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Recretos

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  1. Recretos
    For better orientation, the 380K field is roughly on a similar level as the 100mb field. On average around 14-15 km
  2. Recretos
    GEFS Bias corrected is going quite hard on a wave 2 pattern.
  3. Recretos
    Well, yes I think that too partially, but thinking or believing should not bend the facts a bit, since someone who doesnt know this subject, might get confused when seeing a minor warming with wave 2 or major warming with wave 1. Its just to reduce possible confusion. Wave 1 is a wave 1¸ and wave 2 is wave 2. And minor SSW is minor, and major SSW is major. If there would only be minor SSWs from wave 1s, than I wouldn't say anything, and the same goes for wave 2. The fact is, that one must not link specific wave numbers to specific SSW types, because the stratosphere does not work that way. We had wave 1 major SSW in 12/13 season, and strong wave 2 with no major or even minor SSW in 13/14 season. And again, the final warming is just a secondary name, or kinda like a suffix to the SSW. You can have the final warming without an SSW, and you can have an SSW without the final warming. Its just something that is added to the event later, if the vortex fails to recuperate. Dont get me wrong, I am learning too, as always, and I am just trying to explain a thing or two a bit further, so there wont be any confusion. I know what you meant, but someone who does not know this field very well, might find some things confusing or contradicting down the line. happy holidays, Regards
  4. Recretos
    A very good read altogether BrickFielder, but there are some points that confuse me. Mainly its the bold areas above. Minor, Major, Final warmings kinda classify separately, based on the amount of disturbance or damage done to the polar vortex and the state of its zonal angular momentum in a multilayer spectrum. What i am trying to say, is that you can have minor warmings via wave 2, or major warmings induced by wave 1. The wave number does not specify directly which warming will occur or if at all, but more the dynamics of the polar stratosphere, to put it smple. winters 12/13 and 13/14 are good examples. And Final warming is kinda a seperate feature, which marks the point of no return for the polar vortex, or the warming after which the polar vortex does not reform or re-establish enough energy to revive the PNJ (polar night jet), until next autumn. Or in another words, the state of the polar stratosphere remains mainly zonally reversed. A final warming happens every year, if not with the help of an SSW, than it happens naturally as we head towards spring or into April, may, when the seasonal sun angle changes and the stratosphere seasonally warms, and establishes a polar anti-vortex throughout the summer. Final warming is not really a type of an SSW, but is a rather a sub-classification thing. An SSW is not a final warming, but a sudden stratospheric warming, which can also be a final warming, So basically its both if it happens, but in essence its still treated as an SSW which also happened to be a final warming, if it would happen, lets say in late February or early March, and so on, because its kinda rare to have an SSW worthy of a final warming in early January for example... Regards
  5. Recretos
    To add to the general "flatness" of the stratosphere that Snowking mentioned, two main causes that add to better skill scores for the strat, are mainly the reduced wave frequency, and general higher wave amplitude.
  6. Recretos
    GEFS is normally forecasting a period of stronger zonal mean winds at 60N at 10mb, as the WAFz reduces.
  7. Recretos
    parallel GFS going into serious mode. Which i think is a bit too much of a disturbance. We will see. GEFS sees an upcoming period of intensification, and an unknown terrain afterwards.
  8. Recretos
    Remember where you have seen it first, and who showed you it! This is the new GFS experiment by NCEP, and let me proudly be the first to present you its stratospheric output. And this run looks very potent to say the least. Its in a pre-parallel stage (as noted by Ryan Maue), so it will probably get a tweak or two down the line. As cool as it looks, it could be either a failed run, or just the way the model is currently configured, aka a bias, or it might hold some merit. We will see. To me the vortex looks just simply a bit too much under attack.
  9. Recretos
    Best looking strat forecasts so far, are coming from the bias-corrected GEFS members 19 and 20. 19 has the best heights forecast, and the 20 has the best temp. forecast. Also it can be seen on the GEFS zonal mean zonal wind graph comparison, how much the 19 member deviated. Notice the general reduction of zonal winds at 10mb 60N following the WAFz, and then restrengthening as the WAF reduces. #Cycling
  10. Recretos
    GFS evolution of the zonal mean zonal wind at 60N, by height. It is like looking at the FU Berlin zonal wind plots, but you would cut out the 60N vertical line from 1000mb up to 1mb and run it in the GFS forecast for 16 days.
  11. Recretos
    Was just doing this for twitter, so I decided to drop it here too, since it is a nice example how cool the strat looks like on a decent grid, in this case 0.125°. And even this doesnt do it justice. The strat in reality is far more complex than we can see on those low res. charts at Instant weather maps, and others, or the 1° grid from ECMWF at FU Berlin.
  12. Recretos
    CFSv2 ENS mean from 4 yesterdays runs, still going at a wave 1, with a modest temp wave. Tho its good enough for an ENS mean. Looking further ahead, till around 20th, the pattern does continue to evolve, but not by much actually.
  13. Recretos
    Here is the member dissection of the 06z GEFS for 10mb 60N zonal mean zonal wind.
