The role of land use on the local climate and air quality during calm inter-monsoon in a tropical city

Abstract

The modification of land use is known to be a major climate change driver to the local warming and air quality in cities. Despite the reduction of NOx over the years, the Selangor state has captured a higher level of O3 in year 2011. The measurement result has shown that the surge in O3 level was attributed to the reduction of NOx/NMHC ratio. This paper hence attempted to identify the role of land use change from 1999 to 2011 on the ground ozone air quality in the tropical urban conurbation, Greater Kuala Lumpur (GKL), Selangor, Malaysia. With the state-of-the-art chemical weather prediction tool, WRF-Chem, the external synoptic factors and emission inventory were controlled when comparing the chronological land use changes. The results showed that the urban-induced temperature and wind bias in the tropical region has induced stronger wind to disperse the NOx and carries the TVOC from the suburban to the downwind urban region. The reduction of NOx/TVOC has gradually shifted towards the optimum O3 formation regime in 2011. The formation of highly concentrated ozone becomes more sensitive to the increment of TVOC as the NOx level reduces in the urban. This highlights the essential involvement of TVOC in the ozone formation in lieu of the NOx reduction in the tropical city, a region with growing emitter of reactive biogenic ozone precursors.