## 1 Introduction
### Biros-Vilts \"Suomi NPP\" Data Comparison for the Devastating \"Paradise Fire\" in California/US
Considering the high signal contribution of the hot area parts in fire-occupied pixels, a rough approximation (using two temperatures: \(\rm{T_{\rm{pix\ max}}}\), the maximum blackbody temperature in K when MIR pixel saturation may occur, and \(\rm{T_{\rm{fire\ max}}}\), the maximum fire temperature expected in the scene in K) can be proposed for \(\rm{k_{max}}\):  
\[\rm{k_{max}=[T_{\rm{pix\ max}}/T_{\rm{fire\ max}}]^{4}=A_{\rm{Fmax}}/P_{F}} \tag{3}\]  
This is true, because the signal of a pixel, generated by the product of \(\rm{P_{F}\times T^{4}_{\rm{pix\ max}}}\), is equal to the signal of the product of \(\rm{A_{Fmax}\times T^{4}_{\rm{fire\ max}}}\). Table 6 presents the following physical values and figures for the MODIS MIR band 22, the HSRS (on BIRD, TET-1 and BIROS) MIR band, the SLSTR MIR band F1 and the VIIRS (on Suomi NPP and NOAA-20) MIR band M-13:  
* Values of the nadir ground pixel sizes; \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Date** & **10.11.** & **10.11.** & **12.11.** & **14.11.** & **21.11.** & **22.11.** \\ \hline Local time & 00:19 h & 13:09 h & 13:14 h & 13:19 h & 21:18 h & 10:03 h \\ \hline Acquired by & TET-1 & TET-1 & TET-1 & TET-1 & BIROS & BIROS \\ \hline Aggregated Fire Radiative & \multirow{2}{*}{2792} & \multirow{2}{*}{3327} & \multirow{2}{*}{4953} & \multirow{2}{*}{1089} & \multirow{2}{*}{69.7} & \multirow{2}{*}{3.1} \\ Power/FRP/ (MW) & & & & & & \\ \hline Mean effective fire & \multirow{2}{*}{714} & \multirow{2}{*}{672} & \multirow{2}{*}{658} & \multirow{2}{*}{752} & \multirow{2}{*}{720} & \multirow{2}{*}{891} \\ temperature—T\({}_{\rm{F}}\) (K) & & & & & & \\ \hline Aggregated effective fire & \multirow{2}{*}{20.2} & \multirow{2}{*}{31.5} & \multirow{2}{*}{52.0} & \multirow{2}{*}{88.3} & \multirow{2}{*}{0.0191} & \multirow{2}{*}{0.0052} \\ area—A\({}_{\rm{F}}\) (Ha) & & & & & & \\ \hline Number of the occupied by & \multirow{2}{*}{1511} & \multirow{2}{*}{1738} & \multirow{2}{*}{2241} & \multirow{2}{*}{1173} & \multirow{2}{*}{188} & \multirow{2}{*}{17} \\ fire MIR-pixels & & & & & & \\ \hline Aggregated area of all by & \multirow{2}{*}{4366.79} & \multirow{2}{*}{5022.82} & \multirow{2}{*}{6476.49} & \multirow{2}{*}{3389.97} & \multirow{2}{*}{543.32} & \multirow{2}{*}{49.13} \\ fire occupied MIR-pixels— & & & & & & \\ \(\rm{P_{F}}\) (Ha) & & & & & & \\ \hline Mean area ratio & \multirow{2}{*}{0.0046} & \multirow{2}{*}{0.0063} & \multirow{2}{*}{0.0080} & \multirow{2}{*}{0.026} & \multirow{2}{*}{0.0018} & \multirow{2}{*}{0.011} \\ k = \(\rm{A_{F}}/P_{F}\) & & & & & & \\ \hline \hline \end{tabular} The colors of the three columns in Table 5 coincide with the colors of the fire fronts in Figure 4.  
\end{table} 
Table 5: Fire attributes of the “Paradise” fire for five days in November 2018, derived from four TET-1 records and two BIROS records. * The designed T\({}_{\rm pix\,max}\), i.e., the maximum temperature of an observed blackbody which would not lead to pixel signal saturation;
* The calculated k\({}_{\rm max}\), i.e., the value of the maximum area in the MIR pixels which are partly occupied by a flaming fire with a temperature of 1000 K in the observed scene;
* The derived maximum figures for (assuming a maximum fire temperature, expected in the fire scene of T\({}_{\rm fire\,max}\) = 1000 K): (i) The area of a 1000 K fire in a ground pixel; (ii) The fire front depth, crossing the nadir ground pixels. The mean area ratio k = A\({}_{\rm F}\)/P\({}_{\rm F}\) = 0.026 in the red-colored column of Table 5, calculated for 360 m \(\times\) 360 m FireBIRD MIR band pixels, is greater than k\({}_{\rm max}\) = 0.0208 for an assumed T\({}_{\rm fire\,max}\) = 1000 K in the two \"VIIRS\"-related cases of Table 6. In other words, this means, if the FRP were derived for the \"Paradise\" fire scene from 14 November 2018 using the VIIRS M-13 band data with a 375 m \(\times\) 375 m pixel size, errors might occur due to pixel saturation.