Urban three-dimensional (3D) temperature mapping integrated from earth observations and ground measurements

This study marks the first effort to create a building surface temperature (Ts) dataset on both horizontal (rooftop, ground) and vertical (wall) facades. We measured Ts from four buildings in Valencia city using iButton loggers equipped with a radiation shield at 5-minute intervals. The measurements were conducted over a period that included four heatwaves (HW), spanning from mid-June to early October 2024. Additionally, 18 daytime and 5 nighttime images from Landsat 8/9 throughout the campaign provided the initial Ts. Furthermore, we used two calibrated CIMEL radiometers to obtain simultaneous Ts and emissivity on August 2 across various land covers for validation, with a laboratory uncertainty within 1K for LST.

The diurnal pattern of Ts indicates that the timing of its peaks is influenced by solar position and urban morphology (height, orientation, H/W). During the first heatwave period (July 19 to 21), Ts increased by 0.81-1.83°C and 0.43-1.35°C compared to pre-HW and post-HW periods, respectively. Additionally, variations in Ts across rooms with different H/W ratios and orientations within the same building indicate that peak temperatures are highest in rooms with a larger H/W ratio and a southwest-facing orientation. We believe that facade temperature is primarily governed by sunlight exposure, which is determined by geographical location and further shaped by geometric factors such as orientation, H/W ratio, and SVF. Therefore, we suggest increasing SVF along with a high H/W ratio to enhance thermal comfort levels.

The mock-ups of four buildings were built in the DART model to simulate the 3D temperature distribution at satellite overpass time. Undoubtedly, this dataset serves as a more accurate ground-based simulation for the upcoming new generation of high-resolution thermal infrared sensors, including Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment (TRISHNA), Land Surface Temperature Mission (LSTM) and Surface Biology and Geology (SBG).