Stratosphere Temperature Watch 2015/2016

[knocker]

 

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.

 

 

 

In fact ocean waves are no different. They are traveling oscillations that transfer energy over large distances even though the water itself goes nowhere. It just oscillates as the wave passes by. So in fact all waves have similar properties but of course have different root causes.

[Paul_1978]

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. 

 

  

Keep up the great work! :-)

[Singularity]

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. 

 

  

 

That last chart ties in well with the GFS 00z det. run except that it's a number of days quicker to get there. The GFS version:

 

 

With the vortex looking pained:

 

 

...albeit still mightily cold-hearted!

Edited November 30, 2015 by Singularity

[bluearmy]

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

 

now..NH_HGT_100mb_000.gif   far far away....NH_HGT_100mb_384.gif

 

as low down as 100mb, the gfs fi is as reliable as the trop output though. need to go above 20hpa imo to get a decent reliability on heights at two weeks range. and that high up doesn't generally offer too much insight into trop patterns.

[Cloud 10]

as low down as 100mb, the gfs fi is as reliable as the trop output though. need to go above 20hpa imo to get a decent reliability on heights at two weeks range. and that high up doesn't generally offer too much insight into trop patterns.

 

 

Similar movement of the vortex at 10mb though.and seems to tie in with the recent GFS op run FI Northerlies,so maybe the trop and strat in sync?

 

[Nick B]

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!

 

 

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?

 

I would have thought that if an atmospheric wave is analogous to an ocean one, then there is more to this.

 

With an ocean wave, its propensity to break is surely based on the interplay between between the wavelength, the amplitude and the thickness of the available medium through which it is travelling? i.e. a wave with a higher amplitude in relationship to its wavelength would break more readily when the medium is constricted (I'm imagining an ocean swell as it approaches the beach).

 

Is this why a low amplitude wave can only make minimal impact through the lower part of the stratosphere and at most may cause slight displacement and wobble of the PV for a short period of time before it strengthens once again?  Whereas a real monster of a wave 1 with a big amplitude colliding with a PV is going to break through a very large percentage of the stratosphere, dissipating its energy in many chaotic directions, causing it significant disruption.

 

Some speak of wheels with sticks placed in the spokes, or spinning tops etc. but I'm not sure they're the best analogy.  I think everyone has seen a whirlpool in a round bowl, however, and that might be the easiest to grasp (although not perfect).  In fact, if there are any sediments in the water (they are denser than the water), you could see they will usually find their way to the centre - analogous to the denser cold air being trapped at the heart of the PV.  Set up a whirlpool first (by spinning the water and then leaving it a little while) - then the core (of the whirlpool) is the PV.  Disturb the flow very slowly over a minimal depth and a small cross section, i.e. a little finger near the edge of the bowl and the core of the whirlpool survives - in fact is hardly troubled at all, just maybe displaced temporarily.  You would see very little effect on the sediments  - the cold air stays where it was within the vortex itself.  Do this less slowly, nearer the middle of the vortex, with four fingers and allowing them to penetrate through more of the depth of the water, introducing a little flick to provide a 'wave' and the vortex will have real trouble surviving, and your sediment - the cold air, is forced outwards from the vortex in all manner of chaotic directions.  However, given time, due to the net movement of all the water, the vortex will of course reform.

 

So I think how and where in the stratosphere the wave breaking might occur is dependent on:

1. the amplitude of the wave;

2. the wavelength;

3. the strength of the PV at the time.

 

If you want to trouble a raging PV, it had better be a big wave 1 to begin with, followed by further waves 1 and 2 mixed to offer it minimal chance of re-establishing too quickly.

[Singularity]

I'm not the best person to verify those thoughts Nick, but it seems logical to say the least, thanks for your input 

 

I've been focusing on the waves that manage to achieve significant results - hence the upper strat being the region in which the break occurs. The idea of weaker waves breaking lower down seems to make a lot of sense given what I've seen in the model output lately; modest wave breaking which produces a more pronounced warming at 30 hPa than 10 hPA.

 

 

This thread, like those before it on the same topic, is already looking to be among the best resources out there from an educational perspective 

[Recretos]

You also have to understand that these processes happen all the time, we just happen to notice them when they have large enough of a effect. There are many ways you can track this otherwise invisible energy flowing about. I tend to use 2 or 3 parameters. Horizontal flux divergence and ageostrophic wind flux. The basic idea of these, is tracking abnormalities, in what would otherwise be a perfect vortex. So basically, tracking wave-breaking induced imperfections. 

 

As an example, I will use GFS high res. data from the 06z run today. I will show only 1mb level, where this processes usually appear first or are the most amplified. So I havent editet the text on the graphics. its basically all at 1mb level in the FI. So all graphics belong to the same model and time. 

