[Stratosphere Temperature Watch 2014/2015]

Hi s4 - I meant to answer this earlier but didn't have time to do so. There is no Berlin historical data website that I can find. I have kept some but did lose earlier years due to previous computer crashes..

 

One can always get an idea of the previous years from this site:

 

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

 

or the Merra datasets

 

http://acdb-ext.gsfc.nasa.gov/Data_services/met/ann_data.html

 

 

 

 

 

I now consider it all interlinked. The stronger the strat PV, the stronger any trop jet will be, and that when conditions are right, a stronger wave deflection into the strat occurs as a result. Rather like a long jumper - he will jump a lot further if his run is faster than just a standing jump alone - the wave break into the strat can be considered similar.

 

Yes, Is it correct to state that It requires more energy to disturb a strong vortex but when it happens the effects will be more spectacular? And: a weakened vortex is easier to disturb but the effects are less? There is a lot in between these....

 

On the other hand: a strong trop-jet (caused by a strong start PV) creates more energy and chances for MT's and warming are bigger.

 

Its all a matter of balance but Ideally it would be a weakened strat PV and relative strong trop-jet?

[Stratosphere Temperature Watch 2014/2015]

The current tropospheric pattern with the extremely strong Scandi positive anomaly is catching my eye big time. 

 

 

This is something that we expected with the high SAI and it has not failed.

 

However, look at the upcoming pattern - here are the ECM cumulative anomaly charts

 

Days 1-5

get_orig_img-3.gif

 

Days 6-10

get_orig_img-2.gif

 

Watch that westward progression of the Scandi high - this is often seen prior to a displacement event in the strat

 

Here are the slp anomalies from Cohens paper to watch out for prior to displacement SSW's

 

Screen Shot 2014-11-16 at 21.30.28.png

 

Compare to what is programmed. So any sign of a 'big' wave 1 strat warming.

 

You bet!

 

NH_TMP_1mb_384.gif

 

Game on.

 

That's the point I tried making yesterday evening. The Skandi-high is troposferically holding on due to stratosferical weakening and displacement. Both Gfs and ECM support this up to T240.

 

Chio: in line with your image of two dancers: the troposferic one leads the dance here because the stratosferic dancer allows it or is not able to the take the lead.

 

I expect the first cold spells late nov/early dec. It won't be "big-time" but the first dance sets the tone...

[Stratosphere Temperature Watch 2014/2015]

I think the developments arround T240 are quite interesting: both GFS and ECMWF predict ridging at 500HPA in the direction of Iceland/Greenland:

This introduces a cold spell from the North.

 

http://www.wetterzentrale.de/pics/Recmnh2401.gif

 

https://max.nwstatic.co.uk/gfsimages/gfs.20141115/18/240/npsh500.png

 

the, at that time reinforcing, stratosferic vortex also positions in that place:

 

https://max.nwstatic.co.uk/gfsimages/gfs.20141115/18/240/npst30.png

 

I don't know but it looks to me that at this stage the (shattered) troposferical vortex determines the development of the stratosferic vortex and not the other way.

 

 

.

[Stratosphere Temperature Watch 2014/2015]

It's early days, and Wave 1 activity looks pretty good for the time of year - the FU berlin strat charts based on yesterday's ECM has it heading towards 400 at 30hpa/60 degrees north, which is significantly above average for the time of year

http://acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra/z1n_30_2014_merra.pdf

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=f192&var=ha1&lng=eng

 

Hm, Do I read it correct in this graph that the wave-1 activity in oct. last year was also above average (even way above the upper variancy)?

[Stratosphere Temperature Watch 2014/2015]

I think that is like asking what side a spinning coin will land on. What we do know is where the waves are likely to break into the stratosphere - that is associated with torques from the mountain ranges and the GWO.

 

That software is looking great Recretos - let's hope that we have a better case study for it this year!

 

yeah, that's truth but what I mean is: it will land somewhere either displaced or splitted. Can we say something about the effects that specific "landing-places" have on the tropospheric vortex and thus on the effects on the winter-weather?

