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| Titel |
Inter-comparison of two land-surface models applied at different scales and their feedbacks while coupled with a regional climate model |
| VerfasserIn |
F. Zabel, W. Mauser, T. Marke, A. Pfeiffer, G. Zängl, C. Wastl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 16, no. 3 ; Nr. 16, no. 3 (2012-03-28), S.1017-1031 |
| Datensatznummer |
250013225
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| Publikation (Nr.) |
 copernicus.org/hess-16-1017-2012.pdf |
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| Zusammenfassung |
| Downstream models are often used in order to study regional impacts of
climate and climate change on the land surface. For this purpose, they are
usually driven offline (i.e., 1-way) with results from regional climate
models (RCMs). However, the offline approach does not allow for feedbacks
between these models. Thereby, the land surface of the downstream model is
usually completely different to the land surface which is used within the
RCM. Thus, this study aims at investigating the inconsistencies that arise
when driving a downstream model offline instead of interactively coupled
with the RCM, due to different feedbacks from the use of different land
surface models (LSM). Therefore, two physically based LSMs which developed
from different disciplinary backgrounds are compared in our study: while the
NOAH-LSM was developed for the use within RCMs, PROMET was originally
developed to answer hydrological questions on the local to regional scale.
Thereby, the models use different physical formulations on different spatial
scales and different parameterizations of the same land surface processes
that lead to inconsistencies when driving PROMET offline with RCM output.
Processes that contribute to these inconsistencies are, as described in this
study, net radiation due to land use related albedo and emissivity differences, the
redistribution of this net radiation over sensible and latent heat, for example, due
to different assumptions about land use impermeability or soil hydraulic
reasons caused by different plant and soil parameterizations. As a result,
simulated evapotranspiration, e.g., shows considerable differences of max. 280 mm yr−1. For a full interactive coupling (i.e., 2-way) between PROMET and the
atmospheric part of the RCM, PROMET returns the land surface energy fluxes
to the RCM and, thus, provides the lower boundary conditions for the RCM
subsequently. Accordingly, the RCM responses to the replacement of the LSM
with overall increased annual mean near surface air temperature (+1 K) and
less annual precipitation (−56 mm) with different spatial and temporal
behaviour. Finally, feedbacks can set up positive and negative effects
on simulated evapotranspiration, resulting in a decrease of evapotranspiration South of the Alps a
moderate increase North of the Alps. The inconsistencies are quantified and
account for up to 30% from July to Semptember when focused to an area around Milan, Italy. |
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