Abstract. High spatial resolution measurements of temperature and liquid water content, accompanied by moderateresolution measurements of humidity and turbulence, collected during the Physics of Stratocumulus Top experiment are analyzed. Two thermodynamically, meteorologically and even optically different cases are investigated. An algorithmic division of the cloud-top region into layers is proposed. Analysis of dynamic stability across these layers leads to the conclusion that the inversion capping the cloud and the cloud-top region is turbulent due to the wind shear, which is strong enough to overcome the high static stability of the inversion. The thickness of this mixing layer adapts to wind and temperature jumps such that the gradient Richardson number stays close to its critical value. Turbulent mixing governs transport across the inversion, but the consequences of this mixing depend on the thermodynamic properties of cloud top and free troposphere. The effects of buoyancy sorting of the mixed parcels in the cloud-top region are different in conditions that permit or prevent cloud-top entrainment instability. Removal of negatively buoyant air from the cloud top is observed in the first case, while buildup of the diluted cloud-top layer is observed in the second one.

A layer of intensive mixing (entrainment interface layer, [EIL]) at the top of marine stratocumulus under a strong inversion has been investigated with 10 cm resolution using an ultrafast thermometer (UFT-F; temperature), a particle volume monitor PVM-100A (liquid water content), and a fast forward scattering spectrometer probe (FFSSP; droplet spectra). Measurements were collected on board the NCAR C-130 aircraft during research flight RF05 of DYCOMS-II field study. The EIL consists of mutual filaments of cloudy and clear air at different stages of stirring, mixing, and homogenization. Borders between these filaments are often very sharp, with the 10 cm resolution of the instruments being insufficient to characterize them properly in many cases. Certain classifications of these filaments and hypotheses about the mechanisms of their formation have been proposed. The common occurrence of filaments of sizes smaller than the resolution of instruments has been indirectly confirmed. This is in agreement with the observed cloud droplet spectra showing variations of droplet number concentration without significant change of the mean droplet diameter and spectrum width.

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