Filters








32 Hits in 4.7 sec

A Semi-Analytical Model for Delay/Doppler Altimetry and Its Estimation Algorithm

Abderrahim Halimi, Corinne Mailhes, Jean-Yves Tourneret, Pierre Thibaut, Francois Boy
2014 IEEE Transactions on Geoscience and Remote Sensing  
Index Terms-Altimetry, Cryosat, delay/Doppler (DD) map (DDM), least squares (LS) estimation, synthetic aperture radar (SAR) altimetry.  ...  This analytical formula is obtained for a circular antenna pattern, no mispointing, no vertical speed effect, and a uniform scattering.  ...  Moreau, from Collecte Localisation Satellites, Ramonville-Saint-Agne, France, for the interesting discussions regarding the validation of the proposed model. The authors would also like to thank N.  ... 
doi:10.1109/tgrs.2013.2280595 fatcat:vqw7wn3dxjdijkix5yvyljs5xq

A generalized semi-analytical model for delay/Doppler altimetry

A. Halimi, C. Mailhes, J.-Y Tourneret, F. Boy, T. Moreau
2014 2014 IEEE Geoscience and Remote Sensing Symposium  
OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.  ...  NRE = K k=1 y k − s k θ 2 K k=1 y 2 k . (7) CONCLUSIONS This paper defined a generalized semi-analytical model for delay/Doppler altimetry, taking into account the effect of antenna mispointing.  ...  This paper proposes a generalized semi-analytical model for DDA taking into account the antenna mispointing angle.  ... 
doi:10.1109/igarss.2014.6947651 dblp:conf/igarss/HalimiMTBM14 fatcat:vxzzqsvqczdctbzbd3brl5v5ru

Including Antenna Mispointing in a Semi-Analytical Model for Delay/Doppler Altimetry

Abderrahim Halimi, Corinne Mailhes, Jean-Yves Tourneret, Francois Boy, Thomas Moreau
2015 IEEE Transactions on Geoscience and Remote Sensing  
In a previous paper, we have proposed a semi-analytical model for DDA, which considers some simplifications as the absence of mispointing antenna.  ...  Delay/Doppler altimetry (DDA) aims at reducing the measurement noise and increasing the along-track resolution in comparison with conventional pulse-limited altimetry.  ...  Thibaut, from Collecte Localisation Satellite, Toulouse, France, for the interesting discussions regarding the validation of the proposed model, and N.  ... 
doi:10.1109/tgrs.2014.2326177 fatcat:y42fvfxndzdbja7jx5vc6aedsm

Cramér-Rao Bounds And Estimation Algorithms For Delay/Doppler And Conventional Altimetry

Abderrahim Halimi, Corinne Mailhes, J.-Y. Tourneret
2013 Zenodo  
The first part of this paper introduces the semi-analytical model for delay/Doppler altimetry (DDA) that was recently defined in [2, 3] .  ...  The second contribution of this paper is the study of a new weighted least-squares (WLS) estimator for the parameters of the semi-analytical delay/Doppler model.  ... 
doi:10.5281/zenodo.43524 fatcat:5hlgrbppjjf6pccpkhhthbqdr4

Exploiting Time And Frequency Information For Delay/Doppler Altimetry

Francois Boy, Abderrahim Halimi, Corinne Mailhes, Thomas Moreau, J.-Y. Tourneret
2014 Zenodo  
for delay/Doppler altimetry.  ...  Based on these considerations, we introduced a new estimation algorithm for delay/Doppler altimetry which is the second contribution of this work.  ... 
doi:10.5281/zenodo.43918 fatcat:3oqs2ruqa5bgppklgdna72lgjm

Round Robin Assessment of Radar Altimeter Low Resolution Mode and Delay-Doppler Retracking Algorithms for Significant Wave Height

