Abstract
The paper presents the main features of the urban heat island of Galați city during the summer season for a period of 16 years (2003-2018) using MODIS products. The main objectives were to analyse the extension and geometry of the urban heat island (UHI), its intensity, as well as its connection with land cover. The study is based on LST (Land Surface Temperature), a product obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) sensors located on board of the Terra (EOS AM-1) satellite since 2001 and Aqua (EOS PM-1) satellite since 2003. The boundaries, geometry and spatial extent of the UHI were delimited primarily through the Rodionov test. Through this method, the changing points along four transects over Galați city were identified (North-South, East-West, Northeast-Southwest and Northwest-Southeast) and have been used to delimitate the UHI. Overall, the Galați UHI assessed by satellite information is stronger during the day when the UHI is split in two centres, developed over the industrial area in the west and over the residential part of the town in the east, while during the night the UHI is weaker being developed more clearly over the oldest part of the city. One of the major characteristics of the Galați UHI is that it is highly influenced by the water bodies encircling the city. During the day the intensity of UHI reaches 2-2.5°C while during the night decreases below 2.0°C. The relation of the UHI with land cover and the attenuation of UHI in the surrounding area are also investigated.
Highlights
Urban Heat Island (UHI) is the term associated with the thermal difference between urban and rural areas, being defined in several ways (Schwarz et al, 2011)
The results proved to be much clearer from a spatial point of view as opposed to the initial ones, especially when highlighting the limits of UHI
Boundaries and geometry of the Galati summer UHI The highest intensity of UHI during summer is generated during the heat waves (HWs) and warm spells (WSs) that are generally cloudless and most of these days are covered with satellite information
Summary
Urbanization exerts a very complex action on the climate, both by the appearance of artificial surfaces, and by the changes of the energy fluxes at ground level. The effect of urbanization is synthetized from a climatic point of view by the Urban Heat Island (UHI). UHI is the term associated with the thermal difference between urban and rural areas, being defined in several ways (Schwarz et al, 2011). UHI can be quantified by cross-sectional measurements through. UHI can be quantified through remote sensing (Voogt & Oke, 2003). The quantification of UHI through remote sensing involves the use of LST (Land Surface Temperature) that, unlike the fixed points measurements, is more accurate from a spatial point of view. The effect of UHI depends on several factors such as topography, city surface, altitude above sea level, latitude and atmospheric stability (Wienert & Kuttler, 2005)
Published Version
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