Exploring the thermal characteristics of different local climate zones in Addis Ababa, Ethiopia

One of the major issues in postulating climate mitigation plans in cities is the lack of reliable quantitative climate data regarding city landscapes for climate models. Therefore, performing a climate-based classification of city landscapes is crucial for developing climate-sensitive urban planning strategies. This study aims to analyse the diurnal and nocturnal thermal characteristics of different local climate zones (LCZs) in Addis Ababa. A variety of cloud-free satellite images of Addis Ababa were utilized for mapping LCZs and land surface temperatures (LSTs), including daytime Sentinel Multispectral Imagery (Sentinel 2A), Landsat-8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS), and nighttime Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). To perform climate-based classifications of urban and rural areas, we used the World Urban Database and Portal Tool (WUDAPT). The daytime and nighttime LST maps were derived from Landsat-8 and ASTER data to calculate surface urban heat island intensity (SUHII). Then, by developing the statistical relationship between LCZs and LSTs, we quantified the SUHII and explored the thermal characteristics of LCZs. The results showed that the differences in the dry seasonal average daytime and nighttime LST among LCZs are confirmed to be statistically significant. We also found the highest daytime SUHII in heavy industry (7.78 °C), followed by open high-rise (7.44 °C), and then compact low-rise open high-rise (6.51 °C), which indicates these LCZs have warm thermal characteristics. During the night, the LCZ 2 (compact mid-rise) had the highest SUHII. By contrast, LCZ A (dense trees) and LCZ G (water) were found to be the coolest zones during the day. The overall results acquired from this study can provide advanced insight about the thermal characteristics of different LCZs as well as suggest planning strategies for lessening local warming effects.