Stratosphere Temperature Watch 2013/2014

[lorenzo]

Had a good look at the strat charts this morning, Interesting vorticity charts within the next 24 hours at the Tropopause level and as a result on the 100hpa strat heights chart.

 

Interesting due to the repeat of the trend in the atmosphere which continues for earlier Autumn to deliver troughing deep into the heart of the continent, this energy also diluting the vortex somewhat and leading to clear elongation by day 10. Diagram gives example of the heights of the PV surfaces.

 

EP Flux is interesting also the peak influence as a result of that huge ridge across the other side of the globe, with peaks on the 8th and the 12th. Chart from the 8th has the vectors smashing in all directions which to me is a sign of some of the energy impacting the vortex. The hovmoller plot pretty clear for November.

 

Some activity developing again at day 10 on wave 2 plots.

 

The impact of the displacements caused by that mean Aleutian high, combined with the Atlantic ridging forecast making things interesting as November continues especially where the core of the Vortex is destined again for Siberia, at 50hpa the Strat troughing and relocation.

 

With respect to the AO forecasts and this rampaging negative plot from GEFS, if OPI mean AO figure turns out to be accurate and verified for DJFM as a whole, with this plot verifying for November, what kind of ominous AO figure would we expect for the rest of Winter?

 

 

 

 

 

Edited November 15, 2013 by lorenzo

[bluearmy]

ed - did you remove a post from yesterday? did i dream that you commented on the way the atlantic ridge is propogatng well up into the upper strat ?  still there this morning.

[snowking]

ed - did you remove a post from yesterday? did i dream that you commented on the way the atlantic ridge is propogatng well up into the upper strat ?  still there this morning.

I think it might have been on the Model Thread BA

[bluearmy]

I think it might have been on the Model Thread BA

Jeez, I'd better check through my emails. Nwp like we have at the moment plays havoc with my business!!and the exchange of posts was clearly in the wrong thread!

[Interitus]

Can someone help me grow my knowledge a bit? The 120h chart of zonal wind forecast shows a strange looking reversal up towards the pole at trop level. It's nearly in reverse now - lasts about a week peaking at 120h and then returns to westerly flow again by 168/192.How does this sort of thing come about? I can grasp that warmth higher up causes a slow down and that this can become a reversal and downwell through the atmosphere, but how does a trop reversal like this come about in the trop first? Is it just the product of a pressure rise? And is it possible for a reversal at trop level to upwell regardless of a warming? Or is it linked hand in hand with warming via wave 1 activity? Apologies if that is a jumbled set of sentences - I'm really still trying to learn about the reality of the vertical significance of the atmosphere as a whole!

 

 

 

Without looking for an exact cause, it is a normal tendency towards tropospheric easterly winds in the Arctic, westerlies in the mid-latitudes, and the easterly trade winds in the sub-tropics when averaged over the globe as that wind plot does. It looks fairly normal compared to a composite for November -

 

 

Bear in mind that this chart doesn't have a logarithmic scale so is more or less like the bottom third of the Berlin plot. The large area of westerly winds in the centre is the sub-tropical jet which is near the bottom of the Berlin plot, and the prominent stratospheric vortex can hardly be seen at all right at the very top.

 

One interesting thing about the plot you've posted is it highlights the QBO over the tropics - centred on 30mb at the moment is the current +ve phase, and above this up at 5mb is the next -ve phase descending.

[Catacol]

Without looking for an exact cause, it is a normal tendency towards tropospheric easterly winds in the Arctic, westerlies in the mid-latitudes, and the easterly trade winds in the sub-tropics when averaged over the globe as that wind plot does. It looks fairly normal compared to a composite for November -

 

November zonal wind.png

 

Bear in mind that this chart doesn't have a logarithmic scale so is more or less like the bottom third of the Berlin plot. The large area of westerly winds in the centre is the sub-tropical jet which is near the bottom of the Berlin plot, and the prominent stratospheric vortex can hardly be seen at all right at the very top.

 

One interesting thing about the plot you've posted is it highlights the QBO over the tropics - centred on 30mb at the moment is the current +ve phase, and above this up at 5mb is the next -ve phase descending.

