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Pulse-Pair (Doppler) Processing of Envisat Individual Echoes R. Abileah 1 , S. Vignudelli 2

Pulse-Pair (Doppler) Processing of Envisat Individual Echoes R. Abileah 1 , S. Vignudelli 2 1 jOmegak, San Carlos CA, USA 2 CNR – Istituto di Biofisica, Pisa, Italy. Envisat individual echoes (IE) data Coherence between echoes Doppler processing of IE data Open ocean

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Pulse-Pair (Doppler) Processing of Envisat Individual Echoes R. Abileah 1 , S. Vignudelli 2

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  1. Pulse-Pair (Doppler) Processing of Envisat Individual Echoes R. Abileah1, S. Vignudelli2 1 jOmegak, San Carlos CA, USA 2 CNR – Istituto di Biofisica, Pisa, Italy

  2. Envisat individual echoes (IE) data Coherence between echoes Doppler processing of IE data Open ocean Coastal, tangential track Conclusions More complex examples presented in our companion poster presentation Coastal, perpendicular tracks Lakes Outline Pulse-Pair (Doppler) Processing of Envisat IE

  3. Envisat Individual Echoes (IE) Data Recordings Sample of worldwide distribution of 1-second IE records 1 second = 7 km= 1984 samples 1-second record (amplitude, phase not shown) Pulse-Pair (Doppler) Processing of Envisat IE

  4. Data collection started on September 2004 330 GB / year 1 second out of every 1 minute 1800 Hz Global coverage Level 1b processed data available via GPOD IE Inventory Pulse-Pair (Doppler) Processing of Envisat IE

  5. J. TOURNADRE, Signature of Lighthouses, Ships, and Small Islands in Altimeter Waveforms, 2007 ESA RAIES project  http://earth.esa.int/raies/ ESA SAMOSA http://www.satoc.eu/projects/samosa/ Philippa Berry, et al., Global Analysis of EnviSat Burst Echoes Over Inland Water , IEEE Transactions on Geoscience and Remote Sensing, 50 (5), 1980-1985, 2012-09-04 Specular returns from inland waters Prior IE Exploitations – Incoherent Methods Pulse-Pair (Doppler) Processing of Envisat IE

  6. Christine Gommenginger et al., NEW SCIENTIFIC APPLICATIONS FOR OCEAN, COASTAL, LAND AND ICE REMOTE SENSING WITH ENVISAT RADAR ALTIMETER INDIVIDUAL ECHOES, 2006 Christine Gommenginger, Assessment of Envisat RA-2 Individual Echoes over ocean, 2009 Concluded that low coherence and frequency aliasing made IE data unsuitable for delay-Doppler processing Prior IE Exploitations – Coherent (Doppler) Methods Pulse-Pair (Doppler) Processing of Envisat IE

  7. Doppler Processing Pulse-Pair (Doppler) Processing of Envisat IE

  8. Interpretation of Doppler Velocity Projected orbital vertical + horizontal velocities At Nadir the Doppler velocity corresponds to satellite vertical velocity (H_rate in data header) Pulse-Pair (Doppler) Processing of Envisat IE

  9. Pulse Pair Processing (PPP) Descriptions of the Doppler Spectrum Zero-lag power One-lag power m = 1,…, 128  . Velocity n = 1,…, 1984  Magnitudecoherence (at 1 lag) Pulse-Pair (Doppler) Processing of Envisat IE

  10. Correlation of (unwrapped) PPP Doppler Velocity to Orbital Vertical Velocity (H_rate)(Using many samples from open ocean) Data fit σ=0.2 m/s Pulse-Pair (Doppler) Processing of Envisat IE

  11. Doppler Filtered PPP Waveform M0 Passband filter Conventional waveform zn M0 Doppler filtered waveform H_rate Pulse-Pair (Doppler) Processing of Envisat IE

  12. Open Ocean Example (1/2) Pulse-Pair (Doppler) Processing of Envisat IE

  13. Open Ocean Example (2/2) Pulse-Pair (Doppler) Processing of Envisat IE

  14. Coastal Example (1/2) Pulse-Pair (Doppler) Processing of Envisat IE

  15. Coastal Example (2/2) Pulse-Pair (Doppler) Processing of Envisat IE

  16. Remarks & Conclusions Envisat’s 1800 Hz rate provides sufficient pulse-to-pulse coherence for Doppler processing Filtering at known vertical velocity sharpens altimeter response on Nadir point Producing one 7 km (1 sec) integrated waveform, or perhaps 2-3 segments Doppler filters out land contamination Pulse-Pair (Doppler) Processing of Envisat IE

  17. Our companion Poster presentation includes … • Coherence vs. sea state • Ground tracks perpendicular • to coastline • Slopping sea surface • topography Pulse-Pair (Doppler) Processing of Envisat IE

  18. Salvatore Dinardo and Jérôme Benveniste of European Space Agency provided access to the IE archive Roberto Cuccu of European Space Agency for his help in downloading data through the GPOD service Walter Smith of NOAA suggested the crucial test linking measured Doppler velocity with satellite vertical velocity Keith Raney of JHU/APL for review and comments Acknowledgments Pulse-Pair (Doppler) Processing of Envisat IE

  19. Thank you& special thanks to the CAWS committee for organizing a meeting in this beautiful place. Pulse-Pair (Doppler) Processing of Envisat IE

  20. AppendixMagnitude Coherence

  21. Statistics of Magnitude Coherence |γ| Pulse-Pair (Doppler) Processing of Envisat IE

  22. PPP (red) vs. Power Spectrum (blue) velocity estimates Pulse-Pair (Doppler) Processing of Envisat IE

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