| SCOPE(Soil–Canopy–Observation of Photosynthesis and Energy fluxes) |
SCOPE (Tol et al. 2009) is a soil–vegetation–atmosphere (SVAT) scheme that includes RTMs along with a micrometeorological model for simulating turbulent heat exchange, and a plant physiological model for photosynthesis (Tol et al. 2014). The radiative transfer scheme is based on SAIL (Verhoef 1984b, 1985), extended with a similar radiative transfer for emitted radiation. The emitted radiation includes chlorophyll fluorescence and thermal radiation. Leaf radiative transfer is calculated with Fluspect (Vilfan et al. 2016) which also includes emitted fluorescence radiation. SCOPE is intended as tool to scale processes from leaf to canopy, and to analyse the effects of light scattering. Recent developments include vertical heterogeneity (Yang et al. 2017) and the zeaxanthin–violaxanthin pigment cycles |
| Discrete Anisotropic Radiative Transfer (DART) |
DART model is being developed since 1992 as a physically based 3D computer programme (Gastellu-Etchegorry et al. 1996), which simulates radiative budget and remote sensing (airborne and spaceborne) optical image data of natural and urban landscapes for any wavelengths from the ultraviolet to the thermal infrared part of the electromagnetic spectrum (Gastellu-Etchegorry et al. 1999; Guillevic et al. 2003). It computes and provides bottom and top of the atmosphere spectral quantities (i.e. irradiance, exitance and radiance) that are transformed into reflectance or brightness temperature depending on the user DART mode preferences (Gastellu-Etchegorry et al. 2004). Simulated scenes may include the atmosphere, topography and any natural or anthropogenic objects at any geographical location (Grau and Gastellu-Etchegorry 2013). The latest DART optical development includes also the specular reflectance and the light polarization (Gastellu-Etchegorry et al. 2015). Apart of passive remote sensing data, it also simulates active terrestrial and air-/spaceborne light detection and ranging (LiDAR) discrete return, full waveform, multi-pulse and photon counting measurements (Gastellu-Etchegorry et al. 2016; Yin et al. 2016). In case of vegetation, it can also simulate radiative transfer of the solar-induced chlorophyll fluorescence for any virtual 3D Earth scene numerically and as images (Gastellu-Etchegorry et al. 2017) |
| Librat |
Librat is a 3D Monte Carlo ray-tracing radiative transfer model developed as a library interface to the original ararat (Advanced RAdiometric RAy Tracer) model. The first version of ARARAT was published in 1992 (Lewis and Muller 1993) as part of the Botanical Plant Modelling System (BPMS) (Lewis 1999; Lewis and Muller 1990). Subsequently, the sampling scheme was improved as reported in Saich et al. (2002), and the codes developed into a library in recent years. Librat reads a 3D description of (canopy/soil/topographic) geometry, along with associated information on material scattering properties. The main function in the library then is that a ray is launched from some origin in 3D space, in a specified direction, and the code returns all information about the associated scattering paths and interactions, separated as direct and diffuse components. This core functionality, along with a set of associated sensor models but integrating paths, fired into some volume. It allows for a wide range of radiative transfer calculations, including time-resolved/lidar, splitting of the radiometric information per scattering order as well as straightforward reflectance/transmittance calculations (e.g., Disney et al. 2006; Hancock et al. 2012) |
| FLIGHT |
FLIGHT (Barton and North 2001; North 1996) is a Monte Carlo ray-tracing model designed to rapidly simulate light interaction with 3D vegetation canopies at high spectral resolution, and produce reflectance spectra for both forward simulation and for use in inversion (Leonenko et al. 2013). Foliage is represented by structural properties of leaf area, leaf angle distribution, crown dimensions and fractional cover, and the optical properties of leaves, branch, shoot and ground components. The model represents multiple scattering and absorption of light within the canopy and with the ground surface. It has been developed to model 3D canopy photosynthesis (Alton et al. 2007), to simulate waveform and photon counting lidar (Montesano et al. 2015; North et al. 2010) and emitted fluorescence radiation (Hernández-Clemente et al. 2017). Structural data may be specified as a statistical distribution, derived from field measurements (Morton et al. 2014) or by direct inversion from LiDAR data (Bye et al. 2017) |
