Interdecadal shift of the North Pacific Oscillation and its nonstationary relationship with East Asian climate

• Published in: Atmospheric research Vol. 305; p. 107452
• Main Authors: Li, Gengyu, Zhang, Tuantuan, Diao, Yina, Zhong, Wenxiu, Yang, Song
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2024
• Subjects: Arctic Oscillation; East Asia climate; El Niño–Southern Oscillation; Extreme event; Interdecadal shift; North Pacific Oscillation; Interdecadal shift; East Asia climate; El Niño–Southern Oscillation; Extreme event; North Pacific Oscillation; Arctic Oscillation
• ISSN: 0169-8095; 1873-2895
• DOI: 10.1016/j.atmosres.2024.107452

A pronounced shift of the North Pacific Oscillation (NPO), including its teleconnection with the East Asian winter monsoon, has been observed in recent decades, but the underlying mechanism remains unclear. In this study, we found that interannual variation of the NPO and its relationship with the dominant modes of winter mean and extreme temperatures over East Asia (EA) experienced a significant interdecadal shift in the mid-1980s. Before the shift (during 1950–1985), the NPO emerged and was maintained as a strong regional north-south dipole, manifesting a remarkable tropical-extratropical teleconnection. It significantly modulated the second mode of air temperature over EA (depicted by a north-south dipole) and extreme temperature events over southern EA, mainly through horizontal advection and adiabatic heating induced by the anomalous circulation in the southern lobe of the NPO. After the shift (during 1986–2021), the NPO was characterized by an intensified northern lobe and a weakened and northwestward shifted southern lobe, and by a close teleconnection with the Rossby wave trains at the mid-higher latitudes. In the meantime, tropical-extratropical teleconnections became apparently weak. Correspondingly, the NPO was mainly linked to the interannual variation of air temperature and extreme events over northern EA via horizontal advection. Importantly, the decadal shift of the relationships of the NPO with the Arctic Oscillation and El Niño–Southern Oscillation played an apparent role in modulating EA climate. •Interannual variation of the NPO and its connection with East Asian winter temperature shifted notably in the mid-1980s.•During 1950–1985, the NPO appeared as a local dipole and played a prominent role in modulating southern East Asian climate.•During 1986–2021, the NPO was linked to a global-scale wave-train pattern with its impact limited to northern East Asia.