نتایج جستجو برای: eddy covariance
تعداد نتایج: 44832 فیلتر نتایج به سال:
General comments This paper provides estimates of the carbon balance of Russia based on three forms of measurement (inventory [LEA], eddy covariance and atmospheric inversion. Calculations are also presented for 8 DGVMs but these are not used in providing the final overall estimate of the net carbon balance. Each of these has quite different properties and different levels of uncertainty. The i...
10 Sensible heat fluxes (QH) are determined using scintillometry and eddy covariance over a 11 suburban area. Two large aperture scintillometers provide spatially integrated fluxes across path 12 lengths of 2.8 km and 5.5 km over Swindon, UK. The shorter scintillometer path spans newly built 13 residential areas and has an approximate source area of 2-4 km, whilst the long path extends from 14 ...
Scintillometry, a form of ground-based remote sensing, provides the capability to estimate surface heat fluxes over scales of a few hundred metres to kilometres. Measurements are spatial averages, making this technique particularly valuable over areas with moderate heterogeneity such as mixed agricultural or urban environments. In this study, we present the structure parameters of temperature a...
Coupled terrestrial carbon (C), nitrogen (N) and hydrological processes play a crucial role in the climate system, providing both positive and negative feedbacks to climate change. In this review we summarize published research results to gain an increased understanding of the dynamics between vegetation and atmosphere processes. A variety of methods, including monitoring (e.g., eddy covariance...
of net ecosystem exchange (NEE). They use a Bayesian approach, moving from the regression analysis of rectangular hyperbola fitting daytime data. The argument treated is within the scope of Biogeosciences and the computational instrument they developed is promising. Nevertheless, at this current stage the study suffer from several limitations, not only in the presentational form but also in the...
The planetary boundary layer (PBL) provides an important link between the scales and processes resolved by global atmospheric sampling/modeling and site-based flux measurements. The PBL is in direct contact with the land surface, both driving and responding to ecosystem processes. Measurements within the PBL (e.g., by radiosondes, aircraft profiles, and flask measurements) have a footprint, and...
[1] Combining sap flux and eddy covariance measurements provides a means to study plant stomatal conductance and the relationship between transpiration and photosynthesis. We measured sap flux using Granier-type sensors in a northern hardwood-dominated old growth forest in Michigan, upscaled to canopy transpiration, and calculated canopy conductance. We also measured carbon and water fluxes wit...
Published eddy covariance measurements of carbon dioxide (CO2) exchange between vegetation and the atmosphere from a global network are distilled, synthesised and reviewed according to time scale, climate and plant functional types, disturbance and land use. Other topics discussed include history of the network, errors and issues associated with the eddy covariance method, and a synopsis of how...
Gross Primary Production (GPP) is the largest flux in the global carbon cycle. However, large uncertainties in current global estimations persist. In this study, we examined the performance of a process-based model (Integrated BIosphere Simulator, IBIS) at 62 eddy covariance sites around the world. Our results indicated that the IBIS model explained 60% of the observed variation in daily GPP at...
We use eddy covariance measurements of net ecosystem productivity (NEP) from 21 FLUXNET sites (153 site-years of data) to investigate relationships between phenology and productivity (in terms of both NEP and gross ecosystem photosynthesis, GEP) in temperate and boreal forests. Results are used to evaluate the plausibility of four different conceptual models. Phenological indicators were derive...
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