Joint UK Land Environment Simulator

The community land surface model Joint UK Land Environment Simulator (JULES) is a process-based model simulating the fluxes of carbon, water, energy, and momentum between the land surface and the atmosphere. It can be used as a stand-alone mode driven by forcing data, or be coupled to an atmospheric circulation model.     

The model is based on a tiled scheme of sub-grid heterogeneity: A land grid-box can consist of several fractions of different surface types. These surface types ares defined through Plant Functional Types (PFTs), the five default PFTs are broadleaf trees, needleleaf trees, C3 (temperate) grass, C4 (tropical) grass and shrubs. Further, there are four non-vegetation types - urban, inland water, bare soil and land-ice. For each gridbox, separate surface temperatures, short-wave and long-wave radiative fluxes, sensible and latent heat fluxes, ground heat fluxes, canopy moisture contents, snow masses and snow melt rates are computed for each surface type.

The fractions of surface types within each land-surface grid-box can be provided from an ancillary file or be modelled by the vegetation dynamics model TRIFFID. Air temperature, humidity and wind-speed above the surface and soil temperatures and moisture contents below the surface are treated as homogeneous across a grid-box.

Website: http://jules.jchmr.org/

Licence: Open source, available upon registration

Operating system(s): Linux, Windows

Modelled processes...


  • Best et al. (2011): The Joint UK Land Environment Simulator (JULES), model description – Part 1: Energy and water fluxes. Geosci. Model Dev. 4:677–699.
  • Clark et al. (2011): The Joint UK Land Environment Simulator (JULES), model description – Part 2: Carbon fluxes and vegetation dynamics. Geosci. Model Dev. 4:701–722.