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

Estimation of national fire danger rating system 10 hour timelag fuel moisture content with MSG-SEVIRI data 135
of MSG-SEVIRI applying the algorithm proposed by Sobrino et al. (2008).
With this approach, the dependence of both surface and air temperature is
eliminated for the estimation of W.
Air temperature was retrieved by means of the TVX algorithm. The NDVI was
calculated from SMAC corrected bands centered in 0.6µm and 0.8µm. LST
was retrieved with a split window algorithm (Sobrino et al., 2004). The
algorithm was applied in a window of 7x7 pixels centered in our station,
and adopting a NDVI max of 0.996.
3.2 - Calculation of Equilibrium Moisture Content and 10h FMC
The Equilibrium Moisture Content proposed by Simard (1968) was chosen
due to its simplicity and the wide spectrum in which it has been applied
(Aguado et al., 2007). The formulation only requires as inputs temperature
and relative humidity and it does not take into account hysteresis effects.
The calculation of the 10hr timelag FMC is straightforward by multiplying
the EMC by 1.28 (Bradshaw et al., 1983).
Relative humidity requires water vapor pressure e a as well as saturation
vapor pressure e s . The latter is related to air temperature T following an
exponential relationship (Allen et al., 1998). e a was estimated from remote
sensing data, by empirical fitting between the retrieved W and the vapor
pressure measured at the meteorological station during the year 2005.
4 - Results and discussion
A linear function was found to be the most suitable between e a and W. Eq.2
shows the fitted relationship (R 2 =0.56, p