Abstract
Aircraft observations of a cloud-topped boundary layer were performed during cold air outbreaks in the "water extended cloud experiment" of the "Western North-Pacific Cloud-Radiation Experiment". A three-dimensional sonic anemometer was used to measure the three components of wind velocity relative to the aircraft. The turbulent heat flux due to convection in the sub-cloud layer decreased with height, and the buoyancy flux became negative in the upper part of the sub-cloud layer. It is suggested that the motions in the upper part of the sub-cloud layer are maintained by convection in the cloud layer.
