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Black carbon aerosols over Indian Ocean have unique source fingerprint and optical characteristics during monsoon season.

Krishnakant BudhavantAugust AnderssonH HolmstrandS K SatheeshÖrjan Gustafsson
Published in: Proceedings of the National Academy of Sciences of the United States of America (2023)
Effects of aerosols such as black carbon (BC) on climate and buildup of the monsoon over the Indian Ocean are insufficiently quantified. Uncertain contributions from various natural and anthropogenic sources impede our understanding. Here, we use observations over 5 y of BC and its isotopes at a remote island observatory in northern Indian Ocean to constrain loadings and sources during little-studied monsoon season. Carbon-14 data show a highly variable yet largely fossil (65 ± 15%) source mixture. Combining carbon-14 with carbon-13 reveals the impact of African savanna burning, which occasionally approach 50% (48 ± 9%) of the total BC loadings. The BC mass-absorption cross-section for this regime is 7.6 ± 2.6 m 2 /g, with higher values during savanna fire input. Taken together, the combustion sources, longevity, and optical properties of BC aerosols over summertime Indian Ocean are different than the more-studied winter aerosol, with implications for chemical transport and climate model simulations of the Indian monsoon.
Keyphrases
  • drinking water
  • water soluble
  • climate change
  • molecular dynamics
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  • electronic health record
  • deep learning
  • heavy metals
  • artificial intelligence