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Carbon cycle data assimilation with a generic phenology model

Knorr, W. LU ; Kaminski, T. ; Scholze, M. LU ; Gobron, N. ; Pinty, B. ; Giering, R. and Mathieu, P. P. (2010) In Journal of Geophysical Research - Biogeosciences 115(4).
Abstract

Photosynthesis by terrestrial plants is the main driver of the global carbon cycle, and the presence of actively photosynthesizing vegetation can now be observed from space. However, challenges remain when translating remotely sensed data into carbon fluxes. One reason is that the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), which documents the presence of photosynthetically active vegetation, relates more directly to leaf development and leaf phenology than to photosynthetic rates. Here, we present a new approach for linking FAPAR and vegetation-to-atmosphere carbon fluxes through variational data assimilation. The scheme extends the Carbon Cycle Data Assimilation System (CCDAS) by a newly developed, globally... (More)

Photosynthesis by terrestrial plants is the main driver of the global carbon cycle, and the presence of actively photosynthesizing vegetation can now be observed from space. However, challenges remain when translating remotely sensed data into carbon fluxes. One reason is that the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), which documents the presence of photosynthetically active vegetation, relates more directly to leaf development and leaf phenology than to photosynthetic rates. Here, we present a new approach for linking FAPAR and vegetation-to-atmosphere carbon fluxes through variational data assimilation. The scheme extends the Carbon Cycle Data Assimilation System (CCDAS) by a newly developed, globally applicable and generic leaf phenology model, which includes both temperature and water-driven leaf development. CCDAS is run for seven sites, six of them included in the FLUXNET network. Optimization is carried out simultaneously for all sites against 20 months of daily FAPAR from the Medium Resolution Imaging Spectrometer on board the European Space Agency's ENVISAT platform. Fourteen parameters related to phenology and 24 related to photosynthesis are optimized simultaneously, and their posterior uncertainties are computed. We find that with one parameter set for all sites, the model is able to reproduce the observed FAPAR spanning boreal, temperate, humid-tropical, and semiarid climates. Assimilation of FAPAR has led to reduced uncertainty (by >10%) of 10 of the 38 parameters, including one parameter related to photosynthesis, and a moderate reduction in net primary productivity uncertainty. The approach can easily be extended to regional or global studies and to the assimilation of further remotely sensed data.

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author
; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Geophysical Research - Biogeosciences
volume
115
issue
4
article number
G04017
pages
16 pages
publisher
Wiley
external identifiers
  • scopus:78349239632
ISSN
2169-8953
DOI
10.1029/2009JG001119
language
English
LU publication?
no
id
b136841f-67f6-455f-83b1-bfc2c72182e8
date added to LUP
2019-03-14 21:18:49
date last changed
2024-02-09 13:51:49
@article{b136841f-67f6-455f-83b1-bfc2c72182e8,
  abstract     = {{<p>Photosynthesis by terrestrial plants is the main driver of the global carbon cycle, and the presence of actively photosynthesizing vegetation can now be observed from space. However, challenges remain when translating remotely sensed data into carbon fluxes. One reason is that the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), which documents the presence of photosynthetically active vegetation, relates more directly to leaf development and leaf phenology than to photosynthetic rates. Here, we present a new approach for linking FAPAR and vegetation-to-atmosphere carbon fluxes through variational data assimilation. The scheme extends the Carbon Cycle Data Assimilation System (CCDAS) by a newly developed, globally applicable and generic leaf phenology model, which includes both temperature and water-driven leaf development. CCDAS is run for seven sites, six of them included in the FLUXNET network. Optimization is carried out simultaneously for all sites against 20 months of daily FAPAR from the Medium Resolution Imaging Spectrometer on board the European Space Agency's ENVISAT platform. Fourteen parameters related to phenology and 24 related to photosynthesis are optimized simultaneously, and their posterior uncertainties are computed. We find that with one parameter set for all sites, the model is able to reproduce the observed FAPAR spanning boreal, temperate, humid-tropical, and semiarid climates. Assimilation of FAPAR has led to reduced uncertainty (by &gt;10%) of 10 of the 38 parameters, including one parameter related to photosynthesis, and a moderate reduction in net primary productivity uncertainty. The approach can easily be extended to regional or global studies and to the assimilation of further remotely sensed data.</p>}},
  author       = {{Knorr, W. and Kaminski, T. and Scholze, M. and Gobron, N. and Pinty, B. and Giering, R. and Mathieu, P. P.}},
  issn         = {{2169-8953}},
  language     = {{eng}},
  month        = {{12}},
  number       = {{4}},
  publisher    = {{Wiley}},
  series       = {{Journal of Geophysical Research - Biogeosciences}},
  title        = {{Carbon cycle data assimilation with a generic phenology model}},
  url          = {{http://dx.doi.org/10.1029/2009JG001119}},
  doi          = {{10.1029/2009JG001119}},
  volume       = {{115}},
  year         = {{2010}},
}