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A new mass conservation approach to the study of CO2 advection in an alpine forest

Montagnani, Leonardo; Manca, Giovanni; Canepa, Elisa; Georgieva, Emilia; Acosta, Manuel; Feigenwinter, Christian; Janous, Dalibor; Kerschbaumer, Guenther; Lindroth, Anders LU and Minach, Luigi, et al. (2009) In Journal of Geophysical Research 114.
Abstract
A new method is proposed for the computation of CO2 Net Ecosystem Exchange (NEE) and its components in a forest ecosystem. Advective flux is estimated by taking into account the air mass conservation principle. For this purpose, wind and dry air density values on the surface of the control volume are first corrected and then the advective flux is estimated on the surface of the control volume. Turbulent flux is also computed along the surface of the control volume while storage flux is computed inside the volume. Additional characteristics of this method are that incompressibility of the mean flow is not assumed a priori, and that vertical and horizontal advective fluxes are not treated separately, but their sum is estimated directly. The... (More)
A new method is proposed for the computation of CO2 Net Ecosystem Exchange (NEE) and its components in a forest ecosystem. Advective flux is estimated by taking into account the air mass conservation principle. For this purpose, wind and dry air density values on the surface of the control volume are first corrected and then the advective flux is estimated on the surface of the control volume. Turbulent flux is also computed along the surface of the control volume while storage flux is computed inside the volume. Additional characteristics of this method are that incompressibility of the mean flow is not assumed a priori, and that vertical and horizontal advective fluxes are not treated separately, but their sum is estimated directly. The methodology is applied to experimental data collected with a three-dimensional scheme at the alpine site of Renon during the Advex project (July 2005). The advection flux was found to be prevailing positive at night and negative during the day, as was found in previous studies on advection for the same site, but showed a lower scatter in half-hour calculated values. We tested the effect of its summation on turbulent and storage fluxes to produce half-hourly values of NEE. Nighttime NEE values were used in functional relations with soil temperature, daytime values with PPFD. The effect of addition of the advection component was an increase in the values of parameters indicating ecosystem respiration, quantum yield, and photosynthetic capacity. The coefficient of correlation between NEE and environmental drivers increased. (Less)
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Journal of Geophysical Research
volume
114
publisher
American Geophysical Union
external identifiers
  • wos:000265102100002
  • scopus:67349172570
ISSN
2156-2202
DOI
10.1029/2008JD010650
language
English
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yes
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2ef79b00-5c42-4883-bd9a-a73d6805ddab (old id 1400238)
date added to LUP
2009-06-15 14:49:57
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2017-08-20 03:36:31
@article{2ef79b00-5c42-4883-bd9a-a73d6805ddab,
  abstract     = {A new method is proposed for the computation of CO2 Net Ecosystem Exchange (NEE) and its components in a forest ecosystem. Advective flux is estimated by taking into account the air mass conservation principle. For this purpose, wind and dry air density values on the surface of the control volume are first corrected and then the advective flux is estimated on the surface of the control volume. Turbulent flux is also computed along the surface of the control volume while storage flux is computed inside the volume. Additional characteristics of this method are that incompressibility of the mean flow is not assumed a priori, and that vertical and horizontal advective fluxes are not treated separately, but their sum is estimated directly. The methodology is applied to experimental data collected with a three-dimensional scheme at the alpine site of Renon during the Advex project (July 2005). The advection flux was found to be prevailing positive at night and negative during the day, as was found in previous studies on advection for the same site, but showed a lower scatter in half-hour calculated values. We tested the effect of its summation on turbulent and storage fluxes to produce half-hourly values of NEE. Nighttime NEE values were used in functional relations with soil temperature, daytime values with PPFD. The effect of addition of the advection component was an increase in the values of parameters indicating ecosystem respiration, quantum yield, and photosynthetic capacity. The coefficient of correlation between NEE and environmental drivers increased.},
  author       = {Montagnani, Leonardo and Manca, Giovanni and Canepa, Elisa and Georgieva, Emilia and Acosta, Manuel and Feigenwinter, Christian and Janous, Dalibor and Kerschbaumer, Guenther and Lindroth, Anders and Minach, Luigi and Minerbi, Stefano and Mölder, Meelis and Pavelka, Marian and Seufert, Guenther and Zeri, Marcelo and Ziegler, Waldemar},
  issn         = {2156-2202},
  language     = {eng},
  publisher    = {American Geophysical Union},
  series       = {Journal of Geophysical Research},
  title        = {A new mass conservation approach to the study of CO2 advection in an alpine forest},
  url          = {http://dx.doi.org/10.1029/2008JD010650},
  volume       = {114},
  year         = {2009},
}