飓风古斯塔夫(2008)过境过程风特性研究

Wind characteristics of hurricane Gustavo (2008) in the process of making landing

对飓风Gustavo(2008)登陆美国路易斯安那州的全过程进行了风雨特性实测,共获得高度分别为2.5m、4m、5m、7m、10m处约48h的风速、风向、气压、温度、湿度、雨量数据,将采样数据划分为飓风过境前期、中期、后期三个典型区间;从时域角度分析了10min子样本的阵风因子、紊流强度、紊流积分尺度、相关性、分布特性,从频域角度对各子样本水平相脉动风谱进行了拟合平均;从时频域角度对三个典型区间的Hilbert时频谱进行计算和观测。研究发现:阵风因子和紊流强度在飓风过境之前大于飓风过境之后,紊流积分尺度反之,阵风因子均值为1.67,阵风因子随紊流度的增大呈指数率增长;风速概率密度函数服从高斯分布,水平向脉动风谱的拟合平均值呈现低频偏高和高频偏低于规范风谱的现象;三个典型区间内的脉动风时频谱曲线显示,飓风过境前后的脉动风均为非线性和非平稳过程。

Wind characteristics of hurricane Gustavo （2008） in the whole process of making landing on Louisiana State of USA is observed and analyzed, including wind speed, wind pressure, temperature, air moisture, rainfall, etc, on the height of 2.5m, 4m, 5m, 7m, 10m. Then, observation data are divided into three stages： pre-hurricane, in-hurricane and post-hurricane. Thereafter, gust factor, turbulence intensity, integral scale, correlation function, and probability distribution function are obtained in time domain on 10min samples. Power spectrum of wind speed in horizontal direction is fitted and averaged in frequency do- main. The calculation and observation of HHT spectrum for wind speed on the height of 10m are conducted in time and frequency hybrid domain. Research shows that： Gust factors and turbulence intensities tend to be larger during the pre-hurricane period, while the integral scale shows opposite trend; the averaged values of gust factor is 1. 67; Gust factor increases exponentially with turbulence intensity; The probability density function of fluctuating wind speed of Gustavo （2008） follows a Gaussian distribution; The averaged power spectrum for wind speed in horizontal direction is higher in low-frequency region and lower in high-frequency region compared with the current power spectrums; The fluctuating wind speed for hurricane is shown to be a nonlinearity and instability stochastic process.