7th Workshop on Forest Fire Management - EARSeL, European ...

The global MODIS burned area product: validation results 157
face, (vegetation re-growth, dissipation of ash and charcoal by wind and
rain) and on the spectral bands available for the analysis (Eva and Lambin,
1996; Trigg and Flasse, 2000).
It is always preferable to use two TM acquisitions and then map the area
that burned between the acquisition dates. In this way, fires that occurred
before the first acquisition date are not mistakenly mapped as having
burned between the two acquisition dates. Further, using two acquisitions
provides several interpretative advantages over single date data for mapping
burned areas. These include a reduction in the likelihood of spectral
confusion with spectrally similar static land cover types (e.g. water bodies,
dark soil), and the option to interpret the data by mapping relative changes
rather than using single image classification approaches (Roy et al., 2005).
Figure 1 - regression between proportion of area burned as detected by the MCD45 product (y
axis) and by the Landsat reference data (x axis) over seven sites in Europe and seven sites in
Australia, using 5 x 5 km cells.
3 - Validation results
The MCD45 product run globally for the first time as part of the fourth general
reprocessing of the MODIS products suite (Collection5). The version of
the algorithm used for collection 5 was intentionally a conservative one,
and in several instances the comparison with Landsat data highlights the
presence of ommission errors. A modified, less conservative version of the
algorithm will run as Collection 5.1 during the Summer of 2009, and this
new version will replace the existing Collection5. Figure 1 shows preliminary
results of the validation of a prototype of collection 5.1 over Europe
and Australia, adopting the validation protocol for the reference data and
using the same regression over 5 x 5 km cells adopted for the validation
over Southern Africa of Collection5 (Roy and Boschetti, 2009).