Recretos

my take on QBO time series.

Two of my video sequences, showing some QBO evolution.

Speaking of cooler Atlantic, I have done quite a few meridional cross sections across the Atlantic. it is all on my twitter since its too much to share here, but one for the feels of it.

Comparing past winter with the last super nino winter of 97/98, we see ho much stronger the eastern nino regions were in 97/98. we can also see how this winter we had much cooler Atlantic, from the tropics all up to the north. And if we look at March so far, last 23 days mean, we see the Atlantic difference even more, with a very "-AMOish" signal appearing when comparing it to 1998. But it is also generally cooler north of tropics when compared to last year. And March so far this year. And last 7 days of March versus first 7 days. we can see SSTs have cooled off a bit north of tropics. But what stands out the most is the typical positive IOD phase signature.

All is fine and good. Of course temperature has a major role in all physical dynamics. But my point was of quite a different nature. I was talking to the "general population" about monitoring the stratosphere, where there is this bias towards temperature, which is especially notable when NWP starts drawing potential strat warmings. Be it minor or not. Mostly people naturally expect every strat warming to produce cold shots and severe winter down the line. And that was my point that more parameters need emphasis when *monitoring* the strat. But you are right when it comes to *calculating* the strat dynamics. But that is usually done for us by NWPs. And this year they were doing a good job, with the prediction of the warming and the potential effects. One could say that the strat warming or warm strat temperature, as important in each aspect as it might be, failed us this year, which is just as normal as when it rewards us. Thats just the complexity of the world we live in. Kind regards.

Yarmy explained one major problem why using monthly climatologies for daily data is not really recommended if you want good details. but if you just want a fast overview, its not that bad. That is why I usually use daily mean climatologies for daily mean analysis. The most common example that I use is the UKMOs own OSTIA 0.05° SST analysis, which is an L4 product. Some examples I made today for twitter:

Simply put, there is a disconnection, or weak coupling, together with possible stronger trop-forcing which can override the signal. The temperature has downwelled, but the heights have not responded. Pretty much what I am trying to emphasise the whole season, and which was the "theme" of this winter. The troposphere is kinda playing a game of its own, with partial coupling, but at this point in time the trop and strat are generally slowly starting to de-couple anyway.

Still too much emphasis on the temperature and too little on the other energies involved. Were all this really worthy of hype in terms of super effects, I would be among the first to jump the train. But since its not, that is the reason for my lack of activity in here. Edit: I really do hope that this season was a very good lesson for us all, how each SSW is a unique feature and we cannot handle SSWs with "Wikipedia-ish" approach. One thing that Mr. Judah Cohen also needs to learn, with all due respect. Regardless of the impressive temperature numbers, SSWs, are simply not just temperature-only features, and much more things are involved in the whole process that can make or break a winter period. Regards.

FInal Winter reanalysis.

I made a new animation from the GFS 3D data, showing the actual vortex breakup. it will look better once the breakup period gets within 240h where the temporal resolution is much better.

Well yes, but I am not talking about definitions. I will leave that to people with Phd's. I am talking about actual dynamics. As far as the definitions go, I support multi definitions, or multi category classification.

But thats exactly what it is. Everybody make the same mistake of looking and emphasising the temperature, like its THE alpha and the omega of the strat. All we always hear about is the temperature. But like this year when the warming has a negative effect, people cant seem to understand how and why that is possible "if like the strat warming is like the most certain thing to like make two months of cold shots and like a big greenland block". Those meters per second have a lot more meaning than people give it credit for. Even proffesionals like Judah Cohen Phd. I remember back in my strat beginings 4 years ago I was already emphasizing the importance of the heights when everybody was looking at temperature. Unless it was a split forecasted. Then it gets some attention.

A little verification of the Glosea5 model. It runs 4 members per day, perturbations + 1 control. So I decided to take 5 days worth of data, from 9 to 14 January. That is total of 5 days, which means 20 ens members. Generally, it had a good idea of how the strat dynamics will evolve, with the drop and everything. But it was a bit far out and it had quite a spread. But generally I wouldn't say that it is too bad at all. It did miss out on the recovery period, but some ens have it. edit: Gonna add GEOS5 forecast of changes. Further reveals where the SSW linkage goes and where not.

One more thing. Look at this, how there is a lagged response between 10mb and 300mb. And also notice how the MSLP responds also. Most notably in the second part, when the strat-trop coupling increases. Adding PA 850mb temperature to the mix, since it is under direct SSW response via the cold shot. Notice also here how the strat fastly couples with the trop, showing decent correlations also here, not only in 3D animations.

