The intensity of the MJO during December-March, as measured by daily values of the amplitude of the OMI and the RMM, is shown to be modulated by the QBO across the full breadth of MJO intensities. This is  in contrast to the view that the QBO does not affect the intensity of the MJO but rather makes MJO events last longer or occur more often.  The highest extreme  amplitudes of the  MJO are shown to  occur only during QBOE. Similarly, there are much more occurrences of extreme low amplitude MJO during QBOW, although this difference is less dramatic than for the impact on high amplitudes.  This shift in the PDF of MJO amplitude is detectable from the lowest MJO amplitudes up to the highest amplitudes. The biggest impacts are for MJO  phases 1-2, and  6-8, which show a dramatic increase of occurrence of weak values  during QBOW. This is consistent with notion that QBOE promotes the propagation of the  MJO across the MC region, so leading to stronger amplitudes during  phases 6-8 and 1-2.

                This analysis of daily MJO amplitudes also  allows for an estimation of the difference  in growth rate between QBOE and QBOW. The amplitude  growth rate is shown to be well approximated as a relaxation back to the mean MJO amplitude with timescale ~18 days during both QBOE and QBOW, but the mean (equilibrium)  amplitude is 50% greater during QBOE. The difference in growth rate of the MJO between QBOE and QBOE  is thus independent of MJO amplitude and implies that it takes about  about 30 days for a QBOE-QBOW difference of one amplitude unit to develop. The implication of these results for the mechanism of the impact  of the QBO on the MJO will be discussed.