Universität zu Köln

Post, Hanna, Vrugt, Jasper A., Fox, Andrew, Vereecken, Harry and Franssen, Harrie-Jan Hendricks (2017). Estimation of Community Land Model parameters for an improved assessment of net carbon fluxes at European sites. J. Geophys. Res.-Biogeosci., 122 (3). S. 661 - 690. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-8961

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Abstract

The Community Land Model (CLM) contains many parameters whose values are uncertain and thus require careful estimation for model application at individual sites. Here we used Bayesian inference with the DiffeRential Evolution Adaptive Metropolis (DREAM((zs))) algorithm to estimate eight CLM v. 4.5 ecosystem parameters using 1 year records of half- hourly net ecosystem CO2 exchange (NEE) observations of four central European sites with different plant functional types (PFTs). The posterior CLM parameter distributions of each site were estimated per individual season and on a yearly basis. These estimates were then evaluated using NEE data from an independent evaluation period and data from nearby FLUXNET sites at similar to 600 km distance to the original sites. Latent variables (multipliers) were used to treat explicitly uncertainty in the initial carbon- nitrogen pools. The posterior parameter estimates were superior to their default values in their ability to track and explain the measured NEE data of each site. The seasonal parameter values reduced with more than 50% (averaged over all sites) the bias in the simulated NEE values. The most consistent performance of CLM during the evaluation period was found for the posterior parameter values of the forest PFTs, and contrary to the C3-grass and C3-crop sites, the latent variables of the initial pools further enhanced the quality-of-fit. The carbon sink function of the forest PFTs significantly increased with the posterior parameter estimates. We thus conclude that land surface model predictions of carbon stocks and fluxes require careful consideration of uncertain ecological parameters and initial states.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Post, Hanna UNSPECIFIED UNSPECIFIED UNSPECIFIED Vrugt, Jasper A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fox, Andrew UNSPECIFIED UNSPECIFIED UNSPECIFIED Vereecken, Harry UNSPECIFIED UNSPECIFIED UNSPECIFIED Franssen, Harrie-Jan Hendricks UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-239124
DOI:	10.1002/2015JG003297
Journal or Publication Title:	J. Geophys. Res.-Biogeosci.
Volume:	122
Number:	3
Page Range:	S. 661 - 690
Date:	2017
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-8961
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ORGANIC-MATTER DECOMPOSITION; TERRESTRIAL ECOSYSTEM MODEL; MONTE-CARLO-SIMULATION; EARTH SYSTEM MODELS; DATA ASSIMILATION; TEMPERATURE-DEPENDENCE; DATA FUSION; UNCERTAINTY ESTIMATION; STOMATAL CONDUCTANCE; NONLINEAR INVERSION Multiple languages Environmental Sciences; Geosciences, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23912