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EVALUATION OF URBAN HEAT ISLAND IN ISTANBUL USING REMOTE SENSING 
TECHNIQUES 
U. G. Basar 1 , S. Kaya 1 ' 2 , M. Karaca 3,4 
'Istanbul Technical University, Dept, of Satellite Remote Sensing & Communication 
Maslak 34469, istanbul. umutgul_basar@yahoo.com 
Istanbul Technical University, Dept, of Geodesy and Photogrametry, Maslak 34469, istanbul. skaya@ins.itu.edu.tr 
Istanbul Technical University, Eurasia Institute of Earth Sciences, Maslak 34469, istanbul 
Istanbul Technical University, Dept, of Geology, Maslak 34469, istanbul. karaca@itu.edu.tr 
Commission VII, WG VII/5 
KEY WORDS: Urbanization, UHI, Istanbul, Landsat TM 5, Satellite Sensor Data, Radiance 
ABSTRACT: 
In this study, Urban Heat Island (UHI) in Istanbul has been studied using Landsat 5 TM satellite sensor data and long-term 
temperature data from meteorological stations within and around the city. The thermal remote sensing technique is used to study of 
urban climate in Istanbul for the first time. Thermal and other channels of the Landsat satellite images were used for three different 
years: 1987, 1997 and 2007. In addition, meteorological data which are temperature, precipitation, humidity, for the same period 
which are 25 September 1987, 18 July 1997 and 28 June 2007, were used. The images are classified according to the thermal channel. 
The temperature data and the coordinates of stations have been added to this classification. Two major centers for urban heat island is 
found in Istanbul. Our major finding is that expansion of urban areas in Istanbul lead growth in thermal radiation of land surface in 
highly dense areas. This is mainly due to unplanned and unorganized rapid urbanization in last two decades. 
1. INTRODUCTION 
Urbanization is the development of cities and suburban areas as 
a result of population growth. Approximately 47% of world’s 
population are currently living in cities (Wu and Murray, 2003), 
and this number is expected to increase as more people are 
moving from countryside to cities, especially in the less 
developed countries where the fraction of the population that 
lives in cities (41% in 2005) is much less than that of the more 
developed countries (76% in 2005) (Population Reference 
Bureau, 2005). 
Immigration to urban, because of education, working on a better 
job, entertainment & fashion, has cause using more impervious 
materials on the construction of the structures. Urbanization is 
also a land-use change that was made by humans. To 
understand the urbanization and its relation with climate, lots of 
researches have studied these topics. For example, Amfield’s 
study (2003) presents the progress in urban climatology during 
the two decades after 1980 and Voogt & Oke’s study (2003) is a 
review of the use of thermal remote sensing in the study of 
urban climate. 
Because of the residual structures and increasing population, 
vegetation areas are dissipated. When the vegetation is reduced, 
the natural cooling effect of shading and evapotranspiration 
decrease. Moreover, artificial land surface change induces 
narrow streets and tall buildings which are reduce air flow, and 
this is called “canyon effect”. 
All these effects cause temperature increase in the urban air and 
surface temperatures than the surrounding rural areas, and this is 
called Urban Heat Island (UHI) effect. The heat island is an 
example of unintentional climate modification when 
urbanization changes the characteristics of the Earth’s surface 
and atmosphere (Voogt, 2004, Ezber et al., 2007). The urban 
heat island is best observed at clear and calm nights because 
radiative cooling differences are maximized between urban and 
surrounding rural areas (Voogt, 2002). 
There are three types of heat islands: first canopy layer heat 
island (CLHI), second boundary layer heat island (BLHI), and 
the last one surface heat island (SHI) (Voogt, 2004). The first 
two refer to a warming of the urban atmosphere; the last refers 
to the relative warmth of urban surfaces. The first two refer to a 
warming of the urban atmosphere; the last refers to the relative 
warmth of urban surfaces (Voogt, 2004). The canopy layer heat 
island below the roof tops in the space between buildings (Mills, 
2007) . Above the urban canopy layer lies the urban boundary 
layer, which may be 1 kilometer (km) or more in thickness by 
day, shrinking to hundreds of meters or less at night. It is the 
BLHI that forms a dome of warmer air that extends downwind 
of the city. Wind often changes the dome to a plume shape 
(Voogt, 2004). 
Living in urban areas has been increased rapidly in Turkey for 
last three decades. While the metropolitan population was 24% 
of the total Turkish population in 1945, it increased to 65% in 
2000 (DIE, 2008, Kaya, 2005). 
Population of Istanbul is 680,857 in 1927, 5,475,982 in 1985, 
9,260,438 in 1997 and 12,5 million in 2007 (DIE, 2008, Basar, 
2008) . The aim of this study is to show the relationship 
between growth of urban heat island borders in Istanbul and 
increase in the city’s population using remote sensing 
techniques. 
Urban Heat Island in Istanbul has been previously studied by 
several researchers using long-term temperature data from 
meteorological stations within and around the city. In this work, 
we use the thermal remote sensing to study of urban climate in 
Istanbul from 1987 to 2007 for the first time. Thermal and other