Intraseasonal variability near 10°N in the eastern tropical Pacific Ocean


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dc.contributor.author Farrar, J. Thomas
dc.contributor.author Weller, Robert A.
dc.date.accessioned 2006-06-21T14:47:19Z
dc.date.available 2006-06-21T14:47:19Z
dc.date.issued 2006-05-20
dc.identifier.citation Journal of Geophysical Research 111 (2006): C05015 en
dc.identifier.uri http://hdl.handle.net/1912/1036
dc.description Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 111 (2006): C05015, doi:10.1029/2005JC002989. en
dc.description.abstract New in situ observations from 10°N, 125°W during 1997–1998 show strong intraseasonal variability in meridional velocity and sea surface temperature. The 50- to 100-day oscillations in sea surface height (SSH) have long been recognized as a prominent aspect of oceanic variability in the region of 9–13°N in the eastern Pacific Ocean. We use in situ and satellite data to more fully characterize this variability. The oscillations have zonal wavelengths of 550–1650 km and propagate westward in a manner consistent with the dispersion relation for first baroclinic mode, free Rossby waves in the presence of a mean westward flow. Analysis of 9 years of altimetry data shows that the amplitude of the 50- to 100-day SSH variability at 10°N is largest on 90–115°W, with peak amplitudes occurring around April. Some eddies traveling westward at 10–13°N emanate from near the gulfs of Tehuantepec and Papagayo, but eddies sometimes also appear to intensify well away from the coast while in the North Equatorial Current (NEC). The hypothesis that the intraseasonal variability and its annual cycle are associated with baroclinic instability of the NEC is supported by a spatiotemporal correlation between the amplitude of 50- to 100-day variability and the occurrence of westward zonal flows meeting an approximate necessary condition for baroclinic instability. The notion that baroclinic instability may be involved is further corroborated by the tendency of the NEC to weaken while the eddies intensify, even as the wind works to strengthen the current. en
dc.description.sponsorship The authors gratefully acknowledge support for the fieldwork under the NOAA Office of Global Programs Pan American Climate Studies program (grants NA66GPO130 and NA96GPO428) and for analysis and publication (grants NA87RJ0445 and NA17RJ1223). en
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.publisher American Geophysical Union en
dc.relation.requires http://hdl.handle.net/1912/3562
dc.relation.uri http://dx.doi.org/10.1029/2005JC002989
dc.title Intraseasonal variability near 10°N in the eastern tropical Pacific Ocean en
dc.type Article en
dc.identifier.doi 10.1029/2005JC002989

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