The integrated WRF/urban modelling system: development, evaluation, and applications to urban environmental problems

To bridge the gaps between traditional mesoscale modelling and microscale modelling, the National Center for Atmospheric Research, in collaboration with other agencies and research groups, has developed an integrated urban modelling system coupled to the weather research and forecasting (WRF) model as a community tool to address urban environmental issues. The core of this WRF/urban modelling system consists of the following: (1) three methods with different degrees of freedom to parameterize urban surface processes, ranging from a simple bulk parameterization to a sophisticated multi-layer urban canopy model with an indoor–outdoor exchange sub-model that directly interacts with the atmospheric boundary layer, (2) coupling to fine-scale computational fluid dynamic Reynolds-averaged Navier–Stokes and Large-Eddy simulation models for transport and dispersion (T&D) applications, (3) procedures to incorporate high-resolution urban land use, building morphology, and anthropogenic heating data using the National Urban Database and Access Portal Tool (NUDAPT), and (4) an urbanized high-resolution land data assimilation system. This paper provides an overview of this modelling system; addresses the daunting challenges of initializing the coupled WRF/urban model and of specifying the potentially vast number of parameters required to execute the WRF/urban model; explores the model sensitivity to these urban parameters; and evaluates the ability of WRF/urban to capture urban heat islands, complex boundary-layer structures aloft, and urban plume T&D for several major metropolitan regions. Recent applications of this modelling system illustrate its promising utility, as a regional climate-modelling tool, to investigate impacts of future urbanization on regional meteorological conditions and on air quality under future climate change scenarios. Copyright © 2010 Royal Meteorological Society

The power of perceptions: exploring the role of urban design in cycling behaviours and healthy ageing

Good urban design has the power to aid in the provision of inclusive journey environments, yet traditionally neglects the perspective of the cyclist. This paper starts from the premise that more can be done to understand and articulate cyclists’ experiences and perceptions of the urban environment in which they cycle, as part of a closer linking of urban design qualities with transport planning and infrastructure interventions. This approach is particularly applicable in relation to older cyclists, a group whose needs are often poorly understood and for whom perceptions can significantly influence mobile behaviours. Currently, knowledge regarding the relationship between the built environment and physical activity, including cycling, in older adults is limited. As European countries face up to the challenges associated with ageing populations, some metropolitan regions, such as Munich, Germany, are making inroads into widening cycling’s appeal across generations through a combination of urban design, policy and infrastructure initiatives. The paper provides a systematic understanding of the urban design qualities and built environment features that affect cycling participation and have the potential to contribute towards healthy ageing. Urban design features such as legibility, aesthetics, scale and open space have been shown to influence and affect other mobile behaviours (e.g. walking), but their role as a mediator in cycle behaviour remains under-explored. Many of these design ‘qualities’ are related to individual perceptions; capturing these can help build a picture of quality in the built environment that includes an individual’s relationship with their local neighbourhood and its influences on their mobility choices. Issues of accessibility, facilities, and safety in cycling remain crucial, and, when allied to these design ‘qualities‘, provides a more rounded reflection of everyday journeys and trips taken or desired. The paper sets out the role that urban design might play in mediating these critical mobility issues, and in particular, in better understanding the ‘quality of the journey’. It concludes by highlighting the need for designers, policy makers, planners and academics to consider the role that design can play in encouraging cycle participation, especially as part of a healthy ageing agenda.

A wind tunnel model for quantifying fluxes in the urban boundary layer

Transport of pollution and heatout of streets into the boundary layer above is not currently understood and so fluxes cannot be quantified. Scalar concentration within the street is determined by the flux out of it and so quantifying fluxes for turbulent flow over a rough urban surface is essential. We have developed a naphthalene sublimation technique to measure transfer from a two-dimensional street canyon in a wind tunnel for the case of flow perpendicular to the street. The street was coated with naphthalene, which sublimes at room temperature, so that the vapour represented the scalar source. The transfer velocity wT relates the flux out of the canyon to the concentration within it and is shown to be linearly related to windspeed above the street. The dimensionless transfer coefficient wT/Uδ represents the ventilation efficiency of the canyon (here, wT is a transfer velocity,Uδ is the wind speed at the boundary-layer top). Observed values are between 1.5 and 2.7 ×10-3 and, for the case where H/W→0 (ratio of buildingheight to street width), values are in the same range as estimates of transfer from a flat plate, giving confidence that the technique yields accurate values for street canyon scalar transfer. wT/Uδ varies with aspect ratio (H/W), reaching a maximum in the wake interference regime (0.3 < H/W < 0.65). However, when upstream roughness is increased, the maximum in wT/Uδ reduces, suggesting that street ventilation is less sensitive to H/W when the flow is in equilibrium with the urban surface. The results suggest that using naphthalene sublimation with wind-tunnel models of urban surfaces can provide a direct measure of area-averaged scalar fluxes.

