Development and validation of a new cloud simulation experiment for lab-based aerosol-cloud studies

Area of Science:

• Atmospheric Science
• Cloud Physics
• Aerosol Science

Background:

• The Aerosol Interaction and Dynamics in the Atmosphere (AIDA) chamber is a crucial facility for studying atmospheric processes.
• Understanding aerosol interactions is vital for accurate climate modeling and weather prediction.

Purpose of the Study:

• To introduce and validate the AIDA mini (AIDAm) chamber for automated, long-term ice nucleation measurements.
• To investigate the influence of chemical surface coating on the ice nucleation properties of mineral dust aerosols.

Main Methods:

• Utilized the AIDA mini (AIDAm) chamber, a 20 L extension of the AIDA facility, for automated measurements.
• Validated AIDAm's temperature control for homogeneous freezing of water and immersion freezing by dust aerosols.
• Conducted experiments at cirrus cloud temperatures to differentiate ice formation mechanisms on mineral dust and sulfuric acid particles.
• Monitored ice nucleation activity over 7 hours during slow sulfuric acid coating of dust particles with 6-minute resolution.

Main Results:

• AIDAm demonstrated accurate ice nucleation temperature control and the ability to distinguish between homogeneous and heterogeneous freezing.
• Experiments showed that sulfuric acid coating significantly suppressed heterogeneous ice formation on dust particles.
• A gradual increase in homogeneous freezing was observed as dust particles became coated.

Conclusions:

• The AIDAm chamber is a valuable tool for sensitive, long-term studies of aerosol ice nucleation.
• Chemical processing, such as surface coating, can substantially alter the ice nucleation behavior of aerosols.
• Findings contribute to a better understanding of cloud formation processes and aerosol-cloud interactions in the atmosphere.