Along-Track Zero Padding for the Processing of Unfocused SAR Altimetry Waveforms

Christopher Buchhaupt (TU Darmstadt, Germany)


Luciana Fenoglio (University of Bonn, Germany); Matthias Becker (TU Darmstadt, Germany)

Event: 2017 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Measurement and Retracking

Presentation type: Type Oral

SAR altimeter processing is possible since the Synthetic Aperture Radar (SAR) Interferometric Radar Altimeter (SIRAL) was launched on board of CryoSat-2 on April 2010.

SAR altimetry, also known as Delay-Doppler altimetry (DDA), is pulse-limited, as conventional altimetry (CA), cross-track and beam-limited along-track. It has therefore the potential to provide a better along-track resolution and a higher Signal-to-Noise ratio (SNR). The SAR processing mode expands the calculations into the along track or pulse to pulse direction, involving additional corrections and processing, e.g. another Fourier transform in addition to the range FFT.

Whereas it is known that adding zeros to the end of the echoes prior the range FFT improves the estimation of geophysical parameters at low wave-heights, the effect of zero padding has not been investigated in the along-track direction yet. This study examines the effect of along-track zero padding prior the beam forming process with respect to its influence on the stochastic properties of the estimated geophysical parameters and the choice of the waveform’s surface locations.

Processed unfocused SAR data are compared to a reduced SAR (RDSAR) product having the same surface locations as SAR. The area of interest is the region from 2.5°S to 25.5°S and from 160°W to 85°W (Pacific Box) over the one year interval from October 2012 to October 2013.

The presentation includes the cross comparison of the processed SAR data with a reduced SAR product as well as the spectral analysis of the geophysical parameters sea surface anomaly, significant wave height and backscatter coefficient. The aim is to determine the improvement obtained by oversampling the products from 20 Hz to 40 Hz.


Oral presentation show times:

RoomStart DateEnd Date
Symphony Ballroom IV Tue, Oct 24 2017,11:15 Tue, Oct 24 2017,11:30
Christopher Buchhaupt
TU Darmstadt