Influence of aerosol and meteorological variables on clouds in the summer monsoon and premonsoon season over India

This study emphasizes over the influence of aerosol and meteorology (relative humidity (RH) and vertical velocity (ω)) on cloud properties in the summer monsoon (June-Sept) and premonsoon (March-May) season by using traditional statistical method, followed by geographical detector method (GDM), an alternative statistical approach. Results reveal, in the summer monsoon season, strong influence of meteorology on cloud fraction diminish the effect of aerosol, while the meteorology aids to the influence of aerosol on cloud fraction in the premonsoon season. The interplay between aerosol and meteorology leads to non-linear change in the cloud top height in the summer monsoon season, while in the premonsoon season, it leads to formation of taller clouds in higher aerosol environment due to shallow convection. Both aerosol and meteorology have weak influence on cloud particle radius, however, high RH and strong updraft (negative ω) leads to formation of bigger cloud droplet radius in the summer monsoon season. The GDM is used to determine the relative importance of the effects of aerosol and meteorology and the effects of interaction between aerosol and meteorology on the cloud properties. The interaction between aerosol and meteorology have more effect on the cloud properties unless their interaction weakens each other’s effect. Furthermore, the prevailing meteorology in the season can restrain the influence of aerosol on cloud properties. The work provides valuable insight of the association between aerosol and cloud properties at seasonal time-scale and the influence of meteorological covariations on this relationship and improve the understanding of the aerosol-cloud interaction.