Abstract
Monitoring ecosystems at regional or continental scales is paramount for biodiversity conservation, climate change mitigation, and sustainable land management. Effective monitoring requires satellite imagery with both high spatial resolution and high temporal resolution. However, there is currently no single, freely available data source that fulfills these needs. A seamless fusion of data from the Sentinel-3 and Sentinel-2 optical sensors could meet these monitoring requirements as Sentinel-2 observes at the required spatial resolution (10 m) while Sentinel-3 observes at the required temporal resolution (daily). We introduce the Efficient Fusion Algorithm across Spatio-Temporal scales (EFAST), which interpolates Sentinel-2 data into smooth time series (both spatially and temporally). This interpolation is informed by Sentinel-3’s temporal profile such that the phenological changes occurring between two Sentinel-2 acquisitions at a 10 m resolution are assumed to mirror those observed at Sentinel-3’s resolution. The EFAST consists of a weighted sum of Sentinel-2 images (weighted by a distance-to-clouds score) coupled with a phenological correction derived from Sentinel-3. We validate the capacity of our method to reconstruct the phenological profile at a 10 m resolution over one rangeland area and one irrigated cropland area. The EFAST outperforms classical interpolation techniques over both rangeland (−72% in the mean absolute error, MAE) and agricultural areas (−43% MAE); it presents a performance comparable to the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) (+5% MAE in both test areas) while being 140 times faster. The computational efficiency of our approach and its temporal smoothing enable the creation of seamless and high-resolution phenology products on a regional to continental scale.
Originalsprog | Engelsk |
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Artikelnummer | 1833 |
Tidsskrift | Remote Sensing |
Vol/bind | 16 |
Udgave nummer | 11 |
Sider (fra-til) | 17 |
ISSN | 2072-4292 |
DOI | |
Status | Udgivet - 2024 |
Bibliografisk note
Funding Information:This research was conducted in the context of the project RAMONA, Rangeland Monitoring for Africa, funded by the European Space Agency (ESA) under the EO Science for Society, grant number 4000136180/21/I-NB, and partly funded by DHI\u2019s research contract with the Danish Ministry of Higher Education and Science. T. Tagesson was additionally funded by the Swedish National Space Agency (SNSA 2021\u201300144 and 2021\u201300111) and FORMAS (Dnr. 2021\u201300644). R. Buitenwerf also considers this work to be a contribution to the Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), funded by Danish National Research Foundation (grant DNRF173).
Publisher Copyright:
© 2024 by the authors.