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| Titel |
Detailed vegetation processes within a regional climate model impact the representation of land-atmosphere feedbacks |
| VerfasserIn |
Ruth Lorenz, Edouard L. Davin, Sonia I. Seneviratne |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055853
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| Zusammenfassung |
| European summer climate, especially events such as heat waves and droughts, are impacted
by processes acting at the interface between the land surface and the atmosphere. These
processes are to a large extent associated with soil moisture (SM) dynamics, but also
with vegetation processes, since plants’ transpiration is the largest contributor to
evapotranspiration in many regions.
An approach to investigate land-atmosphere interactions is to run climate model
experiments with prescribed SM values (e.g. Seneviratne et al. 2006, Jaeger and Seneviratne
2010, Lorenz et al. 2010). This removes the two-way SM-climate interactions and allows
to investigate solely the one-way impact of SM on climate. In this study, we use
the COSMO-CLM regional climate model (RCM) to investigate the role of soil
moisture-atmosphere coupling for the European summer climate and the impact of the
representation of vegetation processes for land-atmosphere feedbacks.
We use two different versions of the COSMO-CLM model driven with ERAInterim data
to study the role of vegetation-atmosphere coupling in particular for droughts and resulting
feedbacks to the regional climate: 1) the standard version of COSMO-CLM, which includes a
very simple 2nd-generation land surface parameterization; 2) a new version, referred to as
COSMO-CLM2, which includes the more advanced 3rd-generation Community Land Model
(CLM). COSMO-CLM2 allows for a comprehensive representation of vegetation-climate
interactions at the regional scale (including effects of photosynthesis), and also includes a
detailed soil hydrological module. With both versions we perform a control run and a wet and
dry experiment to evaluate how the representation of land surface processes in the two
different land surface models influence the representation of land-atmosphere coupling in
coupled mode.
The results show marked differences in the representation of land-atmosphere coupling in
the two model versions. Regions of strong land-atmosphere coupling are clearly limited to
southern Europe in COSMO-CLM2, whereas they are more extended in COSMO-CLM.
The patterns in COSMO-CLM2 are found to be more realistic in comparison with
ground observations from the FLUXNET network. A smaller North-South gradient
in latent and sensible heat flux is found as the most likely cause for this clearer
distinction between regions with and without strong land-atmosphere coupling.
These results highlight the importance of the correct representation of vegetation
processes and soil hydrology for land-atmosphere feedbacks in a regional climate
model.
References:
Seneviratne, S. I., Lüthi, D., Litschi, M., Schär, C., 2006. Land-atmosphere coupling and
climate change in Europe. Nature, 443Â (14), 205–209.
Jaeger, E. B., Seneviratne, S. I., 2010. Impact of soil moisture-atmosphere coupling on
European climate extremes and trends in a regional climate model, Clim. Dyn.,
doi:10.1007/s00382-010-0780-8.
Lorenz, R., Jaeger, E. B., Seneviratne, S. I., 2010. Persistence of heat waves and its link to
soil moisture memory, 2010, Geophys. Res. Lett., 37, L09703. |
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