How do aerosols above the residual layer affect the planetary boundary layer height?

Area of Science:

• Atmospheric Science
• Earth System Science
• Environmental Science

Background:

• Aerosols significantly influence the Earth's atmosphere, particularly the planetary boundary layer (PBL).
• Previous research identified absorption and scattering aerosols' effects on PBL development, but their roles at higher altitudes remain underexplored.
• Understanding aerosol-PBL interactions is crucial for climate modeling and air quality predictions.

Purpose of the Study:

• To investigate the impact of absorption and scattering aerosols at various altitudes on PBL development.
• To define the 'dome effective height' for absorption aerosols and its relationship with surface heat flux.
• To compare the inhibitory effects of absorption and scattering aerosols on PBL evolution.

Main Methods:

• Utilized a large-eddy simulation model.
• Constrained simulations with in-situ observations from urban Beijing.
• Analyzed aerosol effects from the morning residual layer (MRL) to the upper atmosphere.

Main Results:

• Absorption aerosols exhibit a 'virtual dome effect' inhibiting PBL development, which weakens with increasing altitude up to a 'dome effective height'.
• Scattering aerosols cause a less significant 'aloft umbrella effect' irrespective of their vertical position.
• The 'virtual dome effect' and 'aloft umbrella effect' are dominant during severe pollution events like sandstorms and volcanic eruptions.

Conclusions:

• Aerosol vertical distribution and type critically determine PBL development.
• The study advances understanding of aerosol-PBL interactions, with implications for diverse environments, including exoplanet atmospheres.
• Findings contribute to improved climate and air quality models by accounting for complex aerosol effects.