 

I know I am placing a big question and I know that understanding the behaviour of the stratospheric vortex is still in early investigation but in-the-end its is all about the effects this has on the troposherical conditions!

[Stratosphere Temperature Watch 2014/2015]

Thanks Chio for your excellent baseline posting!

 

I am following this thread for a couple of years now and I am learning a lot!

 

What still puzzles me very much is the positioning of the stratospheric vortex in wintertime. Clearly a strong vortex will be highly central to the noth-pole but when weakened, displaced or even split, where will it "land"!? And what effect will that position have on the troposferic position. It seems to me this is a question we should be investigating to understand the stratosphere/troposphere coupling and effects on tropospheric blocking?

[Stratosphere Temperature Watch 2012/2013]

Talking about lag-times: on the basis of what is written in this thread it is clear to me that there is a lag time between the occurrence of a SSW and the stratosferical vortex response (displacement, split etc.).

But I am still struggling with the lag time between stratosferical vortex changes and the troposferical effects they have. I understand that there are a lot of processes involved (coupling is discussed in this thread) there but there must be a lag.

It looks to me that the current restoration of the stratosferical vortex almost instantaneously has an effect on the enormous troposferical W-E transport of LP-energy across the Atlantic. It might be a coincidence with historical stratosferical events but I would like to understand this.

Another question: Do (and to what extent) the weather-models take the physical interaction (including SSW's) between stratosphere and troposphere active into the modelling account or are they purely based on historical data?

Any thoughts on these questions?

I know Chio mentioned that the troposferical vortex above Canada is getting disconnected from the stratosferical one but the amount of energie this is moving across the atlantic currently appears to me as a strong troposferical polar Vortex. The 500 Hpa models show that HP intermittently tries to move north but is continously "ironed" away in the coming days/weeks.

I am still very much trying to understand whether and how this troposferical condition relates to previous stratosferical events.

My question about the models is related to that: maybe they dont model/calculate those coupling processes at all... Then I know what the value of model-predictions is.

[Stratosphere Temperature Watch 2012/2013]

Talking about lag-times: on the basis of what is written in this thread it is clear to me that there is a lag time between the occurrence of a SSW and the stratosferical vortex response (displacement, split etc.).

But I am still struggling with the lag time between stratosferical vortex changes and the troposferical effects they have. I understand that there are a lot of processes involved (coupling is discussed in this thread) there but there must be a lag.

It looks to me that the current restoration of the stratosferical vortex almost instantaneously has an effect on the enormous troposferical W-E transport of LP-energy across the Atlantic. It might be a coincidence with historical stratosferical events but I would like to understand this.

Another question: Do (and to what extent) the weather-models take the physical interaction (including SSW's) between stratosphere and troposphere active into the modelling account or are they purely based on historical data?

[Stratosphere Temperature Watch 2012/2013]

Not a stupid question, skatefan.

The tropospheric vortex and residual stratospheric vortex is still strong enough to create this affect. The stratospheric Canadian vortex is being further warmed at 10 hpa which is higher up than 30 hpa. It is only when the vortex is weakened at this level that the tropospheric Canadian vortex begins to wander across the Atlantic.

So, to be sure if i understand you correctly, the warming of the stratosferical Canadian vortex at 10 hpa creates the un-coupling of the troposferical one?

It still leaves me with the question why the movements of the stratosferical vortex and the troposferical movements seem to be happening simultaneously.

[Stratosphere Temperature Watch 2012/2013]

Stratospherically we are still seeing a NH pattern dominated by the recent SSW. Contrary to some opinions, this has downwelled from the mid stratosphere and affected the troposphere. It is always hit and miss how and where the SSW can have knock on effects in the troposphere and it appears that we have been lucky to see the split vortex favourably positioned to prevent the jet stream powering through during the two week mid January period.

However, that is about to change as further warming of the stratospheric Canadian vortex which allows it's tropospheric counterpart to break free. West to east momentum initially is set to carry this across the Atlantic to its Siberian counterpart as can be seen in this 30 hPa chart.

