DART-EB

(DART – Energy Budget)

Work in progress

 The goal of DART-EB model is to simulate the energy balance of the Earth surface. It works with the DART model. It computes heat fluxes and energy budget. An example of DART-EB application for urban areas is shown below: Exemple of street (Rue Alsace-Lorraine à Toulouse) Modelling of the street and of the energy balance Evolution of temperatures and fluxes on the different surfaces  see the vidéo

Why to develop new physical models ?

Here, the term "physical models" refers to "radiative transfer (RT) models" or "energy budget (EB) models".

They use more or less complex mathematical methods for simulating relevant physical processes. For example, RT models can use a Monte Carlo ray tracing method or an N-flux method for tracking radiation propagation and its interaction with continental surfaces. Moreover, RT and EB models work with landscapes that are simulated in a more or less realistic way. They use also models that simulate landscapes in a more or less realistic way. For example, spatial heterogeneity of Earth surfaces is often neglected or accounted for in a very simple way. In short, most common RT and EB models rely on very strong approximations which are no more adapted to presently required precision levels in the context of the study of Earth surfaces, especially with the help of satellite remote sensing. This is the case for applications that rely on the inversion of satellite images, and also for applications related to surface energy budget and to mass and energy fluxes at the "Earth - Atmosphere" interface.

Thus, there is a strong need in the scientific community for improving RT and EB models. This implies an important improvement at different levels: more accurate mathematical modelling of physical processes and more realistic simulation of landscapes. A specificity of our approach is to introduce the 3-D dimension at both levels.

These remarks explain that we are presently developing two types of model :

- Radiative Transfert Model (DART : it simulates radiation budget and satellite images.

- Energy budget model (DARTEB) : it simulates 3D mass and energy fluxes. It uses DART for simulating radiation budget. Apart from strictly scientific applications (e.g., study of vegetation functioning), these models are powerful tools for technical applications. This is typically the case of simulation works conducted for specifying the optimal characteristics of future satellite sensors and also for devising the best inversion procedures to apply to remote sensing measurements. In this context, CNES used DART for specifying the optimal spectral characteristics of Pléiades sensor for mapping purposes. Here, this is illustrated with shadowed roads and with forests observed with different panchromatic bands, and with different atmospheres, sun directions and panchromatic band centers.