Title: Persistent anomalies of the extratropical Northern Hemisphere wintertime circulation as an initiator of El Niño/Southern Oscillation events

Abstract

Climates across both hemispheres are strongly influenced by tropical Pacific variability associated with the El Niño/Southern Oscillation (ENSO). Conversely, extratropical variability also can affect the tropics. In particular, seasonal-mean alterations of near-surface winds associated with the North Pacific Oscillation (NPO) serve as a significant extratropical forcing agent of ENSO. However, it is still unclear what dynamical processes give rise to year-to-year shifts in these long-lived NPO anomalies. Here in this paper we show that intraseasonal variability in boreal winter pressure patterns over the Central North Pacific (CNP) imparts a significant signature upon the seasonal-mean circulations characteristic of the NPO. Further we show that the seasonal-mean signature results in part from year-to-year variations in persistent, quasi-stationary low-pressure intrusions into the subtropics of the CNP, accompanied by the establishment of persistent, quasi-stationary high-pressure anomalies over high latitudes of the CNP. Overall, we find that the frequency of these persistent extratropical anomalies (PEAs) during a given winter serves as a key modulator of intraseasonal variability in extratropical North Pacific circulations and, through their influence on the seasonal-mean circulations in and around the southern lobe of the NPO, the state of the equatorial Pacific 9–12 months later.

Authors:

Anderson, Bruce T.  ^[1];

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Hassanzadeh, Pedram  ^[2];

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Caballero, Rodrigo  ^[3]

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+ Show Author Affiliations

1. Boston Univ., MA (United States). Dept. of Earth and Environment
2. Rice Univ., Houston, TX (United States). Dept. of Mechanical Engineering and Earth Science
3. Stockholm Univ. (Sweden). Dept. of Meteorology and Bolin Center for Climate Research

Publication Date:

2017-08-31

Research Org.:

Boston Univ., MA (United States)

Sponsoring Org.:

USDOE; National Science Foundation (NSF); Swedish Research Council (SRC)

OSTI Identifier:

1430238

Grant/Contract Number:  

SC0004975

Resource Type:

Accepted Manuscript

Journal Name:

Scientific Reports

Additional Journal Information:

Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2045-2322

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES