We analyzed the variations in the mean wind field, turbulence, and
turbulent flux at the landfall sites of three typhoons using
observational data obtained from an offshore monitoring platform. These
variations were different for onshore and offshore winds. The turbulent
fluctuation intensity and friction velocity increased with wind speed
both before and after landfall. However, the turbulent flow decreased
with increasing wind speed during landfall. The relationships between
the friction velocity and drag coefficient and the wind speed were
affected by whether the typhoon makes landfall, and the relative
position of the landfall site of the typhoon and the observation site.