Characterization of SAR Mode Altimetry Data over Inland Waters – SHAPE project

Pierre Fabry (Along-Track, France)


Nicolas Bercher (Along-Track, France); Mònica Roca (IsardSAT, United Kingdom); Albert Garcia Mondejar (isardSAT, United Kingdom); Marco Restano (Serco/ESRIN, Italy); Américo Ambrózio (Deimos/ESRIN, Italy); Jérôme Benveniste (ESA/ESRIN, Italy)

Event: 2016 SAR Altimetry Workshop

Session: Applications, SAR for science

Presentation type: Type Oral

This work is the continuation of the work we presented at Hydrospace2015 as well as LPS2016 on the understanding of SAR mode altimetry in hydrology. It is part of the SEOM Sentinel-3 Hydrologic Altimetry Processor prototypE (SHAPE) study which aims at boosting the use of “SAR” mode altimetry data in hydrology. The main reason why Space Hydrology is still not operational at global scale is the variety of inland water scenes and scenarios which cannot properly be taken into account via a fixed processing chain. The complexity coming from the spatial diversity is emphasized by the strong temporal variability related to seasonal trends, extreme events and human action. The radar backscatter properties of water depend on wind conditions, surface current and trophic phenomenons.
The key aspect of the SHAPE project that is addressed here is the qualitative and quantitative characterization of the existing SAR Mode Altimetry data (CryoSat-2) over the inland water domain.
We run our new conceptual framework that eases and partially automates the analysis of CryoSat-2 measurements over inland waters through the use of water masks and the altimeter footprints. This serves to analyse the altimeter data together with the information on the water fraction within the instrument footprint. Seeveral improvements of our experiment makes it possible now to come with interesting results from the in depth analysis of the following physical and statistical indicators:
the Mean Individual Echoes, Stacks and Waveforms (SAR and RDSAR) as reference signals,
the Kurtosis (peakiness), Skewness (asymmetry), Standard Deviation for Stacks and Waveforms (SAR and RDSAR),
Specifically for the Stacks: Stack centre (mispointing and/or mean surface slope), Range Integrated Power (RIP) statistics, Stacks static & animated plots with a crossing over the non-water area, transition area and water area categories.
Among the improvements have been made in both the computations and the method to analyse the results :
- the 0% and 100% Water Fraction classes have been introduced
- the exercise has been run over 2 consecutive years (2014 and 2015) and over two different baselines (B and C)
- the Scaled Amplitude to Watt conversion has been applied to both waveforms and Stacks
- not only Beam-Doppler limited footprint is used but also Pulse-Doppler limited footprint to beter locate water content,
The outcome of this work may impact future retrackers and ease the mapping of water bodies through water detection criteria. Results are provided over Amazon and Danube.

Oral presentation show times:

RoomStart DateEnd Date
Auditorium Mon, Oct 31 2016,16:30 Mon, Oct 31 2016,16:45
Pierre Fabry