Exploiting simultaneous observational constraints on mass and absorption to estimate the global direct radiative forcing of black carbon and brown carbon
By Xuan Wang, C. Heald, D. Ridley, Joshua P. Schwarz, J. Spackman, A. Perring, H. Coe, Di Liu, A. Clarke. 2014
279 citations recorded by the source corpus.
Abstract. Atmospheric black carbon (BC) is a leading climate warming agent, yet uncertainties on the global direct radiative forcing (DRF) remain large. Here we expand a global model simulation (GEOS-Chem) of BC to include the absorption enhancement associated with BC coating and separately treat both the aging and physical properties of fossil-fuel and biomass-burning BC. In addition we develop a global simulation of brown carbon (BrC) from both secondary (aromatic) and primary (biomass burning and biofuel) sources. The global mean lifetime of BC in this simulation (4.4 days) is substantially lower compared to the AeroCom I model means (7.3 days), and as a result, this model captures both the mass concentrations measured in near-source airborne field campaigns (ARCTAS, EUCAARI) and surface sites within 30%, and in remote regions (HIPPO) within a factor of 2. We show that the new BC optical properties together with the inclusion of BrC reduces the model bias in absorption aerosol optical depth (AAOD) at multiple wavelengths by more than 50% at AERONET sites worldwide. However our improved model still underestimates AAOD by a factor of 1.4 to 2.8 regionally, with the largest underestimates in regions influenced by fire. Using the RRTMG model integrated with GEOS-Chem we estimate that the all-sky top-of-atmosphere DRF of BC is +0.13 Wm−2 (0.08 Wm−2 from anthropogenic sources and 0.05 Wm−2 from biomass burning). If we scale our model to match AERONET AAOD observations we estimate the DRF of BC is +0.21 Wm−2, with an additional +0.11 Wm−2 of warming from BrC. Uncertainties in size, optical properties, observations, and emissions suggest an overall uncertainty in BC DRF of −80%/+140%. Our estimates are at the lower end of the 0.2–1.0 Wm−2 range from previous studies, and substantially less than the +0.6 Wm−2 DRF estimated in the IPCC 5th Assessment Report. We suggest that the DRF of BC has previously been overestimated due to the overestimation of the BC lifetime (including the effect on the vertical profile) and the incorrect attribution of BrC absorption to BC.
Subfields: Atmospheric Science, Global and Planetary Change
View Paper: https://www.semanticscholar.org/paper/094c09bc998cb65d105335bf9c06f29e8144d25d
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Atmospheric Science
In Global and Planetary Change
Citations in the corpus
- Exploring the observational constraints on the simulation of brown carbon (2017, methodology): “and the BC/OA ratio have been confirmed by field measurements (Wang et al., 2016; Gilardoni et al., 2016).”
- Bounding Global Aerosol Radiative Forcing of Climate Change (2020, background): “…scaling of models and the804 suitability of AERONET constraints, instead improving modelled BC by increasing the805 model horizontal resolution (X. Wang et al., 2014), reducing BC lifetime (Samset et al.,806 2014) to reduce overestimations of BC concentrations in remote areas (Kipling et al.,…”
- Deriving brown carbon from multiwavelength absorption measurements: method and application to AERONET and Aethalometer observations (2016, background): “Modeling studies estimate that BrC contributes 20 to 40 % of total carbonaceous aerosol absorption and that its absorption direct radiative effect (DRE) ranges from +0.1 to +0.6 Wm−2 (Feng et al., 2013; Lin et al., 2014; Wang et al., 2014; Saleh et al., 2015; Jo et al., 2016).”