A new perspective on the spatial, temporal, and vertical distribution of biomass burning: quantifying a significant increase in CO emissions

Abstract

A variance-maximization approach based on 19 years of weekly measurements of pollution in the troposphere carbon monoxide (CO) measurements quantifies the spatial-temporal distribution of global biomass burning. Seven regions consistent with existing datasets are discovered and shown to burn for longer, over a more widespread area. Each region has a unique and recurring burning season, with three dominated by inter- and intra-annual variation. The CO is primarily lofted to the free troposphere from where it spreads downwind at 800 to 700 mb with three exceptions: The Maritime Continent and South America where there is spread at 300 mb consistent with deep- and pyro-convection; and Southern Africa which reaches to 600 mb. The total mass of CO lofted into the free troposphere ranges from 46% over Central Africa to 92% over Australia. The global, annual emissions made using two different techniques lead to an increase of biomass burning CO emissions of 47TgCO/year and 99TgCO/year respectively. The larger increase is mainly due to two factors: first, a large amount of the emissions is lofted rapidly upwards over the biomass burning region and subsequently transported downwind, therefore not appearing near the biomass source in space and time and second, an increase in inter-annual variability. Consistently, there is an increase in variability year-to-year and during peak events, from which 35% to more than 80% of the total emissions is lofted into the free troposphere. The results demonstrate a significantly higher CO emission from biomass burning, a larger impact on the global atmospheric composition, and likely impacts on atmospheric chemistry and climate change.

Constraining the relationships between aerosol height, aerosol optical depth and total column trace gas measurements using remote sensing and models

“…5 are found to generally be consistent, with the ratio found to be more so (Table S2). This indicates the NO 2 /CO column ratio over the fire regions tends to be consistent with the fire plumes as a whole and is not found to be significantly influenced by urban sources of NO 2 , which would lead to a vastly faster chemical titration of NO 2 compared to CO. All of these results are also shown to be consistent with recent work (Cohen, 2014;Lin et al, 2014Lin et al, , 2020a, showing that the characteristics of the spatial-temporal variability of fires are quite different from those of urban areas and have a much higher variability both week to week and interannually.…”

“…One advantage of the OMI NO 2 column measurements is that they can often be observed under relatively cloudy or smoky conditions (Lin et al, 2014). Another advantage is that the atmospheric lifetime of NO 2 is only a few hours, and therefore relatively large changes in the temporal-spatial distribution of NO 2 column measurements are highly correlated with wildfire sources (Lin et al, 2020a;He et al, 2020).…”

Using a New Top‐Down Constrained Emissions Inventory to Attribute the Previously Unknown Source of Extreme Aerosol Loadings Observed Annually in the Monsoon Asia Free Troposphere

“…The spatial distribution shows the highest levels of BC over the biomass burning source regions in the north, with a smaller but still significant burden over emissions regions in the south. Second, there is a significant amount of eastward transport observed at all size ranges of BC, with the smaller sizes (BC1 and BC2) having a significant amount of transport two‐thirds of the way across the South China Sea (to about Dongsha Island) and the larger size ranges (BC3–BC6) exhibiting eastward transport all the way to Taiwan or beyond into the Pacific Ocean, consistent with the flow induced by the Indian Ocean monsoon on observations of CO (C. Lin, Cohen, Wang, Lan, et al., 2020). Third the geographic spread of BC4 has the largest total area, reaching as far east as the Western Pacific Ocean, as far South as 7°N, as far southeast as the Philippines, and as far southwest as the Indian Ocean.…”

“…Some work has been able to obtain a good match with respect to ground-based observation of PM2.5 (Le et al, 2020;Zhang et al, 2019), PM10 Wang, 2013), carbon monoxide (CO) (Reid et al, 2013;Reid et al, 2005) , and ozone (Ding et al, 2013), within the respective sub-regions. However, to date, there has been no modeling study able to match the large-scale and coherent plumes in terms of space, time, duration, height, and magnitude over this region of the world, as identified by remotely sensed measurements of AOD from MISR (Cohen, 2014), combination of AOD, fire hotspots, and land-surface change from MODIS (Cohen et al, 2017), a combination of AOD from MISR and Height from CALIOP (Cohen et al, 2018), CO from MOPITT (Lin et al, 2020a;Lin et al, 2020b), and a combination of NO2 from OMI, CO from MOPITT, and height from MISR (Wang et al, 2020).Furthermore, there is no modeling study found able to show a significant amount of transport from Continental Southeast Asia to the Maritime Continent (Reid et al, 2013). Yet, due to the complexity of the geography, meteorology, and dynamics, as well as intense cloud-cover in Southeast Asia, models provide an important component for improving the understanding of the sources and transport of aerosols over this region of the world (Lin et al, 2013;Reid et al, 2012).…”

“…In terms of meteorology, aerosols emitted from Eastern India, Myanmar, Northern Thailand, Laos and Northern Vietnam will have a high chance of being caught in the Southern Himalaya up-slope currents (Stone et al, 2010;Venzac et al, 2008) as well being co-emitted with buoyancy from biomass burning (Cohen et al, 2018;Wang et al, 2020). These two effects lead to a significant amount of aerosols and trace gasses (Lin et al, 2020b) being lofted high above the boundary layer over this region, from 850 mbar up to 650 mbar. In a normal year…”