Major advances in geostationary fire radiative power (FRP) retrieval over Asia and Australia stemming from use of Himarawi-8 AHI

New Tropical Peatland Gas and Particulate Emissions Factors Indicate 2015 Indonesian Fires Released Far More Particulate Matter (but Less Methane) than Current Inventories Imply

“…However, substitution of this EF in place of 9.1 ± 3.5 g·kg −1 would elevate our total PM emissions insignificantly, since our calculations indicate that 95% of the PM 2.5 emissions come from burning peatlands. Himawari FRP data [40] enable the spatio-temporal mapping of the particulate emissions at far higher detail than hitherto possible, and whereas their broad spatial pattern (Figure 12a,b) is similar to that reported by GFASv1.2 ( Figure A1) and GFEDv4.1s ( Figure A2), our 9.1 ± 3.2 Tg PM 2.5 emission total is more than double (~×2.2) of those inventories. Their lower totals are primarily driven by their assumed EF PM2.5 of 9.1 g·kg −1 , irrespective of whether a fire is burning atop peat, which more than counteracts the fact that both GFASv1.2 and GFEDv4.1s estimate DM fuel consumptions for the 2015 Indonesian fire event to be significantly higher than the 358 Tg upon which our 9.1 ± 3.2 Tg PM 2.5 emissions estimate is based (see Table 6).…”

“…This may reflect the fact that sub-surface peat combustion, which was seen occurring across very large regions of peatland during our field campaign (e.g., Figure 2b) and which is described in detail in [9], is likely to be less influenced by the daily meteorological cycles of wind, relative humidity and air temperature, factors which (along with ignition timing) typically drive the diurnal variability of surface vegetation fires occurring in non-peat areas [78]. [40]. Peatland fires have a daytime peak that is wider and occurs later in the day than in non-peatland areas.…”

“…We both update the prior gas-only EF's presented in [12], extend to particulates, and use methods different (and complementary to) those of [39]. We use our new gaseous emissions factors and in situ peat carbon content measurements made at the fire sites to update satellite-derived estimates of Indonesian fuel consumption [12], combine these with our EF PM2.5 measures to estimate fine particulate emissions, and use new very high temporal resolution fire radiative power (FRP) data from geostationary satellites [40] to understand the emissions variability over both individual days and over the fire event itself in more detail than ever before (hourly temporal resolution, 0.05 • ). We also assess the landscape and physio-chemical peat properties of our field sampling sites to help determine factors that may regulate EF variability, and we compare our total dry matter fuel consumption and smoke emissions estimates to those provided by other widely-used global fire emissions inventories.…”

“…This in part reflects the DM fuel consumption differences between these inventories discussed in Section 4.1. Our far higher in situ derived EF PM2.5 values (Section 3.4), along with our updated DM fuel consumptions (Table 6), enables us to provide new PM 2.5 emissions totals, and in addition we can utilize the very high temporal resolution (10-min) fire radiative power (FRP) data recently available from the Himawari geostationary satellite [40] to fully resolve the diurnal cycle of these smoke emissions, which can be important when linking them to atmospheric chemistry transport models (CTMs) [71]. Using the data of Table 4, we derive a mean peatland EF PM2.5 of 28 ± 6 g·kg −1 , calculated as with the carbonaceous gas EFs from a 73% weighting of pure peat burning and 27% vegetation burning atop peat following [12,54,72].…”

“…Further investigations using the geostationary FRP-based methodology of [40] indicates that these extreme SE Asian fires show a diurnal cycle peaking generally later in the day than fires dominating most other tropical forest regions, for example those in parts of South America and tropical Africa [74][75][76]. Specifically, the Indonesian fires show a diurnal cycle peaking on average between 16:00 and 18:00 h local solar time (Figure 13), which appears most similar to the peak timing of Brazilian deforestation fires [74] (where fuel is sometimes piled before burning) and fires in the swamp forests of southern Africa [76] (which include areas of tropical peat).…”