Stratosphere Temperature Watch 2013/2014

[Recretos]

Well, funny enough, speaking of the 1963 event, I went over to the ECMWF data server, and grabbed the ERA-40 reanalysis data for this event. I made two animations for Geopotential height and temperature, on 10mb and 5mb levels. The reanalysis dataset goes all the way up to 1mb, from 1958 to present, which is quite remarkable, since NCEP datasets go only up to 10mb. 

 

Looking at the latest GFS, and previous runs, I think you might find some striking similarities. Data belongs to the ECMWF, I just plotted it. (I usually forget to give credit of the dataset).

 

Notice: There might be a slight positive temperature bias in the time leading up to the event, due to the event itself being in the non-satellite era (at least not in the main one), but the overall positioning and temporal-spatial values are quite on the spot.

Notice2: The colour legends are not the same as on the plots I made above from MERRA and GFS. I usually make custom colouring, based on the values.

Notice3: 62/63 was a strong -ve QBO phase allover. Tho we are in transit from + to .-

Notice4: It is painfully obvious from the animations, that the source region of the temperature wave was North America. Looking at archives and doing some reanalysis, there was actually a strong negative MT event (-2 to -4) over North America prior to the intrusion, and a positive Asian MT event (+2 to +3). Values are averaged over the month. 

Notice5 (and the last one  ): Looking overall, it almost seems like the vortex sealed its own fate through atmospheric succession in the first place, seemingly triggering a chain of events, leading up to its demise. This is just my opinion after going through all the data so far. I haven't read the report yet, that Mr. Gael_Force linked. But in the end, its almost always like this, or is it not (including me, not reading any technical papers ) ? 

The sequence shows the warming appeared on  5mb before 10mb, normally due to downward propagation. So lets look for that upper strat warming over North America, shall we?

 

The main purpose is just to show these animations for comparison, since the 1963 event was pointed out. I am not trying to imply that we are going to have a 63 event allover again. Tho it is not impossible. But lets leave that for another time. 

 

10mb. The "Highs" are in black contours, for better visibility. The time frame is from 01/01 to 31/01 (time included on the plot), when the main activity leading up to the event was in progress. 

 

1963 10mb Animation (37MB)

 

5mb. Again, the highs are in black, for better visibility, and in the same time frame.

 

1963_5mb_Animation (40MB)
 

 

 

Best regards.

Edited December 11, 2013 by Recretos

[cooling climate]

Reading a few previous posts on mountain torque I think you will find with places

like the rockies or Andes for a positive mountain torque the high is to the west

of the mountains and low to the east(+PNA).

On the CDAS global plots for 30.50mb height anomaly levels you can see the wave

continue to increase. This can only be good news.

[Recretos]

Well, looking at the negative MT event in 63, and the recent negative MT spike in NA, I present some reanalysis charts.  

 

 500mb is just for corresponding pattern. The MT itself seems to be calculated from SLP integral and topography gradient. I have just started to look into this, because I have in plan to actually plot MT forecasts from models. I just need to figure out the correct equation/formula and somehow script it into software.

 

 

 

 

  

 

And I would not be surprised if you would find a similar pattern for a positive MT event in S. America.

 

Edited December 11, 2013 by Recretos

[Vorticity0123]

Based on the excellent post about Geopotential Height from Recretos, I'll try to give a positive signal concerning a warming event in the Stratosphere.

Because this is my first post in here (after a year of following the thread), the post will be rather basic and probably contains a few errors, so I apologize for the possible inconvenience.

 

An analysis with the geopotential charts of the ECMWF will be given.

 

First, the geopotential activity of wave 2. At T+168, the ECMWF shows a slight wave 2 activity at the top of the stratosphere (1 mb level)

Geopotential height wave 2 T192

 

However, at T240, a very high activity level can be seen with values up to 700 m'.

 

 

Geopotential height wave 2 T240

If this activity plays out and downwells to lower levels, it might be an indication of a wave 2 event occuring.

 

Also, high wave 2 temperatures can be seen at exactly the same place in the plot below (T240)

Temperature wave 2 T240

 

The forecast of yesterday (is in this situation 9 dec, ECMWF) shows at T240 that there is also some vigorous wave 2 activity occuring at the top of the stratosphere.

