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Ocean-atmosphere interactions and multi-scale climate variability in a changing climate
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What's the role of Atlantic trans-basin forcing in Pacific decadal variability?
Wednesday 9th @ 1350-1410, Concert Hall
Kewei Lyu* , Centre for Southern Hemisphere Oceans Research (CSHOR), CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
Jin-Yi Yu, Department of Earth System Science, University of California, Irvine, California, USA
Presenter Email: kewei.lyu@csiro.au |
| Although it is generally believed that the Pacific decadal variability is mainly intrinsic to the Pacific basin itself, there are also observational and model evidences showing that climate impacts originated from the Atlantic Ocean could extend worldwide through atmospheric teleconnections. Such trans-basin forcing from the Atlantic has been suggested to explain the two-decade long unprecedented intensification of Pacific trade winds since the early 1990s. However, it is still unclear to what extent the Atlantic has contributed to the observed Pacific decadal variability over the historical period. In this study we aim to separate and quantify the Interdecadal Pacific Oscillation (IPO) and Pacific trade wind change signals internally generated in the Pacific and remotely forced by the Atlantic, using observations and partially coupled climate model experiment forced by observed Atlantic sea surface temperatures. We found that while Pacific internal processes dominate the IPO evolutions, trans-basin forcing from the Atlantic could account for ~20% of the Pacific trade wind year-to-year variations with increased contributions towards lower frequency timescales. Over the satellite altimetry period (1993-2012), one third of the Pacific trade wind intensification that was responsible for the rapid sea level rising in the western tropical Pacific can be attributed to the Atlantic forcing. By contrast, the Atlantic contribution to Pacific trade wind change was negligible for recent decade-long global surface warming slowdown period (2003-2012). |
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