Impacts of future anthropogenic aerosol reductions on the tropical precipitation

The impacts of historical aerosol forcing on the tropical climate systems have been well examined, while the relevant influences of expected future reductions of aerosols remain insufficiently explored. This study investigates the impacts of projected anthropogenic aerosol reductions on the tropical precipitation, and the underlying mechanisms based on the atmospheric energetic framework. Anthropogenic aerosol reductions can be divided into two periods: during the first half of the 21st century (2021-2051), emissions are projected to decrease in Europe, North America, and East Asia but continue to rise over South Asia; during the latter half (2070-2100), reductions occur mainly over Asia. During the first period, it shows a pronounced interhemispheric asymmetry in annual-mean tropical precipitation with increase north of the equator and decrease south of the equator, while during the second period precipitation mainly increases over East and South Asia. The differences in the annual-mean spatial pattern of tropical precipitation during the two periods correspond closely to changes in the distribution of atmospheric energy. Future anthropogenic aerosol reductions also exert influence on the annual cycle of tropical precipitation. In both periods, the amplitude of precipitation annual cycle increases, although greenhouse gases remain the dominant driver. During the first period, the phase of the tropical precipitation annual cycle is delayed, mainly associated with the intensification in inter-seasonal difference in cross-equatorial atmospheric energy transport, whereas during the second period, it shows little change with large intermodel uncertainty. These findings provide valuable insights into the role of future anthropogenic aerosol reductions in climate projections.