## 2 The BEAM Toolbox and the Land Surface Temperature Processor
### The LST Processor as a BEAM Plug-In
#### 2.2.2 Description of the LST Processor in BEAM
The NDVI Thresholds Method uses certain NDVI values (minimum/maximum thresholds) to identify the range between pure soil pixels (NDVImin) and pixels of full vegetation (NDVImax). For NDVImin and NDVImax fixed values might be assumed (e.g., 0.2 and 0.5, as suggested by [6]. However, the current processor uses a more dynamic approach by taking the minimum and maximum NDVI from the given scene. Then, a fractional vegetation cover (FVC or Pv) can be computed (Equation (3)) and used in the derivation of the emissivity:  
\[\varepsilon_{B1}=0.982 Pv+0.97(1.0-Pv)+C_{B1},\] \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Dataset** & **Band Name** & **Unit** & **Dimension \#Bytes** \\ \hline All flag bands & l1\_flags\_MERIS & dl & 5\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ from MERIS/AATSR & confid\_flags\_nadir\_AATSR & & \\ collocation product & confid\_flags\_fward\_AATSR & & \\  & cloud\_flags\_nadir\_AATSR & & \\  & cloud\_flags\_fward\_AATSR & & \\ \hline Cloud flag & cloud\_flags\_synergy & dl & NL\({}^{\star}\)NC\({}^{\star}\)4 \\ \hline Latitude and longitude & latitude & deg & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ tie point grids & longitude & deg & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ from MERIS L1 & & dl & dl \\ \hline AATSR nadir & btemp\_nadir\_1200\_AATSR & K & 3\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ brightness & btemp\_nadir\_1100\_AATSR & K & 3\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ temperature & btemp\_nadir\_0370\_AATSR & K & 3\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ \hline AATSR forward & btemp\_fward\_1200\_AATSR & K & 3\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ brightness & btemp\_fward\_1100\_AATSR & K & 3\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ temperature & btemp\_fward\_0370\_AATSR & K & 3\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ \hline MERIS surface & SynergySDR\_620\_MERIS & dl & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ reflectance & SynergySDR\_753\_MERIS & dl & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ at 620 nm and 753 nm & & & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ \hline AATSR nadir & SynergySDR\_nadir\_555\_AATSR & dl & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ surface reflectance & SynergySDR\_nadir\_659\_AATSR & dl & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ at 555 nm and 659 nm & & & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ \hline AATSR forward & SynergySDR\_fward\_555\_AATSR & dl & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ surface reflectance & SynergySDR\_fward\_AATRS & dl & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ at 555 nm and 659 nm & & & 2\({}^{\star}\)NL\({}^{\star}\)NC\({}^{\star}\)4 \\ \hline \hline \end{tabular} Note: confid = confidence, btemp = brightness temperature, fward = forward, SDR= surface directional reflectance, dl = dimensioless, NL = number of columns in a scan line, NC = number of scan lines in a dataset.  
\end{table} 
Table 2: SDR product dataset overview. \[\varepsilon_{B2}=0.984 Pv+0.977(1.0-Pv)+C_{B2}, \tag{6}\]  
with the cavity terms \(C_{B1}\) and \(C_{B2}\) both set to 0.005. B1 makes reference to the thermal band at 11 \(\upmu\)m and B2 to the band at 12 \(\upmu\)m. The arithmetic mean of the emissivities for the two bands is taken as final emissivity:  
\[\varepsilon=0.5(\varepsilon_{B1}+\varepsilon_{B2}). \tag{7}\]  
Both split-window and dual-angle algorithms use a set of regression coefficients \(c_{i}\), i = 0,.., 6, for LST retrieval, as explained in [7] and mentioned in Section 2.2.1. These coefficients are obtained from simulated data using 61 atmospheric profiles representative of different atmospheric conditions. The values of these coefficients are shown in Table 3.  
Figure 5: Screen-shot of the LST retrieval module in the BEAM LST plug-in.