Jump to content
Will it snow? 7 day forecast Weather Radar Will it be cold?
Snow?
Local
Radar
Cold?

Recretos

Members
 View Profile  See their activity

  • Posts

    496

  • Joined

  • Last visited

  • Days Won

    5

 Content Type 

Everything posted by Recretos

  1. Recretos
    Yes, as I expected. Thanks Gino, the link is very good and there are some good parameters on it, but are not really you average "user-friendly" parameters. Too bad it is only analysis. I will add GEFS time-series, so I wont be off topic. @SSIB: You posted before me, so I didnt saw the post until I posted. (how complicated xD). I will give you a quick one, because I am off to work (darn night shift). This technically isnt even an SSW. And the vortex gets briefly split, and not disintegrated or getting its cores height greatly increased, speaking for the mid-lower strat. As I have seen on other weather forums, there is a lot of emphasis on the 10mb warming only, mainly because of that darn Meteociel chart, which is clearly not enough to give an analysis on how the whole strat profile looks like and how the heights are responding. I dont want to be the guy that puts the nail in the coffin for any winter optimism. I am just stating (or interpreting) the obvious from the recent model runs. Regards.
  2. Recretos
    I posted more than 10 graphics just above you, showing the (model calculated) effect on the troposhere. @Gino: Paste some products of those parameters so we can have a look. Tho I use the PV Advection mostly during the storm season. And PV in this parameter does not refer to the Polar Vortex as suggested by the mouseover. It is either Potential Vorticiy or Positive Vorticity. At least that is the common when looking at vorticity advections.
  3. Recretos
    Well, I wont go into details, but I cant really see a neg. NAO developing with the residual vortex core looming not really high over Greenland. SSW (or the processes actually) should among other things, also raise the core height of the vortex and "remove" its connection with the troposphere over the near pole region. I cant really see this happening in our case. Looking at the ECMWF control run from 29.1, it is just the contrary. The vortex gets split, but the remaining cores keep the connection with the troposphere, and with the split, the energy gets focused and "perhaps" that is also the reason the control run intensified the Atlantic low in the expected time frame. And the reformation after, like in every other model, with the "Atlantic" scenario being the likelihood down in the trop. (Looking only at a specific run in this case) In this particular case, the whole relationship can be nicely seen on the 3D perspective of geopotential height. And the latest GFS. At this point, the low skill from the tropospheric output already starts kicking in, but nonetheless: The bottom line: All this breaking and warming and splitting, all just for the intensification of the Atlantic?
  4. Recretos
    I totally forgot about the spaghetti plots. Thanks Gino for giving me the idea. GEFS/GFS:
  5. Recretos
    Re the reverse, the most south as the GFS 12z op run goes, is 69N. Similar on the GEFS suite: And the NCEP "family" is pretty much agreeing what happens after this day 7-10 attempt. Regards P.S.: While I am at it (plotting), here is my next experiment: EP-Flux from ECMWF, NCEP or JRA reanalysis datasets.
  6. Recretos
    It is interesting to note that there is quite a difference in zonal means between ECM and GFS. ECM is much more reversed 75N-90N. While GFS is warmer in the same region of the upper strat.
  7. Recretos
    Look at the 00z op. run if you are interested how the ensemble mean looks like. Edit: Just got home, so I can throw it in a bit more graphical form. The control run kinda follows the story, with the initial split, and then reformation of what is left in the FI. The ensemble mean, not falling far behind: An actual reformation like seen above in mid-Feb, would in my view mean that we will pretty much have to wait for the FW to do us some justice and at least giving us some moral compensation for all the hard time this powerhouse of a vortex gave us. And I also have to give credit to the GEFS. It had a remarkable consistency and even tho the trend gets quite "watered out" with time because of the member spread, it still had a fairly decent idea of the development. Tho it is questionable how it would perform in stronger top down events. There is an upgrade of resolution in plan for GEFS and I hope it gets realized before the next season. Best regards.
  8. Recretos
