Photothermal Single Particle Interferometry of Absorbing Aerosols
Radiative forcing is a measure employed by the Intergovernmental Panel of Climate Change (IPCC) to quantify the influence of an external perturbation on the energy balance of the Earth’s climate system. For many anthropogenic airborne aerosols, radiative forcing is still not known with the required precision, as stated in the recently published sixth assessment report of the IPCC. This uncertainty directly affects the prediction capabilities of global climate models, as forcing potentials are crucial input parameters. The importance of accurate knowledge of the radiative forcing of aerosol particles became recently apparent with the implementation of more stringent regulations by the International Maritime Organization (IMO) on sulfur content in marine fuel. The substantial decrease of sulfate emissions caused a significant decrease in cloud cover, yielding significant warming over popular shipping tracks, which could even be linked to the unprecedented high sea surface temperatures 2023. Similar effects are expected with changes in the emission number of strongly absorbing aerosol species such as black carbon (BC) or organic carbon (OC). As for sulfates, they are subject to significant uncertainties in radiative forcing, as dedicated studies under controlled experimental conditions are lacking.
