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Operational radar and optical mapping in monitoring hydrodynamic, morphodynamic and environmental parameter for coastal management

Exploitable results

Depth maps are the basic information product for bathymetric monitoring in coastal areas. Nowadays, area covering maps are obtained from interpolation of single beam echo soundings with a transect distance of typically 200m. The Bathymetry Assessment System (BAS) constructs depth maps from microware and optical satellite images plus a limited number of echo soundings. With the BAS, the distance between transects can be increased to 600m while retaining the same overall accuracy as with the traditional method. The BAS can be applied for bathymetric monitoring of shoals in shallow seas like the Wadden Sea and in estuaries like the Western Scheldt.
Web enabled tools have been developed with the following functionality referring to bathymetry data: 1. Description and presentation of the source data; 2. Presentation of isolines for interactively selected area dynamically calculated from the data stored in the database; 3. Presentation of bathymetry for the selected cross-sections calculated from the data stored in the database Possible comparison of information for the same cross-section and for selected years; 4. The reading of coordinates in different coordinate systems; 5. Calculation of sediment accretion/erosion in a selected period; and 6. Interactive 3D presentation of bathymetry for a given instant. The portal with a three-tier architecture was developed using ASP.NET, which consisted of the following functional packages: 1. Oracle Spatial data reader module; 2. Data presentation module; and 3. DEM generation and analysis module. Functionality of applications is offered to "thin clients" (e.g. standard Internet browser). This means that all the data analysis is carried out by a server, only the results are send by web to the client, which minimizes network traffic. All data is stored in the Oracle Spatial format, which meets requirements of OpenGIS Consortium.
Interactive presentation and reporting of coastal monitoring results. An integrated system was developed for an IT network which connected the scientific partners (community), monitoring agencies and the public to a centralised data base system. The key element to the system is a graphical user interface to the database, accessible through the Internet. The system was developed using JSP and EJB technologies and access achieved through password login a) for scientists to maintain the actuality of the monitoring data, b) for the monitoring agencies permitting them retrieval and data analysis tools and c) interested public, who would like access to information, which has been certified by the monitoring agencies. The data model developed implements the Dublin-core meta data standard. This is currently integrated into the new ISO meta data standard, so that all meta data of the OROMA data management system are compliant with the ISO standard. However, the ISO is not fully implemented. This is justified by two arguments: (1) the OROMA Data Management System is a prototype for demonstrating the capabilities and possibilities of an interactive presentation layer. It could be shown that meta data which are part of the ISO are part of the system and are sufficient for the purpose of the project. The additional meta data could be added, but this was not necessary for the project. (2) The number of meta data had to be limited in order to make an a-posteriori labelling of the available data possible and also to make the system attractive. It is the experience of the team that a system which requests a large number of meta data is not accepted and used by the scientific community. However, it should be pointed out here that a full implementation of the ISO meta data standard in the data model and interface of the OROMA Data Management System is possible with very little extra effort, should it become necessary. The software systems developed for the DMS were presented during an End User Workshop to a large number of participants. The feedback gathered during the interactive sessions proved that such a system include all the essential functions necessary to bring bathymetry and water quality information in a proper and understandable way to both coastal management and scientists. A paper was delivered at the Annual Conference of the Remote Sensing and Photogrammetric Society in Aberdeen in September 2004 describing the OROMA concept. Within the scope of the proposed ESA-funded GMES Service Element Marcoast initiative it is planned to employ the technologies developed during OROMA and other EU (e.g. REVAMP) and ESA-funded projects into the Water Quality Service to be offered. The primary end-users (customers) of this service will be the national monitoring agencies responsible for implementing EU Directives. It is expected that this Water Quality Service be fully operational and self-sustaining by the year 2008.
The Internet Monitoring Service is an interactive web application, which allows end users to browse the GIS maps, raster images, such as satellite images and other thematic maps, as well as point data. The main purpose for the service is to present and visualise data related to environmental conditions of the Baltic Sea. The service was filled with the data and thematic maps collected and processed during the OROMA project. It is available in the Internet from the following address: http://baltyk.imgw.gdynia.pl/oroma/ The service was developed in Java and DHTML. A free ALOV.org applet was used for visualization of vector maps and raster images. Two language versions, Polish and English, are available. The technical documentation is available in the Internet at: http://baltyk.imgw.gdynia.pl/oroma/docs/Internet_Monitoring_Service.pdf The graphical user interface was implemented in another web service, which was developed later for online access to data collected during monitoring and research cruises. It is fed from the IMGW Oceanographic Database and is available in the Internet only for IMGW end users: http://baltyk.imgw.gdynia.pl/serwis/ (password protected)
