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Stratosphere Temperature Watch 2015/2016


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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset

As per BA's above, it could be a long old December if we don't get wave activity into the mix

post-5114-0-34836700-1448716054_thumb.jp

Westerly QBO helping the u wind drive down to the 30mb level with relative ease, never a pretty sight.

However, I suspect though that the first decent single wave attack is not too far away now, all eyes on Mid December onwards I would say.

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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

That u wind plot also caught by eye Lancia, it's fairly tanking at top of strat. cranking along at 90ms.

 

Great charts again Andrew, agree FIM looks incredible at that grid value. Superb stuff.

 

Couple of forecast plots from the NASA suite.

 

Again the u wind looking robust.

post-7292-0-12194900-1448720365_thumb.jp

 

An extremely cold looking profile across all layers.

post-7292-0-68761300-1448720372_thumb.jp

 

Now to the short term and what can the next trop led heat flux do....

post-7292-0-15266000-1448720359_thumb.jp

 

 Dug out this link again, very fluid animation at 30hPa to run through from IMO.

http://brunnur.vedur.is/kort/gsm025/2015/11/28/00/gsm025_nhem_gh30_t30.html

 

Tip: If you are saving this it will revert to this date, so if you come back to it later remember to alter the dates in the url.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

Well, we can choose to fear a rampant vortex or dream of how dramatically it might break down should the wave activity feedbacks do their thing.

 

The displacement toward Siberia being modelled in the 10-16 day period is pronounced enough for me to allow myself to dream rather than hide behind the sofa. Let's hope that doesn't get toned down much, if at all!

 

Oh and - thanks Ruben for that link to a great example of Wave 1 displacement in Jan 2013, somehow I missed your post until today!  :search:  :rolleyes:

Edited by Singularity
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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

Hi all,

 

Just wanted to take the time to thank you for putting together an excellent and fascinating read about the Stratosphere and its effects on us in the Troposphere. I am a long time weather enthusiast, but never fully understood the mechanisms behind what drives the Stratosphere and in turn our sensible weather at the surface. I came across your site from a Google search looking to learn more about the Stratosphere. I am glad it brought me here :)

 

It seems most of you are from the UK. I am from the U.S. I'm not sure how often I will be posting but definitely wanted to take the time to just say thanks. 

 

Best,

 

Frank

 

Hi Frank, welcome along to Netweather, great to have more international contributions to the thread. Enjoy the thread! Plenty to much in the coming weeks to keep everyone occupied.

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Posted
  • Location: Slovenia, Central Europe 1050m ASL
  • Location: Slovenia, Central Europe 1050m ASL

Hey Frank, glad to have you aboard. Yes, most people in here are either from UK or USA. Personally, I am an "outlier" in that aspect, like a failed ensemble perturbation, being from Slovenia in central Europe. :D

 

To Lorenzo:

Here are some graphics from that NASA model, showing basically what those graphics are showing, a strengthening vortex, temperature and height wise in the core, but as the core of the vortex strengthens, so does the angular momentum of the vortex itself, which is evident on the stronger PNJ in the "surf zone". 

The NASA suite by Recretos :D:

 

t-in-inst33dasmcp2015112.png u-in-inst33dasmcp2015112.png h-in-inst33dasmcp2015112.png

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Hi all,

 

Just wanted to take the time to thank you for putting together an excellent and fascinating read about the Stratosphere and its effects on us in the Troposphere. I am a long time weather enthusiast, but never fully understood the mechanisms behind what drives the Stratosphere and in turn our sensible weather at the surface. I came across your site from a Google search looking to learn more about the Stratosphere. I am glad it brought me here :)

 

It seems most of you are from the UK. I am from the U.S. I'm not sure how often I will be posting but definitely wanted to take the time to just say thanks. 

 

Best,

 

Frank

Welcome to netweather, Frank! :D  :D

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

To start next week I'm intending do a bit of reading to get to grips with how wave breaking can (via a SSW) ultimately lead to temperatures well above freezing even at high levels of the stratosphere and an anticyclonic circulation.

