Numerical Study on Impacts of Multi-Component Aerosols on Marine Cloud Microphysical Properties

Abstract

In this paper impacts of nss-sulfate, sea-salt and organic particles on microphysical properties of marine cloud are investigated, using a mutil-component size-resolving aerosol model. Numerical results show that the number and type of cloud condensation nuclei (CCN) depend on panicle physical and chemical properties (size distribution, chemical composition) of particles, and on environmental conditions (updrafts or supersaturation). Sea-salt particles play a critical role in cloud microphysical processes. Due to its large radius, sea-salt particles are activated into cloud drops in the initial cloud development. Sea-salt activation decreases supersaturation by consuming water vapor and suppresses nss-sulfate activation. Nss-sulfate indirect forcing may be overestimated in some conditions (such as updraft is low), because of the presence of sea-salt particles. Soluble organic components decrease maximum supersaturation, and lead to a decrease of cloud drops activated at the case of a high nss-sulfate and a high updraft velocity. Nss-sulfate CCN account for most variations of the cloud optical depth (COD). Sea-salt increases COD in the case of low nss-sulfate, but decreases COD when nss-sulfate concentration is high. The organic component enhances this influence of sea-salt on COD.