Abstract 086

Abstract ID: 086

ENSO modulation of MJO teleconnections to the North Atlantic & Europe

Lead Author: Robert W. Lee
University of Reading, United Kingdom

Keywords: Madden-Julian Oscillation, El Niño-Southern Oscillation, Teleconnections, Weather Regimes, S2S

Abstract: The teleconnection from the Madden-Julian Oscillation (MJO) provides a source of sub-seasonal variability and predictability to the North Atlantic-European (NAE) region. The El Niño-Southern Oscillation (ENSO) modulates the seasonal mean state, through which the MJO and its teleconnection pattern propagates; however, its impact on this teleconnection to the NAE region has not been investigated. Here we find a robust dependence of the teleconnections from the MJO to NAE weather regimes on the phase of ENSO. We show that the MJO to NAO+ regime tropospheric teleconnection is strongly enhanced during El Niño years, via enhanced Rossby wave activity, and suppressed during La Niña. Conversely the MJO to NAO− regime stratospheric teleconnection is enhanced during La Niña years, and suppressed during El Niño. This dependence on the background state has strong implications for sub-seasonal predictability, including interannual variations in sub-seasonal predictive skill.

Steve J. Woolnough (NCAS, University of Reading)
Andrew J. Charlton-Perez (University of Reading)
Frederic Vitart (ECMWF)