Spatiotemporal Features of the Surface Urban Heat Island of Bacău City (Romania) during the Warm Season and Local Trends of LST Imposed by Land Use Changes during the Last 20 Years

Abstract

Using MODIS and Landsat LST images, the present paper advances a series of results on the characteristics of the surface heat island (SUHI) of Bacău City (Romania) during the warm season (April to September) for a period of 20 years (2001–2020). At the same time, given their higher temporal resolution and their availability for both day and night, MODIS LST was used to understand the spatial features of the SUHI in relation to land use. In this way, a total of 946 MODIS Terra and 483 Landsat satellite images were used to outline the main LST characteristics of the days with clear sky in this middle-sized city in northeast Romania. In order to analyze MODIS LST changes in relation to land use changes in the period 2001–2018, we used the standardized CORINE Land Cover datasets. With the help of the Rodionov test, we were able to determine the geometry and intensity of the SUHI. During the day, the spatial extension of the SUHI reaches its maximum level and is delimited by the isotherm of 31.0 °C, which is 1.5–2.0 °C warmer than the neighboring non-urban areas. During the night, the SUHI has a more regulated spatial extension around the central area of the city, delimited by the 15.5 °C isotherm with LST values that are 1.0–1.5 °C warmer than the surrounding non-urban areas. Additionally, from a methodological point of view, we highlight that resampled MODIS and Landsat images at a spatial resolution of 500 m can be used with confidence to understand the detailed spatial features of the SUHI. The results of this study could help the elaboration of future policies meant to mitigate the effects of urbanization on the SUHI in an era of increasing air temperatures during summer.

Spatiotemporal variation of land surface temperature and its driving factors in Xinjiang, China

“…The LST evolves from a complex energy transfer and transformation process. Its spatial and temporal differentiation is controlled by many geo-environmental factors influencing the water-heat balance, which in turn affects the resource environment and ecosystem structure (Sfîcă et al, 2023), making it vital for agriculture, hydrology, and ecology (Anderson et al, 2008;Zhang et al, 2009;Li et al, 2013). As a key factor in surface physical processes at global and regional scales, analyzing the spatial and temporal pattern divergence and spatial heterogeneity of LST is essential for analyzing regional climate change processes and driving mechanisms (Xi et al, 2023).…”

“…Currently, LST research is widely focused on the urban heat island effect (Ren et al, 2021;Yang et al, 2021;Sfîcă et al, 2023), crop sowing date predictions for agriculture (Zeng et al, 2015;Zhang et al, 2015), drought monitoring (Khan et al, 2018;Hu et al, 2020), soil freeze-thaw analysis (Yue et al, 2021), and human activity intensity research (Portela et al, 2020;Chen et al, 2022a). Although LST is a general term for soil temperature on the surface and at different depths below the ground, there are obvious spatial differences in topography, climatic environment, and underlying surface attributes, which can cause the diversity of LST distribution patterns and the regionality of formation mechanisms (Wu et al, 2022).…”