Keywords: ozone bimodal variation, nocturnal ozone maxima, titration, land use, urbanisation, tropospheric ozone, Hong Kong, air quality, air pollution
Ozone diurnal characteristics in areas with different urbanizations
The influences of the levels of urbanisation over the tropospheric ozone in the Hong Kong Special Administrative Region (HKSAR) have been analysed using its long–term air quality data from 1990 to 2005. Urbanisation was found to have considerable influence on ozone diurnal variations. Different ozone diurnal patterns would be formed under various land uses which are categorised as rural, sub–urban and urban. Titration levels and the diurnal accumulation of tropospheric ozone can be significantly varied in areas with different urbanisations, especially at locations with low altitudes. Focusing on the levels of urbanisation (together with land use and emission structure) is a practical and feasible approach to explore the nocturnal ozone maxima, apart from the traditional theories. A better understanding can be obtained on the linkage between ozone diurnal variations and the levels of urbanisation to help achieve a sustainable urban design and improve air quality of a city.