Tropospheric QBO-ENSO interactions and differences between Atlantic and Pacific

Hansen, Felicitas, Matthes, Katja and Wahl, Sebastian (2016) Tropospheric QBO-ENSO interactions and differences between Atlantic and Pacific Journal of Climate, 29 (4). pp. 1353-1368. DOI 10.1175/JCLI-D-15-0164.1.

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This study investigates the interaction of the Quasi-Biennial Oscillation (QBO) and the El Niño-Southern Oscillation (ENSO) in the troposphere separately for the North Pacific and North Atlantic region. Three 145-year model simulations with NCAR’s Community Earth Sytem Model (CESM-WACCM) are analyzed where only natural and no anthropogenic forcings are considered. These long simulations allow us to obtain statistically reliable results from an exceptional large number of cases for each combination of the QBO (westerly and easterly) and ENSO phases (El Niño and La Niña). Two different analysis methods were applied to investigate where nonlinearity might play a role in QBO-ENSO interactions.

The analyses reveal that the stratospheric equatorial QBO anomalies extend down to the troposphere over the North Pacific during Northern hemisphere winter only during La Niña and not during El Niño events. The Aleutian low is deepened during QBO westerly (QBOW) as compared to QBO easterly (QBOE) conditions, and the North Pacific subtropical jet is shifted northward during La Niña. In the North Atlantic, the interaction of QBOW with La Niña conditions (QBOE with El Niño) results in a positive (negative) North Atlantic Oscillation (NAO) pattern. For both regions, nonlinear interactions between the QBO and ENSO might play a role.

The results provide potential to enhance the skill of tropospheric seasonal predictions in the North Atlantic and North Pacific region.

Document Type: Article
Additional Information: WOS:000370451200003
Keywords: Circulation/ Dynamics, ENSO, Quasibiennial oscillation, Atm/Ocean Structure/ Phenomena, Stratosphere-troposphere coupling, Models and modeling, Climate models
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Kiel University
Refereed: Yes
DOI etc.: 10.1175/JCLI-D-15-0164.1
ISSN: 0894-8755
Projects: NATHAN
Date Deposited: 15 Dec 2015 14:13
Last Modified: 03 May 2017 12:15

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