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In particular, the presence of and the phases of significant MJO events can be linked to an increase of skill in forecasting NAO– circulation patterns  Fig8.2.8-1 compares the bivariate correlation (NAO & BLO) against analysis for forecasts initiated with and without an MJO event.  Forecasts initiated with an MJO event show higher skill (an improvement of the order of one day) between Day8 and Day15.  Correlations are significantly increased for Day11 and Day12 at a 90% confidence level, and for Day10 to Day13 at an 80% confidence level.

Inspection of Hovmoeller and Wheeler-Hendon diagrams can give a guide towards the consistency and intensity of an MJO event.  The distortion of the upper flow associated with an MJO affects monsoon activity and, equally important, modifies the northern and southern hemisphere mid-latitude jets, impacting on predictability of extra-tropical patterns. This can be expressed in terms of weather regime impacts. 

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