The influence of urban intensity on fog evolution in the Beijing-Tianjin-Hebei (BTH) region (China) is investigated numerically with the the Weather Research and Forecasting (WRF) model coupled with the urban canopy p...The influence of urban intensity on fog evolution in the Beijing-Tianjin-Hebei (BTH) region (China) is investigated numerically with the the Weather Research and Forecasting (WRF) model coupled with the urban canopy parameterization-building energy model (UCP- BEM) urban physics scheme. The experiments were designed with a focus on the influence of different urban intensities, which are represented by a different fractional coverage of natural land, buildings, and energy consumption inside buildings in an urban environment. The results of this study indicate that urban areas notably influence fog evolution when natural land is reduced to a small fraction (e.g., less than 10%). Developed land changes fog evolution through urban effects. Higher urban intensity (HUI) generally results in warmer temperatures and lower wind speeds throughout the day, while inhibiting morning specific humidity loss and afternoon specific humidity gain because of the HUI effect on surface heat flux, surface roughness, and surface moisture flux. HUI leads to later and weaker liquid water content formation, with a higher liquid water content base, primarily due to its effect on near surface temperatures. This finding implies that HUI may inhibit the conditions for fog formation. In addition, urban areas with equal natural and developed land coverage seem to greatly enhance the upward surface moisture flux, which is attributed to the combination of a relatively large potential evaporation on developed land and an ample moisture supply from natural land. As a result, the specific humidity increases in the afternoon.展开更多
In a scenario of climate changes and increasing stress upon available fresh water resources like rivers, lakes and aquifers, collecting fog water is a promising yet relatively unexplored potentiality. Providing suffic...In a scenario of climate changes and increasing stress upon available fresh water resources like rivers, lakes and aquifers, collecting fog water is a promising yet relatively unexplored potentiality. Providing sufficient water and reducing water extraction’s environmental impact at the same time can be a challenge with conventional ways, but fog harvesting technology presents itself as a powerful and efficient alternative. Water availability profoundly determined regional economic benefit, social relations and it also influenced environmental security and ecosystem services. Underdeveloped countries have been dealing with water scarcity issue for decades, but also wealthy countries will have to face the water crisis soon, due to unsustainable development processes. A review of the state of the art highlights the most relevant parameters to deal with when discussing about fog water harvesting. In regions with frequent fog events, this technology already proved to be a sustainable drinking water resource for rural communities and their low per capita water usage was provided by basic devices utilization. Nevertheless, in this paper, different fog water harvesting applications are investigated, besides the already existing fresh-water collection, reforestation and agricultural use. Further options, such as building components, outdoor activities and domestic devices are considered, according to different parameters, such as economic benefits, possibility of standardized production, life cycle and market attractiveness. A desirable novel concept would become relevant in specific contexts, thanks to multiple functions, offering locals designed and customized solutions. Also noteworthy are the landscape impact of such devices and the effects of the project in terms of places regeneration, raising awareness and “green” conscience creation. The study of local climatic data and improvement in fog collector applications, integration with architectural and landscape design, will expand the regions where fog harvesting can be applied and its sustainable improvements.展开更多
基金supported by the National Science and Technology Pillar Program of China (Grant No.2008BAC37B01)the National Natural Science Foundation of China (Grant Nos. 40930950 and 40921160379)
文摘The influence of urban intensity on fog evolution in the Beijing-Tianjin-Hebei (BTH) region (China) is investigated numerically with the the Weather Research and Forecasting (WRF) model coupled with the urban canopy parameterization-building energy model (UCP- BEM) urban physics scheme. The experiments were designed with a focus on the influence of different urban intensities, which are represented by a different fractional coverage of natural land, buildings, and energy consumption inside buildings in an urban environment. The results of this study indicate that urban areas notably influence fog evolution when natural land is reduced to a small fraction (e.g., less than 10%). Developed land changes fog evolution through urban effects. Higher urban intensity (HUI) generally results in warmer temperatures and lower wind speeds throughout the day, while inhibiting morning specific humidity loss and afternoon specific humidity gain because of the HUI effect on surface heat flux, surface roughness, and surface moisture flux. HUI leads to later and weaker liquid water content formation, with a higher liquid water content base, primarily due to its effect on near surface temperatures. This finding implies that HUI may inhibit the conditions for fog formation. In addition, urban areas with equal natural and developed land coverage seem to greatly enhance the upward surface moisture flux, which is attributed to the combination of a relatively large potential evaporation on developed land and an ample moisture supply from natural land. As a result, the specific humidity increases in the afternoon.
文摘In a scenario of climate changes and increasing stress upon available fresh water resources like rivers, lakes and aquifers, collecting fog water is a promising yet relatively unexplored potentiality. Providing sufficient water and reducing water extraction’s environmental impact at the same time can be a challenge with conventional ways, but fog harvesting technology presents itself as a powerful and efficient alternative. Water availability profoundly determined regional economic benefit, social relations and it also influenced environmental security and ecosystem services. Underdeveloped countries have been dealing with water scarcity issue for decades, but also wealthy countries will have to face the water crisis soon, due to unsustainable development processes. A review of the state of the art highlights the most relevant parameters to deal with when discussing about fog water harvesting. In regions with frequent fog events, this technology already proved to be a sustainable drinking water resource for rural communities and their low per capita water usage was provided by basic devices utilization. Nevertheless, in this paper, different fog water harvesting applications are investigated, besides the already existing fresh-water collection, reforestation and agricultural use. Further options, such as building components, outdoor activities and domestic devices are considered, according to different parameters, such as economic benefits, possibility of standardized production, life cycle and market attractiveness. A desirable novel concept would become relevant in specific contexts, thanks to multiple functions, offering locals designed and customized solutions. Also noteworthy are the landscape impact of such devices and the effects of the project in terms of places regeneration, raising awareness and “green” conscience creation. The study of local climatic data and improvement in fog collector applications, integration with architectural and landscape design, will expand the regions where fog harvesting can be applied and its sustainable improvements.
