Assessing the impact of self‐lofting on increasing the altitude of black carbon in a global climate model

• Main Authors: Johnson, BT, Haywood, JM
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) / Wiley 2023
• Subjects: Arctic; black carbon
• Online Access: http://hdl.handle.net/10871/132995; https://doi.org/10.1029/2022jd038039

This is the final version. Available from the American Geophysical Union via the DOI in this record Data Availability Statement: All simulation data used in this study were created by the UK Earth System Model (UKESM1), a configuration of the Met Office Unified Model (UM). The UK Earth System model is documented in Sellar et al. (2019). The model outputs and software programs used in this study are accessible via the zenodo repository https://doi.org/10.5281/zenodo.7152687. Due to intellectual property right restrictions, we cannot provide the source code or documentation papers for the UM. The Met Office Unified Model is available for use under licence. A number of research organizations and national meteorological services use the UM in collaboration with the Met Office to undertake basic atmospheric process research, produce forecasts, develop the UM code, and build and evaluate Earth system models. For further information on how to apply for a licence, see http://www.metoffice.gov.uk/research/modelling-systems/unified-model. Black carbon (BC) absorbs solar radiation, increasing the buoyancy and vertical ascent of absorbing aerosol in the atmosphere. This self-lofting process has been observed for individual plumes in the troposphere and lower stratosphere but here we show it occurring at broader scales through enhanced large-scale ascent over BC-rich regions. This is demonstrated in a pair of simulation using the UKESM1 Earth-System model where BC aerosols were modeled either with or without the ability to absorb radiation. With absorption included the annual global mean concentration of BC in the upper troposphere and lower stratosphere (8–22 km) rose by up to 50% and the column loading over some remote oceanic regions more than doubled. The increase in aerosol height was particularly notable over the southeast Atlantic where biomass burning aerosol from Africa was elevated up to 1 km higher when their absorption was included. Similar effects were seen over the Arctic where the absorbing haze was ...