Detection of atmospheric urban heat island through direct measurements in Cluj-Napoca city, Romania

Abstract

In the last decades, cities worldwide have experienced accelerated development, so that continuous urbanization and its impact is presently one of the most important topics in diff erent fi elds of research. The main aim of this study is to identify the intensity of the atmospheric urban heat island in Cluj-Napoca city, through direct observations campaigns by using fi xed points and transect measurements. The data has been collected over a period of 6 months (May-October 2015). The measurements have been performed mainly in anti-cyclonic weather condition, during the night, between 23:00 and 03:00. The profi les trajectories followed the main roads of the city on directions North-South, East-West, and Northwest-Southeast. 8 fi xed points have been chosen in order to highlight best the temperature patt erns in diff erent Local Climate Zones (LCZs). The main fi ndings of the study are the followings: the direct observations performed in three seasons (spring, summer and autumn) revealed the existence of an atmospheric urban heat island in Cluj-Napoca city; the warmest areas are compact high-rise and compact midrise, located in the eastern half of the city, where the temperature increases by more than 2.0 °C, as average value for all campaigns, but the maximum values, recorded in the summer are higher than 3.0 °C; the coolest areas are sparsely built areas and the large low-rise/water areas, where the temperature is quite similar to that recorded in the nearby rural areas (diff erence of 0.0-0.1 °C, as average values); local factors, such as mountain breeze and topography have a great impact on the atmospheric urban heat island confi guration.

The assessment relationship between land surface temperature (LST) and built-up area in urban agglomeration. Case study: Cluj-Napoca, Romania

“…It can be observed that the most extensive areas with LST > 35°C, LST > 38°C and LST > 40°C are located in the northeastern part of the city, these results being in line with the direct observations made by Herbel et al (2016) who have shown that the hottest places are located in the eastern half of Cluj-Napoca municipality.…”

“…In Romania LST estimations in an urban area were made by Imbroane et al (2014), based on Landsat satellite images, for the city Cluj-Napoca, and by Herbel et al (2016), who have been detecting atmospheric urban heat islands. Likewise, in regards to detecting atmospheric urban heat islands based on Modis satellite images we can mention Apostol et al, (2012) for the municipality of Iasi and Cheval & Dumitrescu (2009, 2015 for Bucharest.…”

A review of studies involving the effect of land cover and land use on the urban heat island phenomenon, assessed by means of the MUKLIMO model

“…ere are several ways to study urban heat island. ey include: appropriately designed, purposeful climatological networks (Herbel et al 2016), remote sensing methods (Roth, Oke, Emery 1989;Tran et al 2006;Fabrizi, Bonafoni, Biondi 2010), traverse (or mobile) measurement (Quitt 1978) or modelling (Atkinson 2003).…”

Outdoor thermal comfort research in urban areas of Central and Southeast Europe: A review

“…Cheval and Dumitrescu (2014) and Cheval et al (2015) presented the first results from the enhanced network for UHI monitoring in Bucharest. Herbel et al (2016) assessed UHI in Cluj-Napoca city. Marques et al (2015) performed heat stress assessment of two contrasted outdoor urban environments in two European capitals -Bucharest and Lisbon in order to examine thermal physiological response to heat stress and to quantify the effect of urban green spaces.…”