REDD+ products available for download
One important element of the climate change mitigation discussions is the role of forests and specifically the internationally-agreed activities for Reducing Emissions from Deforestation and forest Degradation while promoting conservation, sustainable management of forests, and enhancing forest carbon stocks (REDD+) (UNEP, 2014). REDD+ consists of forest-related activities implemented voluntarily by developing countries aiming at mitigating climate change. It can represent a cost-effective option for climate change mitigation, with economic, social, and other environmental co-benefits (e.g., conservation of biodiversity and water resources). REDD+ was introduced in the agenda of the UNFCCC in 2005, and has since evolved to an improved understanding of the potential positive and negative impacts, methodological issues, safeguards, and financial aspects associated with REDD+ implementation (Smith et al., 2014). For REDD+ programmes to be successfully devised in countries, technical understanding is needed on carbon accounting, national forest inventories, spatial planning, and biodiversity.
The Sentinel-2 Global Mosaic (S2GM) service, a component of the Copernicus Global Land Service, can contribute to REDD+ monitoring by providing analysis-ready composites from time-series of Sentinel-2 surface reflectance observations to monitor large forest areas (e.g., at country scale) in a timely manner. Analysis-ready refers to satellite data that can be readily used by non-experts, because typical pre-processing and correction steps have already been applied and because data and meta-information are provided in standard formats. The overarching requirement is selecting the most representative spectrum for a given location (i.e., pixel) chosen from the set of observations made during the temporal compositing period. For the REDD+ products, the compositing periods typically range from quarterly to half-yearly products.
In an effort to provide timely information to the REDD+ community, S2GM pre-processed products for REDD+ regions in the tropics according to IFORCE specifications, for pre-defined periods in 2019 and 2020. A detailed description of the regions and periods can be found here. For the processing of the 2019 data, a total of 3513 Sentinel-2 MGRS tiles (10’000 km² each) have been processed, each tile containing multiple observations (roughly every 3 to 5 days) in several spectral channels (6 spectral bands blue to short-wave infrared region). The data for the year 2020 covered 1415 tiles. The size of the output products equals 2.17 TB for the year 2019 and 0.9 TB for the year 2020. The datasets contain the spectral bands as well as metadata including quality indicators and details about the product lineage.
The figures below show quarterly (January to March 2019) and half-yearly (April to September 2019) mosaics of the Cerrado region in Brazil. This example nicely demonstrates how the mosaic provided through the Sentinel-2 Global Mosaic service can help to track changes in a timely manner. In the detailed view (Figure 1, right), human activities close to the forested areas are clearly visible. Comparing the S2GM mosaic products with Google Earth imagery (Figure 2) shows the timeliness of the provided information. In the upper central part, for instance, new agricultural fields are visible in the Sentinel-2 based products (Figure 2b), which are not apparent in the Google Earth imagery (Figure 2a). Thus, the S2GM products allow a faster detection of human-induced land cover changes. Focusing on the smaller region (red rectangular in Figure 2b), one can spot more recent activities on the ground (cf. Figure 3). Again, the comparison between the Google Earth imagery (Figure 3a) and the S2GM product (Figure 3b) clearly demonstrates the value of the mosaicking service.
Figure 1: Quarterly (January to March 2019, left) and half-yearly (April to September 2019, right) mosaicking products for the Cerrado region in Brazil.
Figure 2: Comparison of most recent Google Earth imagery, presumably a composite of the period 2013-2016 (a), and the Sentinel-2 Global Mosaic (S2GM) service product - April to September 2019 (b) for the region indicated with the red rectangular in Figure 1. The S2GM products clearly provide more recent information, which can be seen for instance through the newly evolving agricultural fields in the upper central part in (b). The red rectangular in (b) refers to the detail shown in Figure 3.
Figure 3: Spatial detail indicated in Figure 2, with Google Earth imagery, presumably a composite of the period 2013-2016 (a), and S2GM product - April to September 2019 (b). Again, the added value from the S2GM product is clearly visible with the apparent human-induced changes in the S2GM product.
Smith P., M. Bustamante, H. Ahammad, H. Clark, H. Dong, E. A. Elsiddig, H. Haberl, R. Harper, J. House, M. Jafari, O. Masera, C. Mbow, N. H. Ravindranath, C. W. Rice, C. Robledo Abad, A. Romanovskaya, F. Sperling, and F. Tubiello, 2014: Agricul-ture, Forestry and Other Land Use (AFOLU). In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA)
UNEP (2014) Forests in a Changing Climate: A Sourcebook for Integrating REDD+ into Academic Programmes, United Nations Environment Programme, Nairobi, Kenya