image: January 2009: The four figures show (a) amplitudes and (b) phases of a TerraSAR-X along-track InSAR image of the lower Elbe river (Germany) acquired on June 20, 2008, (c) the line-of-sight surface current field derived from the data, and (d) a corresponding reference current field according to a numerical Elbe model of the German Federal Waterways Engineering and Research Institute (BAW). The test area size (figures a-c) is 16 km × 25 km, and the radar look direction (= orientation of the current component that can be measured) is from left to right. view more
Credit: Roland Romeiser, UM/RSMAS and Steffen Suchandt, Hartmut Runge and Ulrich Steinbrecher, German Aerospace Center (DLR)
VIRGINIA KEY, Fla. — Working closely with the University of Miami's Center for Southeastern Tropical Advanced Remote Sensing (CSTARS), Associate Professor of Applied Marine Physics, Dr. Roland Romeiser, has been awarded a $500,000 grant by the Office of Naval Research (ONR). The project, "Currents in Rivers Observed by Spaceborne Along-Track InSAR (CuRiOSATI)," marks the first ever use of this type of InSAR (interferometric synthetic aperture radar) satellite imagery to determine surface current fields in rivers and in the ocean. These measurements will be valuable in monitoring global river runoff, bathymetric changes in coastal waters, and the spreading of pollutants, as well as in basic research on turbulence characteristics in the open ocean and other promising applications.
'Along-track InSAR' is a new technique that uses high-resolution satellite imagery from a single observation for direct measurements of surface current fields. In spring and summer 2008, Romeiser and project partners at the German Aerospace Center (DLR) got their first opportunity to acquire experimental along-track InSAR images with the new German satellite TerraSAR-X over the Elbe River in Germany. Analyzing amplitudes and phases of the interferometric data and applying some theoretical corrections, Romeiser obtained a solution for the most likely line-of-sight surface current field at the time of each satellite overpass. The results were found to be consistent with a numerical Elbe River model of the German Federal Waterways Engineering and Research Institute (BAW), and with Romeiser's earlier theoretical predictions of the data quality to be expected from TerraSAR-X. A manuscript on this work was submitted to IEEE Transactions on Geoscience and Remote Sensing.
"What we've found from using TerraSAR-X, the first operational satellite with along-track InSAR capabilities, is very experimental data, but the potential of the technique for current measurements from space looks very promising," said Romeiser. "With more experimental data, the applications of this technique may soon become popular with users looking for high-resolution snapshots of surface current fields anywhere around the world, including its use in support of rescue and naval operations, as this new method allows us to render detailed current maps of areas up to about 100 km × 100 km in size, with an effective spatial resolution of about one kilometer, within a few hours."
Romeiser and his collaborators plan to acquire more TerraSAR-X along-track InSAR images and to develop and implement quasi-operational algorithms for satellite-based current measurements at CSTARS. The ONR grant will help fund further research on the technique's suitability for river applications.
Founded in the 1940's, the University of Miami's Rosenstiel School of Marine & Atmospheric Science has grown into one of the world's premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, please visit www.rsmas.miami.edu