南大西洋至几内亚湾冬季海浪传播特性

Propagation Characteristics of Wave from South Atlantic to Gulf of Guinea in Winter

为解决南大西洋至几内亚湾海域的海浪组成成分、传播特性及来源这3个该海域一直需要解决的问题,建立SWAN (Simulating WAves Nearshore)双层嵌套海浪模型对南大西洋至几内亚湾冬季海浪时空分布进行模拟分析,结果表明:南大西洋海浪有效波高呈高纬度区(30°S以南)向低纬度区(30°S以北)递减的趋势,高纬度区海浪传播方向与风场关系密切,低纬度区则与风场差异明显;南大西洋涌浪波高与混合浪波高分布高度相关,涌浪在混合浪中所占比例较大,尤其在风速较小的低纬度海域更为显著;南大西洋中部至几内亚湾存在相对固定的S-SW涌浪系统,其能量在二维海浪谱上分布集中,空间方向上分布范围较窄;模拟时段内几内亚湾呈明显的涌浪主导状态,通过对有效波高最大时刻的一次涌浪过程溯源发现,影响几内亚湾的涌浪可追溯至约6.5天前南大西洋咆哮西风带海域的强风浪。

The detailed composition,propagation characteristics,and sources of waves from South Atlantic Ocean to Gulf of Guinea remain an unsolved problem.The temporal and spatial distribution of waves from South Atlantic to Gulf of Guinea in winter were simulated by constructing a two-layer nested wave model based on SWAN(Simulating WAves Nearshore).The results suggest that the significant wave height decreases from high latitude(south of 30°S)to low latitude(north of 30°S)in South Atlantic.There exists a close correlation between wave propagation direction and wind field in high latitude,but a significant distinction in low latitude.The distribution of swell is highly correlated with the mixed waves,and accounts for a large proportion of the mixed wave in South Atlantic,especially in the low latitude area with a low wind speed.There exists a stable S-SW swell system from the middle of South Atlantic to the Gulf of Guinea,and the simulated two-dimensional spectra shows concentrated swell wave energy in narrow directional distribution.The Gulf of Guinea is obviously swell dominated during the simulation period.The simulation study indicates that the swell system in maximum significant wave height event of the Gulf of Guinea during simulation period could be traced back to the strong wind and waves in the Roaring Forties in South Atlantic about 6.5 days ago.