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 ...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 O_3 in year 2011. The measurement result has shown that the surge in O_3 level was attributed to the reduction of NO_x/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, WRFChem, 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 NO_x and carries the TVOC from the suburban to the downwind urban region. The reduction of NO_x/TVOC has gradually shifted towards the optimum O_3 formation regime in 2011. The formation of highly concentrated ozone becomes more sensitive to the increment of TVOC as the NO_x 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.展开更多
Night-time OH levels have been determined for UK urban surface environments using two methods, the decay and steady state approximation methods. Measurement data from the UK National Environmental Technology Centre ar...Night-time OH levels have been determined for UK urban surface environments using two methods, the decay and steady state approximation methods. Measurement data from the UK National Environmental Technology Centre archive for four urban sites （Bristol, Harwell, London Eltham and Edinburgh） over the time period of 1996 to 2000 have been used in this study. Three reactive alkenes, namely isoprene, 1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method. Hourly measurements of NO, NO〉 03, CO and 20 VOCs were used to determine night-time OH level using the steady state approximation method. Our results showed that the night-time OH levels were in the range of 1 × 10^3-1× 10^6 molecules/cm3 at these four urbap sites in the UK. The application of a t-test of these analyses indicated that except Bristol, there was no significant difference between the OH levels found from the decay and steady state approximation methods. Night-time levels of the OH radical appeared to peak in summer and spring time tracking the night-time 03 levels which also passed through a maximum at this time.展开更多
基金the Ministry of Science Technology and Innovation (MOSTI) of Malaysia for providing financial support for this research workpartly sponsored under contract No. 06-02-12-SF0346University of Nottingham Malaysia Campus for awarding a research scholarship
文摘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 O_3 in year 2011. The measurement result has shown that the surge in O_3 level was attributed to the reduction of NO_x/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, WRFChem, 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 NO_x and carries the TVOC from the suburban to the downwind urban region. The reduction of NO_x/TVOC has gradually shifted towards the optimum O_3 formation regime in 2011. The formation of highly concentrated ozone becomes more sensitive to the increment of TVOC as the NO_x 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.
文摘Night-time OH levels have been determined for UK urban surface environments using two methods, the decay and steady state approximation methods. Measurement data from the UK National Environmental Technology Centre archive for four urban sites （Bristol, Harwell, London Eltham and Edinburgh） over the time period of 1996 to 2000 have been used in this study. Three reactive alkenes, namely isoprene, 1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method. Hourly measurements of NO, NO〉 03, CO and 20 VOCs were used to determine night-time OH level using the steady state approximation method. Our results showed that the night-time OH levels were in the range of 1 × 10^3-1× 10^6 molecules/cm3 at these four urbap sites in the UK. The application of a t-test of these analyses indicated that except Bristol, there was no significant difference between the OH levels found from the decay and steady state approximation methods. Night-time levels of the OH radical appeared to peak in summer and spring time tracking the night-time 03 levels which also passed through a maximum at this time.
