Preliminary results on the ACDC Delay-Doppler processing over CryoSat-2 Open-Ocean data

Eduard Makhoul (isardSAT, United Kingdom)


Chris Ray (Saint Mary’s College, United States); Mònica Roca (isardSAT, United Kingdom); Albert Garcia (isardSAT, United Kingdom); Roger Escolà (isardSAT, United Kingdom)

Event: 2016 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Measurement and retracking (SAR and LRM)

Presentation type: Type Poster

During the last decade there has been a tremendous evolution in radar altimetry from both technological and operational standpoints. This has been concreted in the development of the Synthetic Aperture Radar (SAR) altimetry, with CryoSat-2 as the reference mission and the follow-on Sentinel-3 mission for oceanographic purposes. Such framework represents a breakthrough in altimetry, offering the possibility to investigate new processing approaches in order to enhance the quality of the SAR altimetric products (especially in terms of geophysical retrievals).

In this line and from the experience gained within the Sentinel-6 project, this presentation is devoted to show the first preliminary results on the integration and application of the ACDC (amplitude compensation and dilation compensation) on real FBR CryoSat-2 data over open ocean zones.

ACDC was originally proposed by Chris Ray and isardSAT team within the Sentinel-6 project. The basic idea is to perform a two-step compensation once the stacking has been performed and right after geometry corrections application: 1) along-track amplitude compensation to equalise the Doppler-dependent weighting induced by the acquisition geometry in combination with both antenna and surface radiation patterns; and 2) across-track dilation compensation to correct for the waveform widening when moving away from the central beam. In this way, a better alignment of the waveforms within the stack is obtained focusing the spread along-track energy into a single range bin, such that an improved speckle reduction and signal-to-noise ratio (SNR) are expected. This results in a simpler and more computationally efficient analytical retracker over ACDC L1B waveforms when compared to the conventional SAR analytical retracker on L1B waveforms. As proved over simulated Sentinel-6 data, the combination of the ACDC processing within L1B and the implementation of the simpler ACDC retracker provides improved (less noisier) geophysical retrievals.

Taking into account such considerations, this presentation intends to perform a validation of the capabilities of the ACDC processing technique when integrated in the CryoSat-2 as well as Sentinel-3 processing baselines, comparing the retrieved geophysical parameters with the conventional SAR processing baselines for both missions over FBR CryoSat-2 data on several tracks over open-ocean.


Poster show times:

RoomStart DateEnd Date
Grande Halle Thu, Nov 03 2016,11:00 Thu, Nov 03 2016,18:00
Eduard Makhoul
United Kingdom