Moorland Change Map (England)

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The MCM analysis uses Sentinel 2 Analysis Ready Data from the DEFRA Earth Observation Data Service (EODS), a vector dataset showing Heather dominated habitat, and training data collected from visual assessment of the Sentinel 2 imagery. The MCM process is undertaken primarily through the Python and R scripting language. These access a variety of modules, the majority of which are open source. This process goes through many stages, including calculating a Normalised Difference Vegetation Index (NDVI) difference dataset and thresholding upon this to separate change and no change. The threshold value is set individually for each upland, each year. These values are calculated from the medium threshold value of several models, trained using data collated from reviewing Sentinel 2 data. The analysis takes Sentinel 2 imagery for before and after the burn season. Due to cloud conditions, which are especially problematic in the uplands, the images can be a couple of months before the burn season starts or after the burn season finishes. As such, the change identified will not have necessarily have happened within the managed burn season. Clouds can also still be found obscuring some areas and these are masked from the analysis and marked as cloud in the results. The MCM results, as with all EO analysis, are not 100% accurate and validation is undertaken to assess the level of the analysis. Validation data comes from a combination of field data, collected by Natural England’s local and national teams and further data collected from visual assessment of the Sentinel 2 imagery. Further details of the MCM are available through the Technical Information Note available here: http://publications.naturalengland.org.uk/publication/5699825585881088