Coastal Urban Boundary-layer Interactions with Convection (CUBIC)

Abstract

The TRacking Aerosol Convection interactions ExpeRiment, or TRACER, is aimed at increasing the understanding of convective cloud lifecycles and interactions between aerosol and convection. To accomplish these goals, it is necessary to collect comprehensive observation data sets documenting the environment in the lowest layer of the atmosphere, or the boundary layer, where clouds initiate, grow, and decay. Our proposal addresses this need for high-resolution boundary-layer observations in the larger Houston area by deploying three boundary-layer profiling systems. These systems are capable of observing boundary-layer characteristics and evolution by collecting high-resolution vertical profiles of temperature, humidity, wind components, turbulence parameters, and aerosol backscatter every few minutes. These observations can help TRACER-associated researchers accomplish their goals, and allow us to address specific research questions about boundary-layer processes, coastal environments, sea-breezes, and convective initiation.

We hypothesize that the interactions between sea breezes and urban circulations induced by the Houston metropolitan area affect the structure and evolution of the boundary layer. We thus aim to understand these interactions, their impacts on boundary-layer structure and associated flow patterns. This understanding is critical for investigating the processes that lead to convection initiation. By collecting high-resolution boundary layer profiles in partnership with additional instruments deployed in TRACER, we will explore these five research questions:

–  What are the characteristics of the sea-breeze circulation, and how does it impact the diurnal evolution of the boundary layer?
–  What are the characteristics of the urban boundary layer in the Houston area, and how does urban-induced circulation affect pre-convection environments?
–  How do sea-breezes and urban boundary-layer processes influence aerosol transport and mixing in the atmosphere?
–  How is convective initiation impacted by environmental modifications associated with sea-breezes, urban boundary layers, and aerosol?
–  Can the representation of multi-scale boundary-layer processes in Earth system models be improved by leveraging our observations?

The boundary-layer profiling systems will be deployed for four months, operating continuously. Additionally, high-resolution, multi-scale numerical simulations will be conducted for select cases. Utilization of these observations and simulations in tandem will provide a robust data set for improving the understanding of, and ability to represent, critical boundary-layer processes in coastal urban environments.