Global nitrate aerosol: Production from lightning, and impact on atmospheric composition and radiative forcing
Ashok Luhar
Ashok Luhar*, Anthony Jones**, Jonathan Wilkinson**
*CSIRO Environment, Aspendale, Victoria 3195, Australia
**Met Office, Fitzroy Road, Exeter, EX1 3PB, UK
Aerosols and their impact on cloud properties continue to be the largest source of uncertainty in the anthropogenic forcing of the climate system. Nitrate aerosol, predominantly a secondary inorganic aerosol, is often omitted in global chemistry-climate models, partly due to the chemical complexity of its formation process. Nitrate aerosol is expected to become more important in the future atmosphere due to the continued increase in nitrate precursor emissions and the decline in sulphur dioxide due to stricter emissions regulations. This work addresses two key questions: 1) how does including nitrate aerosol affect atmospheric properties, and 2) how do these effects depend on lightning-generated oxides of nitrogen which are a precursor of the nitrate aerosol? Using a recent version of the Met Office’s Unified Model–UK Chemistry and Aerosol (UM-UKCA) global chemistry-climate model (UM is the atmospheric component of ACCESS), we show that including nitrate aerosol significantly impacts tropospheric composition fields, such as ozone, and radiation. Additionally, lightning-generated oxides of nitrogen influence both nitrate aerosol mass concentrations and aerosol size distribution, which has important implications for radiative fluxes and indirect aerosol effects in climate modelling studies.
Keywords: Climate chemistry, nitrate aerosol, lightning, oxides of nitrogen, radiative forcing, atmospheric composition
Please use this thread for discussion about this talk.