An urban neighborhood temperature and energy study from the CAPITOUL experiment with the SOLENE model

A methodology is proposed to analyze the radiative and thermal exchanges between a small urban neighborhood and the atmosphere based on the use of the thermoradiative model SOLENE and radiometric measurements to optimize the effective values of its constant parameters. Applied to the center of Toulouse, France, the optimization data are building surface temperatures measured with handheld radiometers and a downward-facing pyranometer during one of the intense observation periods of the CAnopy and Particles Interactions in TOulouse Urban Layer (CAPITOUL) experimental campaign. The quality of the simulations is assessed by comparing, without any other model adjustment, the model outputs for two diurnal cycles (1 day in summer and 1 day in winter) against two independent experimental datasets from fixed permanent radiometers and from sensors measuring the solar, infrared and sensible heat fluxes to the atmosphere at the top of a mast 30 m above the roofs. These simulations allow us to further analyze the separate contributions of the different surface classes, roofs, facades and pavement to these fluxes and to compare them with their counterparts observed over a neighborhood of Marseilles city center during a previous experiment. The partition is remarkably similar in Toulouse and Marseilles: 6-7% for the solar radiation, 73-76% for the infrared radiation and 17-20% for the sensible heat flux. The contribution of roofs to the infrared flux appears proportional to their plan area proportion (built density) but not the contributions to the other two fluxes. The contributions of facades to all three fluxes are roughly proportional to their fraction of the total surface area.