## 2 Materials and Methods  
### SCOPE (Soil Canopy Observation of Photochemistry and Energy Fluxes)  
#### 2.1.1 SCOPE Model Description  
SCOPE is a vertical (1-D), integrated, radiative transfer and energy balance model [19]. This model combines radiative transfer of solar radiation and radiation emitted by the vegetation (thermal and SIF) with the energy balance in which a biochemical module handles the fluorescence emission efficiency depending on the two de-excitation pathways: photochemical quenching of excitation energy via electron transport (PQ) and non-photochemical quenching of excitation energy via thermal energy dissipation (NPQ) [40]. It calculates directional top-of-canopy reflected radiation, emitted thermal radiation, and SIF signals together with energy, water, and CO\({}_{2}\) flux. In this work, we employed version 1.61 to interpret SIF and GPP. The model consists of several modules combined to simulate SIF and photosynthesis. The model's main features related to the SIF and GPP simulations are briefly described here (for more details, see [20]). At the leaf level, two modules are used to simulate the SIF emission. One is the leaf radiative transfer module called Fluspect that handles the radiative transfer of incident light and SIF emission in the leaf. The other is the biochemical module that handles the emission efficiencies of photosystems depending on the PQ and NPQ at photosystem level. At the canopy level, the optical radiative transfer module (RTMo) governs the incident light on the individual leaves and the propagation of SIF throughout the canopy based on the scattering of arbitrarily inclined leaves (SAIL) model [41]. It calculates radiation transfer in a multilayer canopy to obtain reflectance and fluorescence in the observation direction as a function of solar zenith angel and leaf inclination distribution. The spectral resolution of the modeled spectra is 1 nm in the range of 400-2500 nm for reflectance and 640-850 nm for fluorescence. Fluspect is an extension of the PROSPECT model [42] that adds SIF radiative transfer within the leaf. Fluspect calculates the probability that excitation at a specific wavelength (400-750 nm) results in fluorescence at a longer wavelength (640-850 nm) at the illuminated and the shaded sides of the leaf. Furthermore, when implementing Fluspect, two photosystems (PSI and PSII) are responsible for fluorescence. As a result, Fluspect's output consists of leaf reflectance and transmittance, as well as four fluorescence excitation-emission probability matrices: one for each photosystem at the illuminated and shaded sides of the leaf [20; 24; 28]. Fluspect's input parameters consist of all the leaf composition parameters as described with the PROSPECT parameters and the fqe1 and fqe2. The biochemical module is employed to scale the SIF emission efficiencies of PSII (i.e., PQ and NPQ) as a function of micrometeorological conditions (e.g., irradiance, temperature, relative humidity, and wind speed) and photosynthesis parameters (e.g., the V\({}_{\text{Cmax}}\) and the Ball-Berry stomatal conductance parameter m) relative to the efficiency in dark or pre-dawn conditions. For representation of photosynthesis (i.e., PQ), either the models proposed by [PERSON] et al. (for C3 species) [43] and [PERSON] (for C4 species) [44] or the model presented by [PERSON] et al. [45; 46] are/is adopted. In these photosynthesis models, V\({}_{\text{Cmax}}\) is an important biochemical variable for carbon assimilation, which describes the maximum carboxylation rate of RuBisCO. It is assumed to decrease exponentially with the depth in the canopy and is calibrated by the temperature correction parameters. When implementing the biochemical module adopted in [25], the response of SIF emission efficiency is empirically calibrated to a number of datasets collected in field and laboratory experiments of unstressed and drought-stressed vegetation, referred to hereafter as TB12 and TB12-D, respectively.