Effect of asymmetrical street canyons on pedestrian thermal comfort in warm-humid climate of Cuba     

José?Rodríguez-AlgecirasEmail authorView author&#;s OrcID profile  Abel?Tablada  Andreas?Matzarakis 《Theoretical and Applied Climatology》2018,133(3-4):663-679

Walkability and livability in cities can be enhanced by creating comfortable environments in the streets. The profile of an urban street canyon has a substantial impact on outdoor thermal conditions at pedestrian level. This paper deals with the effect of asymmetrical street canyon profiles, common in the historical centre of Camagüey, Cuba, on outdoor thermal comfort. Temporal-spatial analyses are conducted using the Heliodon2 and the RayMan model, which enable the generation of accurate predictions about solar radiation and thermal conditions of urban spaces, respectively. On these models, urban settings are represented by asymmetrical street canyons with five different height-to-width ratios and four street axis orientations (N-S, NE-SW, E-W, SE-NW). Results are evaluated for daytime hours across the street canyon, by means of the physiologically equivalent temperature (PET index) which allows the evaluation of the bioclimatic conditions of outdoor environments. Our findings revealed that high profiles (façades) located on the east-facing side of N-S streets, on the southeast-facing side of NE-SW streets, on the south-facing side of E-W street, and on the southwest-facing side of SE-NW streets, are recommended to reduce the total number of hours under thermal stress. E-W street canyons are the most thermally stressed ones, with extreme PET values around 36 °C. Deviating from this orientation ameliorates the heat stress with reductions of up to 4 h in summer. For all analysed E-W orientations, only about one fifth of the street can be comfortable, especially for high aspect ratios (H/W > 3). Optimal subzones in the street are next to the north side of the E-W street, northwest side of the NE-SW street, and southwest side of the SE-NW street. Besides, when the highest profile is located on the east side of N-S streets, then the subzone next to the east-facing façade is recommendable for pedestrians. The proposed urban guidelines enable urban planners to create and renovate urban spaces which are more efficient in diminishing pedestrian thermal stress.  相似文献   

Defining deep decarbonization pathways for Switzerland: an economic evaluation     

Frédéric Babonneau  Philippe Thalmann 《Climate Policy》2018,18(1):1-13

This article simulates deep decarbonization pathways for a small open economy that lacks the usual avenues for large CO₂ reductions – heavy industry and power generation. A computable general equilibrium model is used to assess the energy and economic impacts of the transition to only one ton of CO₂ emissions per capita in 2050. This represents a 76% reduction with respect to 1990 levels, while the population is expected to be 46% larger and GPD to increase by 90%. The article discusses several options and scenarios that are compatible with this emissions target and compares them with a reference scenario that extrapolates already-decided climate and energy policy instruments. We show that the ambitious target is attainable at moderate welfare costs, even if it needs very high carbon prices, and that these costs are lower when either CO₂ can be captured and sequestered or electricity consumption can be taxed sufficiently to stabilize it.

Policy relevance

In the context of COP 21, all countries must propose intended contributions that involve deep decarbonization of their economy over the next decades. This article defines and analyses such pathways for Switzerland, taking into consideration the existing energy demand and supply and also already-defined climate policies. It draws several scenarios that are compatible with a target of 1 ton of CO₂ emissions per capita in 2050. This objective is very challenging, especially with the nuclear phase out decided after the disaster in Fukushima and the political decision to balance electricity trade. Nevertheless, it is possible to design several feasible pathways that are based on different options. The economic cost is significant but affordable for the Swiss economy. The insights are relevant not only for Switzerland, but also for other industrialized countries when defining their INDCs.  相似文献   

For your eyes only? Evaluating a coordinated and multiple views tool with a map,a parallel coordinated plot and a table using an eye-tracking approach     

Izabela Golebiowska  Tomasz Opach  Jan Ketil Rød 《International journal of geographical information science》2017,31(2):237-252

Geographic visualization tools with coordinated and multiple views (CMV) typically provide sets of visualization methods. Such configuration gives users the possibility of investigating data in various visual contexts; however, it can be confusing due to the multiplicity of visual components and interactive functions. We addressed this challenge and conducted an empirical study on how a CMV tool, consisting of a map, a parallel coordinate plot (PCP), and a table, is used to acquire information. We combined a task-based approach with eye-tracking and usability metrics since these methods provide comprehensive insights into users’ behaviour. Our empirical study revealed that the freedom to choose visualization components is appreciated by users. The individuals worked with all the available visualization methods and they often used more than one visualization method when executing tasks. Different views were used in different ways by various individuals, but in a similarly effective way. Even PCP, which is claimed to be problematic, was found to be a handy way of exploring data when accompanied by interactive functions.  相似文献   

