Oceanic, nonisostatic responses to near 5-day Rossby–Haurwitz atmospheric pressure waves have been observed in open oceans; however, such responses based on observations in marginal seas such as the South China Sea have not been reported, owing to the limited ocean bottom pressure Pbot records. The Pbot measurements from pressure recording inverted echo sounders (PIESs) at sites in the northern South China Sea revealed a nonisostatic-like response near 5 days, although the coastal-trapped waves (CTWs) appeared to obscure it because their broadband periods include the near 5-day band. Cross-spectral analysis revealed
that the PIES Pbot records and the sea level (SL) records of Hong Kong all correlate strongly with the at-mospheric pressure and winds over the East China Sea. This is indicative of remotely forced CTWs. The PIES Pbot records showed higher coherence near 5 days with the zonal low-pass wavelength filters applied to the atmospheric pressure, and the phase analysis results strongly suggest nonisostatic oceanic responses to the westward-propagating Rossby–Haurwitz waves. Effective separation of CTWs and the nonisostatic responses from the Pbot records at the near 5-day period was achieved. The oceanic responses to the Rossby–Haurwitz waves in the northern South China Sea were nonisostatic; a 1-mbar change in air pressure resulted in a 1.58-mbar change in Pbot with a phase lag of 14.8°. The mean phase speed of CTWs from Hong Kong to station P3 was estimated to be 9.9 m s-1.
南中国海北部近5天对大气表面压力和陆架陷波的非均衡响应
中文摘要：在开阔海域观测到了近5天的Rossby-Haurwitz大气压力波的海洋非均衡响应，但由于海底压力Pbot记录有限，在南中国海等边缘海区的这种响应尚未被报道。在南海北部的压力记录反向回声测深仪(PIES)的Pbot测量显示，近5天有一个非均衡的响应，尽管陆架陷波(CTWs)似乎掩盖了这一响应，因为其宽带周期包括了近5天的波段。交叉光谱分析显示，香港的PIES Pbot记录和海平面记录都与东中国海面的气压和风有很强的相关性。表明这是远程强迫的CTWs。PIES Pbot记录在大气压力中应用纬向低通波长滤波器后，在近5天内显示出较高的相干性，位相分析结果强烈地表明了海洋对西向传播的Rossby-Haurwitz波的非均衡响应。实现了近5天的CTWs和Pbot记录的非均衡响应的有效分离。南海北部海域对Rossby-Haurwitz波的海洋响应是非均衡的，气压变化1 mbar时，Pbot的变化为1.58 mbar，位相滞后为14.88 mbar。由香港至P3站的清水湾平均相速估计为9.9 m s-1。