POSTER 9: CCMA - UHI mitigation strategies
Impact of urban expansion and densification on local climate
1Australian Research Council Centre of Excellence for Climate System Science; 2Climate Change Research Centre; 3University of New South Wales, Australia
Sydney is the most populous city in Oceania with a 4.7 million population and an estimated 1.6 million increase by 2031. To accommodate this population increase, urban area and density is projected to increase; however, little has been done to examine the effects of urban expansion in this region. In this study, Sydney’s expansion was classified under two forms, internally and externally expanding. Externally expanding areas are non-urban locations which will be converted into urban land-use over the next 20 years. Varying height and urban densities are examined for possible future scenarios in these areas. Internally expanding locations are urban areas whose expansions are projected to be through denser, taller, or higher intensity urban areas. Ensemble simulations for both are produced to determine expansion scenarios which minimize the effect of the urban heat island. This study addresses two main problems – the lack of a diversified urban land-use simulation of Sydney and an exploration on city designs for climate change adaptation through the alteration of city parameters ( such as building heights, aspect ratios, urban cover) within the weather research and forecasting model. A 2km spatial resolution was chosen and simulations were performed for January 2009 over Sydney with a 15 day spin-up. A 4-day heat wave event was also present during this period.
Moderation of summertime heat-island phenomena via modification of the urban form in the Tokyo metropolitan area
1Advanced Institute for Computational Science, RIKEN, Japan; 2Japan Agency for Marine-Earth Science and Technology, Japan; 3University of Tsukuba, Japan; 4National Center for Atmospheric Research, USA; 5National Institute for Environmental Studies, Japan; 6Hiroshima University, Japan; 7Tokyo Institute of Technology, Japan; 8Meteorological Research Institute, Japan
This study investigated the moderation of the urban heat island via changes in the urban form in the Tokyo metropolitan area (TMA). Two urban scenarios with the same population as that of the current urban form were used for sensitivity experiments: the dispersed-city and compact-city scenarios. Numerical experiments using the two urban scenarios as well as an experiment using the current urban form were conducted using a regional climate model coupled with a single-layer urban canopy model. The averaged nighttime surface air temperature in TMA increased by about 0.34°C in the dispersed-city scenario and decreased by about 0.1°C in the compact-city scenario. Therefore, the compact-city scenario had a significant potential for moderating the mean areal heat-island effect in the entire TMA. Alternatively, in the central part of the TMA, these two urban-form scenarios produced opposite effects on the surface air temperature, i.e., severe thermal conditions worsened further in the compact-city scenario because of the denser population. This result suggests that the compact-city form is not always appropriate for the moderation of urban heat-island effect. This scenario would need to combine with some other mitigation strategies, such as the additional greening of urban areas, especially in the central area. This study suggests that it is important to evaluate an adaptation plan to higher urban temperatures due to future global warming and urban heat island from several perspectives, i.e. not only climatological aspect but also influences to inhabitants.
Modeling NOx and benzene emissions and exposure from road traffic and domestic heaters in street canyons: a case-study in Verona, Italy
1University of Trento, Italy; 2CISMA srl
Air quality simulations are carried out over an urban area characterized by the presence of street canyons and typical urban emission sources. Simulations of emission and dispersion of nitrogen oxides (NOx) are performed by considering road traffic and, as an element of novelty, domestic hot-water heaters, which represent the two dominant sources in the area of study. In parallel, to assess the impact of urban air pollution on human health, simulations of emission and dispersion of benzene are carried out taking into account only road traffic, as the dominant source of benzene in urban areas. Emissions from road traffic are estimated by the COPERT 4 algorithm, whilst NOx emission factors from domestic heaters are retrieved by the technical literature. Maps of the annual mean concentrations of NOx and benzene are calculated by the AUSTAL2000 dispersion model, by considering scenarios representing the current situation and scenarios simulating the introduction of environmental strategies for air quality mitigation. The simulations highlight potentially critical situations of human exposure that may not be detected by the conventional network of air quality monitoring stations. The scenarios considering the adoption of mitigation strategies generally lead to improvements in the air quality, although high concentrations still occur within street canyons. The methodology here applied provides a tool for planning air quality monitoring campaigns, re-locating air quality stations and supporting decisions on urban planning. The estimation of the induced cancer risk is an important starting point to conduct zoning analyses and to detect the areas where population is directly exposed to potential risks for health.
Mitigation of Urban Heat Island of Prague
1Czech Hydrometeorological Institute, Czech Republic; 2Faculty of Mathematics and Physics, Charles University; 3Prague Institute of Planning of Development, Czech Republic
The Urban Heat Island of Prague has been concern of not only climatologists but especially urban planners during duration of the
Central European Programme UHI project (finished in 2014). As a part of it, special investigation was done with respect to the possibilities of UHI adaptation and mitigation. In this contribution, we provide results of our studies started during the UHI project regarding this adaptation - for the so called pilot areas in the city. Various adaptation/mitigation strategies are applied and the climate for different seasons of the year is computed (typically as physiological equivalent temperatures) and the results are discussed and possbile solution of the mitigation proposed.