 

Geopotential height wave 2 T240 (=T216 on todays charts)

 

Please note that this is just a small signal and the signal occurs at a rather lengthy timeframe, and therefore, not too much value should be given to the plots. However, there is a general consistency in the ECMWF, which improves the prospects of wave 2 activty.

 

Sources:

http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/
http://theweathercentre.blogspot.nl/2013/01/stratospheric-analysis-and-forecast.html

Edited December 11, 2013 by Vorticity0123

[lorenzo]

With the strong Polar vortex getting a lot of bad press with respect to the current output, thought it only fair to highlight the site below and the mechanics going on in the Stratosphere, this being one of the only animation sites online shows you how good Recretos videos are.

 

The vorticity charts for different layers of the stratosphere are sometimes posted from the Berlin site.

 

On Andreas Dornbrack's site, linked from Berlin page there is a run through diagram of this in motion.

 

Link should be for 600k others are available down to 400k.

 

Completely hypnotic and gives a great representation of the complexity involved as the vortex shifts across the pole.

 

Another great feature is the ability to loop the warming in the higher strat. allowing you to flick through heights to assess propagation.

 

[Duane S.]

Wave 2 watch. Much more like it now from the ECM, still only a forecast of course but certainly worth monitoring,,,

[Recretos]

Thanks to Lorenzo for reminding me about the vorticity.

Not really of much use, but still, the 850K potential vorticity (~10mb) for the 1963 SSW. It doesn't look that pretty because of the low resolution (2.5°). These animations seem more useful as bundles of images, so you can pause on a certain date to see the plot on that day, rather than an animation sequence, because the images are on a 12h interval, because the file size would be really big if I would do the animation on 6h intervals. 

 

1963_850K_Potential vorticity

 

And the 6z GEFS 10mb ensemble mean at 384h. Max temp. at -36°C.

 

 

And all the same as above, only this is the CMC 00z ensemble mean. Max temp. -30°C.

 

[forecaster]

Reading a few previous posts on mountain torque I think you will find with placeslike the rockies or Andes for a positive mountain torque the high is to the westof the mountains and low to the east(+PNA). 

 

High to the west and low to the east => negative mountain torque event. 

[bluearmy]

fi gfs strat output continues to be notable. the shape of the upper strat temp profile becoming very stretched and very cold on an axis not very familiar to me over winters past. seems that there is more oomph in the warming stateside than asian on the current modelling. the lower strat height pattern also showing a stretching vortex (on a siberian/canadian axis as per standard). things are affot - just not sure what the consequences might be. if that very cold stretched upper vortex was to split under the stress ................................

[cooling climate]

 

High to the west and low to the east => negative mountain torque event.

You have this the wrong way round. Cheers. Edited December 12, 2013 by cooling climate

[Interitus]

 You have this the wrong way round. Cheers.

 

It was correct actually, torque is positive (negative) if the surface pressure at the eastern slope is higher (lower) than at the windward side.

[Recretos]

CFS looking similar to other models.

 

 

 

But boy oh boy, does it turn into overdrive just a little bit later.

 

 

 

But there is no reversal at 60N (as it is also obvious from the GPH chart above) at 10mb (around 30.000m). Or it hasn't propagated down yet, since it is reversed in the upper strat. This cross section is over the 60N lat. line around the globe. Distance (X-axis) is equal to 0-360 deg. longitude. So the middle of the map is at 180W for example. I kinda prefer this height-longitude cross sections over the zonal mean charts, because you can get a better feeling of the actual spatial distributions of the zonal momentum.

 

Based on all the stuff I have seen from CFS so far, it really seems that it is always in a hurry to tare the vortex apart, with some godlike wave-breaking at the top of the stratosphere. Or in scientific words, it has a bias.  The forecast of this run is highly questionable, so my main purpose with this post is to present new experimental plots, like the zonal wind for example. And I have managed to finally put a temperature legend on the single level plots.

 

Tho I must admit that it looks quite on par with latest GFS. Or vice-versa.

 

[nick sussex]

Recretos can I just say a big thank you for all the incredible work you put into this thread, you're an absolute star! Especially as English isn't your first language I don't know how you manage to write these posts! I'm stunned!  I'm sure you have an incredible career ahead of you in the sciences.

Edited December 12, 2013 by nick sussex

[Gael_Force]

 Disagree.

