Topographic Rossby waves (TRWs) are oscillations generated on sloping topography when water columns travel across isobaths under potential vorticity conservation. From our large-scale observations from 2016 to 2019, near-65-day TRWs were first observed in the deep basin of the South China Sea (SCS). The TRWs propagated westward with a larger wavelength (235 km) and phase speed (3.6 km day^?1) in the north of the array and a smaller wavelength (80 km) and phase speed (1.2 km day^?1) toward the southwest of the array. The ray-tracing model was used to identify the energy source and propagation features of the TRWs. The paths of the near-65-day TRWs mainly followed the isobaths with a slightly downslope propagation. The possible energy source of the TRWs was the variance of surface eddies southwest of Taiwan. The near-65-day energy propagated from the southwest of Taiwan to the northeast and southwest of the array over ~100–120 and ~105 days, respectively, corresponding to a group velocity of 4.2-5.0 and 10.5 km day^?1, respectively. This suggests that TRWs play an important role in deep-ocean dynamics and deep current variation, and upper-ocean variance may adjust the intraseasonal variability in the deep SCS.

基于深海海流观测的南海深海盆地形罗斯贝波的传播

中文摘要：地形罗斯贝波(TRWs)是水柱在位涡守恒下穿过等深线时在倾斜地形上产生的振荡。基于2016年到2019年的大范围观测，首次在南海中国海盆观测到了近65天的TRWs。TRWs向西传播，在阵列北部有较大的波长(235 km)和相速度(3.6 km day^?1)，而在阵列的西南方有较小的波长(80 km)和相速度(1.2 km day^?1)。射线追踪模型用于识别TRWs的能量来源和传播特性。近65天的TRWs路径主要沿等深线传播，传播方向略有向下。台湾西南海面涡旋的变化可能是TRWs的能量来源。近65天能量从台湾西南部向东北和西南方向传播的时间分别为100-120 天和105 天，对应的群速度分别为4.2-5.0和10.5 km day^?1。这表明TRWs在深海动力学和深海海流变化中起着重要的作用，而上层海洋的变化可能调制了南海深海的季节内变化。