The Experts below are selected from a list of 29475 Experts worldwide ranked by ideXlab platform
Vilaguerau J De Arellano - One of the best experts on this subject based on the ideXlab platform.
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direct and Diffuse Radiation in the shallow cumulus vegetation system enhanced and decreased evapotranspiration regimes
Journal of Hydrometeorology, 2017Co-Authors: Xabier Pedruzobagazgoitia, Huug G. Ouwersloot, M. Sikma, C. C. Van Heerwaarden, C M J Jacobs, Vilaguerau J De ArellanoAbstract:AbstractGuided by a holistic approach, the combined effects of direct and Diffuse Radiation on the atmospheric boundary layer dynamics over vegetated land are investigated on a daily scale. Three numerical experiments are designed that are aimed at disentangling the role of Diffuse and direct Radiation below shallow cumulus at the surface and on boundary layer dynamics. A large-eddy simulation (LES) model coupled to a land surface model is used, including a mechanistically immediate response of plants to Radiation, temperature, and water vapor deficit changes. The partitioning in direct and Diffuse Radiation created by clouds and farther inside the canopy is explicitly accounted for. LES results are conditionally averaged as a function of the cloud optical depth. The findings show larger photosynthesis under thin clouds than under clear sky, due to an increase in Diffuse Radiation and a slight decrease in direct Radiation. The reduced canopy resistance is the main driver for the enhanced carbon uptake by ...
Peter Dowty - One of the best experts on this subject based on the ideXlab platform.
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Advantages of Diffuse Radiation for terrestrial ecosystem productivity
Journal of Geophysical Research: Atmospheres, 2002Co-Authors: Lianhong Gu, Eva M. Falge, D. Baldocchi, Timo Vesala, T A Black, Shashi B. Verma, Peter DowtyAbstract:Clouds and aerosols alter the proportion of Diffuse Radiation in global solar Radiation reaching the Earth's surface. It is known that Diffuse and direct beam Radiation differ in the way they transfer through plant canopies and affect the summation of nonlinear processes like photosynthesis differently than what would occur at the leaf scale. We compared the relative efficiencies of canopy photosynthesis to Diffuse and direct photosynthetically active Radiation (PAR) for a Scots pine forest, an aspen forest, a mixed deciduous forest, a tallgrass prairie and a winter wheat crop. The comparison was based on the seasonal patterns of the parameters that define the canopy photosynthetic responses to Diffuse PAR and those that define the responses to direct PAR. These parameters were inferred from half-hourly tower CO2 flux measurements. We found that: (1) Diffuse Radiation results in higher light use efficiencies by plant canopies; (2) Diffuse Radiation has much less tendency to cause canopy photosynthetic saturation; (3) the advantages of Diffuse Radiation over direct Radiation increase with Radiation level; (4) temperature as well as vapor pressure deficit can cause different responses in Diffuse and direct canopy photosynthesis, indicating that their impacts on terrestrial ecosystem carbon assimilation may depend on Radiation regimes and thus sky conditions. These findings call for different treatments of Diffuse and direct Radiation in models of global primary production, and studies of the roles of clouds and aerosols in global carbon cycle.
Xabier Pedruzobagazgoitia - One of the best experts on this subject based on the ideXlab platform.
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direct and Diffuse Radiation in the shallow cumulus vegetation system enhanced and decreased evapotranspiration regimes
Journal of Hydrometeorology, 2017Co-Authors: Xabier Pedruzobagazgoitia, Huug G. Ouwersloot, M. Sikma, C. C. Van Heerwaarden, C M J Jacobs, Vilaguerau J De ArellanoAbstract:AbstractGuided by a holistic approach, the combined effects of direct and Diffuse Radiation on the atmospheric boundary layer dynamics over vegetated land are investigated on a daily scale. Three numerical experiments are designed that are aimed at disentangling the role of Diffuse and direct Radiation below shallow cumulus at the surface and on boundary layer dynamics. A large-eddy simulation (LES) model coupled to a land surface model is used, including a mechanistically immediate response of plants to Radiation, temperature, and water vapor deficit changes. The partitioning in direct and Diffuse Radiation created by clouds and farther inside the canopy is explicitly accounted for. LES results are conditionally averaged as a function of the cloud optical depth. The findings show larger photosynthesis under thin clouds than under clear sky, due to an increase in Diffuse Radiation and a slight decrease in direct Radiation. The reduced canopy resistance is the main driver for the enhanced carbon uptake by ...
Yanfen Wang - One of the best experts on this subject based on the ideXlab platform.
