## Results
### Timing of the Fires  
The timing of the fire can be derived from the active fire product derived from MODIS data and complemented by the S2 maps. As illustrated in Figure 8, coherence between the two in term of temporal pattern is visible.  
The active fire product gives us the precise date of the fire observation with a daily temporal resolution. The timing detected by S2 strongly depends on the time of acquisition of the image, theoretically every 10 days, and the absence of clouds at the time of acquisition. From the MODIS data active fires, it is observed that fires occur from the 26 December 2015 to the 10 April 2016. From S2 based maps it can be derived that the most important progression of fire happened between end of January and February 2016.  
Figure 8: Timing of the burnt areas detections with Sentinel 2 together with the MODIS active fire product in the north of the Republic of Congo. The logging roads come from [31]. (**A**) In the north of the study area. (**B**) In the south of the study area.  
From MODIS active fire detection and S2 maps (Figure 8), it is evident that fires started in different locations rather than expanding from a single origin. The combination of both products shows that the first fires happened at the southern edge of the Ngombe logging concession, in late December 2015-early January 2016 (Figure 8B). This part of forest is adjacent to a savanna. Following that, active fires are detected in the north of the area where a network of old logging roads exists.  
Burnt areas are observed on the S2 image of 22 January in three distinct locations shown in dark blue in Figure 8A. Two of these areas are located in a previously logged area, close to old logging roads. The third one is located along the main road. From the MODIS active fires data, it can be deduced that these areas started burning from 16 January.  
The fire continued spreading in these three locations but also started in new ones. In 10 days, from 22 January to 1 February, the estimated burnt area increased from less than 2000 ha to more than 18,000 ha. As no observations are available between those two dates, it is impossible to determine from the S2 maps if the fire spread from these places to the other ones or if there were new sources of fire in the meantime. However, from the active fire data, some fires are detected between 27 and 29 January in the northeast of Figure 8A (yellow dots), close to the logging road. Following this, the fire spread to the rest of the area 30-31 January (orange dots in Figure 8A).  
After 1 February, the fire continued spreading but at a lower rate. Ten days later (11 February,) the burnt area has increased of about 4000 ha. The next S2 observation is 12 March where 8300 ha of additional burnt areas are observed. A gap in the acquisition of S2 prevents knowing when those fires exactly happened but the MODIS active fires product helps to determine the temporal dynamic of the fire. In the south of the concession (Figure 8B), most of the fires following the 11 February S2 acquisition seems to have happened around 15-17 February, while in the north (Figure 8A), they were observed 17-19 February. It seems than most of the burnt areas detected with S2 in March and April are events that happened earlier but were not captured by S2 due to the cloud coverage. An area in the south west also burnt during the period of 16-19 February and was only captured in the S2 images of April.