  14. Recretos
    NAEFS is actually inferior to GEFS-alone. Yes, there is half of GEFS in the NAEFS, but the CMC ensembles just ruin the average. Given the configuration, GEFS is now the best freely available stratosphere ensemble forecasting system. It has a model top at 0.2mb, up from 2mb (CMC ensembles have the model top at 10mb btw), and it now has 64 vertical levels. Basically it now uses the same vertical system as the GFS. I also prefer to use the bias-corrected version when available, but given the new configuration, the normal output is sufficient.
  15. Recretos
    Btw, this is how it looks like without the artistic licence.
  16. Recretos
    Well, actually yes, just simple interpolation. I know its kinda pointless since each member is a stand-alone forecast, but it looks better. Will just leave the raw view next time. As for the WAF, i dont have the formula for it to plot it. Some day perhaps. While at ensembles, here are some CFSv2 ensemble trends. They are continuing what the GEFS has started, but given the time period, they feel too slow.
  17. 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.
  18. 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.
  19. 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.
  20. 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.
  21. Recretos
    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.
  22. Recretos
    When I came to this forum in 2011 I think, or at least that was when I started reading it, I didnt even knew what wave1 or wave2 are/were. And in the past few years, during my learning course (which is still ongoing), I discovered and followed 3 simple, yet very important rules, which helped me understand and visualize the stratosphere and the polar vortex in a whole new aspect, and helped me speed up the learning process, without reading any PDFs and complicated studies. I am not really a fan of the PDFs, because I just simply rather have it to learn my own ways, because that helps a lot in actually understanding it practically. In the end, I get to the same result as in the studies anyway, just perhaps on a much longer track. But it is a huge difference between reading a theory in a paper, or getting to it on your own. Or at least getting close to it on your own. Ok, now for the "rules": 1. Keep it as simple as possible. Don't over-complicate. This one is simple. Stratosphere dynamics is a fairly new subject in the world of amateur and partially professional meteorology. And it can get very complicated very fast. So it is very important to at least try and keep it as simple as possible, without too many heavy words and overly complicated physics. You will just tangle yourself deeper in the mystery of the stratosphere by over-complicating it. Trust me, the stratosphere is just as simple as it is hard to understand. 2. Keep the aspect ratio in mind! This is one rule, that pretty much all seem to forget, and it is why some people just cant get a grasp on the size of strat dynamics, which is why they start to over-complicate it. They imagine the warming and the vertical wave propagation, travelling these HUGEE distances and it really appears mind boggling. In reality, if we were to pull the trop. and strat. off of our planet, from the equator to the north pole and would stretch it out flat, do you know how it would look like? It would look thinner then a compact disc (CD). Yep. The trop at strat are as flat as they get. And given the 2D spatial size of the dynamics, they really dont have to travel that much distance. The whole distance from the bottom to the top, the distance that energies have to travel is no more than lets say, the distance across London, from Wembley to Gravesend for example. Or like the distance between the channel, from Dover to Calais. Yep, its that thin, relative to its 2D size. 3. Visualize it practically. This one is optional and varies from person to person. Just try to visualize the stratosphere, all the processes in your mind, how the energies are flowing. Imagine it like a bucket of water, which you spin with your hand. When it is spinning, imagine that as the polar vortex. Then while it is spinning, just put your hand in at the top, and you will see how it disrupts the flow, and you have your own wave-breaking process, and if you would have a bit coloured water, you could see it propagating downwards. Remember, that the atmosphere is like fluid, and fluid dynamics apply to the atmosphere. And try to also visualize, when you look at geopotential height and temperature charts, that the troposphere and stratosphere are basically this volume of water in a bucket. I am the kind of person, which visualizes and imagines a lot, and I can see or imagine force vectors when driving a car or a bicycle uphill, or braking, or imagining energy transfer when doing physical work, etc... Call me weird, but it does the trick in understanding physics on a layman level. And I only had physics for 2 years in elementary school, so there is no excuse that you don't have physics background. Physics are laws of nature. They exist whether you understand them or not. And it really is a part of who we are and a part of our lives, so it can come natural to us to understand it. This is kinda it. I hope it helps in one way or another. It is based on personal experience and not just on theory. Cheers.
  23. Recretos
    Hey Frank, glad to have you aboard. Yes, most people in here are either from UK or USA. Personally, I am an "outlier" in that aspect, like a failed ensemble perturbation, being from Slovenia in central Europe. To Lorenzo: Here are some graphics from that NASA model, showing basically what those graphics are showing, a strengthening vortex, temperature and height wise in the core, but as the core of the vortex strengthens, so does the angular momentum of the vortex itself, which is evident on the stronger PNJ in the "surf zone". The NASA suite by Recretos :
  24. Recretos
    How can it not have one? Its basically from Reforecast/Hindcast.
  25. Recretos
    The new GEFS (bias-corrected) is also eager to jump the Wave 1 train. It has a very compact vortex. Or in another words, it is not looking as dominating as it could be actually. And given that it is being mainly displaced toward the Scandi/Siberian sector, I see it a good thing in the long run. FIM-9 is also jumping the train. Temperature anomalies are all in a similar spirit. Notice the high resolution of the FIM-9 output (0.125 grid).
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