Photochemical activation of chlorine by iron-oxide aerosol     

Julian?WittmerEmail author  Cornelius?ZetzschEmail author 《Journal of Atmospheric Chemistry》2017,74(2):187-204

The photochemical activation of chlorine by dissolved iron in artificial sea-salt aerosol droplets and by highly dispersed iron oxide (Fe₂O₃) aerosol particles (mainly hematite, specific surface ~150 m² g^?1) exposed to gaseous HCl, was investigated in humidified air in a Teflon simulation chamber. Employing the radical-clock technique, we quantified the production of gaseous atomic chlorine (Cl) from the irradiated aerosol. When the salt aerosol contained Fe₂O₃ at pH 6, no significant Cl production was observed, even if the dissolution of iron was forced by “weathering” (repeatedly freezing and thawing for five times). Adjusting the pH in the stock suspension to 2.6, 2.2, and 1.9 and equilibrating for one week resulted in a quantifiable amount of dissolved iron (0.03, 0.2, and 0.6 mmol L^?1, respectively) and in gaseous Cl production rates of ~1.6, 6, and 8?×?10²¹ atoms cm^?2 h^?1, respectively. In a further series of experiments, the pure Fe₂O₃ aerosol was exposed to various levels of gaseous hydrogen chloride (HCl). The resulting Cl production rates ranged from 8?×?10²⁰ Cl atoms cm^?2 h^?1 (at ~4 ppb HCl) to 5?×?10²² Cl atoms cm^?2 h^?1 (at ~350 ppb HCl) and confirmed the uptake and conversion of HCl to atomic Cl (at HCl to Cl conversion yields of 2–5 %, depending on the relative humidity). The Fe₂O₃ experiments indicate that iron-induced Cl formation may be important for highly soluble combustion-aerosol particles in marine environments in the presence of gaseous HCl.  相似文献   

Analysis of the institutional and social responses to the eruption and the lahars of Mount Pinatubo volcano from 1991 to 1998 (Central Luzon, Philippines)     

Frédéric Leone  Jean-Christophe Gaillard 《GeoJournal》1999,49(2):223-238

Mount Pinatubo volcano erupted in June 1991 in the main island of Luzon belonging to the Philippines archipelago. Huge economic losses and population exodus have followed. This major crisis has been relayed with other crises due to rain-fed lahars which have been supplied with eruption deposits. These lahars have occurred every year since 1991 during the rainy season. They will probably last until 2005. After a brief presentation of the Philippine official response system to disasters, this paper draws up a critical analysis of the different kinds of institutional and social responses deployed to manage the different crisis and post-crisis phases of this event. Based on three viewpoints: from population, media and other actors, this analysis attempts to point out the strengths and weaknesses of the official management system, especially by studying the efficiency and the range of the solutions taken. So, it appears that the management of the June 1991 main crisis (eruption) was a success. On the other hand, difficulties have occurred with lahars risk management. Indeed, these lahars have obliged the authorities to protect and relocate thousands of people. In spite of persistent problems, the management system (monitoring/warning/evacuation) of lahar crises improves year after year. Failures appear especially within the rehabilitation program (protection/rehousing). Many direct (lack of means, preparedness, coordination, dialog, etc.) and indirect (politico-administrative, socio-economic, cultural contexts) factors come together to lock the wheels of the institutional response system. They defer the socio-economic start of this vital northern Philippines area. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

A review of the LATEX project: mesoscale to submesoscale processes in a coastal environment   总被引：1，自引：1，他引：0  

Anne A. Petrenko  Andrea M. Doglioli  Francesco Nencioli  Marion Kersalé  Ziyuan Hu  Francesco d’Ovidio 《Ocean Dynamics》2017,67(3-4):513-533

