부산대학교 도서관

Tropospheric anthropogenic aerosols contribute the second-largest forcing to climate change, but with high uncertainty owing to their spatio-temporal variability and complicated optical properties. In this Review, we synthesize understanding of aerosol observations and their radiative and climate effects. Aerosols offset about one-third of the warming effect by anthropogenic greenhouse gases. Yet, in regions and seasons where the absorbing aerosol fraction is high — such as South America and East and South Asia — substantial atmospheric warming can occur. The internal mixing and the vertical distribution of aerosols, which alters both the direct effect and aerosol–cloud interactions, might further enhance this warming. Despite extensive research in aerosol–cloud interactions, there is still at least a 50% spread in total aerosol forcing estimates. This ongoing uncertainty is linked, in part, to the poor measurement of anthropogenic and natural aerosol absorption, as well as the little-understood effects of aerosols on clouds. Next-generation, space-borne, multi-angle polarization and active remote sensing, combined with in situ observations, offer opportunities to better constrain aerosol scattering, absorption and size distribution, thus, improving models to refine estimates of aerosol forcing and climate effects.
Atmospheric aerosols alter Earth’s radiation balance and serve as cloud condensation nuclei, but their climate forcing potential is poorly understood. This Review describes the occurrence of aerosols in the atmosphere, assesses the known impact on climate and proposes approaches to further constrain their climate effects.
Key points: Climate models indicate at least a 30% uncertainty in aerosol direct forcing and 100% uncertainty in indirect forcing due to aerosol–cloud interactions.The amount of aerosol light scattering and absorption, expressed as the aerosol single-scattering albedo parameter, is critical in affecting both aerosol radiation interaction and aerosol–cloud interactions.Current satellite sensors cannot provide global-scale 3D single-scattering albedo measurements. Future observational efforts should combine satellite-based, multi-angle polarization sensors and high-spectral-resolution lidars with international aircraft and surface in situ observation networks.Direct comparison of radiation properties observed by satellites with those derived from climate models that assimilate aerosol parameters will improve the understanding of aerosol microphysical properties.Future work should investigate the mechanisms underlying aerosol–cloud interactions, especially the adjustment of cloud fraction and water for warm clouds and the microphysical processes in ice and mixed-phase clouds.