J6.6 Relative Roles of the MJO and Stratospheric Variability in North Atlantic and European Winter Climate

Wednesday, 25 January 2017: 5:15 PM
606 (Washington State Convention Center )
Chaim I. Garfinkel, Hebrew University, Jerusalem, Israel; and C. Schwartz

European and eastern U.S wintertime weather is strongly in uenced by
 large-scale modes of variability in the Northern Hemisphere such as the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). The negative phase
 of the AO has been linked to both the Madden Julian Oscillation (MJO) phase
 with convection in the West Paci c (phase 6 and 7) and to stratospheric sudden warmings (SSW), but the relative role of each phenomena is not clear,
 and the two phenomena are themselves linked, as more than half of SSW events
 were preceded by these phases of the MJO. Here, we disentangle the relative roles of MJO phase 6/7 and stratospheric variability for northern hemisphere surface weather during boreal winter. We show that stratospheric variability leads to signi cantly different north Atlantic anomalies if it is preceded by MJO phase 6/7. Furthermore, MJO phase 6/7 leads to a robust
 negative AO pattern only if it modulates the stratosphere rst. Hence, proper
attribution of their respective influence on surface weather needs to take into
consideration the linkages between these two phenomena.
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