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Open AccessArticle

Analysis of GEDI Elevation Data Accuracy for Inland Waterbodies Altimetry

1
CIRAD, CNRS, INRAE, TETIS, University of Montpellier, AgroParisTech, 34093 Montpellier CEDEX 5, France
2
INRAE, IRD, Institut Agro, LISAH, Univ Montpellier, 34060 Montpellier CEDEX 1, France
3
AgroParisTech, 75005 Paris, France
4
LEGOS, CNES, CNRS, IRD, UPS-14 Avenue Edouard Belin, Université de Toulouse, 31400 Toulouse, France
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CESBIO (CNRS/UPS/IRD/CNES/INRAE), 18 av. Edouard Belin, bpi 2801, 31401 Toulouse CEDEX 9, France
*
Author to whom correspondence should be addressed.
Remote Sens. 2020, 12(17), 2714; https://doi.org/10.3390/rs12172714
Received: 7 July 2020 / Revised: 7 August 2020 / Accepted: 18 August 2020 / Published: 21 August 2020
The Global Ecosystem Dynamics Investigation (GEDI) Light Detection And Ranging (LiDAR) altimetry mission was recently launched to the International Space Station with a capability of providing billions of high-quality measurements of vertical structures globally. This study assesses the accuracy of the GEDI LiDAR altimetry estimation of lake water levels. The difference between GEDI’s elevation estimates to in-situ hydrological gauge water levels was determined for eight natural lakes in Switzerland. The elevation accuracy of GEDI was assessed as a function of each lake, acquisition date, and the laser used for acquisition (beam). The GEDI elevation estimates exhibit an overall good agreement with in-situ water levels with a mean elevation bias of 0.61 cm and a standard deviation (std) of 22.3 cm and could be lowered to 8.5 cm when accounting for instrumental and environmental factors. Over the eight studied lakes, the bias between GEDI elevations and in-situ data ranged from −13.8 cm to +9.8 cm with a standard deviation of the mean difference ranging from 14.5 to 31.6 cm. Results also show that the acquisition date affects the precision of the GEDI elevation estimates. GEDI data acquired in the mornings or late at night had lower bias in comparison to acquisitions during daytime or over weekends. Even though GEDI is equipped with three identical laser units, a systematic bias was found based on the laser units used in the acquisitions. Considering the eight studied lakes, the beams with the highest elevation differences compared to in-situ data were beams 1 and 6 (standard deviations of −10.2 and +18.1 cm, respectively). In contrast, the beams with the smallest mean elevation difference to in-situ data were beams 5 and 7 (−1.7 and −2.5 cm, respectively). The remaining beams (2, 3, 4, and 8) showed a mean difference between −7.4 and +4.4 cm. The standard deviation of the mean difference, however, was similar across all beams and ranged from 17.2 and 22.9 cm. This study highlights the importance of GEDI data for estimating water levels in lakes with good accuracy and has potentials in advancing our understanding of the hydrological significance of lakes especially in data scarce regions of the world. View Full-Text
Keywords: lidar; GEDI; elevations; lakes; altimetry lidar; GEDI; elevations; lakes; altimetry
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MDPI and ACS Style

Fayad, I.; Baghdadi, N.; Bailly, J.S.; Frappart, F.; Zribi, M. Analysis of GEDI Elevation Data Accuracy for Inland Waterbodies Altimetry. Remote Sens. 2020, 12, 2714. https://doi.org/10.3390/rs12172714

AMA Style

Fayad I, Baghdadi N, Bailly JS, Frappart F, Zribi M. Analysis of GEDI Elevation Data Accuracy for Inland Waterbodies Altimetry. Remote Sensing. 2020; 12(17):2714. https://doi.org/10.3390/rs12172714

Chicago/Turabian Style

Fayad, Ibrahim; Baghdadi, Nicolas; Bailly, Jean S.; Frappart, Frédéric; Zribi, Mehrez. 2020. "Analysis of GEDI Elevation Data Accuracy for Inland Waterbodies Altimetry" Remote Sens. 12, no. 17: 2714. https://doi.org/10.3390/rs12172714

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