Florian Schlembach, Marcello Passaro, Graham D. Quartly, Andrey Kurekin, Francesco Nencioli, Guillaume Dodet, Jean-François Piollé, Fabrice Ardhuin, Jean Bidlot, Christian Schwatke, Florian Seitz, Paolo Cipollini (+1 others)
2020 Remote Sensing  
As a reference for validation, an ERA5-h wave model as well as an in-situ buoy dataset from the CMEMS INSTAC database are used.  ...  Understanding climate change and long-term planning for enhanced storm and flooding hazards are imposing more stringent requirements on the robustness, precision, and accuracy of the estimates than have  ...  Acknowledgments: The authors acknowledge the contribution of all the research groups that accepted to provide data and thus improve the significance of this work.  ... 
doi:10.3390/rs12081254 fatcat:2l3ncwsfw5hodjihmvqaatgrhu

A Facet-Based Numerical Model for Simulating SAR Altimeter Echoes From Heterogeneous Sea Ice Surfaces

Jack C. Landy, Michel Tsamados, Randall K. Scharien
2019 IEEE Transactions on Geoscience and Remote Sensing  
TABLE I COMPARISON I OF PHYSICAL MODELS FOR THE BACKSCATTERED SAR ALTIMETER ECHO Analytical model approximates the rough surface impulse response with a Gaussian function; Semi-analytical model includes  ...  (Note that several other semi-analytical models have been developed for the backscattered SAR altimeter echo from open ocean, e.g. [28, 30] ).  ...  He has used terrestrial and airborne Light Detection and Ranging (LiDAR), as well as satellite laser and radar altimetry, to study the multi-scale properties of sea ice surface roughness and understand  ... 
doi:10.1109/tgrs.2018.2889763 fatcat:cxfmlubukrckle3wyo4ahleksy

The IEEE-SA Working Group on Spaceborne GNSS-R: Scene Study

Hugo Carreno-Luengo, Adriano Camps, Chris Ruf, Nicolas Floury, Manuel Martin-Neira, Tianlin Wang, Siri Jodha Khalsa, Maria Paola Clarizia, Jennifer Reynolds, Joel Johnson, Andrew O'Brien, Carmela Galdi (+13 others)
2021 IEEE Access  
THE MOST GENERIC GNSS-R OBSERVABLE: THE DELAY DOPPLER MAP The basic GNSS-R observables are the so-called delay-waveforms and Delay Doppler Maps (DDMs) (Fig. 3) .  ...  Empirical Geophysical Model Functions (GMFs) for the two Level 1 observables: (a) Delay Doppler Map Average DDMA, and (b) Leading Edge Slope LES, at an incidence angle of ~ 30°, overlaid on log (density  ... 
doi:10.1109/access.2021.3089762 fatcat:4dx5adyg2fe7dnxeet62zjlcdi

Marine Gravity Anomaly Mapping for the Gulf of Tonkin area (Vietnam) using Cryosat-2 and Saral/AltiKa satellite altimetry data

Van-Sang Nguyen, Van-Tuyen Pham, Lam Van Nguyen, Ole Baltazar Andersen, Rene Forsberg, Dieu Tien Bui
2020 Advances in Space Research  
The objective of this study is to present a methodology for estimating marine gravity anomalies from CryoSat-2 and Saral/ AltiKa satellite altimeter data for the Gulf of Tonkin of Vietnam with a high-resolution  ...  GPS/leveling and tidal gauge of 31 tidal stations were used for assessing and choosing the best Earth Geopotential Model and Mean Dynamic Topography models for the study area (EIGEN6C4 and DTU15MDT models  ...  The Delay-Doppler altimeter accuracy on CryoSat-2 has higher range precision than ERS-1 and Geosat altimeters, and in theory, its range precision can be obtained at a 1-cm level for 1 Hz data (Andersen  ... 
doi:10.1016/j.asr.2020.04.051 fatcat:ti6uimnr4zcrdeuforw6gdfpou

Accurate Sea Surface heights from Sentinel-3A and Jason-3 retrackers by incorporating High-Resolution Marine Geoid and Hydrodynamic Models

M. Mostafavi, N. Delpeche-Ellmann, A. Ellmann
2021 Journal of Geodetic Science  
+ SAR for S3A and ALES+ for JA3).  ...  In terms of accuracy, the RMSE (with respect to a corrected hydrodynamic model) of S3A ALES+ SAR and Ocean retrackers based SSH were 4–5 cm respectively, whereas with the JA3 ALES+ and MLE4 associated  ...  , in-situ and modelled data' and PRG1129.  ... 
doi:10.1515/jogs-2020-0120 fatcat:kdjzk7busrdwvgr5dfriw2w3vu

