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

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. Keywords: Land use change, Urban, Ground ozone, TVOC, WRF-Chem, Tropic

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

We present results fromtheOP3 campaign in Sabah during 2008 that allowus to study the impact of local emission changes over Borneo on atmospheric composition at the regional andwider scale. OP3 constituent data provide an important constraint onmodel performance.Treatment of boundary layer processes is highlighted as an important area of model uncertainty.Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South EastAsia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NOx emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere