摘要： This study investigates the nature of a decadal modulation in the coupled bred vectors (BVs) developed to capture the dominant instabilities related to seasonal‐to‐interannual variability in the Equatorial Pacific using the GEOS‐5 atmosphere‐ocean general circulation model. It is found that the coupled BVs, with a monthly rescaling period, successfully reflect the observed decadal modulation of zonal location in the El Niño action center over the equatorial Pacific. By dividing the 30 years of BVs into two epochs, it is shown that the leading Empirical Orthogonal Function (EOF) of BV oceanic temperature shifts from the eastern Pacific during 1981–1999 to the central Pacific during 2000–2010, consistent with decadal changes in the location of the El Niño action center. By performing a budget analysis for BV temperature, it is found that the westward shift of the BV temperature is due to the strengthening of the mean zonal temperature gradient, which acts to amplify the BV temperature growth due to the zonal advection of background temperature by the BV current. Key Points The nature of a decadal modulation in the coupled bred vectors (BVs) is examined The decadal location shift of BV is consistent with El Nino action center shift This shift is due to the strengthening of the mean zonal temperature gradient 其他題名： Geophys. Res. Lett 出版者： Washington, DC: Blackwell Publishing Ltd 出版日期： 2012-10-28 出處： Geophysical research letters, 2012-10, Vol.39 (20), p.n/a 資源來源： Wiley Journals Core Collection (NTUSG) 版權： 2012. American Geophysical Union. All Rights Reserved. 版權： 2014 INIST-CNRS 版權： Copyright American Geophysical Union 2012 版權： Copyright John Wiley & Sons, Inc. 2012 識別號： ISSN: 0094-8276 識別號： ISSN: 1944-8007 識別號： EISSN: 1944-8007 識別號： DOI: 10.1029/2012GL053719 識別號： CODEN: GPRLAJ