Variational Retrievals of High Winds Using Uncalibrated CyGNSS Observables

Estel Cardellach, Yang Nan, Weiqiang Li, Ramon Padullés, Serni Ribó, Antonio Rius
2020 Remote Sensing  
content comes from only one pixel of the broader delay-Doppler map, finest achievable resolution in level-1 products over the sea, and (4) calibrates them against track-wise polynomial adjustments to  ...  Unlike other existing approaches, (1) this one is a variational technique that is based on a physical forward model, (2) it uses uncalibrated bin raw counts observables, (3) the geophysical information  ...  , and potential problems with delay-Doppler pixels that come from two cells on the surface (delay-Doppler ambiguity).  ... 
doi:10.3390/rs12233930 fatcat:c6w5htb6dvabxpjsg53xg6kgr4

Improving the iGNSS-R Ocean Altimetric Precision Based on the Coherent Integration Time Optimization Model

Xuezhi Sun, Wei Zheng, Fan Wu, Zongqiang Liu
2021 Remote Sensing  
It would provide theoretical support for the signal optimization processing and sea surface height retrieval of iGNSS-R altimetry satellites with high precision and high along-track resolution in the future  ...  Depending on the orbital altitude and the roughness of the sea surface, its value may also vary. Moreover, the model can significantly improve the precision for low signal-to-noise ratios.  ...  Acknowledgments: We would like to thank the Institute of Space Sciences (ICE, CSIC) and the Institute for Space Studies of Catalonia (IEEC) for providing the raw data processing results of the airborne  ... 
doi:10.3390/rs13224715 fatcat:jdensyguvrehbnpbrk7zaq542y

Ice Sheet Topography from a New CryoSat-2 SARIn Processing Chain, and Assessment by Comparison to ICESat-2 over Antarctica

Jérémie Aublanc, Pierre Thibaut, Amandine Guillot, François Boy, Nicolas Picot
2021 Remote Sensing  
The Median Absolute Deviation (MAD) between CryoSat-2 and ICESat-2 elevation estimates is 46.5 cm.  ...  About 250,000 space–time nearly coincident observations are identified and examined over the Antarctic ice sheet, and over a one-year period.  ...  They also warmly thank Sandberg Sørensen et al. for developing a SARInM benchmark, and making it available publicly.  ... 
doi:10.3390/rs13224508 fatcat:2jli2quknrbrtfquob5goi6fsy

Potential of ENVISAT Radar Altimetry for Water Level Monitoring in the Pantanal Wetland

Denise Dettmering, Christian Schwatke, Eva Boergens, Florian Seitz
2016 Remote Sensing  
Radar altimetry provides important measurements for monitoring and analyzing water level variations in wetlands and flooded areas.  ...  A comparison between altimetry-derived height variations and six in situ time series reveals accuracies of 30 to 50 cm RMS.  ...  Acknowledgments: The authors thank the following people and institutions for providing data and models: ESA for operating the ENVISAT mission and for disseminates the SGDR datasets. E.  ... 
doi:10.3390/rs8070596 fatcat:xbtuize3irdofl6ys67zziprha

The CYGNSS Mission: On-Going Science Team Investigations

Hugo Carreno-Luengo, Juan A. Crespo, Ruzbeh Akbar, Alexandra Bringer, April Warnock, Mary Morris, Chris Ruf
2021 Remote Sensing  
Each single Delay Doppler Mapping Instrument (DDMI) aboard the eight CYGNSS microsatellites collects forward scattered signals along four specular directions (incidence angle of the incident wave equals  ...  The CYGNSS mission was originally proposed for ocean surface wind speed estimation over Tropical Cyclones (TCs) using Earth-reflected Global Positioning System (GPS) signals, as signals of opportunity.  ...  Similarly, by deriving a semi-analytical expression of vegetation transmissivity, and soil reflectivity, it was demonstrated how SMAP and CYGNSS observations can be concurrently leveraged to estimate either  ... 
doi:10.3390/rs13091814 fatcat:vu44nmgt4be35bckwa5rvnb2pi
« Previous Showing results 1 — 15 out of 32 results