Air quality influenced by urban heat island coupled with synoptic weather patterns.

Abstract Few studies have discussed the association between the urban heat island (UHI) phenomenon and air quality under synoptic weather patterns conducive to UHI. In this study, the authors used statistical analyses to study this association in the Taichung metropolis region. The air quality data obtained from government-owned observation stations and wind field profiles obtained from tethersonde monitoring (performed during 21–29 October 2004) were combined with the simulations of the horizontal wind fields at different heights by the air pollution model (TAPM). The results show that certain specific synoptic weather patterns worsen the air quality and induce the UHI phenomenon: Taichung's UHI appears clearly under the synoptic weather patterns featuring light air or breezes (0.56 m/s ≤ wind speed  2 , CO 2 and CO) increase significantly ( P 3 precursors, as well as other air pollutants, thereby worsening the air quality at that time and also during the following daytime period.