This work uses a mixture of observations from surface remote sensing (AERONET) and satellite remote sensing (OMI) to uniquely compute the atmospheric column loading of black carbon (BC) mass concentration density (MCD) and number concentration density (NCD) on a grid-by-grid, day-by-day basis at 0.25 degrees x0.25 degrees over rapidly developing and biomass burning (BB) impacted regions in South, Southeast, and East Asia. This mixture of observations is uniformly analyzed based on OMI NO2 retrievals, OMI Near ultraviolet band absorption aerosol optical depth and single scattering albedo (SSA), and AERONET visible and near-infrared band SSA observations, in connection with an inversely applied MIE mixing model approach. This method uniquely solves for the unbiased spatial and temporal domains based on variance maximization of daily NO2. These locations in space and time are then used to quantify the distribution of all possible individual particle core and refractory shell sizes as constrained by all band-by-band observations of SSA from AERONET. Finally, the range of NCD and MCD are computed from the constrained range of per-particle core and refractory shell size on a grid-by-grid and day-byday basis. The maps of MCD and NCD are consistent in space and time with known urban, industrial, and BB sources. The statistical distributions are found to be non-normal, with the region-wide mean, 25th, 50th, and 75th percentile MCD [mg/m2] of 90.3, 56.1, 81.1, and 111 respectively, and NCD [x1012 particles/m2] of 8.76, 4.63, 7.39, and 11.3 respectively. On a grid-by-grid basis, a significant amount of variation is found, particularly over Myanmar, Laos, northern Thailand, and Vietnam, with this subregional mean, 25th, 50th, and 75th MCD [mg/m2] of 90.7, 56.1, 81.3, and 112 respectively and NCD [x1012 particles/m2] of 9.66, 5.49, 8.33, and 12.3 respectively. On a day-to-day basis, events are determined 121 days in 2016, during which the computed statistics of MCD and NCD have mean and uncertainty ranges which scale with each other. However, there are 11 days where the uncertainty ratio of NCD values is larger than 1 while the uncertainty ratio of MCD is small, and 5 days where the reverse is observed, indicating that the particle size is strongly atypical on these days, consistent with mixed aerosol sources, a substantial change in the aerosol aging, or other such factors including a substantial region of overlap between BB and urban sources. The high values observed from March to May lead to an extended BB season as compared to previous work focusing on fire radiative power, NO2, and models, which show a shorter season (usually ending in early April). The results are consistent with BC being able to transport significant distances. The new approach is anticipated to provide support for improving radiative forcing calculations, estimating emissions inventories, and providing a basis by which models can compare against observations.

Black carbon (BC) is an important aerosol constituent in the atmosphere and climate forcer. A good understanding of the radiative forcing of BC and associated climate feedback and response is critical to minimize the uncertainty in predicting current and future climate influenced by anthropogenic aerosols. One reason for this uncertainty is that current emission inventories of BC are mostly obtained from the so-called bottom-up approach, an approach that derives emissions based on categorized emitting sources and emission factors used to convert burning mass to emissions. In this work, we provide a first global-scale top-down estimation of global BC emissions, as well as an estimated error range, by using a Kalman Filter. This method uses data of both column aerosol absorption optical depth and surface concentrations from global and regional networks to constrain our fully coupled climate-aerosol-urban model and thus to derive an optimized estimate of BC emissions as 17.85.6 Tg/yr, a factor of more than 2 higher than commonly used global BC emissions data sets. We further perform 22 additional optimization simulations that incorporate the known uncertain ranges of various important physical, model, and measurement parameters and still yield an optimized value within the above given range, from a low of 14.6 Tg/yr to a high of 22.2 Tg/yr. Furthermore, we show that the emissions difference between our optimized and a priori estimation is not uniform, with East Asia, Southeast Asia, and Eastern Europe underestimated, while North America is overestimated in the a priori inventory.