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contributor authorDrenkard, Elizabeth J.
contributor authorKarnauskas, Kristopher B.
date accessioned2017-06-09T17:08:53Z
date available2017-06-09T17:08:53Z
date copyright2014/03/01
date issued2013
identifier issn0894-8755
identifier otherams-80133.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4222992
description abstracteveral recent studies utilizing global climate models predict that the Pacific Equatorial Undercurrent (EUC) will strengthen over the twenty-first century. Here, historical changes in the tropical Pacific are investigated using the Simple Ocean Data Assimilation (SODA) reanalysis toward understanding the dynamics and mechanisms that may dictate such a change. Although SODA does not assimilate velocity observations, the seasonal-to-interannual variability of the EUC estimated by SODA corresponds well with moored observations over a ~20-yr common period. Long-term trends in SODA indicate that the EUC core velocity has increased by 16% century?1 and as much as 47% century?1 at fixed locations since the mid-1800s. Diagnosis of the zonal momentum budget in the equatorial Pacific reveals two distinct seasonal mechanisms that explain the EUC strengthening. The first is characterized by strengthening of the western Pacific trade winds and hence oceanic zonal pressure gradient during boreal spring. The second entails weakening of eastern Pacific trade winds during boreal summer, which weakens the surface current and reduces EUC deceleration through vertical friction. EUC strengthening has important ecological implications as upwelling affects the thermal and biogeochemical environment. Furthermore, given the potential large-scale influence of EUC strength and depth on the heat budget in the eastern Pacific, the seasonal strengthening of the EUC may help reconcile paradoxical observations of Walker circulation slowdown and zonal SST gradient strengthening. Such a process would represent a new dynamical ?thermostat? on CO2-forced warming of the tropical Pacific Ocean, emphasizing the importance of ocean dynamics and seasonality in understanding climate change projections.
publisherAmerican Meteorological Society
titleStrengthening of the Pacific Equatorial Undercurrent in the SODA Reanalysis: Mechanisms, Ocean Dynamics, and Implications
typeJournal Paper
journal volume27
journal issue6
journal titleJournal of Climate
identifier doi10.1175/JCLI-D-13-00359.1
journal fristpage2405
journal lastpage2416
treeJournal of Climate:;2013:;volume( 027 ):;issue: 006
contenttypeFulltext


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