# Fire Activity and Fuel Consumption Dynamics in Sub-Saharan Africa
## 4 Results
### MOD17 Productivity Assessment
The relationship in the northern hemisphere is weak (mean \(r\) = 0.76) and the slope indicates that the FRE-derived fuel consumption estimates are between 11 and 18% of the accumulated PSN. Of 24,249 fire clusters that cover the full time-series, 99% of the clusters have a lower FRE-derived fuel consumption estimates, with an average relative difference of \(-\)73% (mode of 92%) and the average scatter (0.13 Tg), bias (\(-\)0.03 Tg) and RMSD (0.004 Tg) are also high. In contrast, a strong relationship is evident in the southern hemisphere (mean \(r\) = 0.96) with the fuel consumption being 7-8% of the accumulated PSN. Of 30,948 fire clusters, 99% have a lower fuel consumption estimate, with an average percentage difference of \(-\)88% (mode of \(-\)96%) and the average annual scatter (0.57 Tg), bias (\(-\)0.12 Tg) and RMSD (0.07 Tg) are also relatively high. Figure 5: The relationship between FRE-derived fuel consumption (Tg DM) and accumulated MODIS PSN (Tg) on a per-fire cluster basis in the northern (**a**) and southern (**b**) hemisphere Africa as a function of the average number of SEVIRI fire detections per pixel within each fire cluster. The grey shaded area represents the prediction interval and the blue shaded area is the slopes 95% confidence interval. Note that the \(x\)- and \(y\)-axis range differs among plots. The FRE-derived fuel consumption and Copernicus DMP in northern and southern hemisphere Africa (Figure 7) also display a strong relationship although the fuel consumption is 37% (northern  
Figure 6: The relationship between FRE-derived fuel consumption (Tg DM) and accumulated PSN (Tg) per-fire cluster basis for the northern (**a**) and southern (**b**) hemisphere Africa between 2005 and 2015. The grey shaded area represents the prediction interval and the blue shaded area is the slopes 95% confidence interval. Note that the \(x\)- and \(y\)-axis range differs among plots. hemisphere) and 31% (southern hemisphere) of the accumulated DMP. Accounting for the difference in the ratio between MODIS NPP and MODIS PSN discussed in Section 4.2, which indicates PSN estimates were \(\approx\)21% greater than NPP over southern hemisphere Africa, suggests FRE-derived fuel consumption is between 29-31% of the primary productivity estimate. [PERSON] et al., [PERSON] et al., (2018) compared SEVIRI fuel consumption estimates with integrated SPOT VGT NPP estimates over 18 fires and found closer agreement (i.e., higher combustion completeness) than found here, albeit across a far smaller number of samples (and using NPP data derived from SPOT VGT using a process similar to that used for the Copernicus DMP product). This difference in primary production data may help to explain the difference in slope between the analysis conducted here and that of reference [PERSON] et al. (2018). Unlike the comparison between accumulated MODIS PSN and SEVIRI FRE-derived fuel consumption (Figure 6a,b), where the correlation between the datasets differed in northern and southern hemisphere Africa, the relationship shown in Figure 7 is similar in both hemispheres. The comparison between the MODIS PSN and Copernicus DMP (Figure 3), also shows good agreement in the southern hemisphere but a weaker relationship in the northern hemisphere. Studies have found MOD17 productivity estimates to be underestimated in the Sahel region (e.g., references (S  
Figure 8 illustrates the relationship between FRE-derived fuel consumption and accumulated PSD for fire clusters in northern and southern hemisphere Africa for land cover types with >50 fire clusters. Similar to that shown in Figure 6, the correlation between fuel consumption and integrated PSN is strong in the southern hemisphere (the northern hemisphere delivers a weaker relationship), although there is also limited variation in the proportion of fuel consumed as a function of land cover type. Savanna, cropland and grassland are the dominant cover types in both hemispheres, and demonstrate similar slopes between FRE-derived fuel consumption (Tg DM) and MODIS PSN (Tg).