-dimensional in space and time was mapped by a single beam echo sounder during the first period of the field experiment campaign in 2002. This bathymetric data set will be used as the reference data set to study the changes (erosion and deposition) of the sea bed morphology and was transfered to the OROMA server. Normalized Radar Cross Section (NRCS) modulations of the GKSS ship-borne X-band VV polarized radar have been mapped in a sea area covered by sand waves during ebb and flood tidal current phases. The analysis of this data set will start in January 2003. These NRCS modulation data will then be make available to the Bathymetry Assessment System (BAS), a new monitoring system for mapping water depths of shallow coastal waters based on radar measurements which was developed by the private company ARGOSS in the Netherland (workpackage 5). Acoustic Doppler Current Profiler (ADCP) data were simultaneously measured and first results show distinct changes of the three-dimensional current field above sand waves. Relevant air-sea interaction parameters such as wind speed and wind direction can be visualized for each track.
First simulations of the NRCS of quasi resonant internal waves and its influence on the radar imaging mechanism due to sand waves have been performed. Simulations of the total NRCS modulation as a function of strain rate showed that at least a density difference between the two water layers of the order of ?r ˜ 1 kg m-3 should have been developed for a significant contribution of the internal wave effect using in situ data measured during the first Marine Science and Technology (MAST) field experiment in the southern North Sea under contract number MAST-0040-C.
Conductivity-Temperature-Depth (CTD) data measurements showed that the water column was well mixed during the first period of the field experiment in the Lister Tief.

RWS-MD
A good cooperation between the Survey Department on one side and the Directorate Zeeland and Directorate Noord Holland on the other side has been established. Airborne data takes were successfully performed at Marsdiep and Western Scheldt under optimal weather conditions. The data processing system has been adapted to process data obtained form a CASI scanner. A report has been written on the inherent optical properties. Historical soundings of the two sites in the Western Scheldt have been made available. The ESA help and order desk is informed on the data requirements for the year 2003.

University of Dundee (UNIVDUN)
A set of processed SAR images from 1992 - 1999 which show bathymetric and surface roughness features. These will be checked against available meteorological and tidal data.

 

OBJECTIVES • WORKPROGRAM • SCHEDULE • RESULTS • PARTNER • END USER

 

Results

Institute for Coastal Research (GKSS)
- Progress in hardware preparation and first tests for the s° mapping from a ship.

- First current vector maps produced over the shallow water area North of the island Sylt; - first results achieved by the method using the shallow water gravity wave dispersion algorithm. Assessment of the accuracy and error bars; - first experimental maps of the shore line and of shoal positions.