 

Thank you - that is helpful. At my current stage of knowledge I did not realise that easterly winds in the arctic were the norm. So much to learn...!

[Catacol]

 

 

 

Interesting due to the repeat of the trend in the atmosphere which continues for earlier Autumn to deliver troughing deep into the heart of the continent, this energy also diluting the vortex somewhat and leading to clear elongation by day 10. Diagram gives example of the heights of the PV surfaces.

 

 

 

 

 

Yes - this is exactly the source of my own excitement at the moment that keeps pulling me back to the internet when I should be working.

 

We have a stable vortex but a lot of meridional activity in the trop with ridges in the north pacific and soon to come the north atlantic penetrating the arctic with comparative ease. Energy seems to be firing southwards all around the globe with our own burst coming next week and north america also being subjected to troughing.

 

My observation of the dreadful winters of the recent past [oh come on... I write "m0dern era" and it is changed to "christmas pudding?" - someone is having a laugh with that filter!) was that such things just did not happen. The vortex was strong and the pattern stayed flat for what felt like an eternity with only brief toppling highs in the atlantic to break the tedium. 

 

Why are we having such a different pattern now? Again - no stats to back this up - but the start to this winter has a more dynamic feel to it than even the last half dozen winters and in a +QBO and stable vortex context that would lead me, in my infantile state of knowledge, to think that the winter should be flat as before. Is this perhaps due to less sea ice at the pole? (latest plots show that we have lost ground and that sea ice coverage is pretty unremarkable after the fast start...) or is it Solar... or is there something in the ocean SSTs? There is a seasonal forecast chart - cant find it now - over at the CPS where human input has created a forecast of a great deal of blocking over the high lats of the NM this winter based purely on the SST pattern. Unfortunately for me I have no idea how such conclusions are reached.

 

Bringing it back to the Strat Thread... it is fascinating at the moment to witness what appears to be a disconnect between the strat and the trop. More knowledgeable posters willl probably shoot me down for that and explain why my basic interpretation is wrong - but nevertheless it is making very interesting watching and researching. 

Edited November 15, 2013 by Catacol_Highlander

[Tamara]

That excellent post from Lorenzo is a key part of what is interesting and also, potentially, exciting about the NH trends this autumn and also, as he rightly says, as seen in recent ones as well So different to the highly +AO/NAO flat patterned zonal years of, you know, 'that' pre 2007 era.

 

Clearly the changed arctic sea ice patterns (for whatever reason) appear to be a very likely background factor in assisting this meridional pattern on the semi -permanent basis as we are seeing - and thus creating the more favourable stratospheric conditions that we are witnessing, even in a westerly QBO year such as we have atm, that on its own at least, assists a tighter polar stratospheric westerly ribbon and helps keep the vortex stable, more organised and stronger.

 

These more amplified patterns, afterall, have been regular features not just of our short seasons, but of our recent summers as well (including this one even though it has been a warmer and drier one courtesy of emphasis on mid latitude rather than high latitude blocks)

 

It seems clear enough that the shift to highly meridional patterns like we have been seeing encourage and facilitate the catalyst for wave breaking mechanisms that can destabilise the most (at face value) stable upper vortex and force the bulk of its coldest strongest energy to parts of the arctic that enable us to benefit (from a cold and snow fans point of view) from being on the polar side of the jet stream.  The buckled ribbon of the jet stream sets up a polar wave breaking feedback cycle that leads to further lower stratosphere/troposphere interference and this in turn sustains and recycles the amplified pattern which creates strong ridges which progress 'downstream' from source into the atlantic assisted by seasonal wavelength changes.

 

We should also consider that the current and predicted to continue weak/neutral ENSO conditions are an important factor in assisting a more favourable jet stream pattern that is more conduisive to split flow and trough disruption

 

As long as this amplified, trop/lower strat interaction can persist, then we need not fear a colder and more stable upper vortex such as we see at this time. It might make it much harder than in an east QBO winter to develop a complete breakdown of the polar vortex through an SSW, but it can sure keep it on the hop so that it can't sit still over the heart of the pole and Greenland and force the jetstream flatter and further towards higher latitudes.

