The MJO - SSW teleconnection : interaction between MJO - forced 1 waves and the mid - latitude jet

13 The Madden Julian Oscillation (MJO) was shown to a ect both present-day Sudden Strato14 spheric Warming (SSW) events in the Arctic, and their future frequency under global 15 warming scenarios, with implications to the Arctic Oscillation and mid-latitude extreme 16 weather. This work uses a dry dynamic core model to understand the dependence of SSW 17 frequency on the amplitude and longitudinal range of the MJO, motivated by the predic18 tion that the MJO will strengthen and broaden its longitudinal range in a warmer climate. 19 We focus on the response of the mid-latitude jets and the corresponding generated sta20 tionary waves, that are shown to dominate the response of SSW events to MJO forcing. 21 Momentum budget analysis of a large ensemble of spinup simulations suggests the clima22 tological jet response is driven by the MJO-forced meridional eddy momentum transport. 23 The results suggest that the trends in both MJO amplitude and longitudinal range are im24 portant for the prediction of the mid-latitude jet response and for the prediction of SSWs 25 in a future climate. 26