## 6 Conclusions
Instead we simply agree with the suggestions of [PERSON] _et al._[72] that the performance of any SEVIRI active fire detection algorithm would very likely benefit from a custom cloud mask designed specifically for active fire detection applications. Our results have demonstrated quantitatively that the performance of satellite-based active fire detection algorithms varies with geographical variations in active fire characteristics. Moreover, we found that SEVIRI's detection performance and MODIS active fire characteristics varied across the CAR even in the same land cover and percent tree cover, suggesting that it is possible for substantial differences in fire behaviour to occur within similar vegetation types and canopy structures found in the CAR. We concede, however, that SEVIRI's ground footprint subtends a distribution of landcover and percent tree cover such that the values of these parameters used to stratify SEVIRI and MODIS active fire pixels may not adequately represent the full nature of the landscape characteristics. Due to an increase in the MODIS' active fire omission rate away from nadir [57], the evaluation of the SEVIRI FTA detection algorithm depended on MODIS scan angle. Our results strongly suggest that viewing geometries must be taken into account if SEVIRI and MODIS observations are to be properly assimilated (e.g., [73]). We confirm a minimal bias between simultaneous SEVIRI and MODIS measurements of FRP of the same fire clusters, indicating that when both sensors detect the same fire they provide similar measurements of FRP. Hence we reaffirm the assertion of [PERSON] _et al._[17] that sensor-to-sensor differences in regional/seasonal energy budgets are attributed to SEVIRI omission errors, specifically the fact that SEVIRI fails to detect many of the low FRP pixels that MODIS, by virtue of its smaller pixel area at nadir, can in theory detect. Results here further agree with [PERSON] _et al._[17] and [PERSON] and [PERSON] [33] in so far as SEVIRI tends to measure more FRP than MODIS for low FRP active fire pixel clusters, and less FRP than MODIS for high FRP active fire pixel clusters. Without speculating on the reasons for this relationship, such behavior was also noticed in comparisons between MODIS and the Geostationary Operational Environmental Satellite (GOES) imager ([74]; Figure 2 therein). Since SEVIRI's active fire detection performance varies geographically due to spatial variations in active fire characteristics, and given that fire behavior fluctuates over the course of a day and over the course of a season, it can be inferred that SEVIRI's active fire detection performance also varies diurnally and seasonally. Although the coarse spatial resolution of geostationary images imposes a lower limit on the size and intensity (and thus FRP) of a detectable fire [17, 48, 72], we find that the numerous observations per day afforded by SEVIRI can be utilized as a detection strategy, ultimately reducing omission rates when evaluated on a daily basis. Therefore we suggest that future work examine the cumulative impact of SEVIRI's instantaneous active fire detection performance on the characterization of longer term fire regime parameters, such annual fire occurrence and seasonality. Overall this work has contributed significantly to the understanding of the performance of the SEVIRI FTA detection algorithm implemented at the LSA SAF to generate the operational Meteosat SEVIRI FRP-PIXEL product. It is expected that results herein will provide direction and focus for further improvements to the FTA detection algorithm. We also suggest that this work has important implications if SEVIRI observations are to be used to fill gaps between MODIS overpasses, or if SEVIRI is considered for inclusion into a network of geostationary satellites designed to achieve global diurnal active fire monitoring. The authors would like to thank three anonymous reviewers for their time and for providing very useful comments. P.H.F. was funded through a King's College London (SSPP) studentship award, and M.J.W.