 

 - but I've already done a bit of thinking on this over the past couple of hours and I'm wondering how close - or far away - my thoughts are from the reality. Below, I've outlined the process that I'm imagining at this point in time:

 

A wave break punches into the vortex, and is drawn up to higher levels of the stratosphere (assuming the vortex has net rising motion because without that how would it be rotating anticlockwise?), during which time the air within both cools and dries out (via mixing). This inevitably leads to bouyancy being no longer able to counter the mass imbalance and hence the wave descends. Being drier than it was before, warming occurs at closer to (or at) the adiabatic rate, resulting in a greater increase in temperature relative to the drop that occurred on the way up. This results in those balmy temperatures (I'm sure I've seen values of +20*C or so at the hear of a SSW), while the descending motion is responsible for the clockwise circulation.

 

 

So to reiterate the question; how close, or far away, am I with this initial theory that's based largely on what I know of thermodynamics in the troposphere?

 

 

Many thanks in advance for your response(s) - and I don't mind if it's not today as it is Sunday after all, which should to be honest be a day of chilling out - irrespective of the weather conditions!  :good:

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

My thoughts, put in a simple way Singularity ( I am no physicist!), are this.

 

The wave break, if strong enough, affects the top of the stratosphere, both disrupting the polar vortex at this height and introducing warmer air that breaks through the 'surf zone' that normally demarcates the boundary. This then causes further compressive warming as the pressure in the collapsing vortex increases. This compressive wave then descends down the stratosphere until it reaches a point where the pressure inherent in the lower stratosphere is strong enough to prevent full reversal, but the wave can still split or displace the vortex and weaken considerably.

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Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx
Excerpt from Baldwin and Dunkerton 1999 gives the same description as both of the above in the 'science paper' language, also introduces E-P Flux and why we like looking for those poleward arrows !

 

Stratospheric warmings involve interactions between the zonal flow of the polar stratosphere and upward propagating planetary waves consisting primarily of zonal wave numbers 1 and 2. Normally, the zonal flow is very strong in the wintertime lower polar stratosphere and vertically propagating waves tend to be deflected equatorward. But if the lower stratosphere is “pre-conditioned†by earlier wave activity, the zonal flow is weakened or moved poleward and vertically propagating waves tend to be deflected poleward.

 

The vertical component of the E-P Flux (Fz) which is proportional to the poleward heat flux maximizes at about 10 hPa at this time. The area above the heat flux maximum (divergence of wave forcing) acts to decelerate the eastward zonal flow.

 

A residual circulation then induces sinking motion below and poleward of this forcing region. The sinking motion causes the temperatures to increase due to adiabatic warming. This reduces the thermal gradient which in turn reduces the zonal wind speed. These large temperature and wind anomalies then propagate downward  into the lower stratosphere (Baldwin and Dunkerton, 1999; Limpasuvan et al., 2004).

 

Zonal Mean Zonal Wind and EP Flux from JMA

post-7292-0-40169800-1448811370_thumb.gi

 


post-7292-0-43107000-1448811479_thumb.gi

 

Then you get into conditions in the atmosphere which are beneficial and non-beneficial to EP Flux propagation, sea ice, solar flux etc. It's an area that continues to reveal and we learn something new about each season.

 

 

 

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Posted
  • Location: Camborne
  • Location: Camborne

To start next week I'm intending do a bit of reading to get to grips with how wave breaking can (via a SSW) ultimately lead to temperatures well above freezing even at high levels of the stratosphere and an anticyclonic circulation.

 

 - but I've already done a bit of thinking on this over the past couple of hours and I'm wondering how close - or far away - my thoughts are from the reality. Below, I've outlined the process that I'm imagining at this point in time:

 

A wave break punches into the vortex, and is drawn up to higher levels of the stratosphere (assuming the vortex has net rising motion because without that how would it be rotating anticlockwise?), during which time the air within both cools and dries out (via mixing). This inevitably leads to bouyancy being no longer able to counter the mass imbalance and hence the wave descends. Being drier than it was before, warming occurs at closer to (or at) the adiabatic rate, resulting in a greater increase in temperature relative to the drop that occurred on the way up. This results in those balmy temperatures (I'm sure I've seen values of +20*C or so at the hear of a SSW), while the descending motion is responsible for the clockwise circulation.

