Influence of coherent structure on turbulence characteristics of 0814 strong typhoon Hagupit

Abstract

In order to explore the formation mechanism of the nonstationary wind speed in the eye wall regions and eye region of a typhoon, taking the measured data of No.0814 strong typhoon Hagupit as the research object, we identify and extract the coherent structure of the measured wind field by discrete wavelet transform combined with hypothesis testing, and analyze the influence of the coherent structure on the nonstationary and non-Gaussian wind speed and study the influence of the coherent structure on the wind turbulence characteristics. The results show that for the 0814 typhoon Hagupit process, the coherent structure is the main reason that leads to the nonstationary and non-Gaussian fluctuating winds in the typhoon field, and with the coherent structures being exacted from the original winds, the nonstationary and non-Gaussian characteristics of the nonstationary wind samples are significantly weakened. The average contribution of the coherent structure to the turbulence parameters ranges from 6.42% to 32.40%. The duration of the coherent structure is about 10.60% of the sample duration, however, its contribution to turbulent kinetic energy is up to 40.50%. The coherent structure has the characteristics of short duration and high energy content, which is the cause of the abnormally large turbulence parameter value. This study can provide a reference for the refined wind resistance design of structures under the action of nonstationary wind.