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Overview of the science of JULES

A brief overview of the basics of the science of JULES

Basic visual description of the processes modelled by JULES

JULES has a tiled model of sub-grid heterogeneity with 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 computed for each surface type in a grid-box.

Nine surface types are normally used:

  • Five Plant Functional Types (PFTs)
    • Broadleaf trees
    • Needleleaf trees
    • C3 (temperate) grass
    • C4 (tropical) grass
    • Shrubs
  • Four non-vegetation types
    • Urban
    • Inland water
    • Bare soil
    • Land-ice

Except for those classified as land-ice, a land grid-box can be made up from any mixture of the other surface types. Fractions of surface types within each land-surface grid-box are read from an ancillary file or modelled by 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.