Journal of Geophysical Research: Atmospheres Characterization of Wildﬁre-Induced Aerosol Emissions From the Maritime Continent Peatland and Central African Dry Savannah with MISR and CALIPSO Aerosol Products

Aerosol plumes from wildﬁres aﬀect the Earth’s climate system through regulation of the radiative budget and clouds. However, optical properties of aerosols from individual wildﬁre smoke plumes and their resultant impact on regional climate are highly variable. Therefore, there is a critical need for observations that can constrain the partitioning between diﬀerent types of aerosols. Here we present the apparent inﬂuence of regional ecosystem types on optical properties of wildﬁre-induced aerosols based on remote sensing observations from two satellite instruments and three ground stations. The independent observations commonly show that the ratio of the absorbing aerosols is signiﬁcantly lower in smoke plumes from the Maritime Continent than those from Central Africa, so that their impacts on regional climate are diﬀerent. The observed light-absorbing properties of wildﬁre-induced aerosols are explained by dominant ecosystem types such as wet peatlands for the Maritime Continent and dry savannah for Central Africa, respectively. These results suggest that the wildﬁre-aerosol-climate feedback processes largely depend on the terrestrial environments from which the ﬁres originate. These feedbacks also interact with climate under greenhouse warming. Our analysis shows that aerosol optical properties retrieved based on satellite observations are critical in assessing wildﬁre-induced aerosols forcing in climate models. The optical properties of carbonaceous aerosol mixtures used by state-of-the-art chemistry climate models may overestimate emissions for MISR algorithm climatology eight aerosol components distinguishes aerosol types classiﬁedbyopticalpropertieswithoutusingdatafromotherinstruments. Therearefournonabsorbingspher-ical particle optical analogs, two nonspherical-particle analogs, two spherical absorbing particles with single-scattering albedo (SSA) of 0.9 and 0.8 in the midvisible wavelengths 2010). For this study, the joint distributions of aerosol types from the MISR Joint Aerosol Product (JOINT_AS) were processed to generate total, nonabsorbing, and absorbing aerosol optical depth (AOD) on a monthly, 5 ∘ × 5 ∘ latitude-longitude spatial-temporal grid et al., 2016). The absorbing AOD is a sum of the AODs for weakly and strongly absorbing aerosols with a ﬁxed eﬀective radius of 0.12 μ m and SSA of 0.9 and 0.8 respectively. The nonspherical aerosols in the MISR retrieval algorithm are assumed to be nonabsorbing. The nonabsorbing AOD in the current study is an optical depth sum of the three small nonabsorbing spherical aerosols whose eﬀective radii are 0.06, 0.12, and 0.26 μ m, respectively. Lee et al. (2016) use the same com-binations of optical depths for diﬀerent MISR aerosol types and compare them with simulated AODs from chemistry climate models. Kahn and Gaitley (2015) and Kahn et al. (2010) report that MISR’s optical depths for the diﬀerent types of aerosols are reliable over the regions where total AOD (nonabsorbing + absorbing + nonspherical AOD) is greater than 0.15. Therefore, MISR (JOINT_AS) can provide broad pictures of thick smoke plumes from intense wildﬁres. The monthly mean AOD data for the 16 years between March 2000 February 2016 were used in the current study.