 

When we usually look at 1mb, geopotential height, we usually see the vortex, but we are kinda oblivious to the processes that happen in and around that vortex. There is more hint tho by looking at the temperature. 

 

  

 

But there is more to it than just the temperature. here is Ageostrophic flux, which is useful when looking at the surf zone where mainly the wave breaking occurs. Over the pole, that is classic zonal-meridional mumbo jumbo. But we do see two zones of potential energy being at work. One is the Asian sector, and one over the Euro sector. When you look at this, you kinda get the feeling you are looking at the water surface, with all these wave-forms. You can also notice some disturbances over North America, over the Rockies. And keep in mind this is at 1mb height. This graphic, or this parameter is really powerful and useful in its own aspect. 

 

 

 

Next thing is Horizontal flux divergence. here we can get a much better idea how and where the main energy disruption is working. And we do see the main region being the Asian sector, which is where the most warming is occurring in the model at this level.

 

 

 

This is just meant as an example, how you can analyse these otherwise invisible processes in a different aspect. Kinda like putting on glasses and seeing the otherwise invisible stuff. The truth is of course, that you need some plotting and modelling skills to do it on your own, if it is not available otherwise. Almost a recommendation is, to use as high resolution data as possible. I use GFS 0.25° grid in these examples. 

Edited November 30, 2015 by Recretos

[Singularity]

So... the ageostrophic flux is the chaotic variation away from the geostrophic flow that characterises the vortex, while the horizontal flux divergence represents the effect of that on the temperature? I see the time resolution is minuscule there, I guess that's an estimation as GFS data at intervals of 1 second would mean data counts that would... break the internet 

 

However accurate my interpretation, those are excellent charts and with any luck I'll know a way of producing similar things myself one day, as I get a real kick out of creating visual representations of data 

[Recretos]

Sorry for the double post, but I will make one, because it is kinda a different aspect, and a different model. 

 

actually, that is not the factor for time, but rather for the temperature. its not really THAT important, since the spatial distribution is kinda more of importance here, and the units are more for a general urpose of comparison with other events. 

 

why resolution matters? Look at this. This is ageostrophic flux, from FIM9 model, 0.125 grid, at 5mb, at some 336h forecast period, but the main point is, you can actually see or feel the energy processes at this level like it were fluid. Like looking at a water surface, when you throw a rock in.  In 2D and 3D.

 

   

 

I forgot to add one more rule to my previous post.

 

In the stratosphere and generally about the polar vortex, there is much more than meets the eye.

[joggs]

Brilliant Recretos.

[Nick B]

Brilliant Recretos.

Exactly. Not so much the "failed perturbation" as he put it, more the trendsetter (along with chiono!).

[hooch5]

Recretos, Thank you for posting the last 2 frames, absolutely brilliant,  

[Recretos]

Thanks guys!

I sure hope that Cohen is using the new version of the GEFS, since using the old one is kinda pointless for strat. 

[Singularity]

 

From watching the GFS output over the past month at both the 500 mb and 30 hPa levels I gather that having a deep trough setting up over Siberia while a ridge to the east of there extends right up to the pole is an excellent setup for wave breaking capable of displacing the PV in ways that promote favourable blocking patterns wrt cold conditions in the UK.

If that's correct then the ECM 12z det. run of today is an excellent one for some decent wave breaking from the Asian side.

 

Meanwhile the GFS 12z det. undercuts that ridge in a week's time, resulting in an Arctic High that messes with the trop. vortex but doesn't provide that poleward flux that we're looking for to hit the strat. vortex. On the other hand, the messed up trop. vortex does allow for that Siberian trough and poleward ridge to the east combination to develop nicely at the end of the run, with decent strat. warming at 30 hpa for the time of year:

 

 

Given how little faith I place in the GFS' handling of forcing on the AAM beyond maybe 5 days range, and the possibility that ECM may have the same issues (i.e. tending to go too negative with the AAM), I find the ECM run to be the most encouraging - so I hope it's right about the level  wave amplification at that time.

Again, all depending on my interpretation of the Siberian trough/poleward ridge combination being correct! 

[Singularity]

 

From watching the GFS output over the past month at both the 500 mb and 30 hPa levels I gather that having a deep trough setting up over Siberia while a ridge to the east of there extends right up to the pole is an excellent setup for wave breaking capable of displacing the PV in ways that promote favourable blocking patterns wrt cold conditions in the UK.

If that's correct then the ECM 12z det. run of today is an excellent one for some decent wave breaking from the Asian side.

