Some resilient aspects of urban areas to air pollution and climate change, case study: Tehran, Iran

The effects of climate and meteorological factors on urban problems such as air pollution, heat island, and urban hydrology have increasingly become important in terms of mitigation and adaptation issues during the recent years. In the present paper, we discuss some of the climate or meteorological factors affecting air pollution in Tehran. Tehran is a unique megacity in terms of geographic setting, being mountainous and an ever-expanding urban area that suffers from acute air pollution and heat waves episodes. Recent records of air pollutants also show increased trends with some low-frequency variability caused by chaotic atmospheric motions. Moreover, the wind speed has also decreased as a result of the aerodynamic surface roughness increase and probably the decrease in the passage of cyclones over the mid-latitudes according to the recent findings. Mixed-layer height over the city, due to higher-surface heat fluxes (mainly due to the reduction in surface albedo, anthropogenic heat, and lower green spaces), is expected to increase; although it is favorable for reduction in some air pollutants such as CO, it is not eligible for ozone. Finally, an integrated framework for actions regarding impacts, emissions, urban climate change, and monitoring including adaptation and mitigation towards a climate-change resilient city is proposed. (C) 2016 Sharif University of Technology. All rights reserved.