Coupling of Marine Boundary Layer Clouds to the Surface and Relationships with Aerosol Properties from ACTIVATE
Presenter: Kayla McCauley1
Co-Author(s): Andrew Ackerman, Gao Chen, Andrea F. Corral, Ewan Crosbie, Glenn S. Diskin, Simon Kirschler, David Painemal, Michael Shook, K. Lee Thornhill, Christiane Voigt, Hailong Wang, Luke D. Ziemba, Paquita Zuidema
Advisor(s): Dr. Armin Sorooshian
1Department of Hydrology and Atmospheric Sciences, University of Arizona
Quantifying the degree of turbulent coupling of the atmospheric boundary layer is critical for understanding the evolution of low clouds and explaining the vertical distribution of aerosols. In this study, the methodology of previous studies investigating the extent of coupling for marine stratocumulus clouds through vertical profiles of temperature and moisture is revisited using aircraft data from the NASA Aerosol Cloud meTeorology Interactions oVer western ATlantic Experiment (ACTIVATE). The ACTIVATE campaign employs two aircraft that are spatially coordinated over the northwest Atlantic, with the low-flying plane (HU-25 Falcon) capturing data along level legs, including a leg close to the ocean surface (~150 m above sea level; called MinAlt) and a leg immediately below cloud base (BCB). Past studies have relied on the differences in total water mixing ratio (qt) and liquid water potential temperature (θℓ) between the Lifting Condensation Level (LCL) and the mean cloud base height for assessing the boundary layer coupling. The goal of this study is to determine the applicability of previous methodology to the ACTIVATE dataset and to evaluate the extent of coupling based on seasonality since the flights covered winter and summer deployments between 2020 and 2022. In addition, this work characterizes vertical profiles of aerosol properties and concentrations of cloud water species for validation of the different extents of coupling. Analysis shows that (i) MinAlt and BCB data accurately represent the LCL and cloud base levels, respectively, and (ii) thresholds of qt and θℓ used in previous studies to select coupling cases provide a relatively accurate estimate for the Northwest Atlantic and can be confirmed through cloud water species concentrations with weaker confirmation from aerosol properties.