Result description: Ocean colour satellite data are already used for some time to determine chlorophyll and suspended sediment concentrations near the surface of the open oceans. SeaDAS software from NASA can be used to analyse SeawiFS and MODIS data for this purpose. Advances in correction for aerosol over turbid waters by MUMM (Belgium) have made it possible to do this also for coastal waters. Based on SIOP data from Rijkswaterstaat AGI (Netherlands), ARGOSS developed an analytical inversion method to derive concentrations of different constituents simultaneously from the water-leaving radiances estimated from the data. It was applied in OROMA to several sites in the North Sea and Baltic. The analytical method was tested and compared with alternative approaches by Rijkswaterstaat AGI. The results were published in a report and a paper. All the methods mentioned are implemented in an efficient software environment built around SeaDAS, which makes it possible to analyse large datasets efficiently. Some advantages of an analytical method over empirical algorithms are: a single model can be used for different (combinations of) constituents, it can be adapted to a different region by entering the appropriate SIOP data without developing a new algorithm, and it can be applied with general non-linear bio-optical models. Current status: tested, applied to a long dataset of SEAWiFS images, now work is in progress to use MODIS data of various bands/resolutions for retrieving water quality data. High spatial resolution is a requirement for use in environmental monitoring of activities related to dredging.
The bathymetry database of the Vistula river mouth was developed using available historical documents for the period 1893-2002 which have been analysed, and processed into digital format. It allows for a thorough analysis and description of morphological changes nearby the Vistula river mouth related to development of the marine alluvial fan and coastal evolution. This issue is of great importance in view of possible floods due to ice blocking, which can be catastrophic for the region, being a lowland, partly with ordinates of 0.5-1.0m below the mean sea level.
The radar cross section is a quantifying number of a reflecting or backscattering surface in a well defined distance to the antenna. In hydrography this quantifier is proportional to the given sea surface tilt and roughness. The calibration process of the radar cross section is achieved by transmitting in a series of microwave signals with defined amplitudes - produced by a signal generator - into the microwave guide fed in behind the antenna towards the receiver. The acquired signal damping is valid for both signal directions: transmitted and received. The characteristic of the receiver is attained from the acquired damping line. For the calibration the same A/D conversion device as the one used for the field measurement is used. As the antenna gain can be assumed to be invariant in time it could be taken from the producer notifications (see: OROMA delivery report D3.1). Synchronised to the radar data acquisition a precise positioning system is running to allow the geo-coded mapping process. The accuracy of the GPS deduced position is enhanced by using a shore based reference station. This set up allows to track the actual antenna position with an accuracy better then 10cm in x,y and z and their view direction with an accuracy of 0.1°. The positions updating is acquired with 1Hz and the directions updating with 5Hz. By this precise tracking of the radar antenna guarantees that the radar resultion is not degraded by the geo-coding process.
A coherent radar has the potential to acquire in addition to the signal's amplitude it's phase shift. By receiving the backscatter of a time series of signals from the phases the dominant frequency acquired for each "range bin" can be detected. This dominant frequency is effected by the Doppler shift due to relative movements between the antenna and the sea surface element, which scatters the radar signal. In the application of a radar above water this frequency shift is effected by a series of influences. The most important influence is due to the wind locally acting on the sea-surface by friction and by producing the small capillary waves, which are the scatters for the x-band radar signal. The method of "mapping the radial change in current field by coherent radar" is based on the assumption that the wind impact to the surface is the same along the radar range. Then the radial changes along the range are only due to effects due to long waves and current shears. In case of the absence of long waves (for example by measurement within tidal inlets) be this method current shear zones can unambiguously be detected.
A coherent radar has the potential to acquire in addition to the signal's amplitude it's phase shift. By receiving the backscatter of a time series of signals from the phases the dominant frequency acquired for each "range bin" can be detected. This dominant frequency is effected by the Doppler shift due to relative movements between the antenna and the sea surface element, which scatters the radar signal. In the application of a radar above water this frequency shift is effected by a series of influences. The most important influence is due to the wind locally acting on the sea-surface by friction and by producing the small capillary waves, which are the scatters for the x-band radar signal. The method of "mapping the current vector field by ship and shore based coherent radar" bases on the "mapping the radial change in Doppler shift with a coherent radar". There are two main differences: 1. To acquire the full current vector field two merged measurements of the radial Doppler shifts must be taken. The position of the pair of instruments must be chosen in a way to detect both components of the current vector in an area-covering field. 2. To extract the current field from the Doppler measurement the wind impact on the Doppler shift must be known and subtracted from the radial components before they can be combined for the vector detection.
The part of the Gulf of Gdansk located close to the mouth of the Vistula was chosen as a test area for field experiments carried out in 2002-2003 within the OROMA project. The main goal of these experiments was to collect chlorophyll-a in-situ data for comparison with data derived from satellite instruments. On all cruises, the chlorophyll-a concentration was determined at fixed points using the spectrophotometric method. Parallel profiles of chlorophyll-a using the fluorometric method were performed during three cruises in 2002 and three cruises in 2003. This method was chosen in order to provide continuous profiles of the parameter and to enable mapping of chlorophyll a horizontal distribution. The samples were taken every one minute along the profiles using a flow-through fluorometer at a depth of 2.5 m. At the same time, water samples for spectrophometric determination of chlorophyll-a were taken at selected stations at depths 0, 2.5, 5, 10m. Then, all fluorometric data were calibrated and corrected using linear regression against spectrophometric measurements of samples from 2.5m depth. During four cruises, measurements of the vertical distribution of suspended particulate matter (SPM) were also carried out. Fifteen MODIS images were reviewed for match-up comparisons with field measurements from cruises performed in 2002-2003. Only four of them, all from 2003, were selected for the further analysis due to either quality or cloud cover. No suitable MODIS data were found for the time of the experiments in 2002.

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