 

It makes for further interesting watching on the assumption that this virtuous cycle can continue into the heart of the winter (from a cold fans point of view for sure) The AO and NAO start working on a more in-tandem and highly connectable basis into the second half of the winter - and with trough disruption into Europe already a feature of the foresseable modelling this November, then any favourable -AO feedback pattern that can be created through (hopefully) sequences of lower stratosphere wave breaking instability in theory could work well for us later in the winter when both the NAO and AO are less independant of one another. This might serve to repress the Azores High and help with undercutting and sliding low pressure

Edited November 15, 2013 by Tamara תָּמָר

[Recretos]

As Lorenzo has pointed out, there is some wave2 appearing on the EC forecast. The anomalies suggest that, and I also plotted the flux vectors through the Atlantic wave from the GFS for that time, and there is some pressure being applied on the vortex. The left axis is the height in meters.

 

 

The CFS forecast is somewhat in line with the latest GFS runs, but it is kinda slower. It has the similar look on the 10/12 period, which latest GFS runs are promoting for 01/12. Just throwing it here for future verification.

 

 

 

Best regards.

[phil nw.]

Yes some good posts today and the latest Strat.charts underlining the vortex under some stress.

Plenty of wave 2 activity showing on the day 10 chart fron ECM and the GFS day 10 pressure chart at the lowest level(100hPa) alongside, highlighting that Atlantic block near the UK.

 

 

Certainly evidence now of the effect on the mean zonal wind speeds higher up

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

 

slowing as the days go by and down to zero by day 10 at 60N.

 

[Interitus]

The AO and NAO start working on a more in-tandem and highly connectable basis into the second half of the winter - and with trough disruption into Europe already a feature of the foresseable modelling this November, then any favourable -AO feedback pattern that can be created through (hopefully) sequences of lower stratosphere wave breaking instability in theory could work well for us later in the winter when both the NAO and AO are less independant of one another. This might serve to repress the Azores High and help with undercutting and sliding low pressure

 

Is this a forecast?

Because it isn't born out in reality using NCEP figures, here are the smoothed NAO/AO values, they become more disparate as the winter progresses reaching a peak difference in February when just days apart they reach their average highest and lowest annual values

 

[beng]

The buckled ribbon of the jet stream sets up a polar wave breaking feedback cycle that leads to further lower stratosphere/troposphere interference and this in turn sustains and recycles the amplified pattern which creates strong ridges which progress 'downstream' from source into the atlantic assisted by seasonal wavelength changes.

 

 

Great post Tamara - I think we've got to add the PDO index into the mix - that really switched negative during 2007 and has got to be feeding into buckling the jet across the pacific.

[sebastiaan1973]

 

 

Interesting due to the repeat of the trend in the atmosphere which continues for earlier Autumn to deliver troughing deep into the heart of the continent, this energy also diluting the vortex somewhat and leading to clear elongation by day 10. 

Yes - this is exactly the source of my own excitement at the moment that keeps pulling me back to the internet when I should be working.

 

 

Why are we having such a different pattern now? Again - no stats to back this up - but the start to this winter has a more dynamic feel to it than even the last half dozen winters and in a +QBO and stable vortex context that would lead me, in my infantile state of knowledge, to think that the winter should be flat as before. Is this perhaps due to less sea ice at the pole? (latest plots show that we have lost ground and that sea ice coverage is pretty unremarkable after the fast start...) or is it Solar... or is there something in the ocean SSTs? There is a seasonal forecast chart - cant find it now - over at the CPS where human input has created a forecast of a great deal of blocking over the high lats of the NM this winter based purely on the SST pattern. Unfortunately for me I have no idea how such conclusions are reached.

 

Bringing it back to the Strat Thread... it is fascinating at the moment to witness what appears to be a disconnect between the strat and the trop. More knowledgeable posters willl probably shoot me down for that and explain why my basic interpretation is wrong - but nevertheless it is making very interesting watching and researching. 

 

You mean Hugo van Dools chart?

Edited November 15, 2013 by sebastiaan1973

[Tamara]

Is this a forecast?