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Impacts of Diffuse Radiation on light use efficiency across terrestrial ecosystems based on Eddy covariance observation in China.
PLoS ONE, 2014Co-Authors: Kun Huang, Huimin Wang, Shaoqiang Wang, Lei Zhou, Junhui Zhang, Junhua Yan, Liang Zhao, Yanfen Wang, Peili ShiAbstract:Ecosystem light use efficiency (LUE) is a key factor of production models for gross primary production (GPP) predictions. Previous studies revealed that ecosystem LUE could be significantly enhanced by an increase on Diffuse Radiation. Under large spatial heterogeneity and increasing annual Diffuse Radiation in China, eddy covariance flux data at 6 sites across different ecosystems from 2003 to 2007 were used to investigate the impacts of Diffuse Radiation indicated by the cloudiness index (CI) on ecosystem LUE in grassland and forest ecosystems. Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24
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impacts of Diffuse Radiation on light use efficiency across terrestrial ecosystems based on eddy covariance observation in china
PLOS ONE, 2014Co-Authors: Kun Huang, Huimin Wang, Shaoqiang Wang, Lei Zhou, Junhui Zhang, Liang Zhao, Yanfen WangAbstract:Ecosystem light use efficiency (LUE) is a key factor of production models for gross primary production (GPP) predictions. Previous studies revealed that ecosystem LUE could be significantly enhanced by an increase on Diffuse Radiation. Under large spatial heterogeneity and increasing annual Diffuse Radiation in China, eddy covariance flux data at 6 sites across different ecosystems from 2003 to 2007 were used to investigate the impacts of Diffuse Radiation indicated by the cloudiness index (CI) on ecosystem LUE in grassland and forest ecosystems. Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24 <= R-2 <= 0.85), especially at the Changbaishan temperate forest ecosystem (R-2 = 0.85). Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems. Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively. Our research confirmed that the ecosystem LUE at the six sites in China was positively responsive to the Diffuse Radiation, and the cloudiness index could be used as an environmental regulator for LUE modeling in regional GPP prediction.
Huug G. Ouwersloot - One of the best experts on this subject based on the ideXlab platform.
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direct and Diffuse Radiation in the shallow cumulus vegetation system enhanced and decreased evapotranspiration regimes
Journal of Hydrometeorology, 2017Co-Authors: Xabier Pedruzobagazgoitia, Huug G. Ouwersloot, M. Sikma, C. C. Van Heerwaarden, C M J Jacobs, Vilaguerau J De ArellanoAbstract:AbstractGuided by a holistic approach, the combined effects of direct and Diffuse Radiation on the atmospheric boundary layer dynamics over vegetated land are investigated on a daily scale. Three numerical experiments are designed that are aimed at disentangling the role of Diffuse and direct Radiation below shallow cumulus at the surface and on boundary layer dynamics. A large-eddy simulation (LES) model coupled to a land surface model is used, including a mechanistically immediate response of plants to Radiation, temperature, and water vapor deficit changes. The partitioning in direct and Diffuse Radiation created by clouds and farther inside the canopy is explicitly accounted for. LES results are conditionally averaged as a function of the cloud optical depth. The findings show larger photosynthesis under thin clouds than under clear sky, due to an increase in Diffuse Radiation and a slight decrease in direct Radiation. The reduced canopy resistance is the main driver for the enhanced carbon uptake by ...
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Direct and Diffuse Radiation in the Shallow Cumulus–Vegetation System: Enhanced and Decreased Evapotranspiration Regimes
Journal of Hydrometeorology, 2017Co-Authors: Xabier Pedruzo-bagazgoitia, Huug G. Ouwersloot, M. Sikma, C. C. Van Heerwaarden, Cor Jacobs, J. Vilà-guerau De ArellanoAbstract:AbstractGuided by a holistic approach, the combined effects of direct and Diffuse Radiation on the atmospheric boundary layer dynamics over vegetated land are investigated on a daily scale. Three numerical experiments are designed that are aimed at disentangling the role of Diffuse and direct Radiation below shallow cumulus at the surface and on boundary layer dynamics. A large-eddy simulation (LES) model coupled to a land surface model is used, including a mechanistically immediate response of plants to Radiation, temperature, and water vapor deficit changes. The partitioning in direct and Diffuse Radiation created by clouds and farther inside the canopy is explicitly accounted for. LES results are conditionally averaged as a function of the cloud optical depth. The findings show larger photosynthesis under thin clouds than under clear sky, due to an increase in Diffuse Radiation and a slight decrease in direct Radiation. The reduced canopy resistance is the main driver for the enhanced carbon uptake by ...