2025 Reports

Impacts of Urban Redevelopment on Urban Climate and CO₂ Emissions in Seoul

Hong, Jinkyu; Hong, Je-Woo

During three decades of rapid regional economic growth, many Asian megacities have emerged and continue to expand resulting in inevitable short-term urban redevelopment. Urban redevelopment is a complex socio-ecological challenge for sustainability and co-prosperity in Asian megacities. However, in this region the microclimatic impacts of urban redevelopment have not been extensively investigated using long-term in-situ observations. We observed changes in surface sensible heat exchange, heat storage, and anthropogenic heat emissions due to urban residential redevelopment were quantified and analyzed based on a three-year micrometeorological record from the Seoul metropolitan area. The results show that following urban redevelopment of compact high-rise residential buildings: 1) the daily minimum air temperature near the ground surface increased by ~0.6 K; 2) the ratio between surface sensible heat and net radiation increased by ~9% (summer) to 31% (winter), anthropogenic heat emissions increased by 7.6 W m⁻² (summer) to 23.6 W m⁻² (spring), and daily maximum heat storage ranged from 35.1 W m⁻² (spring) to 54.5 W m⁻² (summer), and; 3) there was a transition of local circulation with changes in the surface properties of heat sources and roughness. After the redevelopment to the compact high-rise residential area, the annual CO₂ emission rate is approximately 13.1 kg CO₂ m⁻² yr⁻¹ with traffic, which is the major source of CO₂ (+2.3 μmol m⁻² s⁻¹ per 100 vehicles). We also found a unique coupling of urban surface energy partitioning and CO₂ emission rates with the seasonal progression of the Asian monsoon.