International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
amount of biomass actually consumed by the fires and their
associated GHG emissions, the departure of current fire
occurrence from natural fire regimes, the role of fire in world
deforestation (REDD+), or the main factors behind fire
occurrence trends, on whether they are mostly socio-economic
(land-use transformation, for instance), political (fire
suppression policy) or climatically related.
2. ORGANIZATION OF THE FIRE CCI PROJECT
The fire-cci project is developed by a consortium of ten teams
from five different European countries: University of Alcalá,
CIFOR-INIA and GMV (Spain; GAF, DLR and Julich
(Germany), IRD and LSCE-CEA (France), ISA (Portugal), and
University of Leicester (UK). These groups cover the different
specialities required for the project: Earth Observation
scientists, Climate-atmospheric-vegetation modellers, and
System engineers. Since the project is part of a wider
framework of the CCI program, close relations have been
established with the teams developing other ECVs for the
program, such as aerosols, green-house gases, land cover and
clouds. All ECVs projects are also connected with the Climate
Modelling User Group (CMUG), which is composed by
researchers of the main European climate modelling centers
such as the Hadley Center, the Max Planck Institute,
Meteofrance and the ECMWF. The CMUG aims to reinforce
the connection of the different projects among them and with
the efforts of the climate modelling community.
3. METHODS
3.1 General framework
The fire cci project includes the following main phases (fig. 1):
* User requirement and definition of Product
Specifications.
e Pre-processing: geometric and radiometric processing
of input images.
BA detection and merging algorithms
Production of temporal series of BA data.
Validation and error characterization.
Testing BA data within climate-vegetation models.
Raw Data:
ATER WGT MERIS
(| gorithms |
Round robin |
Figure 1: Modules ofthe fire cci project
3.2 User requirements and product specifications
In order to generate a long and consistent time series of BA
products, which can be used by the climate, atmospheric and
ecosystem scientists for their modelling efforts, it is necessary
to understand in detail their needs. For that purpose a user
14
requirement survey was carried out, both considering the
scientists potentially interested in the BA product and the
literature. references describing actual uses of global BA
information. Forty seven scientists from different fire-related
communities (modellers, remote sensing experts, natural
hazards, forestry sector...) answered the questionnaire with their
specific BA information needs in terms of spatial and temporal
resolution, as well as formats and accuracy.
From that analysis, the product specifications (PSD) were
generated, taking also into account the limitations of the input
data and the CMUG and GCOS requirements. As a result of this
analysis, it was compromised that the fire cci project would
include two BA products, one at pixel level, which will be the
merging of the BA outputs of (A)ATSR, VEGETATION and
MERIS sensors at the best potential resolution, and another one
at grid level, at a 0.5 degree resolution, following the most
standard climate grid modelling (CGM) size. The BA
information will be provided at daily resolution, with temporal
composites of 1 month for the pixel product and 15 days for the
grid product. Each of the two products will be properly
documented, including date of detection, confidence level and
land cover for the pixel product, and sum of BA, confidence
level, number of cloud-free observations, fire size distribution
and dominant vegetation burned for the grid product. The BA
maps will be produced in .HDF and NetcCDF formats, using
the Plate Carré projection.
The target accuracy values of the BA product will be: 85 % of
user and producer accuracy (<15% of omission and commission
errors, with better than 1000 m of geo-location accuracy, + 3.5
days of temporal reporting accuracy, and 15% of temporal
stability.
3.3 Pre-processing
In terms of pre-processing, the BA products of the fire cci
project are based on level-1B and level-2 calibrated radiances
from (A)ATSR, VEGETATION and MERIS. To derive
corrected level2 products advanced image geometrical matching
has been applied to all sensors, using the Landsat GLS2000 as
the reference source. After calibrating the three sensors,
atmospheric and topographic correction based on the ATCOR
algorithm (Brazile et al, 2008) has been carried out with
MERIS and (A)ATSR images (VEGETATION were already
provided in corrected reflectances). Water, cloud snow and
cloud shadow masks have been developed to reduce the
potential confusions in the BA algorithms, since these covers
may present similar spectral characteristics to BA. Particularly
challenging was the water mask, since water bodies may be
seasonal (flooded areas), and the low radiances of water may be
easily mixed up with post-fire char.
The pre-processing chain has been implemented and
demonstrated on ten 500x500 km study sites. Those sites were
selected to test the BA algorithms, as they include different BA
characteristics, both with high and low fire occurrence areas.
They cover the major ecosystems affected by fires, as well as
areas previously reported as problematic for burned area
mapping (fig. 2). For those sites, the full temporal series (1995-
2009) was processed for the sensors available in each period.
3.4 BA algorithms
Burned area algorithms adapted to the three target sensors and
considering the diversity of burned area conditions at global
scale are being developed. They will primarily aim at the ten
study sites to demonstrate the consistency in the processing
chain for the BA product outputs. Algorithms currently tested
by the UAH-INIA and ISA teams are based on multitemporal
Inter
Figure 2
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