Large-eddy and single-column model simulations of boundary-layer clouds over Southern Great Plains and the Azores

Description

Continental shallow cloud case studies are provided by the FAst-physics System TEstbed and Research (FASTER) project, using aircraft and ground-based measurements obtained doing the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) campaign over the Southern Great Plains (SGP) in 2009. The case studies that the FASTER project has selected are three multi-day periods populated by a variety of boundary-layer cloud types. A critical input for the model simulations is provided by aerosol size distributions obtained by the aircraft in situ. Other posters that describe these cases are provided by Vogelmann and co-workers and Endo and co-workers, and Lin and co-workers place these into climatological context.

Shallow maritime cloud case studies are based on observations obtained during the Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) field campaign, an ARM Mobile Facility deployment during 2009–2010 in the Azores. Our focus will be on the commonly observed drizzling marine boundary-layer clouds (Remillard et al. 2012). What the Azores cases lack in aircraft observations is made up for in a rich set of drizzle properties obtained through the W-band ARM cloud radar (WACR) retrievals of Kollias et al. 2011. The Azores case studies are placed into synoptic and climatological context in the Tselioudis et al. poster.

This poster focuses on the development and comparison of cases simulated by the large-eddy simulation code Distributed Hydrodynamic Aerosol and Radiative Modeling Application (DHARMA) and the single-column model version of the Goddard Institute for Space Studies (GISS) general circulation model (GCM). The DHARMA simulations use the bin microphysics code of Ackerman et al. (1995) and the dual-moment scheme of Morrison et al. (2009), while the single-column model (SCM) simulations use the traditional treatment of the GISS GCM (Schmidt et al. 2006) as well as the recent implementation of the dual-moment scheme of Morrison and Gettelman (2008).

Glaring deficiencies expected in the comparisons among the observations and the variety of model simulations will serve as a target for needed improvements in model physics, with an initial focus on reproducing basic cloud microphysics features when dynamics are subject to strong constraints.