Abstract
Airborne measurements within an internal boundary layer were carried out above a coastal region. Here, the free convective internal boundary layer, IBLt, which develops along with the sea breeze is analyzed. Data are classified into several groups considering the horizontal and vertical variations of the potential temperature. When the airplane travels from the stable marine atmosphere into the IBLt, vigorous turbulence is measured earlier than potential temperature begins to increase. The IBLt determined from the turbulence level is about one and a half times higher than the IBLt determined from the temperature. Humidity begins to increase when vigorous turbulence takes place. This seems to be due to the entrainment effect of thermal plumes into the upper marine stable atmosphere. The lapse rate of the marine atmosphere plays an important role in determing the height of the IBLt and potential temperature increase within the layer.
