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contributor authorSchneider, Niklas
contributor authorBarnett, Tim P.
date accessioned2017-06-09T15:25:33Z
date available2017-06-09T15:25:33Z
date copyright1995/05/01
date issued1995
identifier issn0894-8755
identifier otherams-4336.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4182134
description abstractThe relative roles of heat and freshwater fluxes in forcing the tropical Pacific on interannual timescales are investigated using sophisticated atmospheric and oceanic general circulation models. Interannual density flux anomalies due to anomalous precipitation and shortwave and longwave radiation are highly correlated since they all depend on clouds. Their respective contributions to the anomalous surface density flux are of comparable magnitude, with precipitation and longwave anomalies opposing shortwave radiation. This implies that anomalous radiation and precipitation associated with the eastward shift of the centers of deep convection during El Niño change the density flux little since they largely balance. This near cancellation also causes the evaporative component to dominate interannual anomalies of the density flux in the eastern Pacific and in the Indian Ocean and implies that anomalous net surface density fluxes there can be approximated by anomalous evaporation alone. However, in the central and western Pacific, evaporative anomalies are negatively correlated to shortwave anomalies as well, and interannual anomalies of the net density flux are therefore small and deviate considerably from the evaporative component alone. Forcing an oceanic circulation model with the interannual anomalies of the fluxes of heat and freshwater alone yields salinity and temperature anomalies of the same order as observed. Model salinity anomalies explain approximately half of the observations, while temperature anomalies have reversed signs compared to observations. This reflects the negative feedback between surface heat fluxes and the warming caused by interannual anomalies of the wind not included in this simulation. Over most of the tropical ocean, interannual anomalies of surface density are dominated by temperature anomalies. In the central Pacific, salinity anomalies diminish up to half of the effect of temperature. Anomalies of the velocity fields due to interannual anomalies of the surface heat and freshwater fluxes are largest in the eastern equatorial ocean, where the thermocline is shallow and anomalies of the surface flux have the largest impact on vertical mixing.
publisherAmerican Meteorological Society
titleThe Competition of Freshwater and Radiation in Forcing the Ocean during El Niño
typeJournal Paper
journal volume8
journal issue5
journal titleJournal of Climate
identifier doi10.1175/1520-0442(1995)008<0980:TCOFAR>2.0.CO;2
journal fristpage980
journal lastpage992
treeJournal of Climate:;1995:;volume( 008 ):;issue: 005
contenttypeFulltext


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