Seasonal modulations of El Nino-related atmospheric variability: Indo-Western Pacific Ocean feedback

TitleSeasonal modulations of El Nino-related atmospheric variability: Indo-Western Pacific Ocean feedback
Publication TypeJournal Article
Year of Publication2017
AuthorsXie SP, Zhou ZQ
JournalJournal of Climate
Volume30
Pagination3461-3472
Date Published2017/05
Type of ArticleArticle
ISBN Number0894-8755
Accession NumberWOS:000399680500022
Keywordsclimate; combination-mode; dipole mode; enso; events; indian-ocean; predictability; sea-surface temperature; southern-oscillation; summer
Abstract

The spatial structure of atmospheric anomalies associated with El Nino-Southern Oscillation varies with season because of the seasonal variations in sea surface temperature (SST) anomaly pattern and in the climatological basic state. The latter effect is demonstrated using an atmospheric model forced with a time-invariant pattern of El Nino warming over the equatorial Pacific. The seasonal modulation is most pronounced over the north Indian Ocean to northwest Pacific where the monsoonal winds vary from northeasterly in winter to southwesterly in summer. Specifically, the constant El Nino run captures the abrupt transition from a summer cyclonic to winter anticyclonic anomalous circulation over the northwest Pacific, in support of the combination mode idea that emphasizes nonlinear interactions of equatorial Pacific SST forcing and the climatological seasonal cycle. In post-El Nino summers when equatorial Pacific warming has dissipated, SST anomalies over the Indo-northwest Pacific Oceans dominate and anchor the coherent persisting anomalous anticyclonic circulation. A conceptual model is presented that incorporates the combination mode in the existing framework of regional Indo-western Pacific Ocean coupling.

DOI10.1175/jcli-d-16-0713.1
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