Dont forget low solar activity. We have it all covered. Let me just say while at it, that I hope this years SSW, minor or not, was a good reality check for the future. I (we) have said to be careful about not only this one, but every warming in the stratosphere has to be analysed individually. Seeing the warming at 10mb is not nearly enough of a reason to start the hype train and to celebrate. This SSW was an obvious no-game-changer before it even began, and everyone could see it if they would want to, even without the fancy 3D animations and graphics. Trust me, if this whole event would be worth the attention, I would write about it and hype it myself. Now Dr. Cohen still believes in negative AO mid Feb onwards into March, so we will see how everything pans out. I will finish off with another animation, this time its EPV at 10mb, from the NASA GEOS-5 model, showing the SSW wave1 dynamics and the recovery attempt.

Good discussion, and let me be of assistance. The big reason why the models, and ENS generally are going for a more zonal period, does indeed also happen to be stratosphere based (among other stuff). I have made a new animation, showing the polar vortex core dynamics during the SSW and after it. You can see right away how the wave 1 itself helps to bring that cold shot into E USA, but that is about it. The vortex core tries to re-spin, and in the later frames of the forecast we can see the top-down NAM re-linkage of the mid strat vortex core down into the upper troposphere, causing a pattern supportive for positive AO and NAO. I recommend watching in full screen. Stratosphere is not only of importance during SSWs, but all the time...

Not sure why my text is underlined when I post from mobile. But its enough to say that I am really unsatisfied with the current forum visual scheme. I want the old theme back please. There isnt even a preview function anymore. And it ocasionally crashes my browser when viewing it on Android. Enough offtopic. There actually is a very decent correlation signal bettwen solar flux and 500mb pattern in wintertime. Here we see a decent correlation of Solar flux and NAO pattern, which both have a tendency to be positive or negative at the same time. And the good thing about this correlation is that the index is independant, because it is a solar/Sun index, unaffected by Earths weather. So there is no autocorrelation like between SSTs and NAO for example, where we know that they can both affect each other. The reason why it goes just to +-0.5, is not random or a coincidence, but because it is highly dependant on the QBO phase. Correlating specific solar phase with specific QBO phases should give better results.

The only medium term effect of this minor SSW is the small negative dent in AO and NAO and also some other oscillationd. The AO dent is there thanks to the wave 1 phase which helps promote the Alaskan to pole ridge building. The NAO on the other hand, owes its negative dent thanks to the second phase of this minor SSW, which is the grind-off of the wave 1 on the vortex, elongating it and establishing a cross-polar flow in the lower strat, sending decent amount of cyclonic energy into N America. And our negative NAO, west based, owes its existance to this American core, because the warm sector of this core is what causes this relativeny shortlived Atlantic ridge, driven mainly by WAA, and it goes away as soon as the vortex starts to regain its zonal angular momentum, and sending more cyclonic energy i to the Atlantic sector. That is why the NAO negative dent is relatively short lived, because you could say that it resulted from a "fake" warm sector ridge. Yes, its that simple...

