Science Service System

Summary of Proposal OCE0267

TitleCurrent retrievals from sequences of TerraSAR-X images
Investigator Emery, William - University of Colorado, Aerospace Engineering Sciences Dept.
Team Members
Dr, Romeiser, Roland - University of Miami, Division of Applied Marine Physics
Dr. Gade, Martin - University of Hamburg, IFM Zentrum F Meeres and Klimaforschung
Professor Wilkin, John - Rutgers University, Marine Science
Oceanographer Moisan, John - Wallops Island Flight Facility, Observational Science Branch

Objectives: To demonstrate the viability of applying the MCC method to sequential TerraSAR-X imagery by their comparison with coincident surface current fields computed from optical satellite imagery. Also to assess using the Doppler residual technique and eventually the experimental ATI method to directly compute ocean surface currents from individual SAR scenes when compared with coincident current fields computed from sequential optical satellite images. Earlier study (Rud and Gade, 1999, 2000; Fiedler, 2003; Gade et al., 2003) has shown that surface features in optical imagery, such as ocean color, are also apparent in SAR imagery, which suggests that the MCC technique should be able to follow the evolution of these surface features.

The TerraSAR-X surface currents will also be compared with coincident drifting buoy trajectories deployed by the U.S. Coast Guard to test their Search and Rescue operational software.

Methods: The following activities will be carried out in this project:

Approximately 100 TerraSAR-X ScanSAR images will be acquired for the two test areas on the southwest and northeast U.S. coasts combining ascending and descending overpasses, different incidence angles and covering a range of tidal phases and wind conditions. Sequential imagery will be computed from ScanSAR mode cross overs and during periods of parallel operation where the instrument scan angle will be changed to obtain sequences of images of the same test area from neighboring orbits.

Another 20 single-look, complex, Stripmap mode images will be acquired for the computation of the Doppler residual currents.

Surface currents for the times between the TerraSAR-X data will also be computed from all available infrared and ocean color imagery for both regions.

Surface currents will be computed using the Doppler residuals from the TerraSAR-X data and these currents will be compared with coincident currents computed with the MCC method applied to the ScanSAR mode and from optical satellite imagery.

Data requirements: 100 TerraSAR-X ScanSAR mode images will be acquired, half for the U.S. southwest coast and half for the U.S. northeast coast. These images will be used with a direct application of the MCC method to compute surface currents in these two regions where under separate funding 3-day, near real-time surface currents are computed by the Univ of Colorado group.

In addition to the 100 ScanSAR mode images we need to acquire 20 Stripmap mode, single-look, complex TerraSAR-X images for the computation of the Doppler residual surface currents. These currents will not be coincident with the MCC currents computed from the SAR data but both types of SAR derived currents will be compared with simultaneous estimates of surface currents from infrared and ocean color imagery. All of the infrared and ocean color imagery will be acquired and processed by the Colorado, Rutgers and Wallops groups.

Deliverables: Comprehensive final report of all of the surface currents calculated and all comparisons between surface currents made as part of this project. We hope to also publish at least two refereed papers from this study.

Funding: The funding for the US calculation of surface currents from satellite imagery is covered by a NASA Earth Science project for the use of satellite altimetry to W. Emery and J. Wilkin. The extension to supporting the U.S. Coast Guard is presently being proposed to NASA Satellite Data Applications Division where it has already passed as a Step-One project (J. Moisan principal investigator, W. Emery and J. Wilkin co-investigators). Additional funding to cover travel to attend project meetings will be requested from NASA (U.S. participants) and DLR (German participants).

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