TV program - Horizon 17th July

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TV program - Horizon 17th July

Postby Darren Rogers » 2014 Jul 19, 21:23

Did anyone see the Horizon program broadcast on 17th July?
Googling some of the concepts I was unfamiliar with, such as QBOs, I came across a paper produced by the Met Office in February on which
the program appears to have been based. This traced the very wet weather of last winter all the way back to exceptionally wet weather in Indonesia.
This is where the trail stopped with no explanation of why this occurred (it was acknowledged that temperatures in the western Pacific were not abnormal i.e. no La Nina event) or how this event could have shifted the North Pacific jet stream.

Any thoughts? I wonder whether latent heat released high in the Troposphere could have any effect. But I am no physicist!
Darren Rogers
Maulds Meaburn
Cumbria (Half way between Shap and Appleby)

http://www.mauldsmeaburnweather.co.uk
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Re: TV program - Horizon 17th July

Postby greg_gruner » 2014 Jul 19, 21:36

I did read about something called the Madden-Julian oscillation, which is an eastwards-propagating enhancement of tropical rainfall (followed by a "wave" of lower rainfall) though I don't know if this had anything to do with that wet weather in Indonesia.
Greg Gruner
Farnborough, Hampshire
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Re: TV program - Horizon 17th July

Postby Len Wood » 2014 Jul 21, 20:41

Yes Darren, I saw most of it.
I agree the link with wet weather in Indonesia with ours in the UK was a bit difficult to follow.

Forecasting the wiggles in the jet stream is a can of worms.

Weaker zonal winds favour slower Rossby waves (reduced phase speed).

One thought is that high amplitude patterns in the jet stream are associated with extreme weather as the waves move slowly.

Last winter's wetness is all to do with position and number of waves.

Theory is all very well but the fact is the wiggles in the jet stream are baroclinic waves (depressions) influenced by the Rossby effect.

Recent focus has been higher in the atmosphere, to include sudden stratospheric warmings (in winter). This has had rather patchy success.

Nothing is straightforward due to the feedbacks on various time and space scales.
Len

Wembury, SW Devon coast
N50.33 W4.13
Altitude 83 m asl
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