Impacts of an aerosol layer on a midlatitude continental system of cumulus clouds: how do these impacts depend on the vertical location of the aerosol layer?

Abstract

Effects of an aerosol layer on warm cumulus clouds in the Korean Peninsulawhen the layer is above or around the cloud tops in the free atmosphere arecompared to effects when the layer is around or below the cloud basesin the planetary boundary layer (PBL). For this comparison, simulations areperformed using the large-eddy simulation framework. When the aerosol layeris in the PBL, aerosols absorb solar radiation and radiatively heat up airenough to induce greater instability, stronger updrafts and more cloud massthan when the layer is in the free atmosphere. Hence, there is a variationof cloud mass with the location (or altitude) of the aerosol layer. It isfound that this variation of cloud mass is reduced as aerosol concentrations in the layer decrease or aerosol impacts on radiation are absent. The transportation of aerosols by updrafts reduces aerosol concentrations in the PBL. This in turn reduces the aerosol radiative heating, updraft intensity and cloud mass.