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contributor authorChung, Christine T. Y.
contributor authorPower, Scott B.
date accessioned2017-06-09T17:11:19Z
date available2017-06-09T17:11:19Z
date copyright2015/04/01
date issued2015
identifier issn0894-8755
identifier otherams-80795.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4223726
description abstractl Niño?Southern Oscillation strongly influences the interannual variability of rainfall over the Pacific, shifting the position and orientation of the South Pacific convergence zone (SPCZ) and intertropical convergence zone (ITCZ). In 1982/83 and 1997/98, very strong El Niño events occurred, during which time the SPCZ and ITCZ merged into a single zonal convergence zone (szCZ) extending across the Pacific at approximately 5°S. The sea surface temperature anomalies (SSTAs) reached very large values and peaked farther east compared to other El Niño events. Previous work shows that tropical Pacific precipitation responds nonlinearly to changing the amplitude of the El Niño SSTA even if the structure of the SSTA remains unchanged, but large canonical El Niño SSTAs cannot reproduce the szCZ precipitation pattern. This study conducts idealized, SST-forced experiments, starting with a large-amplitude canonical El Niño SSTA and gradually adding a residual pattern until the full (1982/83) and (1997/98) mean SST is reproduced. Differences between the canonical and strong El Niño SSTA patterns are crucial in generating an szCZ event. Three elements influence the precipitation pattern: (i) the local meridional SST maxima influences the ITCZ position and western Pacific precipitation, (ii) the total zonal SST maximum influences the SPCZ position, and (iii) the equatorial Pacific SST influences the total amount of precipitation. In these experiments, the meridional SST gradient increases as the SSTAs approach szCZ conditions. Additionally, the precipitation changes evident in szCZ years are primarily driven by changes in the atmospheric circulation, rather than thermodynamic changes. The addition of a global warming SST pattern increases the precipitation along the equator and shifts the ITCZ farther equatorward.
publisherAmerican Meteorological Society
titleModelled Rainfall Response to Strong El Niño Sea Surface Temperature Anomalies in the Tropical Pacific
typeJournal Paper
journal volume28
journal issue8
journal titleJournal of Climate
identifier doi10.1175/JCLI-D-14-00610.1
journal fristpage3133
journal lastpage3151
treeJournal of Climate:;2015:;volume( 028 ):;issue: 008
contenttypeFulltext


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