Signatures of aerosol-cloud interactions in GiOcean: A coupled global reanalysis with two-moment cloud microphysics

Abstract. Aerosols in the atmosphere affect top of atmosphere radiation through direct interactions with radiation and by affecting cloud properties. Through aerosol-cloud interactions (ACI), and ensuing adjustments, anthropogenic aerosols have led to cooling during the industrial era. However, there is substantial uncertainty in our global models regarding the cooling driven by ACI. In part, global models are subject to substantial disagreement in terms of cloud properties, thermodynamic state, hydrological cycle, and general circulation. Reanalysis provides a useful avenue for exploring the impact of ACI on clouds and radiation because its atmosphere is nudged to observations of these quantities, but until now reanalyses have not included two-moment microphysics coupled to aerosols. Here, we explore the impact of ACI on clouds in the GiOcean reanalysis- the first to incorporate aerosol-cloud adjustments. We develop souce-sink models of ACI in GiOcean and contrast these to satellite observations and allow attribution of changes in cloud droplet number (Nd) and liquid water path (LWP) to aerosol and meteorology.