Seasonal and Interannual Variabilities of the Pacific Ocean Circulation and Their Relevance to ENSO

利用一个高分辨率的大气环流模式（GCM），利用理想化的表面热通量，通过观测到的风强迫，研究了太平洋海洋环流的时空变化。以下是从数值模拟中得出的主要结论。(1)哥斯达黎加圆顶与气旋式环流迅速增长，在晚春和成熟的夏季和初秋与ITCZ的北移雅阁。在冬季，强烈的北风汇聚在最南端的ITCZ上，激发出温暖的反气旋暖涡，侵蚀哥斯达黎加圆顶。哥斯达黎加穹只有在冬季和早春气旋性涡旋的胚胎被预处理时，才能在夏季由气旋性旋度的风维持。(2)棉兰老岛穹演变在晚秋离开菲律宾海岸，由于当地upwellinhs时，一个积极的旋度与东北亚冬季风的增加在该地区。在冬季达到最大值后，它开始在春季衰减，由于入侵的下降流长Rossby波激发在冬季东北信风进一步向东靠近160 -E，以及当地的正风应力旋度撤退。模式棉兰老岛圆顶的季节变化几乎完全由日期变更线以西的西太平洋风场的变化决定。

We have investigated temporal and spatial variabilities of the ocean circulation in the Pacific using a high resolution general circulation model (GCM) forced by the observed winds with idealized surface heat fluxes. The following are major conclusions from the numerical simulations.(1) The Costa Rica Dome with a cyclonic circulation grows rapidly in late spring and matures in summer and early fall in accord with the northward migration of the ITCZ. In winter strong northerns converging the southernmost ITCZ excite warm anticyclonic warm eddies, which erode the Costa Rica Dome. The Costa Rica Dome can be maintained by the winds with the cyclonic curl in summer only when the embryo of a cyclonic eddy is preconditioned in winter and early spring.(2) The Mindanao Dome evolves in late fall off the Philippine coast due to local upwellinhs when a positive curl associated witn the northeast Asian winter monsoon increases over the region. After reaching a maximum in winter it begins to decay in spring due to an intrusion of downwelling long Rossby waves excited in winter by the northeast trade winds farther eastward near 160 -E, as well as a retreat of the local positive wind stress curl. The seasonal variation of the model Mindanao Dome is almost perfectly determined by the change of the wind field in the western Pacific west of the date line.