The main objective of the LAgrangian Transport EXperiment (LATEX) project was to study the influence of coastal mesoscale and submesoscale physical processes on circulation dynamics, cross-shelf exchanges, and biogeochemistry in the western continental shelf of the Gulf of Lion, Northwestern Mediterranean Sea. LATEX was a five-year multidisciplinary project based on the combined analysis of numerical model simulations and multi-platform field experiments. The model component included a ten-year realistic 3D numerical simulation, with a 1 km horizontal resolution over the gulf, nested in a coarser 3 km resolution model. The in situ component involved four cruises, including a large-scale multidisciplinary campaign with two research vessels in 2010. This review concentrates on the physics results of LATEX, addressing three main subjects: (1) the investigation of the mesoscale to submesoscale processes. The eddies are elliptic, baroclinic, and anticyclonic; the strong thermal and saline front is density compensated. Their generation processes are studied; (2) the development of sampling strategies for their direct observations. LATEX has implemented an adaptive strategy Lagrangian tool, with a reference software available on the web, to perform offshore campaigns in a Lagrangian framework; (3) the quantification of horizontal mixing and cross-shelf exchanges. Lateral diffusivity coefficients, calculated in various ways including a novel technique, are in the range classically encountered for their associated scales. Cross-shelf fluxes have been calculated, after retrieving the near-inertial oscillation contribution. Further perspectives are discussed, especially for the ongoing challenge of studying submesoscale features remotely and from in situ data.  相似文献   

Active channel width as a proxy of sediment supply from mining sites in New Caledonia     

Mélanie Bertrand  Frédéric Liébault 《地球表面变化过程与地形》2019,44(1):67-76

Although the channel morphology of upland fluvial systems is known to be strongly controlled by sediment supply from hillslopes, it is still difficult to isolate this effect from the other controlling factors of channel forms, such as the sediment transport capacity (depending notably on the size of the catchment) and local conditions (e.g. confinement, riparian vegetation, valley-floor slope). The rivers in New Caledonia offer an interesting field laboratory to isolate the morphological effect of contrasted sediment supply conditions. Some of these rivers are known to be highly impacted by the coarse sediment waves induced by the mining of nickel deposits that started in the early 1870s, which was particularly intensive between the 1940s and 1970s. The propagation of the sediment pulses from the mining sites can be traced by the presence of wide and aggraded active channels along the stream network of nickel-rich peridotite massifs. A first set of 63 undisturbed catchments in peridotite massifs distributed across the Grande Terre was used to fit a classic scaling law between active channel width and drainage area. A second set of 86 impacted sites, where the presence of sediment waves was clearly attested by recent aerial imagery, showed systematically wider active channels, with a width ratio around 5 (established from the intercept ratio of width–area power laws). More importantly, this second set of disturbed sites confirmed that the residual of active channel widths, computed from the scaling law of undisturbed sites, is statistically positively related to the catchment-scale relative area of major mining sediment sources. It is therefore confirmed that the characterization of sediment supply conditions is crucial for the understanding of spatial patterns of active channel width, and this should be more thoroughly considered in morphological studies of rivers draining environments with contrasted geomorphic activities on hillslopes. © 2018 John Wiley & Sons, Ltd.  相似文献   

Moringa‐Seed‐Based Coagulant Removes Microcystins Dissolved in Water     

Selma Gouvea‐Barros  Maria d. C. Bittencourt‐Oliveira  Jos E. S. Paterniani 《洁净——土壤、空气、水》2019,47(6)

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Ore deposits and epithermal evidences associated with intra-magmatic faults at Aïn El Araâr-Oued Belif ring structure (NW of Tunisia)     

Aissa  Wiem Ben  Aissa  Lassaâd Ben  Amara  Abdesslem Ben Haj  Tlig  Said  Alouani  Rabah 《International Journal of Earth Sciences》2017,106(8):2653-2665

International Journal of Earth Sciences - Hydrothermal ore deposits at Aïn El Araâr-Oued Belif location are classified as epithermal deposits type. The ore bodies are hosted by upper...  相似文献   

Modelling wind-erosion risk in the Laghouat region (Algeria) using geomatics approach     

Djouher Saadoud  Mohamed Saïd Guettouche  Mohamed Hassani  Francisco José Martin Peinado 《Arabian Journal of Geosciences》2017,10(16):363

Wind-erosion risk is a challenge that threatens land development in dry-land regions. Soil analysis, remote sensing, climatic, vegetal cover and topographic data were used in a geographic information system (GIS), using multi-criteria analysis (MCA) to map wind-erosion risk (R_we) in Laghouat, Algeria. The approach was based on modelling the risk and incorporating topographic and climatic effects. The maps were coded according to their sensitivity to wind erosion and to their socio-economic potential, from low to very high. By overlapping the effects of these layers, qualitative maps were drawn to reflect the potential sensitivity to wind erosion per unit area. The results indicated that severe wind erosion affects mainly all the southern parts and some parts in the north of Laghouat, where wind-erosion hazard (H_we) is very high in 43% of the total area, and which was affected mainly by natural parameters such as soil, topography and wind. The results also identified features vulnerable to R_we. The product of the hazard and the stake maps indicated the potential risk areas that need preventive measures; this was more than half of the study area, making it essential to undertake environmental management and land-use planning.  相似文献