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

Abstract

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. <br><br> 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. <br><br> 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

Mechanisms of water supply and vegetation demand govern the seasonality and magnitude of evapotranspiration in Amazonia and Cerrado

“…On the demand side, 21 of the 23 model variants simulated canopy stomatal conductance (g s ), using one of four principal schemes to solve for g s , E, and leaf-level photosynthesis (if simulated) given ambient incoming radiation, air temperature, and humidity: Jarvis-type (Jarvis, 1976) (four model variants), Leuning-type (Leuning et al, 1995) (four model variants), Ball-Woodrow-Berry-Collatz (Ball et al, 1987;Collatz et al, 1991) (11 model variants), or a constant ratio of internal to external leaf CO 2 concentration (2 model variants). Balsamo et al (2009), Best et al (2011, Clapp and Hornberger (1978), Clark et al (2011), Cox et al (1998), de Rosnay and Polcher (1998, Ducoudre et al (1993), Foley et al (1996), Gerten et al (2004), Haxeltine and Prentice (1996), Jacobs (1994), Krinner et al (2005), Medvigy et al (2009), Monteith (1995, Niu et al (2011), Oleson et al (2010, Running and Coughlan (1988), Schaefer et al (2008), Sellers et al (1996), Van den Hurk et al (2000), Verseghy (1991) and Zhan et al (2003).…”

Global evaluation of gross primary productivity in the JULES land surface model v3.4.1

“…JULES is a community land surface model which has evolved from the Met Office Surface Exchange Scheme (MOSES; Cox et al, 1999) and is used for modelling all of the processes at the land surface, in the subsurface soil and in surface exchange processes Clark et al, 2011). JULES can be used offline (i.e.…”

“…The downward shortwave and longwave radiation fluxes play an important role in the surface energy balance, where the downwelling radiation fluxes must equal the outgoing fluxes of sensible heat, latent heat, ground flux, reflected shortwave radiation and upwelling thermal energy, and the calculation of photosynthesis Clark et al, 2011). GPP is the total C uptake by plants in photosynthesis on the canopy scale with potential (without water and ozone stress) leaf-level photosynthesis calculated as the smoothed minimum of three limiting rates: (1) Rubiscolimited rate (determined using surface air temperature and atmospheric CO 2 concentrations), (2) light-limited rate (determined using downward shortwave radiation) and (3) rate of transport of photosynthetic products (C 3 plants) and PEPCarboxylase limitation (C 4 plants; determined using surface air temperature and pressure; Clark et al, 2011). Soil moisture stress is taken into account when calculating leaf-level photosynthesis by multiplying the potential leaf-level photosynthesis by a soil moisture factor (determined using mean soil moisture concentration in the root zone).…”

Understanding terrestrial water storage variations in northern latitudes across scales

“…This ensemble includes HTESSEL-CaMa (Balsamo et al, 2009), JULES Clark et al, 2011), LISFLOOD (van der Knijff et al, 2010), ORCHIDEE (Krinner et al, 2005;Ngo-Duc et al, 2007;d'Orgeval et al, 2008), SURFEX-TRIP (Alkama et al, 2010;Decharme et al, 2013), W3RA (van Dijk andWarren, 2010;van Dijk et al, 2014), WaterGAP3 (Flörke et al, 2013;Döll et al, 2009), PCR-GLOBWB (van Beek et al, 2011Wada et al, 2014), and SWBM (Orth et al, 2013). For consistency, we processed the model estimates in the same manner as our model simulations to directly compare modelled SWE and TWS to observations from GlobSnow and GRACE, respectively.…”