    Here it is, tho you should consider what Ruben is saying. In the meanwhile, 12z GFS comes out with a sobering thought.
  9. Recretos
    And the key point lies more in those height charts than the by far "favoured" 10mb temperature.
  10. Recretos
    :lol: Thanks, but its just simple logic. :DOk, to make it official, the technical SSW occurs at T306.
  11. Recretos
    Without a doubt. If only his "cousins" would follow. It is suspicious that only the 6z run is always so aggressive. Technical SSW at T366 in this 6z run. 10mb time series:
  12. Recretos
    When comparing the latest GFS and ECM, it is clear that ECM has a more beat up vortex. As also seen on the zonal mean zonal wind chart. Not by much, but it can affect the ongoing development in the model.
  13. Recretos
    Yes, it reverses from 372 to 384. At 300, the zonal mean-zonal wind is ~+12m/s at 60N@10mb. What this calculates is basically the zonal (U) component of the mean wind field. More meridional (V) is the wind, lesser the U component. Basically the "angle of attack" of the wind towards the pole (or down from it) plays a role. Talking about the geostrophic wind of course. Negative (positive) zonal mean on its own does not mean or guarantee that the wind is blowing in a straight line from east (west). Yesterday i was talking about waves, so today let me give you a crash course in the infamous zonal mean - zonal wind section. There was an easterly component at 300, but under a steep angle, while the west component was under a lower angle, adding more positive zonality in the mean at 60N. I drew (veeery poorly) the wind vectors, which are not really meant to be proportional to the amplitude. Blue vectors have a west (positive) U component (wind crossing the lat. line on a W->E orientation), and the violet vectors having an east (negative) U component (vice-versa). White line is the 60N lat. line. Basically you can see that there is not much zonality at all, with the intense wave 2 making the main jet pretty much meridional at 60N, which can reduce the amplitude of the zonality in general. But the zonal components that remain are more westward than eastward. And the speed of the west "components" is greater in average (zonal mean) than its east counterpart. As for the 384: Here we have much more and stronger east U-components. The zonal mean was -5 in comparison with the +12 at 300h. The bottom line is: You can give a good estimate of a mean zonal U-mode (east or west) from height charts, but nothing tops calculations. Especially when you want to point at the exact time of the zonal reversal. For example, you misjudged it by 72 hours. You can also draw like I did, but you still cant get an exact clue just how strong is the orientation of the U-component of the geostrophic wind Unless I plot you the actual zonal components. I actually plotted this after I drew the top charts and it seems my estimate was quite good. Its not really that hard to see the orientation, but the intensity is another story. I have noticed that. And you notice that the temperature wave dissipates, while the geopotential wave remains. So at that point you can have wave 2 and 1 temperature wave. I completely understand what your point is, but for the sake of people who are not so familiar with this, lets keep it to the basics, and say that the wave 1 and wave 2 that we usually talk about, refer to geopotential waves. We have separate calculations for temperature waves. On a side note: 12z is actually a downgrade, and it does not have a reversal at 384h (not even close actually). The zonal mean zonal wind is at 21 m/s at 60N@10mb. @Ruben: The difference is expected, since the members are perturbed. And of course the resolution does indeed play a role. And that is actually quite a spread, showing just how complicated things are at the moment for forecasting the medium-long term development in the stratosphere. Regards.
  14. Recretos
    Well. Where to begin. For now, lets just say that this run actually looks like an amplified version of the recent GEFS ensemble mean scenarios. It even caught me as a surprise, and such a change in just one run, does imply that there is some major change in the model forcing (or a run error). I haven't looked at any charts yet, but my bet would be on EAMT (among other things) like on a few occasions so far. I also checked the input data for the 6z run and even tho the main critical data was complete, there was actually an overage of one segment, but 3 opportunity inputs were actually at zero (no input data). The GPS integrated precipitable water, Multi-Agency Profiler (MAP) + SODAR winds and RASS temperatures (NOAA and