Physics of Stratocumulus Top: turbulence at a cloud top and inside a capping inversion

Entrainment of free tropospheric air into a stratocumulus-topped boundary layer (STBL) occurs across a shallow capping inversion of high static stability. Understanding of this process requires detailed information on turbulence inside the cloud top and just above it. Here we extend our experimental characterization of turbulence by applying the bulk Richardson number in physically different layers of the cloud top region: the free troposphere; the entrainment interfacial layer, which consists of the turbulent-inversion and cloud-top mixing sublayers; and the cloud-top layer (Malinowski et al., 2013) on more cases observed during the Physics of Stratocumulus Top (POST) research campaign (Gerber et al., 2013). Using high-resolution (~1.5 m) data of turbulent velocity fluctuations we perform additional characterization of turbulence, and estimation of turbulent kinetic energy dissipation rates and anisotropy of turbulence in the sublayers. We show considerable differences in properties of turbulence in these layers related to various damping by static stability and by the production of windshear. Results allow us to present a description of turbulent-eddy properties responsible for the entrainment-mixing process.

References:

Gerber, H., Frick, G., Malinowski, S. P., Jonsson, H., Khelif, D., Krueger, S. K., 2013: Entrainment rates and microphysics in POST stratocumulus, J. Geophys. Res.-Atmos., 118, 12094–12109, doi:10.1002/jgrd.50878, 2013

Malinowski, S. P., Gerber, H., Jen-La Plante, I., Kopec, M. K., Kumala, W., Nurowska, K., Chuang, P. Y., Khelif, D., and Haman, K. E., 2013: Physics of Stratocumulus Top (POST): turbulent mixing across capping inversion, Atmos. Chem. Phys., 13, 12171-12186, doi:10.5194/acp-13-12171-2013