The delay/Doppler radar altimeter

Raney, R. K.

doi:10.1109/36.718861

Cited by 402 publications

(259 citation statements)

References 12 publications

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“…As suggested in the previous section, this difference between the two sensors is mainly related to the difference in altimetric mode (SAR and pulse limited). In SAR altimetry, the Doppler post-processing allows the surface response to be sharpened and minimise the sensitivity of the waveform shape to surface roughness and volume scattering (Raney, 1998). Consequently, SAR altimetry is less impacted by the variability of ice surface properties than pulselimited altimetry, which enables realistic (positive) freeboard estimates to be retrieved.…”

Section: Comparison Of Along-track Radar Freeboard Estimatesmentioning

confidence: 99%

Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval

et al. 2017

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Abstract. Over the past decade, sea-ice freeboard has been monitored with various satellite altimetric missions with the aim of producing long-term time series of ice thickness. While recent studies have demonstrated the capacity of the CryoSat-2 mission (2010-present) to provide accurate freeboard measurements, the current estimates obtained with the Envisat mission (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) still require some large improvements.In this study, we first estimate Envisat and CryoSat-2 radar freeboard by using the exact same processing algorithms. We then analyse the freeboard difference between the two estimates over the common winter periods (November 2010-April 2011 and November 2011-March 2012. The analysis of along-track data and gridded radar freeboard in conjunction with Envisat pulse-peakiness (PP) maps suggests that the discrepancy between the two sensors is related to the surface properties of sea-ice floes and to the use of a threshold retracker.Based on the relation between the Envisat pulse peakiness and the radar freeboard difference between Envisat and CryoSat-2, we produce a monthly CryoSat-2-like version of Envisat freeboard. The improved Envisat data set freeboard displays a similar spatial distribution to CryoSat-2 (RMSD = 1.5 cm) during the two ice growth seasons and for all months of the period of study.The comparison of the altimetric data sets with in situ ice draught measurements during the common flight period shows that the improved Envisat data set (RMSE = 12-28 cm) is as accurate as CryoSat-2 (RMSE = 15-21 cm) and much more accurate than the uncorrected Envisat data set (RMSE = 178-179 cm).The comparison of the improved Envisat radar freeboard data set is then extended to the rest of the Envisat mission to demonstrate the validity of PP correction from the calibration period. The good agreement between the improved Envisat data set and the in situ ice draught data set (RMSE = 13-32 cm) demonstrates the potential of the PP correction to produce accurate freeboard estimates over the entire Envisat mission lifetime.

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Section: Comparison Of Along-track Radar Freeboard Estimatesmentioning

confidence: 99%

Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval

et al. 2017

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“…Raney, 1998;Gommenginger et al, 2012;Halimi et al, 2014). This, among other techniques, will be facilitated by replacing the conventional low-resolution mode (LRM) altimeter by one that has along-track Synthetic Aperture Radar (SAR) capabilities.…”

Section: Mission Objectivesmentioning

confidence: 99%

Jason continuity of services: continuing the Jason altimeter data records as Copernicus Sentinel-6

et al. 2016

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Abstract. The Sentinel-6 mission is proposed as a multipartner programme to continue the Jason satellite altimeter data services beyond the Jason-2 and Jason-3 missions. The Sentinel-6 mission programme consists of two identical satellites flying in sequence to prolong the climate data record of sea level accumulated by the TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 missions from 2020 to beyond 2030. The Sentinel-6 mission intends to maintain these services in a fully operational manner. A key feature is the simultaneous pulse-limited and synthetic aperture radar processing allowing direct and continuous comparisons of the sea surface height measurements based on these processing methods and providing backward compatibility. The Sentinel-6 mission will also include radio occultation user services.

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“…Delay-Doppler altimetry (DDA) was proposed in the 1990s [71] as a more efficient alternative to conventional altimetry. DDA uses the Doppler information contained in the returns (and essentially due to the satellite motion with respect to the surface) to resolve iso-Doppler subregions within the area illuminated by each altimetric pulse; therefore it allows an integration of the contributions coming from a large number of multiple looks on the same along-track Doppler cell.…”

Section: New Technologies: Delay-doppler Altimetry and Wide-swath Altmentioning

confidence: 99%

Satellite Altimetry and Key Observations: What We've Learned, and What's Possible with New Technologies

Scott¹,

Bourassa²,

Chelton³

et al. 2010

Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society

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The delay/Doppler radar altimeter

Cited by 402 publications

References 12 publications

Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval

Comparison of CryoSat-2 and ENVISAT radar freeboard over Arctic sea ice: toward an improved Envisat freeboard retrieval

Jason continuity of services: continuing the Jason altimeter data records as Copernicus Sentinel-6

Satellite Altimetry and Key Observations: What We've Learned, and What's Possible with New Technologies

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