Abstract In this study we introduce a novel extension of an existing Lagrangian particle dispersion model for application over urban areas by explicitly taking into account the canopy layer. As commonly done, original uses zero-plane displacement as lower boundary condition, while reaches to ground. To achieve this, spatially-averaged parametrizations flow and turbulence characteristics are cre...

This report describes a system for integrating photosynthetically active radiation (PAR) using fi beroptics. Many photoelectric sensors or 1-m-long line sensors that integrate individual interception points for spatial averaging were replaced with fi beroptics, which integrate interception points. Depending on the positioning of optical fi bers and the amount of fi bers terminated at a PAR sens...

With fire suppression, many western forests are expected to have fewer gaps and higher stem density of shade-tolerant species as light competition becomes a more significant influence on stand pattern and composition. We compared species composition, structure, spatial pattern, and environmental factors such as light and soil moisture between two old-growth forests: Pacific Northwest western he...

[1] The dynamics of forest-atmosphere CO2 carbon isotope exchange were examined in a coniferous forest in Colorado, United States. Tunable diode laser absorption spectrometry provided extensive characterization of the carbon isotope content (dC) of CO2. Observed patterns in d C of forest air were associated with photosynthesis, respiration, and atmospheric boundary layer dynamics. Similar relat...

[1] The nocturnal drainage flow of air causes significant uncertainty in ecosystem CO2, H2O, and energy budgets determined with the eddy covariance measurement approach. In this study, we examined the magnitude, nature, and dynamics of the nocturnal drainage flow in a subalpine forest ecosystem with complex terrain. We used an experimental approach involving four towers, each with vertical prof...

Light detection and ranging (Lidar) data can be used to create wall-to-wall forest structure and fuel products that are required for wildfire behavior simulation models. We know that Lidar-derived forest parameters have a non-negligible error associated with them, yet we do not know how this error influences the results of fire behavior modeling that use these layers as inputs. Here, we evaluat...

The spatially explicit and mechanistic model TREEGRASS was used to test the effects of tree density, tree spatial distribution, and tree size distribution on radiation absorption, net primary production (NPP), and, water fluxes for a West African savanna . The model has previously been shown to adequately predict radiation absorption, production, and soil water balance in humid savannas . Using...

the aim of this research was to compare more and less competitiveness of rice cultivars against barnyardgrass for light extinction coefficient and canopy structur. a filed experiment was conducted in 2007 growing season in tonekabon’s rice research station in mazandaran province. the experiment layout was a factorial design with four randomized complete blocks. seven rice cultivars (khazar, sep...

How the spatial perturbations of the first and second moments of the velocity and pressure fields differ for flow over a train of gentle hills covered by either sparse or dense vegetation is explored using large-eddy simulation (LES). Two simulations are investigated where the canopy is composed of uniformly arrayed rods each with a height that is comparable to the hill height. In the first sim...