Kerb and urban increment of highly time-resolved trace elements in PM10, PM2.5 and PM1.0 winter aerosol in London during ClearfLo 2012

Ambient concentrations of trace elements with 2 h time resolution were measured in PM10–2.5, PM2.5–1.0 and PM1.0–0.3 size ranges at kerbside, urban background and rural sites in London during winter 2012. Samples were collected using rotating drum impactors (RDIs) and subsequently analysed with synchrotron radiation-induced X-ray fluorescence spectrometry (SR-XRF). Quantification of kerb and urban increments (defined as kerb-to-urban and urban-to-rural concentration ratios, respectively), and assessment of diurnal and weekly variability provided insight into sources governing urban air quality and the effects of urban micro-environments on human exposure. Traffic-related elements yielded the highest kerb increments, with values in the range of 10.4 to 16.6 for SW winds (3.3–6.9 for NE) observed for elements influenced by brake wear (e.g. Cu, Sb, Ba) and 5.7 to 8.2 for SW (2.6–3.0 for NE) for other traffic-related processes (e.g. Cr, Fe, Zn). Kerb increments for these elements were highest in the PM10–2.5 mass fraction, roughly twice that of the PM1.0–0.3 fraction. These elements also showed the highest urban increments (~ 3.0), although no difference was observed between brake wear and other traffic-related elements. All elements influenced by traffic exhibited higher concentrations during morning and evening rush hours, and on weekdays compared to weekends, with the strongest trends observed at the kerbside site, and additionally enhanced by winds coming directly from the road, consistent with street canyon effects. Elements related to mineral dust (e.g. Al, Si, Ca, Sr) showed significant influences from traffic-induced resuspension, as evidenced by moderate kerb (3.4–5.4 for SW, 1.7–2.3 for NE) and urban (~ 2) increments and increased concentrations during peak traffic flow. Elements related to regional transport showed no significant enhancement at kerb or urban sites, with the exception of PM10–2.5 sea salt (factor of up to 2), which may be influenced by traffic-induced resuspension of sea and/or road salt. Heavy-duty vehicles appeared to have a larger effect than passenger vehicles on the concentrations of all elements influenced by resuspension (including sea salt) and wearing processes. Trace element concentrations in London were influenced by both local and regional sources, with coarse and intermediate fractions dominated by traffic-induced resuspension and wearing processes and fine particles influenced by regional transport.

Determination of anthropogenic and biogenic compounds on atmospheric aerosol collected in urban, biomass burning and forest areas in Sao Paulo, Brazil

This study was conducted at three sites of different characteristics in Sao Paulo State Sao Paulo (SPA), Piracicaba (PRB) and Mate Atlantica Forest (MAT) PM(10), n-alkanes. pristane and phytane, PAHs, water-soluble ions and biomass burning tracers like levoglucosan and retene, were determined in quartz fiber filters. Samplings occurred on May 8th to August 8th, 2007 at the MAT site; on August 15th to 29th in 2007 and November 10th to 29th in 2008 at the PRB site and, March 13th to April 4th in 2007 and August 7th to 29th in 2008 at the SPA site Aliphatic compounds emitted biogenically were less abundant at the urban sites than at the forest site, and its distribution showed the influence of tropical vascular plants Air mass transport front biomass burning regions is likely to impact the sites with specific molecular markers The concentrations of all species were variable and dependent of seasonal changes In the most dry and polluted seasons, n-alkane and canon total concentrations were similar between the megacity and the biomass burning site PAHs and inorganic ion abundances were higher at Sao Paulo than Piracicaba, yet, the site influenced by biomass burning seems lobe the most impacted by the organic anion abundance in the atmosphere Pristane and phytane confirm the contamination by petroleum residues at urban sites, at the MAT site, biological activity and long range transport of pollutants might influence the levels of pristane (C) 2010 Elsevier B V All rights reserved

To what extent are CO2 emissions from intra-urban shopping trips by cars affected by drivers’ travel behaviour and store location?