 

 

So to reiterate the question; how close, or far away, am I with this initial theory that's based largely on what I know of thermodynamics in the troposphere?

 

 

Many thanks in advance for your response(s) - and I don't mind if it's not today as it is Sunday after all, which should to be honest be a day of chilling out - irrespective of the weather conditions!  :good:

 

I'm struggling with the highlighted section. This is more or less a description of the Fohn effect and the rising and falling at different lapse rates but the moisture content of the air at this level is tiny so I'm not sure why it should apply. I can't see what is forcing the air to rise in the first place but I can see where the adiabatic process applies when the cold air 'falls' into the vortex and thus is compressed and warms dramatically after the propagating waves have reversed the eastward flow.

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

I'm struggling with the highlighted section. This is more or less a description of the Fohn effect and the rising and falling at different lapse rates but the moisture content of the air at this level is tiny so I'm not sure why it should apply. I can't see what is forcing the air to rise in the first place but I'm can see where the adiabatic process applies when the cold air 'falls' into the vortex and thus is compressed and warms dramatically after the propagating waves have reversed the eastward flow.

 

r.e. the highlighted section of your quote of my post, I figured that as the waves originate in the troposphere they start off with a lot more moisture than the stratosphere has. How quickly that's mixed out, though, is something I've yet to discover.

 

As for the rising motion in the vortex, that's a good question given that the stratosphere gets warmer with height once above about 20 km altitude - one I somehow overlooked. But with no rising motion, what would cause the cyclonic rotation to get going in the first place? The mystery deepens.

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Posted
  • Location: Camborne
  • Location: Camborne

I'm sure there are others on here who can answer this as it's a bit above my pay grade as I suspect it involves potential vorticity amongst other things. This paper polar vortices may help although I suspect a link to it has already been posted.

Polar vortices.pdf

Edited by knocker
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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

I'll give that one a read tomorrow, thanks Knocker.

 

Chino's post brings into play the effect of compressing an ideal gas to raise temperature. I get how this works as the vortex collapses but I wonder if it is also behind the fact that the peak temperature occurs all the way up at 10 hpa - as air within the stratosphere is compressed ahead of the wave? The use of the phrase 'further compressive warming' seems to imply this.

 

From Lorenzo's post I see the descending motion, which I thought might relate to cooling of the wave, is more a result of the heat maximum at 10 hpa in some way causing the zonal flow to decelerate above it (as flow lines diverge around it?), with convergence forcing subsidence. The 'residual circulation' is... in the vertical? That bit is less clear.

 

 

I have noticed from the 3D animations that having weakened the vortex, the warmest air tends to end up focused as a distinct anticyclonic circulation to accompany the displaced or split vortex - seemingly behaving like a tropospheric high pressure cell. I suppose these tend to correlate well with the areas of blocking high pressure following SSW events - I remember the Aleutians becoming mightily blocked late Jan/early Feb last winter, under the peak warming.

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Posted
  • Location: Camborne
  • Location: Camborne

One thing I meant to mention and forgot. You said this in an earlier post.

 

 

I figured that as the waves originate in the troposphere they start off with a lot more moisture than the stratosphere has. How quickly that's mixed out, though, is something I've yet to discover.

 

As far as I'm aware this is wrong as this isn't how waves work. A wave can be defined as a form or a state of disturbance advancing with a finite velocity through a medium. By means of a wave, energy is transmitted, being passed along from one part of a medium to the next by interaction of adjoining parts. Each wave takes along with it a certain definitive quantity of energy, which remains with it. The wave may be considered as perturbation on the steady slowly changing background.

