## 4 Simulation of the Meteosat Third Generation Imager Fire Channel Potential
The BIRD image fragment has 600 \(\times\) 800 pixels, and its center is located at 40\({}^{\circ}\) N, 7.6\({}^{\circ}\) W. The expected spatial resolutions of MTG-I/FCI at this latitude are 1.06 \(\times\) 1.58 km\({}^{2}\) in the 1 km sampling mode or 2.12 \(\times\) 3.16 km\({}^{2}\) in the 2 km sampling mode, and 5 \(\times\) 8 or 10 \(\times\) 16 BIRD pixels are aggregated for the 1 km pixels or 2 km pixels of MTG-I/FCI, respectively. The MTG-I/FCI fire application channel simulation results are summarized in Table 9.  
The small difference between 35 hot clusters detected in the MODIS image fragment (Figure 10, left image) and 30 hot clusters detected in the simulated MTG-I/FCI 1 km resolution image fragment (Figure 11) can be explained by the slightly higher spatial resolution of MODIS compared to the simulated MTG-I/FCI resolution in the 1 km mode, which results in a pixel size of 1.06 \(\times\) 1.58 km over Portugal. However, MODIS data permit calculating a total, i.e., aggregated over the whole scene, FRP of only 12.0 GW for this scene. This is low compared with the total FRP of 15.9 GW in the simulated MTG-I/FCI image with the 1 km sampling mode. A total of 2 out of 97 hot pixels in the simulated MTG-I/FCI image in the 1 km sampling mode slightly exceed the 450 K saturation level of its MIR channel, while in the 2 km sampling mode, all MIR pixel temperatures are below 422 K. The hot pixels in the MTG-I/FCI TIR channel remain again far from the saturation level of 400 K for both the 1 km and 2 km sampling modes. The analysis of the bi-spectral retrievals for fire attributes leads to similar conclusions to the Benin fire scenario for the Portugal fire scenario (see Table 9):  
* In spite of the fact that MTG-I/FCI detects much fewer active fires than BIRD, due to the omission of weaker or smaller fires, it registers nearly the same total FRP. * The total FRP value differences from BIRD are still smaller for the Portugal fire scenario (15.9 and 15.2 GW for the 1 and 2 km MTG-1/FCI sampling modes compared with 15.9 GW for BIRD), since the proportion of large fires in Portugal was higher than in Benin. * In the 1 km sampling mode, the simulated MTG-I/FCI MIR and TIR channel data allow the retrieval of the following, both for a much smaller number of hot clusters, compared with the BIRD data:
* The effective fire temperature applying the accuracy condition of 100 K;
* The effective fire area applying the \"factor of 2\" accuracy condition. * However, in the 2 km sampling mode, the simulated MTG-I/FCI MIR and TIR channel data do not meet these applied accuracy conditions for all the detected hot clusters. Nevertheless, for the Portugal and Benin fire scenarios, the \"30% FRP accuracy\" condition is achieved for two out of every three hot clusters in both MTG-I/FCI sampling modes, which corresponds to the 63-67% in the outer right column of Table 9.  
Figure 11: Simulated MTG-I/FCI 1 km sampling mode MIR image using the BIRD image obtained over the Castelo Branco region in Portugal on 4 August 2003 at 12:04 h GMT. The performed simulation allows the following assessment of the fire detection and analysis capability of the MTG-I/FCI fire application channels for typical African and European wildfire scenarios (such as the Benin and Portugal scenes):  
* The specified dynamic range of the MTG-I/FCI MIR channel--with a 450 K saturation temperature (see \"Maximum Signal\", in Table 7 for fire application channels)--would allow: \(\circ\) Unsaturated imaging of all the fires in the 2 km mode; \(\circ\) Nearly unsaturated imaging in the 1 km mode (only 2 out of 97 hot pixels in the Portugal fire scene had an MIR channel pixel temperature of 460-470 K, i.e., higher than the expected saturation level at 450 K). * The MTG-I/FCI TIR channel--with a 400 K saturation temperature--will be far from saturation for all the fires.