Transportation is seen as one of the major sources of CO2 pollutants nowadays. The impact of increased transport in retailing should not be underestimated. Most previous studies have focused on transportation and underlying trips, in general, while very few studies have addressed the specific affects that, for instance, intra-city shopping trips generate. Furthermore, most of the existing methods used to estimate emission are based on macro-data designed to generate national or regional inventory projections. There is a lack of studies using micro-data based methods that are able to distinguish between driver behaviour and the locational effects induced by shopping trips, which is an important precondition for energy efficient urban planning. The aim of this study is to implement a micro-data method to estimate and compare CO2 emission induced by intra-urban car travelling to a retail destination of durable goods (DG), and non-durable goods (NDG). We estimate the emissions from aspects of travel behaviour and store location. The study is conducted by means of a case study in the city of Borlänge, where GPS tracking data on intra-urban car travel is collected from 250 households. We find that a behavioural change during a trip towards a CO2 optimal travelling by car has the potential to decrease emission to 36% (DG), and to 25% (NDG) of the emissions induced by car-travelling shopping trips today. There is also a potential of reducing CO2 emissions induced by intra-urban shopping trips due to poor location by 54%, and if the consumer selected the closest of 8 existing stores, the CO2 emissions would be reduced by 37% of the current emission induced by NDG shopping trips.

Public transport and pedestrian access, the impact of suburban planning on adolescence

The following paper discusses the impact of suburban life for adolescents in relation to public transport and pedestrian access. The research compares the morphology and level of connectivity of two planning models, cul-de-sac and regular grid, with respect to two suburbs which share a similar socio-economic profile, Rowville and Caulfield. These are subsequently evaluated in terms of ABS statistics, in particular year 12 or equivalent levels of education, and transport statistics. The results of the investigation are discussed in reference to the four key tasks of adolescence (Carr-Greg & Shale 2002)', in order to establish the degree to which morphology and access levels of suburbs impact on adolescent development.

The health equity dimensions of urban food systems

There is increasing recognition that the nutrition transition sweeping the world’s cities is multifaceted. Urban food and nutrition systems are beginning to share similar features, including an increase in dietary diversity, a convergence toward “Western-style” diets rich in fat and refined carbohydrate and within-country bifurcation of food supplies and dietary conventions. Unequal access to the available dietary diversity, calories, and gastronomically satisfying eating experience leads to nutritional inequalities and diet-related health inequities in rich and poor cities alike. Understanding the determinants of inequalities in food security and nutritional quality is a precondition for developing preventive policy responses. Finding common solutions to under- and overnutrition is required, the first step of which is poverty eradication through creating livelihood strategies. In many cities, thousands of positions of paid employment could be created through the establishment of sustainable and self-sufficient local food systems, including urban agriculture and food processing initiatives, food distribution centers, healthy food market services, and urban planning that provides for multiple modes of transport to food outlets. Greater engagement with the food supply may dispel many of the food anxieties affluent consumers are experiencing.

Destinations that matter: associations with walking for transport

Associations between access to destinations and walking for transport were examined. Households (N=2650) were selected from 32 urban communities varying in walkability and socio-economic status. Respondents reported perceived proximity of destinations, transport-related walking, reasons for neighbourhood selection, and socio-demographic characteristics. Geographic Information Systems data defined objective measures of access to destinations. Measures of access to destinations were associated with transport-related walking. Associations depended on socio-demographic factors and type of destinations. Workplace proximity was the most significant contributor to transport-related walking, especially among women. Regular walking to work resulted in the accrual of sufficient physical activity for health benefits.

"Tell us something new!" : the response of planning and transport professionals to public health guidance on the built environment and physical activity

A large proportion of non-communicable disease can be attributed to modifiable risk factors such as poor nutrition and physical inactivity. We present data on planning and transport practitioners' perceptions and responses to government public health guidance aimed at modifying environmental factors to promote physical activity. This study was informed by questions on the role of evidence-based guidance, the views of professionals towards the guidance, the links between guidance and existing legislation and policy and the practicality of guidelines. A key informant 'snowball' sampling technique was used to recruit participants from the main professional planning organisations across England. Seventy-six people were interviewed in eight focus groups. We found that evidence-based public health guidance is a new voice in urban and town planning, although much of the advice is already reflected by the 'accepted wisdom' of these professions. Evidence-based health guidance could be a powerful driver affecting planning practice, but other legislated planning guidance may take priority for planning and transport professionals.

Perceptions of representatives of public, private, and community sector institutions of the barriers and enablers for physically active transport

Active transport bridges many shared concerns in the public health and transport sectors. To positively affect opportunities for active transport, public health and transport professionals are engaging with other sectors, including urban planning, housing, recreation, retail, education, and employer groups. A first step in such inter-sectoral collaboration is to understand the perceptions of key players in all of these sectors. This paper describes the results of structured interviews with senior and middle-level administrators from public, private, and community groups in a rapidly developing region in Queensland, Australia, to assess the perceived barriers and enablers to active transport. Key themes emerged relating to infrastructure delivery, public transport services, walk- and cycle-friendly community attributes, political leadership and government coordination, and societal travel norms and culture. There were also themes relating to limits due to resources and limited relevant technical expertise, institutional and practitioner cultures, and agencies not identifying with their roles in active transport. Policies and cross-government initiatives were seen to hold promise, including economic incentives and built environment guidelines, campaigns targeting public attitudes and opinions, and community participation in policy-making. These elements are potential keys to positively promoting comprehensive active transport initiatives among gatekeepers and leaders across different sectors.

