Multiple Scale Variations of the Western Boundary Currents Off Philippines

Abstract:

Multiple scale variations of the North Equatorial Current bifurcation latitude (NECBL) and the Mindanao Dome (MD) are investigated using data analysis and numerical modeling. Although both of the interannual variations of NECBL and MD show significant correlations with El Niño-Southern Oscillation (ENSO), there are still some inconsistent variabilities in some years that can not be explained by ENSO. The East Asia Monsoon (EAM) has important impact on the interannual and longer time scale variations of the MD, whose relationship with ENSO is modulated by Pacific Decadal Oscilation (PDO). The inconsistent variations of the NECBL and MD with ENSO can be explained by the variation of EAM. As connected through the Mindanao Current (MC) and the North Equatorial Current (NEC), variations of MD are closely related to the NECBL both on seasonal and interannual time scales. Mean while, the non-ENSO eddy parameters and the non-ENSO NECBL at the interannual time scale are identified based on the altimeter data analyses. It is suggested that the NECBL perturbed northward by CE and southward by AE, which is evidenced by experiments using a quasi-geostrophic ocean model.