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Summary of Proposal COA0090

TitleTowards a better understanding of ship generated waves using Terra SAR X
Investigator Horstmann, Jochen - NATO Undersea Research Center, N/A
Team Members
Prof. Dr. Soomere, Tarmo - Talin University of Technology, Institute for Cybernetics
Dr. Thompson, Donald - Johns Hopkins University Applied Physics Laboratory, Space Department
Dr. Schulz-Stellenfleth, Johannens - Deutsches Zentrum für Luft- und Raumfahrt e.V., Institut für Methodik der Fernerkundung
Summary

The understanding of the SAR imaging of ocean surface waves has been investigated in detail over the last three decades. Several authors, including the representatives of this project, have investigated the SAR imaging mechanisms and demonstrated the SAR imaging of ocean surface waves utilizing X-band as well as C-band SAR data. It is well known that SAR provides 2-D information on ocean surface gravity waves. Studies were carried out concerning the estimation of 2-D ocean wave spectra as well the analysis of sea surface elevation fields. For the extraction of wave information from SAR data both the real aperture radar (RAR) modulation mechanisms as well as the velocity bunching mechanism have to be taken into account. However, up to today the SAR imaging mechanisms are still not fully understood and the choice of suitable models to describe these mechanisms is still debated in the scientific community.

The analysis of ship wakes on high resolution Terra SAR X data could make important contributions to a better understanding of SAR ocean imaging mechanism, which is the basis for the optimization of ocean wave as well as current retrieval algorithms in general. Furthermore, the study can help to develop sophisticated ship wake detection and classification methods. The combination of numerical simulations and Terra SAR X observations of ship wakes is an innovative approach which is interesting from both the scientific and the commercial point of view.

We will use our detailed understanding of ship generated Kelvin waves in deep water together with the very high resolution of Terra SAR X data to investigate the SAR imaging mechanisms in detail. Therefore, we will consider the local wind and current situations from numerical models and measurements as well as the detailed description of the ship generated waves utilizing numerical models as well as measurements. The SAR imaging mechanisms will be investigated systematically utilizing Terra SAR X data of different spatial resolutions (integration times) and polarizations. From these investigations we expect to achieve more detailed insights into the different modulation mechanisms (tilt- and hydrodynamic modulation as well as velocity bunching). In the next step we will use our gained knowledge of the SAR imaging mechanism to learn more about the ship wakes in shallow water, where they can only be reliably modeled within 3 to 5 ship lengths of the ship.

Total duration: The project duration is 18 months and is planed to start in Sep. 2006 and end in Feb. 2008.

Data requirements: About 20 Terra SAR X images of the test site need to be acquired A few reference data will be acquired on a routine basis, some data will be collected during the project, which will be financed from internal resources. For additional data acquisitions funding will still have to be applied from external sources.

Deliverables: Comprehensive final report and online presentations for experts and potential users, describing the methodologies as well as all important findings.

Funding: The scientific work will be financed from internal resources of the participants, who are interested in stimulating oceanic applications of SAR. The JHUAPL and GKSS have submitted two proposals for NOAA grants and have included the investigation of Terra SAR X data in their proposals. We are planning to apply for additional funding from DLR-Bonn/BMBF for traveling, publications, and overhead costs as well as considering Terra SAR X in future EU projects. For additional data acquisitions funding will still have to be applied from external sources.

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