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- Title
Wetlands Water Level Measurements From the New Generation of Satellite Laser Altimeters: Systematic Spatial‐Temporal Evaluation of ICESat‐2 and GEDI Missions Over the South Florida Everglades.
- Authors
Palomino‐Ángel, Sebastián; Wdowinski, Shimon; Li, Shanshan
- Abstract
The ICESat‐2 and GEDI missions were launched in 2018, becoming the new generation of space‐borne laser altimeters. These missions provide unprecedented global geodetic elevations, opening great opportunities for water level monitoring. The potential of these altimeters has been demonstrated in open‐water environments such as lakes, rivers, and reservoirs. However, detailed evaluations in vegetated environments, such as wetlands, floodplains, and other areas not constrained by water canal networks, are essential for continued improvement and further hydrological application. We developed a systematic accuracy assessment of ICESat‐2 ATL08, and GEDI L2A products to monitor spatial‐temporal water level and depth dynamics over the South Florida Everglades wetlands. The evaluation was performed on data acquired between 2020 and 2021, using gauge‐based water level and depth estimates as references. The results showed an RMSE of 0.17 m (water level) and 0.15 m (water depth) for ICESat‐2 and 0.75 m (water level) and 0.37 m (water depth) for GEDI. The analysis suggested that nighttime acquisitions were more accurate for both missions than daytime ones. The low‐power beams achieved slightly higher accuracies than those of the high‐power beams over the evaluated wetlands. Water level retrieval was more problematic in densely vegetated areas; however, we derived a correction model based on the leaf area index that improved the accuracy by up to 75% for water depth retrievals from GEDI. Furthermore, the analysis provides new insights to understand the potential of the altimeters in monitoring the spatial‐temporal dynamics of water levels in the evaluated wetlands. Plain Language Summary: Monitoring water dynamics in wetlands is essential for understanding the ecosystem's functioning. Satellite‐based measurement of wetland water levels is an effective way of studying wetlands hydrology. In recent decades, available data from new satellites has increased, representing an opportunity to advance wetland monitoring. This study evaluated the latest generation space technology—satellite laser altimeter—which uses laser pulses to measure the elevation of land, ice, water, and vegetation on the Earth's surface. We used data from the ICESat‐2 and GEDI laser altimeters to measure water levels over the South Florida Everglades, a wide‐wetland area monitored by a dense ground‐based monitoring network. We evaluated the altimeters' accuracy by comparing them with the ground‐based measurements. Our findings demonstrated a strong agreement between the space‐ and ground‐based water levels, suggesting that altimeters can be used to monitor water levels in various wetlands. However, the altimeter characteristics and wetland vegetation influenced the observation's accuracy. The errors for ICESa‐2 were 0.17 m, and for GEDI were 0.75 m. We proposed a correction that reduced errors by up to 75% for GEDI. In summary, the new laser altimeters provide valuable measurements that can improve our understanding of water dynamics in wetlands worldwide, especially in data‐scarce regions. Key Points: We present a systematic accuracy assessment of the ICESat‐2 and GEDI missions for water level and depth retrieval in the Everglades wetlandsThe study proposes a correction model for the observations of the altimeters based on the leaf area indexThe results demonstrate the potential of the missions for monitoring the spatial‐temporal dynamics of water level and depth in wetlands
- Subjects
EVERGLADES (Fla.); FLORIDA; LASER altimeters; WETLANDS; WATER depth; WETLAND hydrology; LEAF area index; WETLAND conservation; WATER levels
- Publication
Water Resources Research, 2024, Vol 60, Issue 3, p1
- ISSN
0043-1397
- Publication type
Article
- DOI
10.1029/2023WR035422