Improved representations of coupled soil–canopy processes in the CABLE land surface model (Subversion revision 3432)
CABLE is a global land surface model, which has been used extensively in offline and coupled simulations. While CABLE performs well in comparison with other land surface models, results are impacted by decoupling of transpiration and photosynthesis fluxes under drying soil conditions, often leading...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-09-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/9/3111/2016/gmd-9-3111-2016.pdf |
| Summary: | CABLE is a global land surface model, which has been used
extensively in offline and coupled simulations. While CABLE performs well in
comparison with other land surface models, results are impacted by
decoupling of transpiration and photosynthesis fluxes under drying soil
conditions, often leading to implausibly high water use efficiencies. Here,
we present a solution to this problem, ensuring that modelled transpiration
is always consistent with modelled photosynthesis, while introducing a
parsimonious single-parameter drought response function which is coupled to
root water uptake. We further improve CABLE's simulation of coupled
soil–canopy processes by introducing an alternative hydrology model with a
physically accurate representation of coupled energy and water fluxes at the
soil–air interface, including a more realistic formulation of transfer under
atmospherically stable conditions within the canopy and in the presence of
leaf litter. The effects of these model developments are assessed using data
from 18 stations from the global eddy covariance FLUXNET database, selected to
span a large climatic range. Marked improvements are demonstrated, with
root mean squared errors for monthly latent heat fluxes and water use
efficiencies being reduced by 40 %. Results highlight the important roles
of deep soil moisture in mediating drought response and litter in dampening
soil evaporation. |
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| ISSN: | 1991-959X 1991-9603 |