西北太平洋船载海面风速脉动资料校正及湍流特征分析*
收稿日期: 2012-02-27
修回日期: 2012-06-07
网络出版日期: 2013-08-28
Correction of ship-based turbulent wind velocity and characterization of turbulence in the Northwest Pacific
Received date: 2012-02-27
Revised date: 2012-06-07
Online published: 2013-08-28
对西北太平洋海域2005年9—11月“东方红Ⅱ”船载风速脉动资料的功率谱分析发现, 在频率区间0.06—0.26Hz普遍存在一个由于船体晃动而产生的异常峰值, 本文提出了一种消除船体晃动干扰的滤波校正改进方法。校正方法数据处理步骤如下：在双对数坐标系下, 利用受干扰频率区间前后的功率谱密度值, 线性拟合得到该区间内的功率谱趋势线；然后利用原始功率谱和趋势线反演得到受干扰频率区间的校正功率谱；最后通过傅里叶逆变换得到校正后的海面风速脉动资料序列。通过对校正后风速脉动资料湍流特征量的分析表明了该方法用于校正船体晃动对船载海面风速脉动观测影响的可行性。观测期间西北太平洋海区大气多处于热力作用较强的弱不稳定及不稳定条件, 无量纲风速标准差与稳定度参数z/L之间能很好地符合1/3次方定律；各方向湍流强度分别为0.091、0.076、0.043；拖曳系数约为(1.30±0.26)×10-3, 与他人在该海域的观测结果类似。
王洁 , 段自强 , 姚小红 , 高会旺 . 西北太平洋船载海面风速脉动资料校正及湍流特征分析*[J]. 热带海洋学报, 2013 , 32(3) : 9 -15 . DOI: 10.11978/j.issn.1009-5470.2013.03.002
Ship-based turbulent wind velocities were measured in the Northwest Pacific from September to November in 2005. The analysis results of turbulent wind velocity power spectrum showed an unexpected peak in the frequency range of 0.06-0.26 Hz, which was believed to be caused by platform rocking. This study proposed a new approach, i.e., an improved filtering correction, to minimize the interference from platform rocking on the signal of turbulent wind velocity. In a dual-logarithm coordinates system, the power spectral densities in the whole range except that from 0.06 to 0.26 Hz were used to linearly fit the trend of the power spectra between 0.06 and 0.26 Hz. Combined the original power spectra and the trend inversion, the corrected power spectra were obtained. Through the inverse Fourier transform, the new turbulent wind velocity data was obtained. Using the corrected turbulent wind velocity data, we estimated a few turbulent parameters in the Northwest Pacific during the observational period. These results showed that the atmospheric thermal action was strong during the observational period, leading to weakly unstable and unstable stratifications. When the standard deviation of dimensionless velocity was plotted against the stability parameter, their relationship accorded with the 1/3 power law. Intensities of turbulence in u, v, and wdirection were estimated to be 0.091, 0.076, and 0.043, respectively. The drag coefficient was estimated to be (1.30±0.26)×10-3, which is similar to the values reported in this region by other investigators.
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