Because it isn't born out in reality using NCEP figures, here are the smoothed NAO/AO values, they become more disparate as the winter progresses reaching a peak difference in February when just days apart they reach their average highest and lowest annual values

 

NAO AO.jpg

I read extensively on another forum a little while back (a recognised US one) where there was a long thread that discussed a study into AO/NAO coupling behaviour through the winter. It would seem that the majority conclusions from there disagree with the link you have posted, but that doesn't change what is mooted overall wrt the possible stratosphere patterns themselves. It was therefore not a definitive AO/NAO forecast of course, but simply a suggestion based on what I read, and have believed, that may or may not come into play later in the winter - should we see continued stratospheric coupling between the lower/mid stratosphere and the tropsophere.

 

In simple terms, I think that the prevailing stratospheric patterns determine the AO base state...+ or - and then the NAO profile can be influenced accordingly. It is true to say that last winter f.e it took till towards the late part of the winter and most especially the Spring before we saw a really dynamically productive cohesive AO/NAO combo with properly undercutting low pressure We remember in that respect the failed easterly of December where despite a favourable stratospheric and -AO trend (towards the SSW that followed thereafter) the NAO stayed stubbornly neutral/rather positive and 'that ECM' chart remained a fantasy . This rather bears out as an example of my suggestion.

 

This is one for another thread however - as whether it is has credence or not, as stated it is simply a factor that potentially could favourably augment any consequences at our tropospheric surface of any conduisive stratospheric patterns that we hope may be present through the winter as discussed in this thread

 

@ beng - yes I agree

Edited November 15, 2013 by Tamara תָּמָר

[Interitus]

 

EP Flux is interesting also the peak influence as a result of that huge ridge across the other side of the globe, with peaks on the 8th and the 12th. Chart from the 8th has the vectors smashing in all directions which to me is a sign of some of the energy impacting the vortex.

ep_12z_tr_nh.gif

 

There has been a fair amount of EP flux but that chart shows it has had minimal impact on the stratosphere and nothing particularly out of the ordinary with regards to wave propagation so far compared to other years - http://www.esrl.noaa.gov/psd/data/epflux/

 

[Catacol]

You mean Hugo van Dools chart?

 

Yes - that's the one.

[Interitus]

I read extensively on another forum a little while back (a recognised US one) where there was a long thread that discussed a study into AO/NAO coupling behaviour through the winter. It would seem that the majority conclusions from there disagree with the link you have posted, but that doesn't change what is mooted overall wrt the possible stratosphere patterns themselves. It was therefore not a definitive AO/NAO forecast of course, but simply a suggestion based on what I read, and have believed, that may or may not come into play later in the winter - should we see continued stratospheric coupling between the lower/mid stratosphere and the tropsophere.

 

In simple terms, I think that the prevailing stratospheric patterns determine the AO base state...+ or - and then the NAO profile can be influenced accordingly. It is true to say that last winter f.e it took till towards the late part of the winter and most especially the Spring before we saw a really dynamically productive cohesive AO/NAO combo with properly undercutting low pressure We remember in that respect the failed easterly of December where despite a favourable stratospheric and -AO trend (towards the SSW that followed thereafter) the NAO stayed stubbornly neutral/rather positive and 'that ECM' chart remained a fantasy . This rather bears out as an example of my suggestion.

 

This is one for another thread however - as whether it is has credence or not, as stated it is simply a factor that potentially could favourably augment any consequences at our tropospheric surface of any conduisive stratospheric patterns that we hope may be present through the winter as discussed in this thread

 

 

The source for that graph was purely the daily NCEP data, but a similar result can be seen using other related formulations eg. the NAMI/NAOI by Li and Wang-

http://ljp.lasg.ac.cn/dct/page/65544

 

It is well known that NAO and AO represent different features atmospherically and a good overview of the differences and similarities for starters would be the paper by Ambaum et al. - Arctic Oscillation or North Atlantic Oscillation? -http://www.met.rdg.ac.uk/~sws97mha/articles/jclim2001.pdf

 

This is pertinent to this stratosphere thread, as the authors point out -

 

The winds in the stratosphere are also strongly associated with the NAO index. As can be seen in Fig. 7, when this index increases, the strength of the polar night jet increases by nearly 10 m s21 in both the Atlantic and Pacific sectors. The connection of the NAO index to the strength of the polar night jet is well established and can be related to the propagation of planetary waves from the troposphere to the stratosphere [Charney and Drazin (1961); see also Hartmann et al. (2000)]. There are also suggestions that independent changes of the stratospheric circulation may force a tropospheric response in the NAO or AO (Baldwin and Dunkerton 1999; Hartmann et al. 2000), although these links appear to be weaker and are only present in winter mean data.

