The Experts below are selected from a list of 1086 Experts worldwide ranked by ideXlab platform
M J Savage - One of the best experts on this subject based on the ideXlab platform.
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sensible heat flux by surface layer scintillometry and eddy covariance over a mixed grassland community as affected by bowen ratio and most formulations for unstable conditions
Journal of Hydrometeorology, 2009Co-Authors: George O. Odhiambo, M J SavageAbstract:Abstract Measurements of sensible heat flux for an extended period for unstable conditions using surface layer scintillometry (SLS) and eddy covariance (EC) and supplemented by Bowen ratio measurements for a mixed grassland community on the eastern seaboard of South Africa are presented. Measurements of SLS sensible heat flux density were compared with those obtained using EC for a wide range of Bowen ratio (β). Also presented is an analysis of the different forms of the Monin–Obukhov similarity theory (MOST) functions used in Micrometeorology and suggested by various authors, done by comparing EC sensible heat and measured by SLS through the use of an iterative determination of Monin–Obukhov parameters. A comparison of the SLS-measured structure parameter of air temperature CT2 corrected for β and uncorrected was carried out, with the results showing good correspondence but with a slight bias indicating that not correcting SLS measurements of CT2 for β would also result in a slight bias in H. Eddy covari...
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sensible heat flux by surface layer scintillometry and eddy covariance over a mixed grassland community as affected by bowen ratio and most formulations for unstable conditions
Journal of Hydrometeorology, 2009Co-Authors: George O. Odhiambo, M J SavageAbstract:Abstract Measurements of sensible heat flux for an extended period for unstable conditions using surface layer scintillometry (SLS) and eddy covariance (EC) and supplemented by Bowen ratio measurements for a mixed grassland community on the eastern seaboard of South Africa are presented. Measurements of SLS sensible heat flux density were compared with those obtained using EC for a wide range of Bowen ratio (β). Also presented is an analysis of the different forms of the Monin–Obukhov similarity theory (MOST) functions used in Micrometeorology and suggested by various authors, done by comparing EC sensible heat and measured by SLS through the use of an iterative determination of Monin–Obukhov parameters. A comparison of the SLS-measured structure parameter of air temperature CT2 corrected for β and uncorrected was carried out, with the results showing good correspondence but with a slight bias indicating that not correcting SLS measurements of CT2 for β would also result in a slight bias in H. Eddy covari...
George O. Odhiambo - One of the best experts on this subject based on the ideXlab platform.
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sensible heat flux by surface layer scintillometry and eddy covariance over a mixed grassland community as affected by bowen ratio and most formulations for unstable conditions
Journal of Hydrometeorology, 2009Co-Authors: George O. Odhiambo, M J SavageAbstract:Abstract Measurements of sensible heat flux for an extended period for unstable conditions using surface layer scintillometry (SLS) and eddy covariance (EC) and supplemented by Bowen ratio measurements for a mixed grassland community on the eastern seaboard of South Africa are presented. Measurements of SLS sensible heat flux density were compared with those obtained using EC for a wide range of Bowen ratio (β). Also presented is an analysis of the different forms of the Monin–Obukhov similarity theory (MOST) functions used in Micrometeorology and suggested by various authors, done by comparing EC sensible heat and measured by SLS through the use of an iterative determination of Monin–Obukhov parameters. A comparison of the SLS-measured structure parameter of air temperature CT2 corrected for β and uncorrected was carried out, with the results showing good correspondence but with a slight bias indicating that not correcting SLS measurements of CT2 for β would also result in a slight bias in H. Eddy covari...
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sensible heat flux by surface layer scintillometry and eddy covariance over a mixed grassland community as affected by bowen ratio and most formulations for unstable conditions
Journal of Hydrometeorology, 2009Co-Authors: George O. Odhiambo, M J SavageAbstract:Abstract Measurements of sensible heat flux for an extended period for unstable conditions using surface layer scintillometry (SLS) and eddy covariance (EC) and supplemented by Bowen ratio measurements for a mixed grassland community on the eastern seaboard of South Africa are presented. Measurements of SLS sensible heat flux density were compared with those obtained using EC for a wide range of Bowen ratio (β). Also presented is an analysis of the different forms of the Monin–Obukhov similarity theory (MOST) functions used in Micrometeorology and suggested by various authors, done by comparing EC sensible heat and measured by SLS through the use of an iterative determination of Monin–Obukhov parameters. A comparison of the SLS-measured structure parameter of air temperature CT2 corrected for β and uncorrected was carried out, with the results showing good correspondence but with a slight bias indicating that not correcting SLS measurements of CT2 for β would also result in a slight bias in H. Eddy covari...
