Changes in the Seoul metropolitan area urban heat environment with residential redevelopment

Since the Industrial Revolution, the geographical extent of cities has increased around the world. In particular, following three decades of rapid regional economic growth, many Asian megacities have emerged and continue to expand, resulting in inevitable short-term urban redevelopment. In this region, the microclimatic impacts of urban redevelopment have not been extensively investigated using long-term in situ observations. In this study, changes in surface sensible heat exchange, heat storage, and anthropogenic heat emissions that are due to urban residential redevelopment were quantified and analyzed on the basis of a 3-yr micrometeorological record from the Seoul, South Korea, 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 from ~9% (summer) to 31% (winter), anthropogenic heat emissions increased by from 7.6 (summer) to 23.6 (spring) W m^-2, and daily maximum heat storage ranged from 35.1 (spring) to 54.5 (summer) W m^-2; and 3) there was a transition of local circulation with changes in the surface properties of heat sources and roughness.