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Towards operational remote sensing of forest carbon balance across Northern Europe

Olofsson, Pontus LU ; Lagergren, Fredrik LU ; Lindroth, Anders LU ; Lindström, Johan LU ; Klemedtsson, Leif and Eklundh, Lars LU (2007) In Biogeosciences Discussions 4(5). p.3143-3193
Abstract
onthly averages of ecosystem respiration (ER), gross primary production (GPP) and net ecosystem exchange (NEE) over Scandinavian forest sites were estimated using regression models driven by air temperature (AT), absorbed photosynthetically active radiation (APAR) and vegetation indices. The models were constructed and evaluated using satellite data from Terra/MODIS and measured data collected at seven flux tower sites in northern Europe. Data used for model construction was excluded from the evaluation. Relationships between ground measured variables and the independent variables were investigated.



It was found that the enhanced vegetation index (EVI) at 250 m resolution was highly noisy for the coniferous sites, and... (More)
onthly averages of ecosystem respiration (ER), gross primary production (GPP) and net ecosystem exchange (NEE) over Scandinavian forest sites were estimated using regression models driven by air temperature (AT), absorbed photosynthetically active radiation (APAR) and vegetation indices. The models were constructed and evaluated using satellite data from Terra/MODIS and measured data collected at seven flux tower sites in northern Europe. Data used for model construction was excluded from the evaluation. Relationships between ground measured variables and the independent variables were investigated.



It was found that the enhanced vegetation index (EVI) at 250 m resolution was highly noisy for the coniferous sites, and hence, 1 km EVI was used for the analysis. Linear relationships between EVI and the biophysical variables were found for both coniferous and deciduous data: correlation coefficients ranged from 0.91 to 0.79, and 0.85 to 0.67, respectively. Due to saturation, there were no linear relationships between normalized difference vegetation index (NDVI) and the ground measured parameters found at any site. APAR correlated better with the parameters in question than the vegetation indices. Modeled GPP and ER were in good agreement with measured values, with more than 90% of the variation in measured GPP and ER being explained by the coniferous models. The site-specific respiration rate at 10°C (R10) was needed for describing the ER variation between sites. Even though monthly NEE was modeled with less accuracy than GPP, 61% and 75% (dec. and con., respectively) of the variation in the measured time series was explained by the model. These results are important for moving towards operational remote sensing of forest carbon balance across Northern Europe. (Less)
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author
organization
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Contribution to journal
publication status
published
subject
keywords
NPP, MODIS, carbon balance, respiration, NEE, remote sensing, NDVI
in
Biogeosciences Discussions
volume
4
issue
5
pages
3143 - 3193
publisher
EGU / Copernican Publications
ISSN
1810-6277
language
English
LU publication?
yes
id
5743763b-b1ee-4214-aa05-ab633de7b516 (old id 4856620)
alternative location
http://www.biogeosciences-discuss.net/4/3143/2007/bgd-4-3143-2007.pdf
date added to LUP
2014-12-04 08:03:15
date last changed
2016-10-11 08:43:22
@article{5743763b-b1ee-4214-aa05-ab633de7b516,
  abstract     = {onthly averages of ecosystem respiration (ER), gross primary production (GPP) and net ecosystem exchange (NEE) over Scandinavian forest sites were estimated using regression models driven by air temperature (AT), absorbed photosynthetically active radiation (APAR) and vegetation indices. The models were constructed and evaluated using satellite data from Terra/MODIS and measured data collected at seven flux tower sites in northern Europe. Data used for model construction was excluded from the evaluation. Relationships between ground measured variables and the independent variables were investigated.<br/><br>
<br/><br>
It was found that the enhanced vegetation index (EVI) at 250 m resolution was highly noisy for the coniferous sites, and hence, 1 km EVI was used for the analysis. Linear relationships between EVI and the biophysical variables were found for both coniferous and deciduous data: correlation coefficients ranged from 0.91 to 0.79, and 0.85 to 0.67, respectively. Due to saturation, there were no linear relationships between normalized difference vegetation index (NDVI) and the ground measured parameters found at any site. APAR correlated better with the parameters in question than the vegetation indices. Modeled GPP and ER were in good agreement with measured values, with more than 90% of the variation in measured GPP and ER being explained by the coniferous models. The site-specific respiration rate at 10°C (R10) was needed for describing the ER variation between sites. Even though monthly NEE was modeled with less accuracy than GPP, 61% and 75% (dec. and con., respectively) of the variation in the measured time series was explained by the model. These results are important for moving towards operational remote sensing of forest carbon balance across Northern Europe.},
  author       = {Olofsson, Pontus and Lagergren, Fredrik and Lindroth, Anders and Lindström, Johan and Klemedtsson, Leif and Eklundh, Lars},
  issn         = {1810-6277},
  keyword      = {NPP,MODIS,carbon balance,respiration,NEE,remote sensing,NDVI},
  language     = {eng},
  number       = {5},
  pages        = {3143--3193},
  publisher    = {EGU / Copernican Publications},
  series       = {Biogeosciences Discussions},
  title        = {Towards operational remote sensing of forest carbon balance across Northern Europe},
  volume       = {4},
  year         = {2007},
}