## 1 Introduction
### Biros-Vilts \"Suomi NPP\" Data Comparison for the Devastating \"Paradise Fire\" in California/US  
The devastating \"Paradise\" bushfires in California, USA, were observed by FireBIRD between 10 and 14 November 2018. Figure 4 shows the movement of the \"Paradise\" fire fronts in a map projection of three FireBIRD data-takes. This map projection was developed by the DLR \"Zentrum fur satellitesetutzte Kriseninformation\", i.e., the Center for Satellite Based Crisis Information, to support the decisions of the regional authorities and the fire fighters. The small circles in Figure 5 show the pixel centers of VIIRS band I-4 records conducted from 8 to 14 November 2018. An excellent coincidence of the fire front movement observed by FireBIRD and VIIRS can be found in Figure 4 (the non-colored small circles in the center of Figure 4 stem from VIIRS data acquired on 8 November 2018, when FireBIRD could not observe the \"Paradise\" fire). Table 5 shows the following fire attributes of the \"Paradise\" fire for five days in November 2018, derived from FireBIRD data acquired for the fire zone shown in Figure 4 for the indicated dates and local times:  
* The aggregated FRP, i.e., the summarized Fire Radiative Power of all fires given in megawatts (MW);
* The mean effective fire temperature \(\mathrm{T_{F}}\), i.e., the calculated mean value of the effective fire temperature of all fires, in kelvin (K);
* The aggregated effective fire area \(\mathrm{A_{F}}\), i.e., the summarized burning area of all fires, in hectares (Ha);  
Figure 4: Yellow-, orange- and red-colored “Paradise” fire fronts, observed by VIIRS and TET-1 on 10, 12 and 14 November 2018, respectively. The non-colored small circles in the center stem from VIIRS data obtained on 8 November 2018. The number of MIR band pixels occupied or \"infected\" by fire of all fires (\"occupied\" means that the fire pixel area is, as the rule, partly filled with fire; N\({}^{>}\) 1 is the difference from the background pixels, which are not touched by fire);
* The aggregated area of all MIR band pixels occupied by fire \(\rm{P_{F}}\), i.e., the summarized pixel area of all pixels \"infected\" by fire, in Ha;
* The ratio k of the aggregated effective fire area \(\rm{A_{F}}\) to the aggregated area of all MIR band pixels occupied by fire \(\rm{P_{F}}\). The values of the fire attributes are presented in Table 5 for the whole fire scene, which is, by the way, quite different to the content of Table 4, where the fire attributes are shown for the single fire clusters. However, the estimates of the fire attributes in both tables were derived from the sub-pixel domain. It also seems interesting to mention that in the \"Paradise\" fire scene, the aggregated effective fire area \(\rm{A_{F}}\) is mostly two orders of magnitude lower than the aggregated area of all MIR pixels occupied by fire \(\rm{P_{F}}\). The area ratio of \(\rm{k=A_{F}/P_{F}}\) quantifies the mean value of the area of MIR pixels partly occupied by the detected fires in the observed scene. As the numbers in the lower line of Table 5 show, the values of k vary between 0.0018 (0.18%) and 0.026 (2.6%). According to these considerations, it is relevant to define the maximum possible \(\rm{k_{max}}\) indicating the upper threshold of MIR pixel occupation by fire; beyond this--due to the Stefan-Boltzmann law (the Stefan-Boltzmann law states that the total radiation of a blackbody is proportional to \(\rm{T^{4}}\), where T is the temperature of the blackbody, given in K)--signal saturation may occur.