 

From this stratospheric circulation anomalies are caused mainly by wave forcing from the dense troposphere. Stochastic variations in the troposphere lead to high-frequency changes in the planetary wave flux upward into the stratosphere. When these waves break, they deposit momentum in the stratosphere, slowing the zonal mean wind and weakening the polar vortex. The interaction of the waves with the mean flow tends to draw these zonal wind anomalies downward through the stratosphere.

Edited by knocker
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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

Recretos - we often call it KISS

 

Keep It Simple Stupid!

 

One of the things that I always try and do (not always successfully) is explain physical processes simply and in the way that the reader understands. I hope that those who are studying meteorolgy (singularity?) and physics can come and do this back when they move onto the next level!

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Posted
  • Location: Catchgate, Durham,705ft asl
  • Location: Catchgate, Durham,705ft asl

In the spirit of keeping things as simple as possible, :D i'm quite liking the shape and position of the PV that GFS is touting in FI,especially when compared with now.

 

now..post-2839-0-43345700-1448874575_thumb.gi   far far away....post-2839-0-89374200-1448874241_thumb.gi

 

 

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

One thing I meant to mention and forgot. You said this in an earlier post.

 

 

As far as I'm aware this is wrong as this isn't how waves work. A wave can be defined as a form or a state of disturbance advancing with a finite velocity through a medium. By means of a wave, energy is transmitted, being passed along from one part of a medium to the next by interaction of adjoining parts. Each wave takes along with it a certain definitive quantity of energy, which remains with it. The wave may be considered as perturbation on the steady slowly changing background.

 

From this stratospheric circulation anomalies are caused mainly by wave forcing from the dense troposphere. Stochastic variations in the troposphere lead to high-frequency changes in the planetary wave flux upward into the stratosphere. When these waves break, they deposit momentum in the stratosphere, slowing the zonal mean wind and weakening the polar vortex. The interaction of the waves with the mean flow tends to draw these zonal wind anomalies downward through the stratosphere.

 

Blimey, I was taught that about waves in secondary school (with respect to the ocean in that case) yet I completely failed to make the connection. Talk about not seeing the wood for the trees!

 

So having thought about your words for a few minutes, I'm seeing a wave moving the atmosphere one way then the other, deflecting upward from the troposphere to affect the stratosphere, where upon breaking (which I'm getting the impression must happen at the top of the strat) it may interfere with the zonal flow by adding momentum in other directions, resulting in a net reduction in the zonal mean wind. Faster zonal wind upstream then leads to convergence and warming.

 

Imagining a 3D wave with a peak magnitude that also causes the peak warming, I can see stratospheric warming in a new light. Either that or I'm more confused than before!

 

 

 

I actually look upon meteorology in a similar way to Chiono and Recretos by default; in fact I completed a Masters in the subject despite being in no way a mathematical genius and having had a D in Physics at A-Level. Admittedly I did have to bring by understanding of thermodynamics up to expert level in the sense of equations etc, but for the most part I still visualise systems where I can.

 

This aspect regarding waves is probably the key I've been missing. I was visualising them like ocean waves crashing into a cliff face, the upward spray being the deflection talked about wrt planetary waves. That's a result of spending some time looking at mountain torque events, where it's about a flow of the atmosphere coming up against high terrain - which I was thinking of as a wave of the atmosphere.

 

 

Thinking about the bucket of water analogy, the intrusion is the residual momentum following the wave break, right?

 

My goal in meteorology is to understand as much as I can in ways that can be explained as simply as possible, as much of my work involves doing just that to clients who require forecasts that use complex theories yet can be justified with the minimum of jargon. If it involves talking about buckets of water, then so be it!  :D

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Posted
  • Location: Slovenia, Central Europe 1050m ASL
  • Location: Slovenia, Central Europe 1050m ASL

Not keen on your new avatar Recretos!

 

its just music and art, nothing else. :) But I have changed it nonetheless. :)

 

So this post wont be totally offtopic, I will add some latest CFS ENS projections. Its really keen on the wave1 scenario, progressing it (perhaps even too slow) all the way into January. 

 

geopotentialheightisobar.png temperatureisobaric-in-1.png geopotentialheightisobar.png

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