Southern Annular Mode

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wembley
Posts: 158
Joined: Fri 22/03/2013 11:18
Location: Cromwell

Southern Annular Mode

Unread post by wembley »

Is there any way to predict how the Southern Annular Mode (SAM) is going to behave over any given season?
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Cyclone Tracy
Posts: 2488
Joined: Thu 07/09/2017 19:25
Location: North Shore, Auckland

Re: Southern Annular Mode

Unread post by Cyclone Tracy »

Good question. What drives this climate pattern is still under plenty of research. The AAO 7 / 10 / 14 day outlook is the best and only real forecast indicator to my knowledge. The BoM's current research suggests an El Nino event leads to more negative SAM's and a La Nina event leads to more positive SAM's pushing the westerlies more south.
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TonyT
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Joined: Thu 08/05/2003 11:09
Location: Amberley, North Canterbury

Re: Southern Annular Mode

Unread post by TonyT »

I prefer AAO as its a better descriptor of what it is. My view (and I think this is probably a little counter to that of many) is that the AAO is not a climate driver. Its a measure (symptom) of the interaction of other drivers. I dont believe that the AAO makes anything happen, rather, its a way of showing what is happening due to other factors. As such, I dont believe its predictable beyond the time frame of the synoptic modelling (day to day weather models) that we use to "measure" it.
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NZstorm
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Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland

Re: Southern Annular Mode

Unread post by NZstorm »

Chart here of the long term trend in the AAO. This trend suggests less cold breaks over NZ now.
SAM.JPG
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Simon Culling
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Joined: Mon 23/11/2009 06:41
Location: Tiverton, Devon, UK

Re: Southern Annular Mode

Unread post by Simon Culling »

This graph, giving the SAM since Sept 2018 and the current 14 day forecast, was placed on the MetService Twitter feed today:

https://twitter.com/MetService/status/1 ... 9436691456
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