Envisat RA-2 Individual Echoes: A Unique Dataset for a Better Understanding of Inland Water Altimetry Potentialities
Abstract
:1. Introduction
2. Theoretical Model of Specular Returns from Inland Waters
2.1. The Theoretical Complex Radar Altimeter Echo, (n,r)
- -
- There is zero reflectivity from land: all reflectivity is from water surfaces.
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- Water surfaces are flat: there is no wind roughening.
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- The water surface area is known exactly: location and extent.
2.2. The Spatial Extent of Specular Echoes and Its Implications
2.3. Very Small Water Bodies
2.4. Model Examples for Larger Water Bodies
3. Range Determination for a Specular Target
3.1. Phase-Focused Method
3.2. Simplified Algorithm
3.2.1. Doppler Velocity Estimation
3.2.2. Coherence Estimation
3.2.3. Water Level
4. Selected Case Studies
4.1. Description of the Dataset
4.2. Rio Nahuapa
4.3. Semliki River
4.4. Prek Toal Flood Area
5. Discussion and Concluding Remarks
Acknowledgments
Author Contributions
Conflicts of Interest
Abbreviations
AGC | Automatic Gain Control |
CPA | Closest Point of Approach |
ESA | European Space Agency |
GPU | Graphics Processing Unit |
IE | Individual Echo |
Jason-CS | Jason Continuity of Service (now Sentinel-6) |
LRM | Low Resolution Mode |
MSC | Magnitude Squared Coherence |
OSTST | Ocean Surface Topography Science Team |
PRF | Pulse Repetition Frequency |
RA-2 | Radar Altimeter 2 |
RAIES | RA-2 Individual Echoes and S-band data for new scientific applications for ocean, coastal, land and ice remote sensing |
RCS | Radar Cross Section |
RGW | Range Gate Width |
SAR | Synthetic Aperture Radar |
SARAL | Satellite with ARgos and ALtiKa |
SNR | Signal-to-Noise ratio |
SWOT | Surface Water and Ocean Topography |
Appendix A. Fitz Doppler Algorithm
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Parameter | Value |
---|---|
Orbital height | 773 km |
Orbital inclination | 98.276° |
Radar frequency | 13.5753 GHz |
Doppler velocity Nyquist | 9.91 m/s |
Range gate | 0.4688 m |
PRF | 1795 |
Number of echoes in a record | 1984 (1.1 s) |
Ground distance between echoes | 3.8 m |
Date | Tonle Sap Level (m) (Ref. ESA) |
---|---|
30 May 2007 | 3.8 |
4 July 2007 | 5.1 |
8 August 2007 | 6.7 |
12 September 2007 | 9.1 |
17 October 2007 | 10.4 |
21 November 2007 | 10.3 |
26 December 2007 | 7.5 |
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Abileah, R.; Scozzari, A.; Vignudelli, S. Envisat RA-2 Individual Echoes: A Unique Dataset for a Better Understanding of Inland Water Altimetry Potentialities. Remote Sens. 2017, 9, 605. https://doi.org/10.3390/rs9060605
Abileah R, Scozzari A, Vignudelli S. Envisat RA-2 Individual Echoes: A Unique Dataset for a Better Understanding of Inland Water Altimetry Potentialities. Remote Sensing. 2017; 9(6):605. https://doi.org/10.3390/rs9060605
Chicago/Turabian StyleAbileah, Ron, Andrea Scozzari, and Stefano Vignudelli. 2017. "Envisat RA-2 Individual Echoes: A Unique Dataset for a Better Understanding of Inland Water Altimetry Potentialities" Remote Sensing 9, no. 6: 605. https://doi.org/10.3390/rs9060605