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

Burned area data time series from ltdr dataset for Canada (1981-2000) 267
tions: 1) a burned pixel could not be neighbor to water; and 2) a burned
pixel could not be isolated. In addition, to handle data uncertainty: 1) a
potentially burned was flagged as burned if it had a neighbor burned; and
2) a potentially burned pixel was flagged unburned if it did not have at
least two burned neighbors.
The algorithm trained with 298 burned pixels and 895 unburned in 1989
was applied to the entire study site, from 1984 to 1999. After inspecting
the results, we selected 1989, 1993, 1994, 1995 and 1998 for training.
1989 was used to estimate burned area from 1984 to 1992, whereas 1998
from 1996 to 1999. The method was the same as the one described above,
defining new minimum requirements, selecting the most significant variables
and keeping the same total probability thresholds for burned, potential
and unburned pixels.
3 - Results and discussion
Figure 1 shows the results of the LTDR burned area calculated for Western
Canada in comparison to the LAC (Chuvieco et al., 2008) and PAL (Riaño et
al., 2007) products. LTDR, when trained only with year 1989, showed similar
trends to LAC but burned area was underestimated. When training with
1989, 1993, 1994, 1995 and 1998 results matched much better LAC. 1984-
1992 corresponds to AVHRR 7, 9 and 11 satellites. 1993, 1994 were the end
of life for AVHRR 11 with high orbital degradation, 1995 was the beginning
of AVHRR 14, and r 2 was inconsistent between AVHRR 11 and 14 (Moreno
Ruiz et al., 2009). The algorithm does not overestimates burned area, but
needs to be retested in other parts of Canada to ensure that it is not overfitting
the test site. The use of the previous season to map burned area was
not significant, but the year after the fire was critical. French et al., (1995)
mapped burned area analyzing the burned scars the year following the fire,
since boreal forest takes more than a year to recover from burning.
Figure 1 - Burned
area estimations)
for different AVHRR
products.