 

As someone in the learning process, I'm finding this quite confusing - you seem to be sure of the definition, can you point me towards some material that explains the preconditions for mountain torque.

[Duane S.]

Looking at historical Geopotential heights for Wave 2 episodes it struck me quite how strong the wave 2 amplification was in February of that dreaded winter of 88/89. Taking 10mb, 30mb and 100mb values it was certainly would appear to have upwelled rather than downwelled looking at the way above/below it responded (if that makes sense?). But such was the intensity of that notorious vortex it took wave after wave to disassemble and by which time of course the winter was all but over. Shocking stuff.I sorted the highest recorded wave 2 daily figures @ 10mb 60N and interestingly (to me at least) along with Feb 1989, the five other periods that pop up in the top 20 dates or so are all fairly well know cold Northern Hemisphere episodes. Why was 1989 stuck in there with the good ones? Is it more incidental (quite possible I guess) than for some tangible reason?Not really sure what my point is to be honest other than to ask what do people think 'went wrong' in 88/89?

 

Zonal wind speeds were at the highest (and very high indeed matched only by 1983) during the January of 1989 and the very strong Wave 2 activty followed shortly after zonal winds had peaked later on in January. But early that winter, November December, although fairly strong westerlies were present, zonal wind speeds appeared nothing out of the ordinary and Wave 2 attacks were also fairly prevalent late 1988 as well to boot.I'm not trying to draw comparisons with that horrific winter (hold back the lynch mob!) but more was drawn to that winter when delving deeper into the available Wave 2 data.

[Recretos]

Recretos can I just say a big thank you for all the incredible work you put into this thread, you're an absolute star! Especially as English isn't your first language I don't know how you manage to write these posts! I'm stunned!  I'm sure you have an incredible career ahead of you in the sciences.

 

Wow, thank you very much for your positive opinion! I've been learning English for about 17 years now, since I was 5 years old, so I guess that in such a long period I should know some basics of the language.   The professional terminology on the other hand, is something totally different.

About that career, well, I have no formal education in meteorology and/or physics, so that is out of the question. But nonetheless, I really enjoy learning on my own, step by step. Lets face it, just a year ago when I joined this forum, I hardly knew what wave 2 actually was and how to interpret it. So at this point it is my turn to say thank you to all who contribute to this great thread in any way and also help us all to learn more and contribute to the collective knowledge. 

 

 

Since the paragraph above is perhaps a bit offtopic, I made some GFS plots of the zonal (U) and meridional (V) wind components, to keep the post on topic.

I changed the perspective to lat/lon grid instead of the usual polar stereographic, because this perspective really gives you the feeling of the overall connection between the north and south hemisphere, the QBO and the fairly textbook wave-2 height pattern.

 

 

 

 

 

And the +ve QBO struggling to keep its composure at 30mb.  And I must say it is quite interesting to see that there is no +ve phase whatsoever to bee seen above the new negative phase coming down to 10mb. Tho I guess there is still time for that to develop.  

 

Best regards.

 

P.S.: I apologise if my usage of smiley icons is perhaps excessive. 

[lorenzo]

Some of the strongest looking wave 2 activity so far this year on the ECM plots this morning, monitoring - not a prediction..

 

Zonal wind profile appears to be tightening.

 

Way up at the top of the strat. a nice run across 1hPa culminates in this plot at day 10, context provided at 30hPa.

 

GLAAM forecast from 5 days ago has trended away from Phase 2 Nina state back towards the origin, little sign of frictional torque building and developing an EAMT, not sure where this will go from here to be honest having seen this plotted with certainty to move into Phase 2 then on through 3 - 4.

 

Either way, indicative of pattern change, which I guess will take 7-10 days to settle in and then we can take a read on where it is headed through January, some thoughts on twitter mention the Pacific Jet cranking up will keep track of these.

 

The 30hPa chart is the key one for me, it's a seemingly immovable object this year!

 

 

 

 

 

Edited December 14, 2013 by lorenzo

[sebastiaan1973]

http://solarham.net/solarflux.htm Solar flux remains relatively  high. Around 140-170 in the last two weeks.

