Meetings > PI / Science Team Meeting > Posters

1. RACORO-FASTER: case study generation

 
Poster PDF

Authors

Andrew M. Vogelmann — Brookhaven National Laboratory
Ann M. Fridlind — NASA - Goddard Institute for Space Studies
Satoshi Endo — Brookhaven National Laboratory
Wuyin Lin — Brookhaven National Laboratory
Tami Fairless — Pacific Northwest National Laboratory
Yangang Liu — Brookhaven National Laboratory

Category

Modeling

Description

As part of the FAst-physics System TEstbed and Research (FASTER) project, a series of case studies are being constructed to assess and improve model representation of continental boundary-layer clouds (stratus, stratocumulus, cumulus) using aircraft data from the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign and ARM ground-based remote sensing observations. Three 60-hour case study periods are selected that capture the temporal evolution of cumulus, stratiform, and drizzling boundary-layer cloud systems under a range of conditions, intentionally including those that are relatively more mixed or transitional in nature versus being of a purely canonical type. In each case study, boundary-layer systems are simulated from sunrise on day one to sunset on day three. Collectively, the case studies include: daytime stratus, stratocumulus, and cumulus formation and breakup under varying aerosol conditions; strong and weak nocturnal jets; and nighttime stratus formation and deepening within a residual layer. The aircraft data include aerosol number size distributions, which have been fit to lognormal modes for concise representation in models with two-moment microphysics. The case studies are being developed to run side-by-side using large eddy simulation (LES) models (see Endo et al.) and single-column models (see Lin et al.). The goal is to provide a diverse set of observationally constrained cases of cloudy boundary-layer evolution for use by FASTER and the general modeling communities to improve our understanding of continental cloudy boundary layers, aerosol influences upon them, and their representation in cloud-scale and global-scale models (see Ackerman et al.). These continental case studies offer an important complement to previous case studies, which mainly focus on marine boundary-layer clouds. Additional unique features of these cases are: they address the temporal evolution of different/mixed cloud types (versus the steady state of canonical types); they include observed profiles of aerosol size distributions and cloud condensation nuclei; and they include a wide range of observed aerosol loadings. Overall, the periods sample a wide range of cloudy boundary-layer conditions, but all case studies use a modular specification, which makes it easy for modelers to run them all.