## 2 Material and Method
### Implementation of SCOPE  
We first used the codes for SCOPE inversion to retrieve biophysical and biochemical parameters of the peatland vegetation [20; 32]. The inversion was performed through a numerical optimization algorithm where the measured reflectance between 400 to 900 nm is fitted to get the best fit for the modeled apparent reflectance.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Vegetation Indices** & **Formula** & **References** \\ \hline NDVI & \(\frac{(6860-6670}{\rho 800-16\rho 70}\) & [29] \\ \hline EVI & \(2.5\left[\frac{(6860-6670)}{(\rho 860)+(66\rho 60)-7.5(\rho 480)+1}\right]\) & [30] \\ \hline NIRv & \(\rho 860\frac{(6860-6670}{\rho 860+6670}\) & [9] \\ \hline \hline \end{tabular}
\end{table}
Table 1: Spectral vegetation indices calculated from ground-based spectroscopy (\(\rho\)–reflectance at a given wavelength; NDVI is Normalized Difference Vegetation Index; EVI is Enhanced Vegetation Index, and NIRv is Near-Infrared Reflectance of vegetation.  
An example of the spectral fitting obtained is shown in Figure 2. The principle behind SCOPE retrieval is described in [PERSON] et al. (2018) and extended by [PERSON] et al. (2018). As our ecosystem is an evergreen ecosystem due to the presence of Sphagnum and _Oxyococcus palstris_, the chlorophyll concentration for the canopy can never be zero. Therefore, we set up the lower boundary for chlorophyll to be 5 \(\upmu\)g cm\({}^{-2}\), whereas the upper boundary was set to 40 \(\upmu\)g cm\({}^{-2}\) (the ecosystem is nutrient-poor, and our ground measurements showed we can never cross this value). The lower and upper boundaries and initialization values for different parameters are indicated in Table 2. The solar-zenith angle from each campaign was used, whereas the Full Width at Half Maximum (FWHM) for the FLAME spectrometer was 1.3 nm. All the parameters were left free to vary during the application of SCOPE inversion. A fit of modeled reflectance spectra was observed with the measured one (the spectral fit is shown in Figure 2). The obtained parameter from SCOPE inversion was combined with data such as radiance, temperature, humidity, and zenith angle to run the SCOPE forward model.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Parameters** & **Unit** & **Lower Boundary** & **Upper Boundary** & **Initial Value** \\ \hline Soil brightness (B) & - & 0 & 0.9 & 0.89 \\ Spectral shape latitude (lat) & - & 20 & 40 & 40 \\ Spectral shape longitude (lon) & - & 40 & 60 & 40 \\ Soil moisture volume percentage (smp) & \% & 5 & 80 & 50 \\ Chlorophyll content (Cab) & \(\upmu\)g cm\({}^{-2}\) & 5 & 40 & 15 \\ Dry matter content (Cdm) & g cm\({}^{-2}\) & 0.00 & 0.02 & 0.007 \\ Leaf water thickness equivalent (Cw) & cm & 0 & 0.2 & 0.080 \\ Senescent material (Cs) & fraction & 0 & 0.4 & 0.114 \\ Carotenoids content (Cca) & \(\upmu\)g cm\({}^{-2}\) & 0 & 25 & 8.381 \\ Anthocyanin content (Cant) & \(\upmu\)g cm\({}^{-2}\) & 0 & 40 & 1.4 \\ Leaf structure parameter (N) & & 1 & 3.5 & 1.5 \\ Leaf area index (LAI) & m\({}^{2}\) m\({}^{-2}\) & 0.1 & 5 & 2 \\ Leaf inclination (lidfa) & - & \(-1\) & 1 & \(-0.3\) \\ Leaf inclination bimodality (lidfb) & - & \(-1\) & 1 & \(-0.114\) \\ \hline \end{tabular}
\end{table}
Table 2: Parameters variability applied in Soil Canopy Observation of Photosynthesis and Energy fluxes inversion.  
Figure 2: Representative reflectance spectra from a plot showing the fitting of reflectance obtained by SCOPE inversion and SCOPE to the measured reflectance spectrum in the range of 400 to 900 nm of wavelength (wl).