National Repository of Grey Literature 3 records found  Search took 0.00 seconds. 
Improvement of CO2 eddy fluxes modelling in topographically complex terrain
Šigut, Ladislav
Annual sums of net ecosystem exchange (NEE) estimated by eddy covariance method (EC) are often used for comparisons among sites. But application of EC in topographically complex terrain restrains application of standard methods for their estimation. Analysis of friction air velocity response of night-time CO2 fluxes and estimation of mean daily ecosystem respiration from daytime NEE showed that night-time data and fluxes measured early after sunrise or late before sunset are not sufficiently reliable for computation of accurate annual sums of NEE. Therefore presented method takes into account auxiliary soil chamber measurements and applies correction factor in ecosystem respiration model calibrated to biomass inventory results. Also automated algorithm for computation of light response curve parameters in constrained range was established. This method produced accurate annual sums of NEE that were only 7.2% ± 5.2 higher than values determined by biomass inventory method.
Analysis of turbulent flow over forested terrain
Potužníková, Kateřina ; Sedlák, Pavel ; Šauli, Petra
The aim of the present study is to assess and describe low-frequency oscillations and coherent structures in temporal series of temperature and wind velocity components sampled at three different levels within the forest (z/h = 0.3, 0.5 and 1, where h is the canopy height). The wavelet transform is used as a basic tool for our analysis. The periods of detected structures depend on the temperature gradient in the canopy, and furthermore seem to vary with the different local circulations regimes.
Modelování profilů rychlosti větru naměřených sodarem v komplexním terénu
Hošek, Jiří
The wind profiles with two Doppler sodars were measured in wide range of synoptic situations in Ore mountains (Erzgebirge) and in the region of Orlické hory (mountains), both in the Czech republic. Ore mountains represent the region most suitable for construction of wind turbines in the Czech republic. Concerning the observed wind profiles, their generalization may serve for improvement of precision of the simulated wind profile fields. In the second part of the work, we performed the modelling of wind speed profiles in the complex terrain of above-mentioned mountain ranges. We have applied the non-hydrostatic meso-scale models KAMM and PIAP. The numerical simulations with the models were performed for different situations of the ambient flow, described by geostrophic wind speed and direction, and temperature stratification.

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