[bluearmy]

the gfs fi 10 hpa vortex temperature profiles which were looking very stretched have now tempered somewhat.  however, the model did pick up on the warmings at the top of the strat which ecm is now showing pre day 10. reflected in the increased wave 2 activity high up.  remembering that ecm eps suite now includes the area above 5hpa, any downwelling leading to a trop response within a fortnight should be visible on the extended output.   the mid strat vortex below looks pretty able to deal with this although quite a few gefs members are not showing a strong trop p/v in 2 weeks time.  at least we no longer have the disconnect between the necp and cmc ens which went to the top of the strat and the ecm ones which topped at 5hpa.

[chionomaniac]

More wobbles from the top on the 12Z:

 

 

 

 

Classic wave 2 activity starting to be predicted to affect the vortex now (right on cue) - but how far away is the performer from respinning....

 

 

[cooling climate]

As someone in the learning process, I'm finding this quite confusing - you seem to be sure of the definition, can you point me towards some material that explains the preconditions for mountain torque.

Sorry for the confusion. I must admit to being in the wrong. When the synoptics show a positive

PNA (pacific north America) pattern where there is high pressure in the east Pacific or far western

north America and low pressure further east I have always assumed it was a positive mountain

torque. My bad.

[Recretos]

The 30hPa chart is the key one for me, it's a seemingly immovable object this year!

 

You pretty much explained it with the rest of your post.

I still cant decide if I like this wave 2 or not, to be honest. I guess that it can be both a blessing and a curse at some point. But it is always good to see some activity, rather than an overpowered polar vortex, "wreaking havoc" on us with positive NAM.  (tho we really aren't far from it at all)

 

Looking at the 5mb 384h forecast from the latest 12z GFS: 

 

Really an impressive wave 2 pattern. The "Highs" really compress the vortex, and this is as close to the Chiono's balloon analogy as it can get at this point. They also tighten the pressure gradients, thus increasing the polar jet speed (/zonal flow). That is also why you see the jet tightening, and the strong easterlies allover tropical stratosphere on the FU-Berlin plots. That is also evident on the GFS U/V plots I presented just a few posts back. At this point I do feel that this easterly phase in the tropical stratosphere due to the wave2, is more important as the +ve QBO down at 30-50mb. But lets leave that for some other time. 

 

  

 

 

Basically one of the "problems" I have with this wave 2 pattern, is that the Atlantic wave normally blocks the disposition that would otherwise occur with just one wave (and boy would that be a decent wave1 in this case). And it is also keeping it in place or immovable. But that is a logical assumption, so what's really "bothering me", is the question what would happen if we would have just wave1 disposition and how much it would affect the low-strat/trop. pattern. But I guess we will never know.

 

Another forecasted effect of this wave2 is on the momentum or energy of the vortex. The vorticity forecast for 5mb 384h, from the 12z GFS, does show just how the Pacific high is interacting with the vortex, showing the "hook" feature, indicative of wave breaking. But overall, the vortex still has a fairly good composure, tho quite under pressure (no pun intended). Left (in green/blue) is relative vorticity, and on the right (in many colours) is isentropic potential vorticity (IPV) ~5mb. Both showing the well defined, almost textbook "leak" of the vortex' energy, induced by wavebreaking. 

 

 

 

 

Speaking of wave breaking, another indicator of the latter, can sometimes also be spotted on the ageostrophic wind plots, basically due to it showing geostrophic wind imbalance and deviations, which can be induced by fluxes in wave breaking. Normally in a healthy textbook polar vortex, you don't expect to see much ageostropchic wind, since it is a quite balanced planetary scale feature. And usually the only thing disrupting it, is wavebreaking in the upper strat. 

To put it in practice, lets look at the ECMWF wave chart and some ageostrophic wind plots.

 

Strong wave activity, focused between 35N and 65N in mean, maxed in upper strat. at around 50N.

 

 

The GFS plot for 1mb ageostrophic flux for the same time period as the ECM above, is quite in the same area actually, on the outskirts of the vortex and in the waves. Tho there are some differences to be expected, since we are talking about two different models here. GFS does seem to be weaker with the wave2 at this point, based solely on the ageostrophic plot, which would also explain why the ECM is much warmer and aggressive at the highest level of the strat. than GFS at the same time period. Notice the strong fluxes over tropics, but that is a different system.

