Higher order moments in the entrainment zone of turbulent penetrative thermal convection

In a simulation of the lifting of an atmospheric inversion layer in the laboratory, measurements have been made to understand the dynamics in the interfacial region capped by a stable, linearly stratified layer. Instantaneous values of vertical and horizontal components of velocity have been measured using a two-component dual-beam laser Doppler anemometer. Temperature fluctuations have been made simultaneously. Detailed measurements of all relevant horizontally averaged one-point moments including heat flux and third-order joint vertical velocity-temperature moments have been obtained. The negative heat flux region is well defined in the entrainment zone, and varies in thickness with different stable layer temperature gradients. The entrainment mechanism is probably most important only in the top part of the interfacial zone. The present data supplement data obtained in the atmosphere, and they compare favorably with the existing data in the literature.