The evolution of the global aerosol system in a transient climate simulation from 1860 to 2100

[摘要] The evolution of the global aerosol system from 1860 to 2100 is investigatedthrough a transient atmosphere-ocean General Circulation Model climatesimulation with interactively coupled atmospheric aerosol and oceanicbiogeochemistry modules. The microphysical aerosol module HAM incorporatesthe major global aerosol cycles with prognostic treatment of theircomposition, size distribution, and mixing state. Based on an SRES A1Bemission scenario, the global mean sulfate burden is projected to peak in2020 while black carbon and particulate organic matter show a lagged peakaround 2070. From present day to future conditions the anthropogenic aerosolburden shifts generally from the northern high-latitudes to the developinglow-latitude source regions with impacts on regional climate. Atmosphericresidence- and aging-times show significant alterations under varyingclimatic and pollution conditions. Concurrently, the aerosol mixing statechanges with an increasing aerosol mass fraction residing in the internallymixed accumulation mode. The associated increase in black carbon causes amore than threefold increase of its co-single scattering albedo from 1860 to2100. Mid-visible aerosol optical depth increases from pre-industrial times,predominantly from the aerosol fine fraction, peaks at 0.26 around thesulfate peak in 2020 and maintains a high level thereafter, due to thecontinuing increase in carbonaceous aerosols. The global mean anthropogenictop of the atmosphere clear-sky short-wave direct aerosol radiativeperturbation intensifies to −1.1 W m⁻² around 2020 and weakensafter 2050 to −0.6 W m⁻², owing to an increase in atmosphericabsorption. The demonstrated modifications in the aerosol residence- andaging-times, the microphysical state, and radiative properties challengesimplistic approaches to estimate the aerosol radiative effects from emissionprojections.

[学科分类] 大气科学