Radiative transfer in the atmosphere

The representation of solar and infra-red radiation, and its interaction with clouds, is a critical component of our climate and weather forecast models.

Various radiative processes occur in the atmosphere: gases, aerosols, cloud droplets and ice crystals absorb radiation and emit thermal radiation. Aerosols, cloud particles and air molecules scatter radiation. The surface absorbs, reflects and emits radiation. The radiative properties of atmospheric constituents may vary rapidly with frequency and the geometrical arrangement of clouds is an important influence on the radiation budget. The modelling of atmospheric radiation is therefore potentially very complicated and must involve some  approximations to be efficient enough for weather and climate applications.

Key Aims

  • Increasingly accurate and efficient representation of atmospheric radiative processes in weather and climate models.

  • Improved understanding and parametrization of the interaction of radiation with clouds and aerosols.

  • Improved understanding and representation of the interaction of radiation with surface features.

Current projects

  • The treatment of sub-grid cloud inhomogeneity for climate and global forecast models.

  • The effects of resolved surface slopes and sky-view on the radiative transfer in local area forecast models.

  • Improvements to the treatment of gaseous absorption.

  • Determination of the optical properties of ice-crystal aggregates in clouds.

  • Optimal sampling of radiation calculations in time and space.

Last updated: 3 September 2013