The use of public transport in coastal Australia : modes of travel to work and greenhouse emissions

Commuting to work is one of the most important and regular routines of transportation in towns and cities. From a geographic perspective, the length of people’s commute is influenced, to some degree, by the spatial separation of their home and workplace and the transport infrastructure. The rise of car ownership in Australia from the 1950s to the present was accompanied by a considerable decrease of public transport use. Currently there is an average of 1.4 persons per car in Australia, and private cars are involved in approximately 90% of the trips, and public transportation in only 10%. Increased personal mobility has fuelled the trend of decentralised housing development, mostly without a clear planning for local employment, or alternative means of transportation. Transport sector accounts for 14% of Australia’s net greenhouse gas emissions. Without further policy action, Australia’s emissions are projected to continue to increase. The Australian Federal Government and the new Department of Climate Change have recently published a set of maps showing that rising seas would submerge large parts of Victoria coastal region. Such event would lead to major disruption in planned urban growth areas in the next 50 years with broad scale inundation of dwellings, facilities and road networks. The Greater Geelong Region has well established infrastructure as a major urban centre and tourist destination and hence attracted the attention of federal and state governments in their quest for further development and population growth. As a result of its natural beauty and ecological sensitivity, scenarios for growth in the region are currently under scrutiny from local government as well as development agencies, scientists, and planners. This paper is part of a broad research in the relationship between transportation system, urban form, trip demand, and emissions, as a paramount in addressing the challenges presented by urban growth. Progressing from previous work focused on private cars, this present paper investigates the use of public transport as a mode for commuting in the Greater Geelong Region. Using a GIS based interaction model, it characterises the current use of the existing public transportation system, and also builds a scenario of increased use of the existing public transportation system, estimating potencial reductions in CO2 emissions. This study provides an improved understanding of the extent to which choices of transport mode and travel activity patterns, affect emissions in the context of regional networks. The results indicate that emissions from commuting by public transportation are significantly lower than those from commuting by private car, and emphasise that there are opportunities for large abatment in the greenhouse emissions from the transportation sector related to efforts in increasing the use of existing public transportation system.

Do the individual, social, and environmental correlates of physical activity differ between urban and rural women?

In this article, associations between individual, social, and environmental factors and physical activity among 3,669 women (18-45 years) living in socioeconomically disadvantaged urban and rural areas were compared. In 2007-2008, participants reported levels of leisure-time physical activity (LTPA) and transport-related physical activity (TRPA) as well as five individual, four social, and three environmental factors. Physical activity self- efficacy demonstrated stronger associations with LTPA among urban relative to rural women; child care was associated with LTPA and intentions with TRPA among urban women only, and enjoyment was associated with TRPA among rural women only. Correlates of physical activity among urban and rural women were generally similar, although some tailoring of physical activity promotion strategies may be warranted.

Walking for recreation and perceptions of the neighbourhood environment in older chinese urban dwellers

Engagement in walking for recreation can contribute to healthy aging. Although there is growing evidence that the neighborhood environment can influence walking for recreation, the amount of such evidence in relation to older adults is scarce and limited to Western low-density urban locations. Asian urban environments are typified by distinctive environmental and cultural characteristics that may yield different patterns to those observed in Western countries. Therefore, the main aim of this study was to examine associations of perceived environmental attributes with overall and within-neighborhood walking for recreation in Chinese elders (65+ years) residing in Hong Kong, an ultradense Asian metropolis. A sample of 484 elders was recruited from 32 neighborhoods stratified by socio-economic status and walkability (dwelling and intersection densities). Validated questionnaires measuring perceived neighborhood environment and weekly minutes of overall and within-neighborhood walking for recreation were interviewer administered. Results showed that the level of recreational walking was twice to four times higher than that reported in Western adults and elders. While overall walking for recreation showed a general lack of associations with perceived environmental attributes, within-neighborhood recreational walking was positively related with proximity of recreational facilities, infrastructure for walking, indoor places for walking, and presence of bridge/overpasses connecting to services. Age and educational attainment moderated the associations with several perceived environmental attributes with older and less-educated participants showing stronger associations. Traditional cultural views on the benefits of physical activity and the high accessibility of facilities and pedestrian infrastructure of Hong Kong may explain the high levels of walking. Although specific neighborhood attributes, or their perception, may influence recreational walking within the neighborhood, the compactness and public transport affordability of ultradense metropolises such as Hong Kong may make it easy for elders to compensate for the lack of favorable neighborhood attributes by walking outside the neighborhood.