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Riccardo

OCTOBER PATTERN INDEX (OPI) MONITORING WINTER SEASON 2014-2015

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Posted (edited)

I think the problem is that some people latched onto this and proclaimed it was a guarantee that the winter that year was going to be cold, which is nonsense because nothing is certain in weather and predictions are based on probabilities. The same way the papers latch onto the Met Office contingency planners and misinterpret them to create their headlines of a BBQ summer or freezing winter. It leaves people (perhaps unfairly) sceptical that there is any use to such predictions and parameters.

Edited by MattStoke

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Posted (edited)

Just another feeble attempt at pattern matching under a glamorous name, designed to sound intellectual and pseudo-scientific. It's already been demonstrated time and time again that pattern matching, under whatever guise, and no matter how intellectual the process is dressed up to sound, has a success rate no better than pure random chance. As such, one might as well use a crystal ball.

Edited by Thundershine

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Posted (edited)
1 hour ago, coldwinter said:

Plenty of papers on the subject as @interitus said in the other thread

imageproxy.php?img=&key=8d7953939bb9d610
RMETS.ONLINELIBRARY.WILEY.COM

 

 

Yes, the Kryjov paper, was going to repost this link. At the time back in 2015, way up this thread, it was paywalled. By using 500mb data at an arbitrary random location on the Taymyr peninsula it was possible to get an October geopotential - winter AO correlation of 0.62 over the 1976-2013 period, not quite the 0.9 touted for the mythical OPI but promising nonetheless. The method used in the paper above was alluded to in a follow up which shows it as calculated slightly differently - area averaged and at different altitude. Importantly their results appeared to be stationary over time which gives some hope that it may retain its utility.

The main raft of papers commonly refer to Arctic sea ice or northern hemisphere snow cover, either individually or in combination with various other indices eg QBO etc Work such as the Cohen SAI have famously shown strong links to winter AO though have since been questioned as non-stationary - the correlations may be more an artefact of a causative link rather than the cause itself. Also the proposed trop-strat-trop pathways have been difficult to reproduce in modeling studies.

To single out one author as a starting point, the works of Yannick Peings are a treasure trove -

His work on Ural blocking for example demonstrates that as well as generating the wave driven strat response, also leads to the Kara sea ice and Siberian snow cover which are suggested as possible causative factors by others.

Edited by Interitus

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53 minutes ago, Thundershine said:

Just another feeble attempt at pattern matching under a glamorous name, designed to sound intellectual and pseudo-scientific. It's already been demonstrated time and time again that pattern matching, under whatever guise, and no matter how intellectual the process is dressed up to sound, has a success rate no better than pure random chance. As such, one might as well use a crystal ball.

Indeed, Thundershine.

And if one were to wait for that absolutely perfect pattern-match to come along (anything-else simply won't do!) one may just as well wait for the wind to reassemble sandcastles...? For each perfect match there will be (from a deterministically chaotic perspective) an almost infinite number of utterly useless nearly-but-not-quite scenarios...

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10 minutes ago, Interitus said:

Yes, the Kryjov paper, was going to repost this link. At the time back in 2015, way up this thread, it was paywalled. By using 500mb data at an arbitrary random location on the Taymyr peninsula it was possible to get an October geopotential - winter AO correlation of 0.62 over the 1976-2013 period, not quite the 0.9 touted for the mythical OPI but promising nonetheless. The method used in the paper above was alluded to in a follow up which shows it as calculated slightly differently - area averaged and at different altitude. Importantly their results appeared to be stationary over time which gives some hope that it may retain its utility.

The main raft of papers commonly refer to Arctic sea ice or northern hemisphere snow cover, either individually or in combination with various other indices eg QBO etc Work such as the Cohen SAI have famously shown strong links to winter AO though have since been questioned as non-stationary - the correlations may be more an artefact of a causative link rather than the cause itself. Also the proposed trop-strat-trop pathways have been difficult to reproduce in modeling studies.

To single out one author as a starting point, the works of Yannick Peings are a treasure trove -

His work on Ural blocking for example demonstrates that as well as generating the wave driven strat response, also leads to the Kara sea ice and Siberian snow cover which are suggested as possible causative factors by others.

Not much point reading, as its just pseudo-scientific 😉  The Ural blocking in November is definitely interesting to watch, we had an anomaly there last year, which helped disrupt the PV, not quite giving the cold here that a lot of people wanted, but close and then eventually culminating in the  SSW. Everything is linked and the atmosphere gives us clues, it's never as simple as A+B=C which i think people keep getting confused with 

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