Mots-clé
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Representativeness of site observations; regional signal extraction; land-atmosphere interactions; model validation; spatial representativness; Up-Scaling; Fluxnet; Climate Model Validation
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Programme de recherche
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COST-Action ES0804 - Advancing the integrated monitoring of trace gas exchange between biosphere and atmosphere
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Description succincte
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Land-climate interactions are one of the main contributors of uncertainty in current global and regional climate models (Koster et al., 2004, Friedlingstein et al., 2006, Seneviratne et al., 2006a, Betts, 2007, Pitman et al., 2009, Orlowsky and Seneviratne, 2009). Their better understanding from e.g. FLUXNET observations can therefore strongly benefit model development. However, validation of climate models with observations is not straightforward, since models produce areal (grid cell) data whereas observations are generally point-scale data. In this project, we will analyse the extractability of regional signals from the FLUXNET sites, and use these regional signals for the investigation of land-atmosphere interactions and the validation of climate models. This project will address five main topics: (i) the assessment of the consistency of spatial patterns in climate models (and further gridded data sets) vs. FLUXNET data; (ii) the extraction of regional signals from single FLUXNET sites (up-scaling); (iii) the analysis of the geographic reach of representativeness of individual FLUXNET sites, and of the factors limiting this reach; (iv) the evaluation of the agreement between modeled time series and up-scaled FLUXNET data; (v) the analysis of land-atmosphere interactions based on regional signals and diagnostics derived from FLUXNET data. The envisaged methodological framework will not be limited to FLUXNET data, but will also advance the general understanding of how to derive observational constraints for coupled climate models.
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Autres indications
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Full name of research-institution/enterprise: ETH Zürich Land-Climate Interactions Institut for Atmospheric and Climate Science CHN N11
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Partenaires et organisations internationales
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CH, DE, DK, ES, FI, FR, GR, HU, IE, IL, IT, LT, LU, NL, NO, PL, SE, UK
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Résumé des résultats (Abstract)
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This project has addressed the following main topis: (i) the assessment of the consistency of spatial patterns in climate models (and further gridded data sets) vs. FLUXNET data; (ii) the extraction of regional signals from single FLUXNET sites (up-scaling); (iii) the analysis of the geographic reach of representativeness of individual FLUXNET sites, and of the factors limiting this reach; (iv) the evaluation of the agreement between modeled time series and up-scaled FLUXNET data; (v) the analysis of land-atmosphere interactions based on regional signals and diagnostics derived from FLUXNET data. Relatively early during the project phase, we had started to work on three papers addressing these topics. However, our analyses have yielded an unexpected variety of additional questions, which have delayed the actual submission so far. E.g., for the first paper (topics i and v) on pattern correlations of diagnostics of land-atmosphere diagnostics, the since recently available CMIP5 ensemble needs to be taken into account. For the second paper (topics ii, iii and v) on the station representativeness over Switzerland we found it necessary to expand the study area to continental Europe. Our analysis shows an interesting seasonal dependence of the patterns of representativity, which can be interpreted, at least in parts, in terms of large scale atmospheric dynamics. Especially the work for the third paper (topics iv and v) on the FLUXNET energy fluxes over the US and their comparison to reanalysis and observation based products has expanded substantially and led to an intensive collaboration with groups in the US and UK. A thorough analysis of the coupling of the fluxes to rainfall occurrence has uncovered substantial issues in the land-surface models used for some reanalysis products and enables us to provide a systematic evaluation of different data products with respect to land-surface precipitation interactions.
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Références bases de données
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Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. +41 31 322 74 82 Swiss Project-Number: C09.0157
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