Field Observations of Threshold Wind Friction Velocity for Sand Transport

Abstract

This study conducted field observations in terms of the number of blown sand particles and wind velocity in the period of 12-16 Jan 2005 at an open ocean beach in Japan, in order to investigate effects of climate change on the threshold wind friction velocity of blown sand. The data of blown sand number and wind velocity were logged at a frequency of 1Hz and then divided into 5-minute segments to estimate the threshold wind velocity using Time Fraction Equivalence Method (TFEM). Time-series of the threshold wind velocity (estimated using the TFEM) demonstrated that the threshold corresponded with the value estimated using the Bagnold equation and increased notably during rainfall. The threshold decreased as the mean wind velocity increased.