References of "Manca, Giovanni"
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See detailApplication of a mass consistent flow model to study the CO2 mass balance of forests
Canepa, Elisa; Georgieva, Emilia; Manca, Giovanni et al

in Agricultural and Forest Meteorology (2010), 150(5), 712-723

The reconstruction of the wind field is one of the main issues in the mass conservation approach for calculation of CO2 advection in forest ecosystems and still remains a challenging problem. In the ... [more ▼]

The reconstruction of the wind field is one of the main issues in the mass conservation approach for calculation of CO2 advection in forest ecosystems and still remains a challenging problem. In the current study, we present an advancement of this approach: the use of a mass consistent flow model (WINDS) which takes into account measured wind data and simulates the 3-D flow field, while imposing airmass conservation in the control volume. We apply the WINDS model to alculate half hourly mean total advective flux terms at the CarboEurope-IP site of Renon (Bozen/Bolzano Autonomous Province), in Northern Italy. The data used refer to six time periods of one day representing three different meteorological conditions observed during the ADVEX campaign from April to September 2005. Current results are compared with results obtained in two other studies for the same time periods. One of these studies is based on the mass conservation approach as well, but applies only interpolations to reconstruct the wind field; the other study makes use of tilt correction (sectorwise planar fit method) for the vertical wind component. In the present study, the effect of the wind field reconstruction method on the estimation of the advective fluxes is discussed. The possibility of using reduced input wind data (i.e. number of towers) for WINDS is also investigated. The results suggest that the representativeness of wind tower measurements is of primary importance for estimating CO2 advection terms and their uncertainty in complex terrain. [less ▲]

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See detailClimate control of terrestrial carbon exchange across biomes and continents
Yi, Chuixiang; Ricciuto, Daniel; Li, Runze et al

in Environmental Research Letters (2010), 5(3),

Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating ... [more ▼]

Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various ecosystems over six continents with a total of 559 site-years. We find that NEE observed at eddy covariance sites is (1) a strong function of mean annual temperature at mid-and high-latitudes, (2) a strong function of dryness at mid-and low-latitudes, and (3) a function of both temperature and dryness around the mid-latitudinal belt (45 degrees N). The sensitivity of NEE to mean annual temperature breaks down at similar to 16 degrees C (a threshold value of mean annual temperature), above which no further increase of CO2 uptake with temperature was observed and dryness influence overrules temperature influence. [less ▲]

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