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| Titel |
Implementation of a soil albedo scheme in the CABLEv1.4b land surface model and evaluation against MODIS estimates over Australia |
| VerfasserIn |
J. Kala, J. P. Evans, A. J. Pitman, C. B. Schaaf, M. Decker, C. Carouge, D. Mocko, Q. Sun |
| 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 ; 7, no. 5 ; Nr. 7, no. 5 (2014-09-23), S.2121-2140 |
| Datensatznummer |
250115725
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| Publikation (Nr.) |
 copernicus.org/gmd-7-2121-2014.pdf |
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| Zusammenfassung |
| Land surface albedo, the fraction of incoming solar radiation reflected by
the land surface, is a key component of the Earth system. This study
evaluates snow-free surface albedo simulations by the Community Atmosphere
Biosphere Land Exchange (CABLEv1.4b) model with the Moderate Resolution
Imaging Spectroradiometer (MODIS) and the Satellite Pour L'Observation de la
Terre (SPOT) albedo. We compare results from offline simulations over the
Australian continent. The control simulation has prescribed background
snow-free and vegetation-free soil albedo derived from MODIS whilst the
experiments use a simple parameterisation based on soil moisture and colour,
originally from the Biosphere Atmosphere Transfer Scheme (BATS), and adopted
in the Common Land Model (CLM). The control simulation, with prescribed
soil albedo, shows that CABLE simulates overall albedo over Australia
reasonably well, with differences compared to MODIS and SPOT albedos within
±0.1. Application of the original BATS scheme, which uses an eight-class soil
classification, resulted in large differences of up to −0.25 for the near-infrared (NIR) albedo over large parts of the desert regions of central
Australia. The use of a recalibrated 20-class soil colour classification from
the CLM, which includes a higher range for saturated and VIS (visible) and NIR soil
albedos, reduced the underestimation of the NIR albedo. However, this soil
colour mapping is tuned to CLM soil moisture, a quantity which is not
necessarily transferrable between land surface models. We therefore
recalibrated the soil color map using CABLE's climatological soil moisture, which further
reduced the underestimation of the NIR albedo to within ±0.15 over most
of the continent as compared to MODIS and SPOT albedos. Small areas of larger
differences of up to −0.25 remained within the central arid parts of the
continent during summer; however, the spatial extent of these large
differences is substantially reduced as compared to the simulation using the
default eight-class uncalibrated soil colour map. It is now possible to use
CABLE coupled to atmospheric models to investigate soil-moisture–albedo
feedbacks, an important enhancement of the model. |
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