Microphysical effects determine macrophysical response for aerosol impacts on deep convective clouds

Area of Science:

• Atmospheric Science
• Climate Science
• Cloud Physics

Background:

• Deep convective clouds (DCCs) are vital to Earth's climate system, influencing circulation, energy, and water cycles.
• Aerosol particles are known to affect DCCs, but their influence across the entire cloud life cycle remains incompletely understood.

Purpose of the Study:

• To comprehensively investigate the impact of aerosols on the full life cycle of deep convective clouds.
• To differentiate between thermodynamic and microphysical effects of aerosols on DCC properties and radiative forcing.

Main Methods:

• Utilized monthlong cloud-resolving simulations with spectral-bin cloud microphysics.
• Modeled summer convective clouds and precipitation in tropical and midlatitude regions.
• Validated modeling findings with extensive field measurements from diverse environments.

Main Results:

• Aerosols significantly increase DCC cover, cloud top height, and thickness, particularly in mature and dissipation stages.
• Microphysical effects, inducing more numerous, smaller, longer-lasting ice particles, are key drivers, surpassing thermodynamic invigoration.
• The overall aerosol indirect effect results in atmospheric radiative warming (3-5 W m⁻²) and surface cooling (-5 to -8 W m⁻²).

Conclusions:

• Aerosol-induced microphysical changes are dominant in shaping DCC evolution and radiative impacts.
• The study refines understanding of aerosol-cloud interactions beyond the commonly emphasized thermodynamic invigoration.
• Findings highlight the complex role of aerosols in climate regulation, confirmed by observational data.