# Fire Activity and Fuel Consumption Dynamics in Sub-Saharan Africa
## 4 Results  
### Annual and Seasonal Fire Dynamics  
The interannual dynamics of the SEVIRI-derived FRE estimates for the northern and southern African hemispheres (shown in Figure 1a) match quite closely those of the MODIS burned area measurements (Figure 1b) and GFED total fuel consumption estimates (Figure 1c), though in general somewhat greater interannual variability is seen in the FRE data. The annual variation in SEVIRI FRE indicates that, in the northern hemisphere, fire activity peaked in 2007 and is decreasing by 11 Tj/year. A decreasing trend in also evident in the annual burned area (\(-2.75\) Mha/year) although it is less pronounced than that of the FRE. Using the same burned area product although a different time-series (2001-2012), reference [16] found a decreasing trend in burned area in the northern hemisphere which was attributed to the expansion of cropland into savanna reducing the occurrence of fire. In the southern hemisphere, trends in these parameters are similar and are rather weak but slightly negative over the thirteen years examined and with local peaks around 2010/11. Over a different time frame, reference [16] found an increasing burned area trend in southern hemisphere Africa which was attributed to El Nino Southern Oscillation (ENSO) climate anomalies leading to increased fire activity. Figure 1b clearly demonstrates a fall in burned area since 2012, however. As evident from Figure 1a,b, annual dry matter (DM) fuel consumption estimates from GFED (version 4; not yet including the unvalidated small fire correction of reference [58]; Figure 1c), follow a similar trend to burned area and FRE, but do exhibit some different dynamics. Figure 1: _Cont._Using the conversion factor (0.37 kg DM MJ\({}^{-1}\)) described in reference [20] and whose magnitude has recently been confirmed as valid for satellite data retrievals by reference [28], SEVIRI-derived FRE retrievals deliver annual fuel consumption estimates ranging from 127-214 Tg and 208-299 Tg in northern and southern hemisphere Africa respectively, far lower than the GFED fuel consumption estimates (by 77 to 85%). Cloud obscuration, tree cover obscuration of surface fire FRP, and the inability of SEVIRI to detect fires burning below \(\approx\)40 MW very likely contribute to these low totals, but the relatively consistent ratio between the FRE-derived and GFED estimates (0.14-0.23 between 2004-2016) shown in Figure 1a,c suggests a relationship between these two approaches which apply quite different methods to estimate landscape fire fuel consumption. Despite the findings of reference [28], other relatively recent research suggests that the relationship between FRE and fuel consumption might not be the same for larger fires, which contain propagating fire fronts and greater fuel moisture variability [35; 59]. The annual dynamics of monthly FRE-derived fuel consumption in northern and southern hemisphere Africa (Figure 2a,b) indicates that the months in which fuel consumption is greatest are broadly consistent on an annual basis, whilst fuel consumption outside of the fire season is more variable albeit much lower in magnitude. June, July, August and September are the peak months of fuel consumption in the southern hemisphere although annual variations of 25-50% are evident in the latter two months. The peak months of fuel consumption (June-September) are characterised by very weak trends over time (both positive and negative). Fire activity during the biomass burning season, which in the northern hemisphere occurs between November-March and May-October in the southern hemisphere, drive the interannual trends observed in Figure 1a. The large increases in southern hemisphere fuel consumption in August and September in 2008 and 2010 coincide with the extensive fire activity that occurred in Botswana in these two years, where 11 and 13 Mha burned, respectively [60].