- Luke Boxall
New MJO Correlations
The MJO teleconnection is something that is often referred to when predicting the medium range weather outlook. For those not in the know, it is effectively a measure of where there is enhanced convection in the tropics, the theory being, if you have anomalous ascending air in one part of the world - you would expect there to be corresponding descending air elsewhere and thus a knock on effect on a variety of global weather patterns including the weather experienced over Europe.
The MJO was brought to the fore-front of sub-seasonal weather forecasting in part due to a Paper from Cassou (2008) that linked the 8 Phases of the MJO to general weather patterns over the European region (NAO-, NAO+, ATL Ridge and Scandi blocking) seen below:
This is still in use to this day as a leading paper in MJO Correlation to European Weather patterns.
The trouble is, these 4 patterns are too broad to look at the specifics of what this would mean for a number of applications, Energy Production/Demand being an example - as NAO- could mean warm southerly or cold northerly.
I was recently involved in a MSc Project that looked at linking the MJO to the GWL (Grosswetterlangen) patterns in association with the MetSet Tool that I have developed. Joshua Lee wrote the paper, with Dr Robert Lee and Professor Steve Woolnough being the other supervisors from the University of Reading.
It yielded some interesting results - rather than just a flare up in NAO+ regime as we cycle through Phase 3 to 5 it seems there is more detail to it, firstly we get an increase risk in Southerly patterns/South-Westerly patterns first and then Westerly Anticyclonic (WA) before moving onto Westerly Cyclonic (WZ). It also gives insights into what paterns are most favoured for the different phases - Please see the full charts for each of the 29 patterns below: