The Brazilian Cerrado, the largest tropical savanna region in the world, covering approximatelly 45% of South America, is marked by a pronounced contrast in precipitation, a large land cover and floristic diversity and rapid human induced changes.
Due to its geographical extension and strong seasonality of the main physiognomies, remote sensing based assessments and mapping of the Cerrado landscapes is a major challenge.
Within this context, moderate resolution imagery datasets, as those provided by the MODIS sensor onbord the Terra and Aqua platforms are certainly the best alternative available for systematic land cover monitoring. The MODIS data is made available, in HDF format and at no cost, atmospherically corrected, cloud screened, and geocoded, through different standard data products, including the “MOD13” vegetation indices (VI). The MOD13 comprises two vegetation indices, the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI), which are indeed a compositing of multiple observations within a 16 days period. In addition, the MOD13 product includes a set of reflectance bands (blue, red, NIR, and MIR) and is accompanied with Science Data Sets (SDS) of ancillary information, including solar zenith angle, sensor view angle, and quality assurance (QA) metadata layers that describe on a per pixel basis, the quality of the reflectance input data and computed VI output data.
Althought its “ready-to-use” format, the MOD13, particularly concerning its QA layer decoding, require some cautious prior to its utilization. With this respect, and as part of its mission to be a geographical data and information provider for the Cerrado biome, the Image Processing and GIS Lab of the Federal University of Goias (LAPIG / UFG), is compiling MOD13Q1 (250m resolution) QA screened GeoTiff mosaics for the entire Cerrado biome, considering every compositing period of the 2001 - 2005 timeframe.
The expectation is that these datasets, though primarily focused on the “Modeling and Synthesis of the Effects of Land Use Change on Carbon and Trace
Gas Budgets over the Amazon and Cerrado Regions” (LBA - III / TG 30), will be instrumental for a better monitoring and understanding of the Cerrado landscapes.
Science Theme: LC (Land Use and Land Cover Change)