Observational and theoretical studies on the North Pacific upper ocean circulation and its variability

• Published in: Oceanography in Japan Vol. 32; no. 3-4; pp. 67 - 93
• Main Author: Qiu, Bo
• Format: Journal Article
• Language: English
• Published: The Oceanographic Society of Japan 25.08.2023
• Subjects: Delayed negative feedback; Midlatitude ocean-atmosphere coupling; Pacific Decadal Oscillation; Wind-forced circulation variability
• ISSN: 0916-8362; 2186-3105
• DOI: 10.5928/kaiyou.32.3-4_67

This article reviews the four major circulation systems in the wind-driven subtropical gyre of the western North Pacific Ocean: the North Equatorial Current in the southern limb of the gyre, the Subtropical Countercurrent traversing the gyre center latitudes, the bimodal Kuroshio paths south of Japan, and the Kuroshio Extension as the gyre outflow into the open North Pacific Ocean. Although each of these circulation systems has its unique properties and time-varying signals, cases are made that it is dynamically beneficial to consider them in an inter-connected way through external forcings or mutual interactions. Rather than passively responding to the external forcings, such as that related to the Pacific decadal oscillations, it is emphasized that the low-frequency Kuroshio/KE variability can feedback to the overlying atmospheric storm-tracks and form a coupled feedback loop that enhances the decadal variance in the midlatitude North Pacific ocean-atmosphere system.