George Banweiss - One of the best experts on this subject based on the ideXlab platform.
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the impact of heat mitigation strategies on the energy balance of a neighborhood in los angeles
Solar Energy, 2019Co-Authors: Mohammad Taleghani, Peter J Crank, Arash Mohegh, David J Sailor, George BanweissAbstract:Abstract Heat mitigation strategies can reduce excess heat in urban environments. These strategies, including solar reflective cool roofs and pavements, green vegetative roofs, and street vegetation, alter the surface energy balance to reduce absorption of sunlight at the surface and subsequent transfer to the urban atmosphere. The impacts of heat mitigation strategies on meteorology have been investigated in past work at the mesoscale and global scale. For the first time, we focus on the effect of heat mitigation strategies on the surface energy balance at the neighborhood scale. The neighborhood under investigation is El Monte, located in the eastern Los Angeles basin in Southern California. Using a computational fluid dynamics model to simulate Micrometeorology at high spatial resolution, we compare the surface energy balance of the neighborhood assuming current land cover to that with neighborhood-wide deployment of green roof, cool roof, additional trees, and cool pavement as the four heat mitigation strategies. Of the four strategies, adoption of cool pavements led to the largest reductions in net radiation (downward positive) due to the direct impact of increasing pavement albedo on ground level solar absorption. Comparing the effect of each heat mitigation strategy shows that adoption of additional trees and cool pavements led to the largest spatial-maximum air temperature reductions at 14:00 h (1.0 and 2.0 °C, respectively). We also investigate how varying the spatial coverage area of heat mitigation strategies affects the neighborhood-scale impacts on meteorology. Air temperature reductions appear linearly related to the spatial extent of heat mitigation strategy adoption at the spatial scales and baseline meteorology investigated here.
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micrometeorological simulations to predict the impacts of heat mitigation strategies on pedestrian thermal comfort in a los angeles neighborhood
Environmental Research Letters, 2016Co-Authors: Mohammad Taleghani, David J Sailor, George BanweissAbstract:The urban heat island impacts the thermal comfort of pedestrians in cities. In this paper, the effects of four heat mitigation strategies on Micrometeorology and the thermal comfort of pedestrians were simulated for a neighborhood in eastern Los Angeles County. The strategies investigated include solar reflective “cool” roofs, vegetative “green roofs”, solar reflective cool pavements, and increased street-level trees. A series of micrometeorological simulations for an extreme heat day were carried out assuming widespread adoption of each mitigation strategy. Comparing each simulation to the control simulation assuming current land cover for the neighborhood showed that additional street-trees and cool pavements reduced 1.5m air temperature, while cool and green roofs provided cooling at heights above pedestrian level. However, cool pavements increased reflected sunlight from the ground to pedestrians near pavements in unshaded areas. This reflected radiation intensified the mean radiant temperature and consequently increased physiological equivalent temperature (PET) by 2.2°C during the day, reducing the thermal comfort of pedestrians. In locations near roadways with preexisting tree cover, cool pavements caused significant reductions in surface air temperatures and small changes in mean radiant temperature during the day, leading to decreases in PET of 1.1°C, and consequent improvements in thermal comfort. For improving thermal comfort of pedestrians during the afternoon in unshaded locations, adding street trees was found to be the most effective strategy. However, afternoon thermal comfort improvements in already shaded locations near streets were most significant for cool pavements. Green and cool roofs showed the lowest impact on the thermal comfort of pedestrians since they modify the energy balance at roof level, well above the height of pedestrians.
Chad W. Higgins - One of the best experts on this subject based on the ideXlab platform.
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Remarkable agrivoltaic influence on soil moisture, Micrometeorology and water-use efficiency.
