Time-series satellite data for assessment of Bucharest city thermal environment

Abstract

Spatial change in the urban landscape related to land cover conversion due to urbanization is recognized as the critical factor affecting the formation and intensity of Urban Heat Island (UHI), which under summer Heat Waves (HWs) substantially modifies the land surface-aerodynamic properties, the energy and water balances and urban thermal environment. One of the most important goals of satellite-based urban thermal environment investigations is the better understanding of the physical content of different satellite-derived biophysical parameters. The specific object of this study is to use time-series Landsat TM/ETM + and MODIS Terra/Aqua satellite data for assessing of urban land cover-air and land surface temperature interactions during period between 2000 and 2022 years over Bucharest metropolitan area. The air (TA) and land surface temperature (LST), key parameters in urban climate research are analyzed in relation with land surface albedo and Normalized Difference Vegetation Index (NDVI) variables, and quantified the spatiotemporal cooling effects of urban green landscape characteristics impacts on urban thermal environment dynamic at city level. The rank correlation analyses revealed that, at the pixel-scale, during summer season (June-August) TA and LST presents a strong positive correlation (r= 0.86%, p<0.01). During summer periods (June -August), LST-NDVI shows a negative correlation (for central city areal r= -0.23, p< 0.05; and for metropolis areal r= -0.67, p<0.01). Also, the monthly mean UHI intensity belongs to the range of (1.3 o C to 6.5 o C), and the most intense UHI occurs during the day-time in the summer season in synergy with heat waves periods. Several urban/periurban zones and landscapes bring diurnally and seasonally different contributions to the local and regional thermal environment.