 

The presumption that the strat will be controlling the troposphere ignores the fact that the reverse relationship is usually stronger. The strat vortex isn't totally separate at the moment and strengthening in isolation, the recent +NAO has most likely been assisting.

[BLAST FROM THE PAST]

 

 

 

 

 

Yes - this is exactly the source of my own excitement at the moment that keeps pulling me back to the internet when I should be working.

 

We have a stable vortex but a lot of meridional activity in the trop with ridges in the north pacific and soon to come the north atlantic penetrating the arctic with comparative ease. Energy seems to be firing southwards all around the globe with our own burst coming next week and north america also being subjected to troughing.

 

My observation of the dreadful winters of the recent past [oh come on... I write "m0dern era" and it is changed to "christmas pudding?" - someone is having a laugh with that filter!) was that such things just did not happen. The vortex was strong and the pattern stayed flat for what felt like an eternity with only brief toppling highs in the atlantic to break the tedium. 

 

Why are we having such a different pattern now? Again - no stats to back this up - but the start to this winter has a more dynamic feel to it than even the last half dozen winters and in a +QBO and stable vortex context that would lead me, in my infantile state of knowledge, to think that the winter should be flat as before. Is this perhaps due to less sea ice at the pole? (latest plots show that we have lost ground and that sea ice coverage is pretty unremarkable after the fast start...) or is it Solar... or is there something in the ocean SSTs? There is a seasonal forecast chart - cant find it now - over at the CPS where human input has created a forecast of a great deal of blocking over the high lats of the NM this winter based purely on the SST pattern. Unfortunately for me I have no idea how such conclusions are reached.

 

Bringing it back to the Strat Thread... it is fascinating at the moment to witness what appears to be a disconnect between the strat and the trop. More knowledgeable posters willl probably shoot me down for that and explain why my basic interpretation is wrong - but nevertheless it is making very interesting watching and researching. 

 

A very good post, the Jetstream hemispherically has changed both in being more generally south and very loopy and wavy in pattern and seems to have come very much in play since 2007 when the perturbation cycle changed.  In past time we wouldn't and couldn't see anything blocked and cold with a very strong and organised vortex but it seems now nigh on anything is on the playing field.

Is there a disconnect?  I think it was brought up last year and look forward to more indulgence from the techs 

 

BFTP 

[John Badrick]

Could the good synoptics appearing in the charts at the moment be due to the +QBO and the increase in solar activity?

[John Badrick]

Ironic really if some forecasters are looking at low solar activity being a persecutor of cold winters

[UV-RAY]

Ironic really if some forecasters are looking at low solar activity being a persecutor of cold winters

Activity is still low in the grander scheme of things.

[John Badrick]

Maybe we need an uptake in solar activity?

[chionomaniac]

This is what we have been waiting to see -

 

 

Guess when we have seen this before?

[MattH]

This is what we have been waiting to see -

 

ecmwf30f240.gif

 

Guess when we have seen this before?

 

Decent increase in wave 2 activity as well;

 

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha2_f240.gif

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ta2_f240.gif

 

This better not be another ECMWF model error, once is enough!

 

Not sure on year Ed...awaiting your answer.

 

M.

[chionomaniac]

Decent increase in wave 2 activity as well;

 

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha2_f240.gif

http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ta2_f240.gif

 

This better not be another ECMWF model error, once is enough!

 

Not sure on year Ed...awaiting your answer.

 

M.

Hi Matt we have seen splits like this prior to the early winter cold spells in both 2009 and 2010.

 

For the local trop induced wave split upwards into the lower strat is very favourable for producing significant cold in our neck of the woods.

 

Here is 2009 strat link  http://forum.netweather.tv/topic/57364-stratosphere-temperature-watch/?p=1625056

 

And 2010 (but with charts missing) http://forum.netweather.tv/topic/64621-stratosphere-temperature-watch/?p=1952060

 

We could see some interesting trop output. What a time for the ECM to upgrade its model especially wrt to strat input.