Periodic Reporting for period 1 - MOVES (MOnitoring VEgetation status and functioning at high spatio-temporal resolution from Sentinel-2)
Periodo di rendicontazione: 2019-10-21 al 2021-10-20
High spatiotemporal resolution LAI/FAPAR/FCOVER products are urgently needed to characterize terrestrial ecosystem processes, supporting crop management activities at the parcel level and for better understanding land greening and browning phenomena at local scales. The overall objective of this project is to develop a robust, efficient and highly accurate LAI/FAPAR/FCOVER retrieval algorithm for Sentinel-2 data and therefore achieve the operational monitoring of vegetation structure and functioning at a high spatiotemporal frequency.
Due to the adverse impact of Covid-19, it is very hard to implement the project fully following the WP. For example, the time spending on field measurement, secondment and conference was significantly reduced because of the strict confinement. However, our project still achieved fruitful results. Main project results include:
(1) Proposed an integrated method for Sentinel-2 topographic and angular normalization, which could estimate the intrinsic vegetation reflectances and improve retrieval accuracy of biophysical parameters.
(2) Validated decametric (Sentinel-2) and kilometric LAI (MODIS, CGLS, SAF, GLASS and C3S) product in Maize Crops, which informed the retrieval algorithm improvement.
(3) Proposed a multiband constraint harmonization method for combined use of Sentinel-2 and Landsat 8, which contributes to generate spatiotemporally continuous time series of decametric data from the MSI-OLI virtual constellation.
(4) Developed an algorithm to generate daily 16-m biophysical parameter maps by the combination of LAINet observation system and Gaofen-1/6 satellite images, which is crucial for agricultural monitoring.
(5) We also compared the performance of structure and physiology vegetation indices for photosynthetic phenology monitoring, and extend the application of CCI (a reliable proxy for tracking GPP dynamics) to sentinel-2 by replacing narrowband green with broadband green.
The results of the above work have been and will further be made available to targeted peers:
(1) Parts of results have been published in top-ranking journal on EO (6 SCI papers, with 1 on Geophysical Research Letters, 1 on IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 1 on IEEE Geoscience and Remote Sensing Letters, and 3 on Remote Sensing), and others are in review (1 on Photogrammetric Engineering and Remote Sensing and 1 on Journal of Remote Sensing) or preparation.
(2) A project website was successfully established: https://www.creaf.cat/monitoring-vegetation-status-and-functioning-high-spatio-temporal-resolution-sentinel-2
(3) Our results will inform the decision-making for the stakeholders in agriculture, forestry, and insurance.
Representativeness is the prerequisite for improving the retrieval accuracy of biophysical parameter from remote sensing data. We collected field measurements from multi-instruments, including LAI-2000, digital hemispherical photography, and wireless sensor network, and constructed a training dataset with high representativeness. A machine learning (specifically, random forest) model was trained to link the collected field measuremts with corresponding reflectances. These technologies support us generating LAI/FAPAR/FCOVER maps of decametric resolution with daily revisiting frequency. In addition, we proposed a new threshold-based phenology extraction method which is directly applied to daily nonsmoothed time series without any additional preprocessing steps. This method is robust and computationally efficient for high spatiotemporal phenology monitoring.
With the help from our Chinese colleagues, we refined our wireless sensor network-based unattended field measurement system to support temporally continuous automatic measurement. We also developed a ground measurement method based on smartphone camera, which significantly improve the flexibility of the field work. With the collected field dataset from our newly developed instruments, we validated several decametric (Sentinel-2) and kilometric LAI (MODIS, CGLS, SAF, GLASS and C3S) products in Maize Crops.
The research results achieved during the grant period would be successively published on scientific journal, and social media (e.g. Twitter, Youtube). In future, the ER will devote himself to becoming a messenger to promote the exchange of science and technology between the European Union (EU) and China.