HR: 1340h
AN: P13B-0155    [Abstracts]
TI: Variation in Threshold Wind Velocity of Blown Sand on a Beach
AU: * Udo, K
EM: udo@pari.go.jp
AF: Port and Airport Research Institute, 3-1-1 Nagase, Yokosuka, 239-0826 Japan
AB: Field experiments at Hasaki Beach in Japan investigated the wind-driven sand transport and wind velocity, and revealed the effect of increase in the mean wind velocity on the threshold wind velocity of blown sand. Data included observations of the number of blown sand particles and wind velocity recorded over a period of several months. The blown sand number was measured with a piezoelectric sensor at 100 kHz response rate. The wind velocity was measured with a three-axis ultrasonic anemometer. Data were logged at a frequency of 1 Hz and then divided into 5-minute segments. The threshold wind velocity for each segment was calculated using the time fraction equivalence method (TFEM) of Stout and Zobeck (1997). The results from the TFEM show that the threshold wind velocity during low to moderate wind speeds decreases independently of the wind angle as the mean wind velocity increases. The threshold is most likely influenced by beach morphology, bed elevation change through the experiments, and sand moisture; however, the decrease in the threshold is generally obtained.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 1815 Erosion
DE: 1824 Geomorphology: general (1625)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
SC: Planetary Sciences [P]
MN: Fall Meeting 2005