MODélisation des échanges RADiatifs dans la canopée urbaine pour évaluer les formes URBaines dans le contexte du changement climatique

The objective of the project is to evaluate, in the context of climatic change, urban forms and adaptation strategies based on urban vegetation for their potential to mitigate urban heat islands. The method is based on a paradigm shift in radiative exchange modelling in urban climate models to better represent radiation (solar and terrestrial infrared), which is a crucial process for urban climate, building energy consumption and human thermal comfort.

Coordination: CNRM
Responsible at CNRM: Robert Schoetter
Start of the project: June 2019
Duration: 3 years

Scientific and technical objectives

  1. Quantification of errors due to approximations of radiative exchange calculation made by urban climate models by using a reference model for radiative transfer (Monte-Carlo ray tracing library ED-STAR).
  2. Improving radiation modelling in an urban climate model (TEB) to improve simulations of urban climate and building energy consumption of various urban forms.
  3. Application of the improved version of TEB to a selection of cities and urban morphologies in France to quantify their performance in the context of climate change.
  4. A technical objective is to adapt the Monte-Carlo ray tracing library ED-STAR to real urban geometries, which will enable its use by consultants, as well as meteorologists and climatologists to enhance and evaluate their models.

Projet description

  1. Task 1 consists of applying ED-STAR first to a variety of idealised cities of different morphology to quantify radiative quantities relevant for the evaluation of urban forms and the uncertainties due to the simplifications made by the urban climate models. Secondly, ED-STAR will be evaluated for real cities (London, Paris).
  2. Task 2 consists of adapting the open-source Monte-Carlo ray tracing library ED-STAR to real cities (read of data on building geometry, urban vegetation, physical properties of urban materials).
  3. Task 3 consists of coupling the open-source urban climate model TEB with the new urban radiation scheme SPARTACUS-Urban, which will allow to distinguish a larger variety of urban morphologies with TEB.
  4. Task 4 consists of applying the improved version of TEB to evaluate different urban forms distinguished by building density, building height, building form, and urban vegetation for Paris, Toulouse, and La Rochelle to calculate building energy consumption and human thermal comfort by taking into account regional climate change and urban climate. A methodological guide synthetising the results will be presented to urban planning agencies during the final colloquium of the project.

Project partners
This project is conducted by CNRM and the company Méso-Star, which develops a tool to simulate 3D radiative exchanges. These two partners cooperate with international experts on radiative exchange and urban climate based in Reading (United Kingdom).