As this occurs there will be a corresponding increase in Atlantic mobility allowing the westerlies to reach the UK rather than be held at bay. The stratospheric vortex even though weak will be positioned on the Atlantic sector meaning a far less meridional jet stream whereas the Pacific sector will have a far more disturbed flow due to the upper ridge holding strong. This pattern will be as of a direct consequence to recent stratospheric events - but the wheel of fortune will be dropping off the meridional cold flow elsewhere in the NH.

So the main question that everyone is asking is will we likely to see a pattern re- emerge that can bring back the cold and blocking to our shores. And the answer is not immediately but definitely not no!

With the weakened vortex conditions likely to persist for a period of time then it is only a matter of time before realignment occurs in line with the MJO and GWO.

The stratospheric forecasts during the next 10 days right up to 10 hPa are showing and will show signs of increased fluctuations in the exact position of the vortex.

There are signs of another split occurring around day 10 and this will need to be watched carefully.

If this does occur then we could quite easily see the door to returning cold opened back up again. I think we will need to keep an eye on the strat forecasts very closely in this period.

Dear Chio, thanks for all your interesting and exciting posts. I think that you contributed a lot to the knowledge about stratosferical processes and the the prediction and effects of SSW's! My compliments for your work here.

I am still struggling, though, with the developments of next week. You state that the stratosferical canadian vortex (30 hpa chart) is moving to the atlantic and is trying to move to/merge with the siberian vortex. Why is that movement so strong with a heavily weakened vortex?

Troposferically (500 hpa) i see the same movement: a lot off LP-energie comes across the atlantic and is moving to Skandinavia, the Jet is moving further North.

It suggests that those stratosferical and troposferical movements are coupled. They coincide at least in time. You wrote in your post that due to continued warming of the stratosferical vortex above Canada, the troposferical one brakes free. Am I overseeing something or is this just coincidence.

I am eager to learn so please forgive me my possible stupid question.

[Stratosphere Temperature Watch 2012/2013]

More interesting stratospheric charts today.

So, so far this winter we have seen early tropospheric wave breaking into the lower strat whilst simultaneously the mid strat has cooled dramatically. A massive increase in wave 1 activity then has led to a displacement SSW and this has immediately been followed by an increase in wave two activity leading to a split vortex and another warming. And that is pretty much where we are today.

Looking at the 10 hPa charts we see a strong Canadian vortex with a weker Siberian vortex in situ with a ridge keeping them apart.

BY day three the Canadian vortex comes under further attack and weakens further increasing the strength of the ridge:

The net result at 100 hPa is that the ridge displaces somewhat towards the Atlantic sector but not fully, and critically there is a developing Greenland ridge in place at this level by day 5.

The net result is that any tropospheric trough trying to cross the Atlantic is likely to weaken and be displaced on a more southerly track - perhaps even more so then we have seen on the tropospheric model output so far.

And behind this is there a possiility that tropospheric Greenland heights are being under estimated? (Remember Cohen?)

So does a strong Atlantic trough fit in with the MJO phases?

http://www.cpc.ncep....clivar_wh.shtml

Errr, no not at all - the MJO is showing signs that it will move into phase 7 which the anomaly suggests the outlook is this:

A stonking Atlantic ridge - compare this to the GFS ensemble mean anomaly chart:

Unable to get ECM ones but the earlier output suggested better ridging.

So my thoughts - well I think that the GFS is overplaying the strength of the mid Atlantc ridge some what. Yes we are likely to see some energy cross the Atlantic however this is likely to be followed by pressure rises behind linking up with the retrogressing high and a strong greenland block to develop after.

So any breakthrough is likely to be either temporary, non existant, or limited to the very south followed by a blocked Atlantic.

This is then going to allow one mighty cold blast from the NE get jolly close to the UK!!!!!

I think GFS is supprting your theory. On the 500 Hpa today the (both 12Z and 18Z) western circulation will be, due to the Greenland HP, squeezed and somewhat forced a lower path. What puzzles me is the Skandinavien High: will it stay or will it go: is there any indication from the stratosferic movements?