Surveying of Heat waves Impact on the Urban Heat Islands: Case study, the Karaj City in Iran
Introduction
Heatwave patterns and urban heat island phenomena have influenced environmental conditions by creating numerous problems in societies. Most of the human activities are sensitive to extreme temperature (Cox and Tikvart, 1990). Heat waves are the main point of the contemporary global climate changes that are caused damaged to live and properties in terms of its frequency of occurrence (Cohen, 2008). In meteorological terms, a heat wave is defined as a prolonged period of unusually hot weather (Hajat et al., 2002, Diaz et al., 2002, Kyselý, 2004, Michelozzi et al., 2004).
Statistically, heat waves imply to make positive fluctuation over the mean daily temperature that is continuity referring to consecutive days (sometimes weeks or months) in certain geographical spaces. According to definition, two factors of time and geographical region have become more important for occurrence or non-occurrence of heat waves. For example, high temperature upper than 24 °C is the heat wave threshold in the UK, but in Iran this threshold is much higher. The heat wave threshold is about 42 °C when the high temperature is continued for at least two days or more. In classification of environmental hazards, heatwave is the subgroup of extreme temperatures (Oke et al., 1999).
Urban heat island (UHI) is a well-known and thoroughly researched phenomena in urban climatology. In certain cities of the temperate climatic zone, structures and features of the UHI are well documented (Jerome et al., 2005, Kovatsand and Hajat, 2008). A higher urban-rural temperature forms the basis of UHI effect, which is a common urban phenomena (Arnfield, 2003).
Studies about UHI illustrate that temperature difference between municipal, rural and suburb areas is more obvious in minimum temperature condition (Bulut et al., 2008, Süleyman and Yilmaz, 2010). A number of reasons for this temperature differences can be the release of anthropogenic global warming (Zhang et al., 2014, Zhang et al., 2014), increase in urban pollution layer by absorption of longwave radiation emitted from the surface of that part will emit to the surface of land again (Shahmohamadi et al., 2011). Geometry of the cities with high buildings creates a unique three-dimensional edifice by producing air stagnation or slow speed of wind which in return creates lower cold air entrance to cities, changing the in land shield, spoiling vegetation, forming impermeable surfaces. Constructed materials such as asphalt and concrete have upper heat capacity and thus decrease evaporation, transpiration and release the absorbed energy slowly (Grize et al., 2005). The UHI intensity is greatest when it is under system conditions of stationary high-pressure, stable air and clear sky. This tends to disappear if cloudiness and wind speed increases.
Unprecedented heat wave in 2014 has brought many damages to Karaj city. The objective of present study is to determine if urban heat islands are present or not and to confirm whether any apparent urban-rural differences are statistically significant. Moreover, this study will identify circulation patterns in superheat days through synoptic approach. Then the UHI's impact on the environmental conditions of the Karaj city will be quantified and it will be shown how human health conditions could be exacerbated due to the intense UHIs. Heat waves will exacerbate by urban heat island effect which in return could have this potential to negatively influence the health and welfare of urban residents. In Section 2 we will bring materials and methods in which a brief discussion about importance and motivation of study for the chosen area is brought up and tools which used to investigate the question of study are fully described. Then in the third section findings and results of this work are fully discussed and addressed, and finally in Section 4, conclusions are brought up.
Section snippets
Research background
The increase of extreme climatic conditions is either the most important and as well, the worst effect of global warming. There exist significant relations between heat wave occurrence and mortality (Susanna et al., 2007). UHIs are associated with thermal and hygrometric discomfort because of the rise in temperature (Amorim, 2005). Correlation of atmospheric processes and Heat Waves involve significant mid troposphere anomalies that extended periods of subsidence and clear skies, light winds,
Synoptic patterns: recognition and analysis
According to previous studies (Kim and Baik, 2002, Rodriguez and Jimenez, 2000, Roth, 2012, Stewart, 2011, Yague et al., 1991), synoptic conditions strongly exert control on the heat island magnitude, In addition, the prevailing weather conditions during heat island measurements, as well as antecedent conditions leading up to a heat island event, strongly affect the observed temperature differences between urban and rural sites (Stewart, 2011).
In order to recognize the predominant sea level
Conclusions
The accelerated development of the Karaj city has changed the urban environment fiber. Surfaces have become impermeable and dry because of replacement of vegetation with other seats like asphalt. Continuation of this trend has warmed urban and the suburb of the region, which in return this has created heat islands with higher temperatures. Comparing the urban areas of Karaj city with its suburbs, the results demonstrated a considerable UHI sign whereby temperature amount was warmer > 2.5 °C at
Acknowledgements
We would like to acknowledge Karaj Meteorological Organization for obtaining marmonix temperature datalogger in order to register synoptic data during the research that was very useful.
References (93)
- et al.
Analyzing the land cover of an urban environment using high-resolution orthophotos
Landsc. Urban Plan.
(2003) - et al.
A statistical procedure for determining the best performing air quality simulation
Atmos. Environ.
(1990) - et al.
