Coupled and decoupled stratocumulus-topped boundary layers: turbulence properties

Abstract. We compare turbulence properties in coupled and decoupled marine stratocumulus-topped boundary layers (STBLs) using high-resolution situ measurements performed by the helicopter-borne Airborne Cloud Turbulence Observation System (ACTOS) platform region of eastern North Atlantic. The thermodynamically well-mixed STBL was characterized a comparable latent heat flux at surface cloud-top region, substantially smaller sensible entire depth. kinetic energy (TKE) efficiently generated buoyancy cloud surface, dissipated with rate across Structure functions power spectra velocity fluctuations inertial range were reasonably consistent predictions Kolmogorov theory. close to isotropic. In STBL, decoupling most obvious humidity profiles. Heat fluxes buoyant TKE production similar case. Around transition level, decreased zero consumed weak stability. almost vanished significantly than for dissipation inside varied between its sublayers. deviated from scaling. This more pronounced subcloud layer comparison mixed layer. anisotropic horizontal dominating. degree anisotropy largest STBL. Integral length scales, order 100 m both cases, indicate turbulent eddies depth or sublayers hypothesize that produced is redistributed but rather only where it case Scattered cumulus convection, developed below stratocumulus base, may play role transport those