DART: a 3D radiative transfer model for urban studies.

The three-dimensional (3D) geometry of cities greatly influences their radiation regime and, consequently, their temperature. However, current remote sensing algorithms often treat urban pixels as Lambertian planes. 3D radiative transfer models such as DART that simulate the radiative budget as well as sensor images of cities (short and long waves) avoid this "Lambertian plane" simplification, which should allow a more accurate assessment of the urban radiation regime. DART can simulate any experimental (e.g., urban geometry with vegetation and topography, sun direction, atmosphere conditions) and sensor (e.g., spatial and spectral resolution) configurations. DART is freely available for education and research (dart.omp.eu). Here we present the application of DART to the inversion of satellite images as maps per type of urban element (i. e. , roofs, streets, …): optical properties in the short wave, and emissivity and temperature in the long wave.