Well. Not sure where to begin. A lot has been said in the last few pages. And the reason I was absent was not because I wouldn't have time, but because there was nothing for me to write about, what I haven't already said. And what happened was, everybody or almost everybody did actually jump the SSW wagon (not a gun, for which people actually mocked me for) and drove off into the unknown, expecting to arrive to a new land, abundant with snow and cold. Well, its time that we do a reality check and see just how far this wagon has actually got. 10 days, 240h later, we are exactly where we are supposed to be as predicted. With a minor wave1 displacement SSW. Despite all the hype, in the current phases what it will actually do, is displace the cyclonic energy, dropping it into the north Atlantic/Canadian sector, and the wave 1 anti-vortex will help to promote Alaskan ridge building. Great imagery from weatherbell, by Ryan Maue, and a good example how to properly use anomalies in stratospheric forecasting. And my share. Looking at the NASA model, here is the 120h 5-day change of the zonal mean-zonal wind. We can see the reduction of the zonal components from 60N to 90N. Yet at the same time, we can see the slight increase of tropospheric zonal components, mainly to do with the fact that the displacement that causes the reduction of the stratospheric zonal winds also causes not only the energy to build the Alaskan ridge, but also to support the cyclonic energy in the Canadian/Atlantic sector. That is more profound after 240h, when the polar vortex tries to sustain/recover its angular momentum. That can sometimes be quite a bursty process, and in our case it actually is enough burst to have a fast trop response and the connection between upper and lower core is established briefly, enough for some energy to transfer besides the general one, and kinda mixing the charts for us even more. And what the wave 1 actually manages to do, is as it grinds along the vortex, it actually creates a brief cross-polar flow and helping to further spin-out the south lobe of the vortex, helping it to recover down the line, and sending the cyclonic energy down into the trop as it intensifies and the pressure drops. Much like you see above on the GEFS charts. the reach of the polar anticyclone is not really that far down reaching, and is weaker than the trop response to the re-spin of the vortex core, and sending a cold trough into North America. On its eastern flank downwind, the ridge could briefly build in north Atlantic, but I do not believe it would be any long-lasting ridge, since its will be later under the affect of the upper core transfer. What else to say. I was trying to be the voice of reason, to prevent euphoria due to misunderstanding of the strat dynamics, and to explain just how each event is different than others, and must be taken with an analytical approach across multiple layers and multiple parameters. For some time I was trying to emphasise just how important the height fields are. The event might be called stratospheric warming, but temperature on its own is not even nearly enough for anything significant. The actual effects and to track them, we must focus on the height fields. That is why the zonal mean zonal wind is also so important because is directly related to the geopotential height field via geostrophicy. What we can all learn from this event, is that we need to learn more. All of us. And no, I do not have a Phd in meteorology. Not even close. I have finished agricultural high-school, so I am a farmer officially. I had physics for 2 years in elementary school. But I tend to put a lot of focus into what I do. Anything. Especially if it is something I am passionate about, like meteorology. So bottom line, I am just an amateur/enthusiast like 95% of people on this great forum. So I am not necessarily correct in everything I state in this post or any other. just a disclaimer (not even some pro's are). But what I am trying to say is that you can learn new stuff and you can learn about stratospheric dynamics, even without heavy physics background. Just think logically, since physics are 95% of logic. it just needs to be explained in the correct matter. heavy scientists usually like to over-complicate it with 10-miles long equations and technical terms that make your tongue split in half like a wave 2 major SSW. Finishing off with another animation to help explain dynamics, from 10mb to 150mb. it shows vorticity. You can see how big of a dent the wave1 leaves in the vortex core, but its not very down reaching. The later spin-off of the polar vortex as the wave 1 grinds along it, has a stronger effect. based on all the graphics and animations and everything you can imagine, I would suggest that there is a buffer zone somewhere along the 70mb, and down, through which the minor SSW effects are not translated very well. The cyclonic energy on the other hand is stronger so it has no big problems penetrating down. best regards

Interestingly, following the great post by interitus above, the GEOS5 from NASA simulated a ave break event originating over the European sector. nothing special, but cool to see this events in model output. Also we have the best GEFS run till date.

Well, I think I meant right Meaning: to support a cause only because it is popular to do so. If you 'jump on the bandwagon', you join a growing movement in support of someone or something when that movement is seen to be about to become successful.

This warming is very undefined as such, and the only response as I have shown in 3D in the first phase is the Alaskan ridge formation. Do not also forget about the unusually strong Azore/African ridge area. And lets keep the strat splits out of the discussion since there is wave1 domination atm, and first deal with the displacement. And I am not a pesimist, but a cautius realist. We are not dealing with a major SSW, like the 09 one or 2013. A major SSW is not even forecasted yet, except ocasionally by some individual GEFS perturbations. We are dealing with a minor SSW until further notice, and so the rules of the game are different. Things could go in Europe's favour, but sweat and tears are needed for that. So lets not jump the wagon, shall we... Just a friendly reminder.

Here is my latest animation, from 00z GFS showing geopotential height layers in 3D. Top down are 10mb, 30mb, 70mb, 250mb and 600mb. You can see the upward induced split, the effect of the Azores high, reaching into lower strat, and the downward propagating wave from the strat wave 1, creating the Alaska ridge in the process. GEFS also sees the connection of the strong wave 1 with the troposphere, so here we have our fast coupling response. The Alaskan ridge is not all strat induced, but is greatly helped by the strat wave, makin more room for the ridge.

I would be very careful regarding trop-strat couplings and trop responses and feedbacks and UK cold shots and so on.... Just a friendly reminder. 06z GFS actually gave an example if a quick response.

Darn, forgot to add it. its 10mb.