Estimating modes of inter-decadal variability and predictability in coupled climate models

Abstract

A methodology is described that allows a separation of inter-decadal variability into components associated with intra-decadal noise and potentially predictable slow decadal processes. The method is applied to a 1200 year simulation of internal variability of sea surface temperature in a coupled atmosphere-ocean model using parameters and radiative forcing associated with the year 2000. The analysis shows large predictability in the extratropical regions. The two leading modes associated with intra-decadal variability are shown to be related to interannual variability in the El Nino--Southern Oscillation and the Atlantic Multi-decadal Oscillation. The leading four slow modes are shown to be related to slow decadal variability in the Pacific Decadal Oscillation, the Atlantic Multi-decadal Oscillation and the Arctic Oscillation. References C. S. Frederiksen, X. Zheng and S. Grainger. Simulated modes of inter-decadal predictability in sea surface temperature. Clim. Dyn. , 46 :2231–2245, 2016. doi:10.1007/s00382-015-2699-6 . J. Lou, X. Zheng, C. S. Frederiksen, H. Liu, S. Grainger and K. Ying. Simulated decadal modes of the NH atmospheric circulation arising from intra-decadal variability, external forcing and slow-decadal climate processes. Clim. Dyn. , 48 :2635–2652, 2016. doi:10.1007/s00382-016-3229-x Z. Liu. Dynamics of interdecadal climate variability: a historical perspective. J. Clim. , 25 :143–162, 2012. doi:10.1175/2011JCLI3980.1 H. von Storch and F. W. Zwiers. Statistical Analysis in Climate Research . Cambridge University Press, 484pp, 2001.