Abstract's details
Some surprisingly wonderful aspects of fully focused SAR altimetry
CoAuthors
Event: 2016 SAR Altimetry Workshop
Session: Innovative SAR processing methods
Presentation type: Type Oral
Contribution: PDF file
Abstract:
We are experimenting with fully focused coherent processing of radar altimeter echoes. Our experiments to date use CryoSat2 FBR SAR data, but our methods could also be used with similar data from Sentinel-3 or Sentinel-6. We have presented previous results at the 2015 OSTST and the 2016 ESA Living Planet symposia. This presentation will present the method in more detail, and will discuss some intriguing aspects revealed by fully focused altimetry, including:
(1) the calculation is so sensitive to antenna motion that we can detect errors of a few microseconds in datation of pulse bursts in CryoSat FBR SAR data, and can properly correct for them.
(2) over small inland water bodies and small leads in sea ice, the calculation is very sensitive to the along-track dimension of the water surface. It appears that small smooth water bodies act as ideal radiators, in effect having their own antenna gain pattern or directivity, which can be exploited to measure their extent if fully focused processing is used.
(3) even over the ocean, a presumably homogeneously rough surface, coherent processing yields a better waveform than unfocused delay/Doppler processing (the process currently used in the ESA L1b and L2 SAR products), and it appears that the effective number of looks at the surface per length of track flown is much better with fully focused processing.
(4) the uncertainty in water surface height measurements is much smaller if fully focused processing is used than if unfocused d/D SAR is used. This is true in both open ocean and also leads in sea ice.
Additional results and applications will be in another presentation given by A E Egido.
(1) the calculation is so sensitive to antenna motion that we can detect errors of a few microseconds in datation of pulse bursts in CryoSat FBR SAR data, and can properly correct for them.
(2) over small inland water bodies and small leads in sea ice, the calculation is very sensitive to the along-track dimension of the water surface. It appears that small smooth water bodies act as ideal radiators, in effect having their own antenna gain pattern or directivity, which can be exploited to measure their extent if fully focused processing is used.
(3) even over the ocean, a presumably homogeneously rough surface, coherent processing yields a better waveform than unfocused delay/Doppler processing (the process currently used in the ESA L1b and L2 SAR products), and it appears that the effective number of looks at the surface per length of track flown is much better with fully focused processing.
(4) the uncertainty in water surface height measurements is much smaller if fully focused processing is used than if unfocused d/D SAR is used. This is true in both open ocean and also leads in sea ice.
Additional results and applications will be in another presentation given by A E Egido.