Features

FR EN

General description

The SIRANE software is an operational atmospheric dispersion model for urban areas, appropriate to the scale of a neighborhood or a city. Given the physical phenomena taken into account, the model can be used at a scale from few hundred meters to ten kilometers.

The SIRANE software provides the spatial and temporal evolution of concentration for different pollutants in an urban area. These results are provided in the form of cartography on a mesh or in the form of time series of concentration at different receptors. Statistical results are calculated over the period of study.

Applications of SIRANE concern the effects of air pollution in urban areas:
  • Cartography of air pollution at the neighborhood scale, in addition to the measurements
  • Determination of the representativity of sensors
  • Exposure assessment of the population
  • Impact of new urban development, travel plans or policies to reduce emissions
  • Forecasting air quality

Physics of the model

The SIRANE software allows to take into account the main effects which affect the dispersion of pollutants in urban areas:
  • Transport of pollutants in the urban canopy:
    • Containment of pollutants between buildings (street canyon)
    • Exchange of pollutants with the external atmosphere
    • Exchange of pollutants at street intersections
  • Transport of pollutants in the atmospheric boundary layer above the roof level:
    • Meteorological preprocessing and characterization of the atmospheric stability
    • Vertical structure of the boundary layer (velocity, temperature, turbulence)
    • Continuous parameterization of the turbulent dispersion
  • Physicochemical processes:
    • Chemical transformations (Chapman cycle \(NO\)-\(NO_2\)-\(O_3\))
    • Transport and deposition of particles
    • Rain scavenging (wet deposition)
SIRANE is an "operational" tool, which uses simplified theoretical models and formulations which can realistically represent these phenomena. It is therefore suitable for the treatment of a large number of streets in a very limited computing time.

Numerical features

SIRANE the software is a computer code developed in C langage. It is available for different operating systems (Windows, Linux).

SIRANE is not limited in term of number of streets or domain size. Only the limits of physical validity restrict the software application to areas of about 20 km.

SIRANE is currently operating without a graphical user interface, using data files and results described in the user documentation. A graphical interface is under development and will be available soon

SIRANE is parallelized to exploit the multi-processors, multi-core and multi-threaded performances of computers. A version of SIRANE software is also available for AASQA at the HPC center CRIHAN.

Validation

The SIRANE software has been validated by comparison with numerical simulations, detailed wind tunnel experiments and field measurements.

This work is presented in different scientific publications.