PLOS ONE, 2018Co-Authors: Elnaz Hassanpour Adeh, John S. Selker, Chad W. HigginsAbstract:Power demands are set to increase by two-fold within the current century and a high fraction of that demand should be met by carbon free sources. Among the renewable energies, solar energy is among the fastest growing; therefore, a comprehensive and accurate design methodology for solar systems and how they interact with the local environment is vital. This paper addresses the environmental effects of solar panels on an unirrigated pasture that often experiences water stress. Changes to the microclimatology, soil moisture, water usage, and biomass productivity due to the presence of solar panels were quantified. The goal of this study was to show that the impacts of these factors should be considered in designing the solar farms to take advantage of potential net gains in agricultural and power production. Microclimatological stations were placed in the Rabbit Hills agrivoltaic solar arrays, located in Oregon State campus, two years after the solar array was installed. Soil moisture was quantified using neutron probe readings. Significant differences in mean air temperature, relative humidity, wind speed, wind direction, and soil moisture were observed. Areas under PV solar panels maintained higher soil moisture throughout the period of observation. A significant increase in late season biomass was also observed for areas under the PV panels (90% more biomass), and areas under PV panels were significantly more water efficient (328% more efficient).
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Remarkable agrivoltaic influence on soil moisture, Micrometeorology and water-use efficiency - Fig 1
2018Co-Authors: Elnaz Hassanpour Adeh, John S. Selker, Chad W. HigginsAbstract:a) Aerial photo of 35th Street agrivoltaic solar array, Oregon State University Corvallis campus (this photo is taken in winter and shadow pattern is different from the measurements which held in summer) Copyright: Oregon State University, b) Solar panel set up, c) Control area set up, d) Shade zones in solar panel, e) Schematic drawing of shade zones (H is object height and L is shadow length).
T B Parkin - One of the best experts on this subject based on the ideXlab platform.
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comparison of closed chamber and bowen ratio methods for determining methane flux from peatland surfaces
Journal of Environmental Quality, 1998Co-Authors: A S K Chan, J H Prueger, T B ParkinAbstract:Methane (CH 4 ) is an important greenhouse gas, and it has been estimated that 50% of annual CH 4 comes from terrestrial systems. Better and more accurate methods are needed to quantify CH 4 flux from terrestrial environments. Two general methods commonly applied to measure trace gas fluxes are soil cover (chamber) techniques, and Micrometeorology methods. Both of these methods has advantages and disadvantages, yet little information is available concerning the relative performance of the techniques. This study was conducted to compare CH 4 flux measurements obtained by using a dosed-chamber soil cover technique and a micrometeorological method (Bowen-ratio Energy Balance [BREB]). Methane flux rates obtained by both methods were compared using nine time points over 3 d at a peatland site in north central Minnesota. Mean CH 4 fluxes obtained by both methods were of the same magnitude (2.43-5.88 mg CH 4 m -2 h -1 ; however, differences were observed in the magnitudes of temporal variability as well as the detection sensitivities (minimum detectable flux). The minimum detectable flux for the closed-chamber method was 9.32 x 10 -2 mg CH 4 m -2 h -1 , while the minimum detectable flux for the BREB method ranged from 2.16 to 25.5 mg CH 4 m -2 h -1 . Due to analytical uncertainties associated with gas chromatographic determination of CH 4 gradients, the BREB is not recommended.
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comparison of closed chamber and bowen ratio methods for determining methane flux from peatland surfaces
Journal of Environmental Quality, 1998Co-Authors: A S K Chan, J H Prueger, T B ParkinAbstract:Methane (CH 4 ) is an important greenhouse gas, and it has been estimated that 50% of annual CH 4 comes from terrestrial systems. Better and more accurate methods are needed to quantify CH 4 flux from terrestrial environments. Two general methods commonly applied to measure trace gas fluxes are soil cover (chamber) techniques, and Micrometeorology methods. Both of these methods has advantages and disadvantages, yet little information is available concerning the relative performance of the techniques. This study was conducted to compare CH 4 flux measurements obtained by using a dosed-chamber soil cover technique and a micrometeorological method (Bowen-ratio Energy Balance [BREB]). Methane flux rates obtained by both methods were compared using nine time points over 3 d at a peatland site in north central Minnesota. Mean CH 4 fluxes obtained by both methods were of the same magnitude (2.43-5.88 mg CH 4 m -2 h -1 ; however, differences were observed in the magnitudes of temporal variability as well as the detection sensitivities (minimum detectable flux). The minimum detectable flux for the closed-chamber method was 9.32 x 10 -2 mg CH 4 m -2 h -1 , while the minimum detectable flux for the BREB method ranged from 2.16 to 25.5 mg CH 4 m -2 h -1 . Due to analytical uncertainties associated with gas chromatographic determination of CH 4 gradients, the BREB is not recommended.