The Joint UK Land Environment Simulator (JULES), model description. Part 2: Carbon fluxes and vegetation dynamics

The Joint UK Land Environment Simulator
(JULES) is a process-based model that simulates the
fluxes of carbon, water, energy and momentum between the
land surface and the atmosphere. Many studies have demonstrated
the important role of the land surface in the functioning
of the Earth System. Different versions of JULES
have been employed to quantify the effects on the land carbon
sink of climate change, increasing atmospheric carbon
dioxide concentrations, changing atmospheric aerosols and
tropospheric ozone, and the response of methane emissions
from wetlands to climate change.
This paper describes the consolidation of these advances
in the modelling of carbon fluxes and stores, in both the vegetation
and soil, in version 2.2 of JULES. Features include
a multi-layer canopy scheme for light interception, including
a sunfleck penetration scheme, a coupled scheme of leaf
photosynthesis and stomatal conductance, representation of
the effects of ozone on leaf physiology, and a description
of methane emissions from wetlands. JULES represents the
carbon allocation, growth and population dynamics of five
plant functional types. The turnover of carbon from living
plant tissues is fed into a 4-pool soil carbon model.
The process-based descriptions of key ecological processes
and trace gas fluxes in JULES mean that this community
model is well-suited for use in carbon cycle, climate
change and impacts studies, either in standalone mode or as
the land component of a coupled Earth system model.