 

Meanwhile the GFS 12z det. undercuts that ridge in a week's time, resulting in an Arctic High that messes with the trop. vortex but doesn't provide that poleward flux that we're looking for to hit the strat. vortex. On the other hand, the messed up trop. vortex does allow for that Siberian trough and poleward ridge to the east combination to develop nicely at the end of the run, with decent strat. warming at 30 hpa for the time of year:

 

 

Given how little faith I place in the GFS' handling of forcing on the AAM beyond maybe 5 days range, and the possibility that ECM may have the same issues (i.e. tending to go too negative with the AAM), I find the ECM run to be the most encouraging - so I hope it's right about the level  wave amplification at that time.

Again, all depending on my interpretation of the Siberian trough/poleward ridge combination being correct! 

 

Addition 2nd Dec: The evening runs today feature enough periods of wave amplification to maintain the hopeful stance from yesterday. 

Interesting how ECM's 12z det. is more progressive in the middle but manages a sharper trough/ridge combo toward the end which happens to place the UK on the cold side of things - the possible cold snap that I alluded to a day or two ago following consideration of the AAM projections from GEFS. 

[Frank_Wx]

Has anyone heard / seen this plot from Meteorologist Ryan Ashoka? It suggests strong early Autumn PVs lead to dramatic weakening by late Dec / early Jan. Interesting. 

[chionomaniac]

7 hours ago, Frank_Wx said:

Has anyone heard / seen this plot from Meteorologist Ryan Ashoka? It suggests strong early Autumn PVs lead to dramatic weakening by late Dec / early Jan. Interesting. 

I hadn't see this particular graph but it is well known that strong vortex conditions rarely last throughout a whole season. Having said that this vortex is particularly strong and is forecast to get even stronger in the coming weeks. Hopefully the upcoming pattern in around 10 days will start on the weakening.

[Ruben Amsterdam]

Ryan Ashoka? If this is the Ryan Ashoka (winterexpert?) I think it is, this may not be a reliable source...

[Recretos]

Well, after the first period of strengthening, the GEFS does take the vortex into an offset mode, basically with the induced wave1, reducing the zonal mean zonal wind at 10mb at 60N latitude. 

The biggest (almost shocker) spin comes from the Bias Corrected GEFS, which is now in the new version only. The old GEFS is dead, so to speak.

It has a really interesting situation, with a strong spatial temperature wave and a GW1 to reckon with. Impressive for an ensemble mean at 384h. The normal GEFS (non-BC) is really also quite similar. 

  

This is getting interesting.

 

 

Edited December 3, 2015 by Recretos

[Ruben Amsterdam]

29 minutes ago, Recretos said:

 

I Like this graph! Let's see if in two-three days time the yellow and green colors get more dominating and closer to +144hrs. 

[chionomaniac]

17 minutes ago, Ruben Amsterdam said:

I Like this graph! Let's see if in two-three days time the yellow and green colors get more dominating and closer to +144hrs. 

Recretos, did you use a bit of ' artistic licence' to get each distinct ensemble member to look like they blend into each other? Also do you know the ensemble means at T+96 and T+384? Cheers 

[Glacier Point]

.. and this little bomb is interesting...

Deep low pressure system tracking through the North Pacific trough, allied to around 10 days worth of low level wave forcing in the region. Very amplified Pacific sector as well, strong +dt/daam overlaying this, and +MT over N. America within 5 days.

Edited December 3, 2015 by Glacier Point

[chionomaniac]

 

31 minutes ago, Glacier Point said:

.. and this little bomb is interesting...

Deep low pressure system tracking through the North Pacific trough, allied to around 10 days worth of low level wave forcing in the region. Very amplified Pacific sector as well, strong +dt/daam overlaying this, and +MT over N. America within 5 days.

Hi Stewart, I hope that you are well. We have started this season with a pretty miserable period of Vortex Intensification and we have had pretty little to go on to disrupt this so this change is welcome.

This NP trough was showing pretty well on the 10- 15 day EPS ensembles 00Z leading to a great amplified flow. When I checked the 850's the temp anomaly for East North America is as great as I've ever seen ( and we think it is warm over here, lol).

 

I seem to have trouble looking for a WAF forecast chart right up into the strat (like Cohen blog) - I dont know if you hacve access to one or whether Net weather or Recretos could construct one from a data file - Is there one available? I've been using the following to help but they don't go far enough out and the strat effect Andrej has produced in the GEFS is the best evidence of any change we have seen so far andf that is mild to moderate only so far.

 http://acdb-ext.gsfc.nasa.gov/Data_services/Current/seasonal_strat/seasonal_strat.html

 

Berlin charts are back up and running for those that may have noticed.

[Glacier Point]

Hi Ed. I'm sorry I don't have access to any WAF type forecast plots.

I'm not surprised in the least about the vortex this far. There are reasons outside of ENSO and the QBO which have flagged this for some time (although at this stage I'm unable to detail them).

Thus far, we do have a text book Cohen model response - October snow cover, November Siberian High, December Aleutian Low. Just need that to be sustained (and latest EC week 4 plot was good for that) and it's over to the strat response.