# The DLR FireBIRD Small Satellite Mission: Evaluation of Infrared Data for Wildfire Assessment
## 3 Results and Discussion
This analysis is performed by a comparison of yielded FRP results between the systems. Figure 4: FireBIRD active fire data (derived using the MWIR method) and reference data for a fire event in Palestine and Israel, November 2016. (**a**) shows active fires derived from a single FireBIRD/HSRS overpass (25 November 2016), pigmented by FRP. (**b**) shows MODIS active fire data of the Aqua/Terra overpass in closest temporal vicinity to the respective FireBIRD overpass. (**c**) shows VIIRS active fire data of the Suomi-NPP overpass in closest temporal vicinity to the respective FireBIRD overpass. Background: Stamen/OpenStreetMap shaded terrain map, shown in gray scale. As can be seen in the next line of the table, named _TP FRP ratio_, the FRP values derived from FireBIRD data are 11% higher on average than the reference data when the MWIR method is used on the subset with similar acquisition times. This result is in accordance with findings by [PERSON] et al. [5], who calculated a difference of 15% for the HSRS on the BIRD satellite with regard to a MODIS reference. In comparison to VIIRS, the FireBIRD average FRP values are 31% higher, representing a considerable bias with respect to MODIS. This is due to a lack of available FireBIRD active fire detections regarding the VIIRS reference, in the subset with a time lap of less than 45 min. Although the FireBIRD dataset with corresponding, timely MODIS overpasses contains 1398 fire detections in total (when using the LWIR method), only 346 detections are available for corresponding VIIRS overpasses. The MODIS results are thus considered to be more representative. Regarding the complete dataset, the difference to MODIS accounts for 24%, as well as 15% for VIIRS. Figure 5: FireBIRD active fire data (derived using the MWIR method) and reference data for a fire event in Chile, January 2017. (**a**) shows active fires derived from two FireBIRD/HSRS overpasses (26-31 January 2017), pigmented by FRP. (**b**) shows MODIS active fire data of the Aqua/Terra overpasses in closest temporal vicinity to the respective FireBIRD overpasses. (**c**) shows VIIRS active fire data of the two Suomi-NPP overpasses in closest temporal vicinity to the respective FireBIRD overpasses. Background: Stamen/OpenStreetMap shaded terrain map, shown in gray scale. When using the MWIR/LWIR method, the results range between 195% and 156% for both reference datasets. The MWIR method shows a higher degree of correspondence than MWIR/LWIR between FireBIRD and the reference results, since the same method is used for both products. The bias regarding reference FRP values is significantly greater in most cases when the LWIR/MWIR method is used. However, since the MWIR method is known to underestimate low intensity fires (<600 K), the real FRP values must be considered to be higher, and thus closer to the results of the MWIR/LWIR method. Although the methodology of deriving the FRP is different in these methods, they are both based on the same process of determining whether a pixel does contain an active fire. This means that the total number of determined active fires is identical for both methods. The slightly lower number when using the MWIR/LWIR method can be explained by the higher numerical complexity of the required subpixel analysis for this method. Detections are neglected when it is impossible to solve the calculation for \(T_{sub}\) and \(p\) numerically, as described in the methodology section. The MWIR method represents a simpler approach, which is advantageous in some cases because it is applicable to the complete set of active fire pixels. Figure 6: FireBIRD active fire data (derived using the MWIR method) and reference data for a fire event in California/USA, December 2017. (**a**) shows active fires derived from a single FireBIRD/HSRS overpass (12 December 2017), pigmented by FRP. (**b**) shows MODIS active fire data of the Aqua/Terra overpass in closest temporal vicinity to the respective FireBIRD overpass.