Helicopter observations of the sea breeze over a coastal area

Thermodynamical observations by a helicopter have been conducted to study t he internal structure of the sea breeze blowing inland from Tosa Bay during three periods (September 1993, November 1994 and 1995). Inland-intrusion d istances of the midday sea breeze observed at each flight leg were in the 1 0-25-km range, depending on the intensity of the ambient flow associated wi th the gradient wind, atmospheric stratification, and the geographical feat ures of the observed area. The sea breeze observed over the sea had well-defined features, in particul ar a turbulent wake behind the head of the sea-breeze front and a closed se a-breeze circulation cell containing the subsidence of the return Row. In a ddition, a moist layer distributed around 15-20 km offshore forms because t he land breeze moves in this region. Moreover, a calm condition exists from the coast to about 10 km offshore. Both phenomena are found before the ons et of the sea breeze in the early morning. Such remarkable characteristics of the sea breeze are found over the sea, with a background of land-sea con figuration that consists of a flat plain with small mountains and a bay ope ned out to sea.