Dynamic features of long Rossby wave in the North Pacific Subtropical Countercurrent

作者：Liu QY^*; Wang SX; Liu ZY; Yang HJ

来源：Chinese Journal of Geophysics, 2001, 44: 28-37.

• Subtropical Countercurrent
• long Rossby wave
• quasi 90-day oscillation

Using the baroclinic 2.5 layer ocean model with the dissipation, the dynamic features of long Rossby wave with wavelength of 450-840 km have been discussed for the North Pacific Subtropical Countercurrent (STCC). The tong Rossby wave is a neutral wave in STCC region without dissipation. The period of its faster mode is 88-110 days and phase speed is -0.06-0.09 m/s, almost identical to the group speed. The dissipation effect can make the long Rossby wave become weak damped wave, but it has little effect on the phase speed and the period of the long Rossby wave. The quasi 90-day oscillation of Sea Sruface Height (SSH) corresponds to the faster mode of the long Rossby wave, but it is not only in zonal long wave but also with meridional. long wave in this area. The long wave disturbance amplitude of the faster mode is about 5 times of the slower mode. Three necessary conditions for existence of the quasi 90-day oscillation of SSH are as follows: the limited westward mean flow (0.02-0.04m/s) in the second layer, the thickness of two active layers in 2.5 layer greater than 480m; and the scond layer density limited in 25.8+/-1.0sigma(theta). Because the three conditions are satisfied, the quasi 90-day oscillation appears in STCC area. The propagation of faster mode of the long Rossby wave is not closely related with heat flux change in sea surface, which can produce effect on the propagation of the slower mode.

• 出版日期2001
• 单位中国海洋大学