Climate change and human health: impacts, vulnerability, and mitigation
Lancet
(2006) - et al.
The impact of the 2003 heat wave on mortality in Shanghai, China
Sci. Total Environ.
(2010) - et al.
Analysis of the green roof thermal properties and investigation of its energy performance
Energy and Buildings
(2001) City size and the urban heat island
Atmos. Environ.
(1973)- et al.
Urban heat island dynamics in Montreal and Vancouver
Atmos. Environ.
(1975) - et al.
The energy balance of central Mexico City during the dry season
Atmos. Environ.
(1999) - et al.
Death toll exceeded 70,000 in Europe during the summer of 2003
C. R. Biol.
(2008) - et al.
Heat waves observed in 2007 in Athens, Greece: synoptic conditions, bioclimatological assessment, air quality levels and health effects
Environ. Res. J.
(2010)
An analysis of heat waves in Serbia
Glob. Planet. Change J.
Statistical analysis of the Madrid urban heat island
Atmos. Environ.
The cooling effect of urban green spaces as a contribution to energy-saving and emission-reduction: a case study in Beijing, China
Build. Environ.
Assessment and zoning of tourism climate of Iran using tourism climate index (TCI)
Phys. Geogr. Res. Q.
Excess mortality during heat waves, Tehran Iran: an ecological time series study
J. Res. Health Sci.
The relation between pressure distribution and air pollution concentration in Tehran
Effects of apparent temperature on daily mortality in Lisbon and Oporto, Portugal
Environ. Health J.
Intensidade e forma da ilha de calor urbana em Presidente Prudente/SP
Geosul
Two decades of urban climate research: a review of turbulence, exchanges of energy and water, and the urban heat island
Int. J. Climatol.
The influence of weather types on the urban heat island's magnitude and patterns at Paranhos (Porto): a case study from November 2003 to January 2005
Urban-rural climatic differences over a 2-year period in the City of Erzurum, Turkey
Atmosfera
Temporal variability of the Buenos Aires, Argentina, urban heat island
Theor. Appl. Climatol.
A synoptic climatology of summertime heat and humidity in the Piedmont region of North Carolina
J. Appl. Meteorol. Climatol.
Analog European Heat waves for U.S. cities to analyze impacts on heat-related mortality
Bull. Am. Meteorol. Soc.
Mapping a wind-modified Urban Heat Island in Tucson, Arizona (with comments on integrating research and undergraduate learning)
Bull. Am. Meteorol. Soc.
Making climate change part of global health, interview by Mark Honigsbaum
Lancet
Heat waves in Madrid 1986–1997: effects on the health of the elderly
Int. Arch. Occup. Environ. Health
Assessing a small summer urban heat island in rural south central Pennsylvania
Geogr. Bull.
Métodos e monitoramento da variabilidade Espaçotemporal da ilha de calor em cidades de porte médio—Rennes/França e Presidente Prudente/Brasil
Intra-urban nocturnal temperature differences: multivariate approach
Clim. Res.
Influence of sea surface temperature on the European heat wave of 2003 summer. Part I: an observational study
Clim. Dyn.
The Cambridge History of Iran, Physical Geography
de Calor Como Mitigar Zonas de Calor em Áreas Urbanas
La isla de calor en Madrid: Avance de un estudio de clima urbano
Estud. Geogr.
Guide for estimating differences in building heating and cooling energy due to changes in solar reflectance of a low-sloped roof
Urbanization and global environmental change: local effects of urban warming
Geogr. J.
Heatwave 2003 and mortality in Switzerland
Swiss Med. Wkly.
The impact of temperature on mortality in Tianjin, China: a case-crossover design with a distributed lag nonlinear model
Environ. Health Perspect.
Impact of hot temperatures on death in London: a time series approach
J. Epidemiol. Community Health
Mortality displacement of heat-related deaths: a comparison of Delhi, São Paulo, and London
Epidemiology
Validation of humidex in evaluating heat stress in the outdoor jobs in arid and semi-arid climates of Iran
Journal of Health and Safety at Work (JHSW)
The urban heat island in winter at Barrow, Alaska
Int. J. Climatol.
Significant inversions and rapid in situ cooling at a well-sited Oklahoma Mesonet station
J. Appl. Meteorol. Climatol.
The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
Pseudovertical temperature profiles and the urban heat island measured by a temperature datalogger network in Phoenix, Arizona
J. Appl. Meteorol.
Urban modification of diurnal temperature cycles in Birmingham, U.K.
J. Climatol.
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2022, Sustainable Cities and SocietyCitation Excerpt :Vegetation cover in the study area includes gardens, municipal green areas, parks, agricultural lands, and dense and sparse rangelands (Mokhtari, Barghjelveh & Sayahnia, 2021). Karaj has followed a significant sprawl and scattered pattern of development expansion (Ghobadi, Khosravi & Tavousi, 2018; Taleshi & Ghobadi, 2012), leaving plenty of vacant and barren land within the urban environment (Fig. 1). Currently, the city hosts a population of over 1592,000 people (https://www.amar.org.ir).