 

 

Now going to latest GFS 12z 384h, lets look at 5mb (left) and 1mb (right). Added on the plot is the ageostrophic flux vector (arrows).

It kinda goes wild, but if you look at the 1mb height that Chionomaniac has posted, it is logical that somewhat decent wavebreaking could be occurring. Poleward ageostrophic fluxes also sometimes seem to correspond with areas of increased temperature. But it can be situational. Just some of my experimenting with stratosphere modelling.  

 

 

 

Now of course, some might want to know what all this mumbo jumbo really means in terms of possible SSW.

First we have to realize that these graphics are basically just model forecasts. And in those forecasts, we have decent wave activity occurring and quite some pressure is being applied on the vortex, tho I must say that it is one beastly vortex to bring down. But you know what they say, the bigger they are, the harder they fall.

 

Chionomaniac has pointed out a thing, that is actually the second problem I have with this upcoming wave2. 

 

Classic wave 2 activity starting to be predicted to affect the vortex now (right on cue) - but how far away is the performer from respinning....

 

 

Wave activity does not last forever. It either ends on its own, through the change of forcings, couplings, propagations, etc... or by an SSW also. Now something is telling me that an SSW is not likely to end this wave 2 domination, at least not by what the forecasts are showing right now. So we might waste all this time with the wave2 without much of an effect in the end. But that is quite a bold statement, I admit.

Is the wave 2 activity expected to apply pressure onto the vortex? Yes. Do we have forecasted warm air intrusions into the core of the vortex? Not yet.

In my view, a cold vortex is a healthy vortex. At least what we have on the charts with an overall strong momentum around the vortex. I don't think that the pressure-gradient force is enough to disrupt or even split the vortex on its own. Or looking back at the 1963 event, where there was also wave 2 with decent pressure-gradient force, but the vortex kept its composure without much problem, until the warm air finally began engulfing it, and warmed the core of the vortex, reducing the overall pole-tropics thermal gradient, raising heights and pretty much split it down the middle with ease, since warmer air also promotes height rises and so it was easier for the two waves to connect through, while it would be almost impossible to penetrate a -85°C cold core vortex just by pressure gradients alone. At least I haven't seen that before, and I've been through quite a few historic SSW events in the last year, by reanalysis. So please feel free to correct me if I am wrong. 

 

So to sum it up: Tho the upper strat height charts look really nice in the FI period, I would really like to see some warmer temperature to go with it, which should be our main "wish" at the moment. It really pains me to see such a pattern and just -35°C max. temperature over only a few grid points. Even the CMC ensemble mean is warmer than GFS operational, not the mention the CMC control run, with quite an area of -30°C. But the model forecasts are not perfect, and there might be a cool temperature bias at the moment on GFS, especially if we compare the GFS to EC. I would personally expect quite higher temperatures to go with such intense wavebreaking in GFS. Basically I am suspecting that GFS is greatly underestimating the temperature aspect of this wave, from run to run. Occasionally we do get a warm run, and then the next 3 are cold ones. So perhaps the GFS cant really handle such intense processes the right way in the FI? 

 

So many questions, but almost no answers. I guess only time will tell. At least we have some very interesting stuff to work with at the moment (tho it could/should be warmer ).

 

Best regards.

[chionomaniac]

Good post Recretos.

 

I suspect that if the vortex is to be broken then it will not occur until well into the new year. However, the increased tropospheric/ stratospheric wave activity feedback is starting to show. Initially, the warm air rides the 'surf zone' and fails to break through and hence the distorted balloon look of the vortex - but like a distorted balloon once the pressure from the wave activity reduces, the vortex quickly resumes its shape. We do often see quasistationary type 1 waves, that keep the comma shaped distortions for periods of time, and these can build and build and eventually break the vortex, though I think these are less common with wave 2's.

 

I think my point is as per the winter forecast is that by January, repeated wave 2 activity is likely to put pressure on the vortex and now this is beginning to show at the end of the runs.

 

 

 

If this continues will we see the vortex broken in February when it is in decline and the wQBO is reducing..... questions, questions that we are yet to know the answer to......

[sebastiaan1973]

We know that the chance of a SSW increases when high solarflux is around 150 or more, in combination of a wQBO. I wonder why? What is the mechanism?

[bluearmy]

yesterday's berlin data not available at the moment. is this the only place to view ecm data ?