Kazuyo Fukuda

BEHAVIORS OF SEA BREEZE ABOVE FUKUOKA CITY

Behaviors of sea breeze above Fukuoka City have been investigated on the basis of AMeDAS data and field observations. The land and sea breeze is influenced strongly by the topography near Fukuoka City and blows steady along the northwest-southeast line. Sea breeze observations performed by using a doppler sodar have revealed the existence of a coherent structure consisted of a pair of ascending and descending currents. The cross-correlation coefficients between horizontal andvertical velocities vary with 30 min period and take a value nearly equal to zero when the time lag is 0. Therefore, it is concluded that the coherent structuremay be due to the internal wave motion induced by the shear instability.

Turbulent Properties of an Atmospheric Boundary Layer in Day and in Night

A field observation was made to investigate turbulent characteristics in the lower region of an atmospheric boundary layer in day and in night. Horizontal and vertical wind speeds, and wind direction were measured by using a doppler sodar at 13 points in the range of 55m to 425m above the ground. Vertical profiles of the mean wind speeds, the Reynolds stress and the turbulent intensities were obtained from the measured data. The diurnal profiles were compared with the nocturnal ones. Their profiles show that the diurnal boundary layer had a strong convection caused by the solar-heating and the nocturnal layer was relatively stable. The Reynolds stress decreased linearly with height both in day and in night.