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Advances in Meteorology
Volume 2014, Article ID 547974, 19 pages
http://dx.doi.org/10.1155/2014/547974
Research Article

Mitigating the Urban Heat Island Effect in Megacity Tehran

1Institut für Meteorologie, Freie Universität Berlin, Carl-Heinrich-Becker-Weg 6-10, 12165 Berlin, Germany
2Resilient Urban Planning + Development (RUPD) GbR, Eichendorffstr. 1, 10115 Berlin, Germany
3Department of Architecture, Faculty of Engineering and Built Environment, University Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia

Received 1 May 2014; Revised 18 July 2014; Accepted 20 July 2014; Published 7 September 2014

Academic Editor: Sultan Al-Yahyai

Copyright © 2014 Sahar Sodoudi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Cities demonstrate higher nocturnal temperatures than surrounding rural areas, which is called “urban heat island” (UHI) effect. Climate change projections also indicate increase in the frequency and intensity of heat waves, which will intensify the UHI effect. As megacity Tehran is affected by severe heatwaves in summer, this study investigates its UHI characteristics and suggests some feasible mitigation strategies in order to reduce the air temperature and save energy. Temperature monitoring in Tehran shows clear evidence of the occurrence of the UHI effect, with a peak in July, where the urban area is circa 6 K warmer than the surrounding areas. The mobile measurements show a park cool island of 6-7 K in 2 central parks, which is also confirmed by satellite images. The effectiveness of three UHI mitigation strategies high albedo material (HAM), greenery on the surface and on the roofs (VEG), and a combination of them (HYBRID) has been studied using simulation with the microscale model ENVI-met. All three strategies show higher cooling effect in the daytime. The average nocturnal cooling effect of VEG and HYBRID (0.92, 1.10 K) is much higher than HAM (0.16 K), although high-density trees show a negative effect on nocturnal cooling.