The effect of continental aerosols on cloud-rain transition processes in winter based on aircraft observations

Abstract

To comprehend how continental aerosols influence the cloud-to-rain transition process, we deployed a series of airborne observation devices combined with a single-particle aerosol sampler to conduct aircraft-based cloud penetration observations. Our study yielded patterns of cloud droplet growth and the effective radius of cloud droplets. We conducted an in-depth analysis of the condensation and collision-coalescence of cloud droplets impacting aerosol particle size. Employing a fitting approach, we modeled the concentration of cloud droplets as a function of cloud droplet spectral dispersion under the influence of continental aerosols. Subsequently, we elucidated the physicochemical properties of continental aerosols at high altitudes and assessed the indirect radiative forcing of aerosols based on their dispersion degrees. These findings reveal that cloud droplets in the cloud underwent successive processes of condensation, collision-coalescence, and evaporation, resulting in a concomitant increase in the sizes of corresponding aerosols. The dispersion of cloud droplet spectra decreased with an increased concentration of cloud droplet numbers. This trend is associated with the impact of dispersion on the indirect radiative forcing of aerosols. We found that an 11 % increase in the indirect radiative forcing of aerosols was attributable to the dispersion effect. This underscores the complex interplay among aerosol characteristics, cloud microphysics, and radiative forcing, providing valuable insights into the mechanisms of the cloud-to-rain transition process under the influence of continental aerosols.