Black carbon concentrations and sources in the marine boundary layer of the tropical Atlantic Ocean using four methodologies

Abstract

Combustion-derived aerosols in the marine boundary layer have been poorly studied, especially in remote environments such as the open Atlantic Ocean. The tropical Atlantic has the potential to contain a high concentration of aerosols, such as black carbon, due to the African emission plume of biomass and agricultural burning products. Atmospheric particulate matter samples across the tropical Atlantic boundary layer were collected in the summer of 2010 during the southern hemispheric dry season when open fire events were frequent in Africa and South America. The highest black carbon concentrations were detected in the Caribbean Sea and within the African plume, with a regional average of 0.6 µg m −3 for both. The lowest average concentrations were measured off the coast of South America at 0.2 to 0.3 µg m −3 . Samples were quantified for black carbon using multiple methods to provide insights into the form and stability of the carbonaceous aerosols (i.e., thermally unstable organic carbon, soot like, and charcoal like). Soot-like aerosols composed up to 45 % of the carbonaceous aerosols in the Caribbean Sea to as little as 4 % within the African plume. Charcoal-like aerosols composed up to 29 % of the carbonaceous aerosols over the oligotrophic Sargasso Sea, suggesting that non-soot-like particles could be present in significant concentrations in remote environments. To better apportion concentrations and forms of black carbon, multiple detection methods should be used, particularly in regions impacted by biomass burning emissions. Peak concentrations of black carbon in the remote marine Published by Copernicus Publications on behalf of the European Geosciences Union.

Simulations of black carbon (BC) aerosol impact over Hindu Kush Himalayan sites: validation, sources, and implications on glacier runoff

“…Further, the impact of BC aerosols on the snowpack, surface radiation, and temperature changes over the HKH region based on simulations in global climate models suggest a considerable impact of anthropogenic forcing over the HKH region as compared to that over the Tibetan Plateau. However, the ability of coarse-gridded models to adequately simulate the snow depth and thereby the BC concentration in snow and atmospheric BC radiative forcing is limited (Menon et al, 2010;Ménégoz et al, 2014;Qian et al, 2015).…”

response to Review of acp-2018-869 (Anonymous Referee #2)

“…studies (e.g., Qian et al, 2015;Ménégoz et al, 2014;Matt et al, 2018). It is also, therefore, necessary to carry out a more detailed validation of model estimates for BC aerosols along with the meteorology with a widely distributed observations across the HKH sites.…”

Simulations of black carbon (BC) aerosol impact over Hindu-Kush Himalayan sites: validation, sources, and implications on glacier runoff

“…It is observed that while BC concentration and BC-AOD due to emissions from the IGP has a slightly higher value during pre-monsoon than winter, it is vice-versa for that due to emissions from AFWA. This feature is inferred likely due to emissions of biomass burning (crop-waste and forest fires) which is more prominent during pre-monsoon over the IGP but that during winter over AFWA as obtained from the information of firecounts data from satellite-based measurements (Pohl et al, 2014;Verma et al, 2014).…”