Analysis of Southeast Asian pollution episode during June 2013 using satellite remote sensing datasets Krishna Prasad Vadrevu * , Kristofer Lasko, Louis Giglio, Chris Justice Department of Geographical Sciences, University of Maryland College Park, 4321 Hartwick Road, College Park, MD 20740, USA article info Article history: Received 27 February 2014 Received in revised form 5 June 2014 Accepted 9 June 2014 Available online 30 July 2014 Keywords: Indonesia Haze Aerosols CO Southeast Asia abstract In this study, we assess the intense pollution episode of June 2013, in Riau province, Indonesia from land clearing. We relied on satellite retrievals of aerosols and Carbon monoxide (CO) due to lack of ground measurements. We used both the yearly and daily data for aerosol optical depth (AOD), fine mode fraction (FMF), aerosol absorption optical depth (AAOD) and UV aerosol index (UVAI) for characterizing variations. We found significant enhancement in aerosols and CO during the pollution episode. Compared to mean (2008e2012) June AOD of 0.40, FMF-0.39, AAOD-0.45, UVAI-1.77 and CO of 200 ppbv, June 2013 values reached 0.8, 0.573, 0.672, 1.77 and 978 ppbv respectively. Correlations of fire counts with AAOD and UVAI were stronger compared to AOD and FMF. Results from a trajectory model sug- gested transport of air masses from Indonesia towards Malaysia, Singapore and southern Thailand. Our results highlight satellite-based mapping and monitoring of pollution episodes in Southeast Asia. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Vegetation fires are an immense source of air pollution in several tropical countries. In particular, biomass burning in Southeast Asia is extensive and an important source of trace gases and aerosols (Folkins et al., 1997; Chan et al., 2006; Hyer et al., 2013). In the region, fire is used as a management tool for clearing land through slash and burn agriculture (Tomich et al., 1998), disposing of agricultural residues (Dobermann and Fairhurst, 2002; FAO, 2013) and for clearing forests for developing palm oil plantations by private companies (Greenpeace, 2013; Miettinen et al., 2011). The fire season in this region coincides with the dry weather season and the southwest monsoon. Earlier researchers reported several biomass burning-related haze episodes from the region during August to September 1982, September 1983, September 1987, August 1990, AugusteSeptember 1991, AugusteOctober 1994, AugusteOctober 1997 (Nichol, 1998; Radojevic, 2003; See et al., 2006). During the air pollution events, aerosols and pollutants can be transported long distances and persist for weeks to months, impacting not only air quality but also human health, biogeochemical cycles, atmospheric chemistry, weather and climate (Radojevic, 2003). Among Asian countries, Indonesia accounts for 15.7% of total fires (Vadrevu and Justice, 2011). For Indonesia, the most recent, signifi- cant recorded haze episode occurred during 1997/1998 from the combination of human factors and dry conditions during an El Ni ~ no- Southern Oscillation cycle. During that time, the haze persisted for weeks in Indonesia and in the neighboring countries of Singapore and Malaysia (Murdiyarso et al., 2004). It is estimated that more than 11 Mha of forest were burned (Siegert, 2001; Taylor, 2010). Close to the vegetation fires at Palangkaraya on Kalimantan and Jambi on Sumatra up to 4000 mg/m 3 total particulate matter was measured, exceeding the Indonesian national ambient air quality standard by a factor of 15 (Heil and Goldammer, 2001). In Indonesia, peatland fires are common (Nara et al., 2011; Hyer et al., 2013). Peatlands occupy 170,000e270,000 km 2 (Heil and Goldammer, 2001) and it is esti- mated that they store 57,367Gt of carbon (Page et al., 2011). Thus, peatland fires release huge amounts of carbon into the atmosphere. Most of the peatland fires are attributed to anthropogenic factors, however, theyget aggravated by the coincidence of dry season (Usup et al., 2004). During recent times, one of the major projects that led to peatland degradation was the Mega Rice Project in central Kali- mantan, Indonesia. The project aimed to create large rice cultivation area, however, it failed and resulted in the drainage of 1 Mha of unmanaged peatlands. The drained peatlands are highly susceptible to fires as they are relatively dry with a low water table, enabling combustion of top peat layers (Miettinen et al., 2011). Fires from the peatlands are hard to detect from space, as peat fires are typically low temperature smoldering fires involving both above-ground as * Corresponding author. E-mail addresses: krisvkp@umd.edu, krisvkp@yahoo.com, krivadrevu@gmail. com (K.P. Vadrevu). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol http://dx.doi.org/10.1016/j.envpol.2014.06.017 0269-7491/© 2014 Elsevier Ltd. All rights reserved. Environmental Pollution 195 (2014) 245e256