Overview of the science of 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
- Four non-vegetation types
- Inland water
- Bare soil
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.