The Joint UK Land Environment Simulator (JULES), Model description –  Part 1: Energy and water fluxes

Best, Martin; Pryor, Milton; Clark, Douglas B.; Rooney, G. G.; Essery, Richard; Ménard, Cécile B.; Edwards, John M.; Hendry, Margaret A.; Porson, Aurore; Gedney, Nicola; Mercado, L.; Sitch, Stephen; Blyth, Eleanor; Boucher, Oliviér; Cox, Peter M.; Grimmond, Sue; Harding, R. J.

doi:10.5194/gmdd-4-595-2011

Cited by 159 publications

(185 citation statements)

References 73 publications

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“…This is because the marginal water cost of carbon (often termed λ) is observed to vary widely and non-linearly within a single species in response to soil water stress [36–38]. One piece of evidence that the classical empirical models may not be adequate during drought is that, with recent exceptions of models with water transport [26,29], most large-scale ecosystem models include a rarely-tested soil moisture stress function, that shuts stomata as soil water potential falls [39–41]. …”

Section: Introductionmentioning

confidence: 99%

Plant water potential improves prediction of empirical stomatal models

et al. 2017

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Climate change is expected to lead to increases in drought frequency and severity, with deleterious effects on many ecosystems. Stomatal responses to changing environmental conditions form the backbone of all ecosystem models, but are based on empirical relationships and are not well-tested during drought conditions. Here, we use a dataset of 34 woody plant species spanning global forest biomes to examine the effect of leaf water potential on stomatal conductance and test the predictive accuracy of three major stomatal models and a recently proposed model. We find that current leaf-level empirical models have consistent biases of over-prediction of stomatal conductance during dry conditions, particularly at low soil water potentials. Furthermore, the recently proposed stomatal conductance model yields increases in predictive capability compared to current models, and with particular improvement during drought conditions. Our results reveal that including stomatal sensitivity to declining water potential and consequent impairment of plant water transport will improve predictions during drought conditions and show that many biomes contain a diversity of plant stomatal strategies that range from risky to conservative stomatal regulation during water stress. Such improvements in stomatal simulation are greatly needed to help unravel and predict the response of ecosystems to future climate extremes.

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Section: Introductionmentioning

confidence: 99%

Plant water potential improves prediction of empirical stomatal models

et al. 2017

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“…Where ΔS i is change in soil moisture (mm), P i is precipitation (mm), E i is evaporation (mm), Ro i is runoff (mm) and Ru i is potential recharge (mm). However, there are major differences in the complexity with which they represent the land surface: Penman–Grindley (PG) (Grindley, ): constant crop canopy surface; vegetation‐based bucket model. UN Food and Agricultural Organization (FAO) (Allen et al ., ): constant crop canopy surface and single‐layer soil zone bucket model. SPAtial Distributed Evaporation (SPADE) (Finch, ): constant or dynamic crop canopy with partitioning of vegetation and bare soil surfaces; multiple‐layer soil zone bucket model. Joint UK Land Environment Simulator (JULES) (Best et al ., ; Clark et al ., ): constant or dynamic crop canopy with partitioning of vegetation and bare soil surfaces; coupling of photosynthesis and transpiration; multiple‐layer soil zone based on finite difference approximation of the Richards equation.…”

Section: Introductionmentioning

confidence: 99%

Comparison of varied complexity models simulating recharge at the field scale

Sorensen¹,

Finch

Ireson

et al. 2013

Hydrological Processes

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Numerical models are frequently used for the regional quantification of groundwater recharge. However there is a wide range of potential models available that represent the land surface with varying degrees of complexity, but which are rarely tested against observations at the field scale. We compared four models that simulate potential recharge at four intensively monitored sites with different vegetation and soil types in two adjacent catchments. These models were: Penman–Grindley, UN Food and Agricultural Organization, SPAtial Distributed Evaporation and Joint UK Land Environment Simulator. Standardized, unoptimized land surface datasets and pertinent literature were used for parameterization to reflect practice in regional water resource management and planning in the UK. The models were validated against soil moisture observations at all sites, as well as observed transpiration and interception and calculated total evaporation over a year at a woodland site. Soil moisture observations were generally reproduced well, but there were significant differences in how the models apportioned precipitation through the hydrological cycle. This demonstrates that soil moisture data alone are not a good diagnostic for groundwater recharge models. Significant differences in potential recharge were produced by models at both grassland sites, although simulated average annual potential recharge varied by only 15% at the grassland site on permeable soil. At the woodland sites, soil moisture contents were reproduced least accurately, and there were large differences in potential recharge at both woodland sites. This predominantly resulted from varied and inaccurate simulation of evaporation, particularly in the form of interception losses where this was explicitly represented in models. Differences in model structure, such as runoff representation, and parameter selection also influenced all results. Hydrological Processes © 2013 John Wiley & Sons, Ltd.

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“…The scheme has already been coupled to the Lund Potsdam Jena Dynamic Global Vegetation Model (LPJ-DGVM; Sitch et al, 2003) and to the Lund Potsdam Jena General Ecosystem Simulator (LPJ-GUESS; Smith et al, 2001), and applied at both regional (Arneth et al, 2008b) and global (Arneth et al, 2007a) scales. In this paper, we describe the validation of a modified version of the Arneth et al (2007b) scheme that has been implemented in the Joint UK Land Environmental Simulator (JULES; Best et al, 2011;Clark et al, 2011;www.jchmr.org/jules). A version of JULES including isoprene will be the land-surface component of the new Hadley Centre Global Environmental Model (HadGEM3).…”

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confidence: 99%

Evaluation of a photosynthesis-based biogenic isoprene emission scheme in JULES and simulation of isoprene emissions under present-day climate conditions

et al. 2011

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Abstract.We have incorporated a semi-mechanistic isoprene emission module into the JULES land-surface scheme, as a first step towards a modelling tool that can be applied for studies of vegetation -atmospheric chemistry interactions, including chemistry-climate feedbacks. Here, we evaluate the coupled model against local above-canopy isoprene emission flux measurements from six flux tower sites as well as satellite-derived estimates of isoprene emission over tropical South America and east and south Asia. The model simulates diurnal variability well: correlation coefficients are significant (at the 95 % level) for all flux tower sites. The model reproduces day-to-day variability with significant correlations (at the 95 % confidence level) at four of the six flux tower sites. At the UMBS site, a complete set of seasonal observations is available for two years (2000 and 2002). The Comparison with the satellite-derived isoprene-emission estimates suggests that the model simulates the main spatial patterns, seasonal and inter-annual variability over tropical regions. The model yields a global annual isoprene emission of 535 ± 9 TgC yr −1 during the 1990s, 78 % of which from forested areas.

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The Joint UK Land Environment Simulator (JULES), Model description – Part 1: Energy and water fluxes

Cited by 159 publications

References 73 publications

Plant water potential improves prediction of empirical stomatal models

Plant water potential improves prediction of empirical stomatal models

Comparison of varied complexity models simulating recharge at the field scale

Evaluation of a photosynthesis-based biogenic isoprene emission scheme in JULES and simulation of isoprene emissions under present-day climate conditions

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