The interdecadal Pacific oscillation (hereafter termed IPV, using "variability" in lieu of "oscillation") and the Atlantic multidecadal oscillation (hereafter AMV, similar to IPV) are regulators of global mean temperature, large-scale atmospheric circulation, regional temperature and precipitation, and related extreme events. Despite a growing recognition of their importance, the combined influence of these modes of lowfrequency sea surface temperature (SST) variability remains elusive given the short instrumental record and the difficulty of coupled climate models to simulate them satisfactorily. In this study, idealized simulations with two atmospheric global climate models (AGCMs) are used to show a partial cancellation of the North Pacific atmospheric response to positive IPV (i.e., deeper Aleutian low) by the concurrent positive phase of the AMV. This effect arises from a modulation of the interbasin Walker circulation that weakens deep convection in the western Pacific and the associated Rossby wave train into the northern extratropics. The weaker Aleutian low response is associated with less upward wave activity flux in the North Pacific; however, the associated stratospheric jet weakening is similar to when the +IPV alone forces the vortex, as additional upward wave activity flux over Siberia makes up the difference. While comparable warming of the polar stratosphere is found when the positiveAMVis included with the positive IPV, the downward propagation of the stratospheric response is significantly reduced, which has implications for the associated surface temperature extremes. The robust anticorrelation between the positive IPV and positive AMV signals over the North Pacific and their lack of additivity highlight the need to consider the IPV-AMV interplay for anticipating decadal changes in mean climate and extreme events in the Northern Hemisphere.

In Table 2 of Elsbury et al. (2019), titled "The atmospheric response to positive IPV, positive AMV, and their combination in boreal winter," the number and frequency of sudden stratospheric warmings (SSWs) for various background interdecadal Pacific variability (IPV) and Atlantic multidecadal variability (AMV) states are incorrect. The reproduction of the Charlton and Polvani (2007, 2011) SSW algorithm used includes final warmings, which increases the SSW occurrences. Following correction, the number of SSWs decreases across all simulations. These results are printed in Table 2 below. The climatological frequency is 0.52 events per season in our control, lower than the frequency detected in reanalysis, but consistent with the frequency retrieved by Marsh et al. (2013), who also use WACCM4. With the correction, the percent increase in SSWs relative to control remains very similar, equaling 15% for 1AMV, 26% for 1IPV, and 33% for 1AIV (1AMV and 1IPV together). These figures appear correctly in the table. In general, these errors do not change any of the major findings of the manuscript. We apologize for the confusion the suspiciously high SSW results may have caused.