Articles | Volume 5, issue 6
Geosci. Model Dev., 5, 1377–1393, 2012

Special issue: The externalised surface model SURFEX

Geosci. Model Dev., 5, 1377–1393, 2012

Model description paper 09 Nov 2012

Model description paper | 09 Nov 2012

Inclusion of vegetation in the Town Energy Balance model for modelling urban green areas

A. Lemonsu1, V. Masson1, L. Shashua-Bar2, E. Erell2, and D. Pearlmutter2 A. Lemonsu et al.
  • 1Météo France/CNRS, URA1357, Centre de Recherches Météorologiques, Toulouse, France
  • 2Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel

Abstract. Cities impact both local climate, through urban heat islands and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representation into urban models will allow us to address more accurately these questions. This paper presents an improvement of the Town Energy Balance (TEB) urban canopy model. Vegetation is directly included inside the canyon, allowing shadowing of grass by buildings, better representation of urban canopy form and, a priori, a more accurate simulation of canyon air microclimate. The surface exchanges over vegetation are modelled with the well-known Interaction Soil Biosphere Atmosphere (ISBA) model that is integrated in the TEB's code architecture in order to account for interactions between natural and built-up covers. The design of the code makes possible to plug and use any vegetation scheme. Both versions of TEB are confronted to experimental data issued from a field campaign conducted in Israel in 2007. Two semi-enclosed courtyards arranged with bare soil or watered lawn were instrumented to evaluate the impact of landscaping strategies on microclimatic variables and evapotranspiration. For this case study, the new version of the model with integrated vegetation performs better than if vegetation is treated outside the canyon. Surface temperatures are closer to the observations, especially at night when radiative trapping is important. The integrated vegetation version simulates a more humid air inside the canyon. The microclimatic quantities (i.e., the street-level meteorological variables) are better simulated with this new version. This opens opportunities to study with better accuracy the urban microclimate, down to the micro (or canyon) scale.