Journal
ATMOSPHERE-OCEAN
Volume 55, Issue 2, Pages 110-120Publisher
CMOS-SCMO
DOI: 10.1080/07055900.2017.1291411
Keywords
ENSO; North Pacific; interdecadal variability; Aleutian Low; West Pacific teleconnection
Categories
Funding
- National Natural Science Foundation of China [91437216, 91637312, 41575075]
- Ministry of Science and Technology of China [2016YFA0601801, 2015CB453201, 2015CB953904]
- Public Science and Technology Research Funds projects of ocean [201505013]
- Innovation Project of Jiangsu Province [1344051501004]
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The interdecadal change in the relationship between the El Nino-Southern Oscillation (ENSO) and atmospheric circulation over the North Pacific is investigated using both observational data and an atmospheric general circulation model. There are two prominent modes of winter mid-latitude atmospheric variability in the North Pacific: the West Pacific (WP) teleconnection and the Aleutian Low (AL). The relationship between ENSO and the WP-AL patterns changed notably around the late 1970s. From 1957 to 1975, during the mature phase of ENSO, significant sea surface temperature anomalies (SSTAs) occurred, mainly in the equatorial eastern Pacific Ocean; the associated atmospheric circulation anomaly pattern resembles the negative phase of a WP teleconnection pattern. In contrast, for the 1978-2011 period, significant negative SSTAs were observed in the western and extratropical Pacific in both hemispheres, with some significant positive SSTAs appearing over the eastern Pacific. This is in agreement with the defined regions of a mega-ENSO, the associated atmospheric circulation anomaly pattern resembles the AL mode. Further analysis suggests that a negative-positive anomaly pattern in the 500hPa geopotential height throughout the entire North Pacific, possibly enhanced by the SSTAs in the extratropical North Pacific associated with the mature phase of ENSO, is responsible for modulating the relationship between ENSO and the North Pacific atmospheric circulation. Resume[Traduit par la redaction] Nous etudions la modification interdecennale de la relation entre le phenomene El Nino-oscillation australe (ENSO) et la circulation atmospherique sur le Pacifique Nord, et ce, a l'aide d'observations et de donnees issues d'un modele de circulation generale de l'atmosphere. Il existe deux modes dominants de variabilite dans le nord du Pacifique : la teleconnexion du Pacifique Ouest et la depression des Aleoutiennes. La relation entre l'ENSO et les configurations liees au phenomene du Pacifique Ouest et a la depression des Aleoutiennes a considerablement change vers la fin des annees 1970. De 1957 a 1975, durant la phase de maturite de l'ENSO, des anomalies notables de temperatures de surface de la mer (SST) sont survenues principalement dans l'est equatorial de l'ocean Pacifique. La circulation atmospherique anomale associee ressemble a la phase negative de la teleconnexion du Pacifique Ouest. En revanche, de 1978 a 2011, des anomalies negatives notables de SST ont ete observees dans le Pacifique Ouest et extratropical, dans les deux hemispheres. Des anomalies positives notables de SST sont aussi survenues dans l'est du Pacifique. Ces emplacements correspondent aux regions propices a un important ENSO. La circulation atmospherique anomale associee ressemble au mode de la depression des Aleoutiennes. Des analyses subsequentes laissent penser qu'une configuration d'anomalies negatives et positives des hauteurs geopotentielles a 500 hPa sur le nord du Pacifique, possiblement renforcee par des anomalies de SST associees a la phase de maturite de l'ENSO, dans la region nord extratropicale du Pacifique, module la relation entre l'ENSO et la circulation atmospherique du Pacifique Nord.
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