Haze in Singapore – Source Attribution of Biomass Burning from Southeast Asia.

This paper presents a study of haze in Singapore caused by biomass burning in Southeast Asia over the six year period from 2010 to 2015, using the Lagrangian dispersion model, NAME. The major contributing source regions are shown to be Riau, Peninsular Malaysia, South Sumatra, and Central and West Kalimantan. However, we see differences in haze concentrations and variation in the relative contributions from the various source regions between monitoring stations across Singapore, as well as on an inter-annual timescale. These results challenge the current popular assumption that haze in Singapore is dominated by emissions/burning from only Indonesia. It is shown that Peninsular Malaysia is a large source for the Maritime Continent off-season biomass burning impact on Singapore. As should be expected, the relatively stronger southeast monsoonal winds that coincide with increased biomass burning activities in the Maritime Continent create the main haze season from August to October (ASO), which brings particulate matter from several and varying source regions to Singapore. In contrast, atypical haze episodes in Singapore are characterised by atypical weather conditions, ideal for biomass burning, and emissions dominated by a single source region (for each event). The two most recent atypical haze events in mid 2013 and early 2014 have different source regions, whereas a different set of five regions dominate as major contributing source regions for most of the recent ASO haze seasons. Haze in Singapore varies across year, season, and location it is influenced by local and regional weather, climate, and regional burning. The study shows that even across small scales, such as in Singapore, variation in local meteorology can impact concentrations of particulate matter significantly, and emphasises the importance of the scale of modelling both spatially and temporally. [ABSTRACT FROM AUTHOR]