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| Titel |
Implementation of an optimal stomatal conductance scheme in the Australian Community Climate Earth Systems Simulator (ACCESS1.3b) |
| VerfasserIn |
J. Kala, M. G. Kauwe, A. J. Pitman, R. Lorenz, B. E. Medlyn, Y.-P. Wang, Y.-S. Lin, G. Abramowitz |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 12 ; Nr. 8, no. 12 (2015-12-08), S.3877-3889 |
| Datensatznummer |
250116701
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| Publikation (Nr.) |
 copernicus.org/gmd-8-3877-2015.pdf |
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| Zusammenfassung |
| We implement a new stomatal conductance scheme, based on the optimality
approach, within the Community Atmosphere Biosphere Land Exchange
(CABLEv2.0.1) land surface model. Coupled land–atmosphere simulations are
then performed using CABLEv2.0.1 within the Australian Community Climate and
Earth Systems Simulator (ACCESSv1.3b) with prescribed sea surface
temperatures. As in most land surface models, the default stomatal
conductance scheme only accounts for differences in model parameters
in relation to the photosynthetic pathway but not in relation to
plant functional types. The new scheme allows model parameters to vary
by plant functional type, based on a global synthesis of observations
of stomatal conductance under different climate regimes over a wide
range of species. We show that the new scheme reduces the latent heat
flux from the land surface over the boreal forests during the Northern
Hemisphere summer by 0.5–1.0 mm day−1. This leads to
warmer daily maximum and minimum temperatures by up to
1.0 °C and warmer extreme maximum temperatures by up to
1.5 °C. These changes generally improve the climate
model's climatology of warm extremes and improve existing biases by
10–20 %. The bias in minimum temperatures is however degraded
but, overall, this is outweighed by the improvement in maximum temperatures as
there is a net improvement in the diurnal temperature range in this region.
In other regions such as parts of South and North America where ACCESSv1.3b
has known large positive biases in both maximum and minimum temperatures
(~ 5 to 10 °C), the new scheme degrades this bias by up to
1 °C. We conclude that, although several large biases remain in
ACCESSv1.3b for temperature extremes, the improvements in the global climate
model over large parts of the boreal forests during the Northern Hemisphere
summer which result from the new stomatal scheme, constrained by a global
synthesis of experimental data, provide a valuable advance in the
long-term development of the ACCESS modelling system. |
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