海南岛南部海区非线性内波特征分析

NONLINEAR INTERNAL WAVE CHARACTERISTIC IN THE SOUTH TO HAINAN ISLAND

2004年6月在南海海南岛南部海域进行了内波观测实验,实验中使用了3条温度链组成链阵,来估计内波在该海区传播的方向和速度。实验中发现了非线性内波群的活动。对潮汐的测量表明,非线性内波群出现在海区的涨潮时刻。计算得到实验海区内波(非线性波群)速度约为0.54m/s。测量有效数据从29日10:00~30日14:00,只发现了一组非线性内波群,说明该海区的非线性内波群不同于别的海区所观测到具有半日潮周期的非线性内波。对非线性内波波形分析可以看出,KdV(Korteweg-de Vries)方程的dn2(x,t)解能比较好的描述得到的内波波形。数据表明非线性内波群在爬坡传播过程中随波包范围的不断扩张,波峰间距离有减小的趋势。对高频线性内波(非线性内波出现前后)的分析表明,高频线性内波中周期为15min^12min的波动成份的能量比较突出,这与非线性内波群中单个波包周期基本吻合,说明非线性内波群在传播扩张过程中其衰落的尾迹分散到了两个非线性波包之间的水体中。

An internal waves （IWS） observation experiment was carried out in the south sea area to Hainan Island, July, 2004. Three moored vertical arrays of thermistors were placed in the experiment area and the data measured are used to compute propagation direction and velocity of IWS. From collected data, non-linear IWS was found. Tide at experiment site was measured using depth sensors in the array of thermistors. Non-linear IWS was found at flood tide time of wee hour. Calculation result indicates that the velocity of IWS is 0.54m/s. Valid data of IWS is from 29 July 10：00 to 30 July 14.00, during measuring time, only one group non-linear IWS was found, and it is different from the non-linear IWS of half day period in other areaE13Ez3. The cnoidal model of KdV （Korteweg-deVries） functions is used to simulate waveform of non-linear IWS. Wave crest interval of non-linear IWS is becoming shorter when propagation of IWS at up slop. Power spectra of high frequency linear IWS show linear IWS, that has similar period with non-linear IWS, is dominative. That implies the failing tail of non-linear IWS infect the water between two non-linear IWS and waveform of non-linear IWS＇s tail is evolved from non-linear to linear.