Multi-Agency). I guess that the 12z will show if the input data played a role, or perhaps GFS finally sobered up and decided to follow its ensemble cousin. I will add a few graphics later in the evening, once the 12z runs gets out. Dont want to spend 2 hours making graphics for a possible run error (hopefully it is "too legit to quit"). Sometimes the only way to get an SSW, is in your bucket. And yes, as some have said it before me, 06z is officially with an SSW, with -5m/s U-mean U-wind at 60N@10mb. At T300, there is no technical SSW. And the 3D profile: From top down, 1mb, 3mb, 5mb, 10mb and 30mb. It shows the geopotential height in 3D and color. The perspective is the "USA in front" like on the Instant weather maps. That 30mb level just doesn't want to give in (also trying to be too legit to quit :lol:) , tho it is severely weakened. Best regards.
  15. Recretos
    I agree with Chiono. You also have variations, like top-down warming events related with wave breaking or bottom-up wave propagations that do not necessarily mean associated warming. And you can have some level of temperature increase because of the increased geopotential height (insert virtual temperature somewhere in here ), but that is not the same as wave-breaking induced warming that we are typically waiting for to show up in the models. For example (I just love practical examples) here you have wave 2 on the geopotential height, but only "wave 1" temperature-wise (or 1 temperature wave). On the left and in the centre you only have some g.height increased "warmth" which I could never call a temperature wave. As you will see, the main 2 "daughter vortices" were actually the result of the wave breaking, originating from the main vortex. I made the animation of the whole process, which should give you the exact idea. 1mb_anim.mov Actually, while looking at the PV animation, all vortices did originate from the main vortex. And on a side note, I really like the 1mb level, because with wave breaking, the dynamics look almost as intense as in the troposphere. In layman terms, its like taking the terrain of the Earth and putting it upside down in the upper stratosphere. Hint hint at mountain torques? Kinda like spinning water in a large bucked, and then putting fingers or your hand on the water surface. If you hold your hand there long enough, it will disrupt the flow quite deep down. That reminds me of an experiment I used to play with, when trying to simulate a mesocyclone. I used a large bucked (150l of water ), and I put some very fine dark soil at the bottom. I filled it up with water and then I spin the whole mass really fast. Then I watched how the vorticity from the large spinning water mass gets increased and focused on small specific random locations at the bottom (or like ground surface in reality) where the soil was, and it even formed quasi-funnel shaped forms. it lasted for a short period and then disappeared and reappeared at a different random location. I was basically simulating tornadogenesis by fluid dynamics. Now you could try this at home, and when you spin up the water mass, you will notice how in the centre the water level will decrease, and on the sides the water level will increase. That is pretty much an accurate simulation of the geopotential height and now you have your own atmosphere dynamics in your bucket. Now you put your hand top down into the water surface, deeper each time, and observe how the dynamics change with depth. It is nice if you have some very fine soil or some fine light material in the water, so you can actually see how the flow changes with depth. You can actually simulate your own SSW with fluid dynamics, which is pretty much what our atmosphere is "running on". I am also thinking of ways to simulate wave 2. I have thought about inflating balloons, but I guess I need to think some more. I really hope someone will decide to make this experiment, because it is first hand intro into stratospheric dynamics, and pretty much as close as you can get at home to simulating stratosphere/polar vortex without a computer. And if you make this experiment, you kinda get the feeling just what big of a player the stratosphere really is. Especially when considering that the depth/length proportions of the polar vortex are about the same as those of a "CD" disc. Oh, I just wandered a bit there. Here is the PV animation I mentioned above. 1mb_PV.mov And I will add temperature animation while at it. 1mb_Temperature.mov Regards.
  16. Recretos
    Well, here we go again. Hopefully no power outage this time. I will continue where you have ended. The demonstration. As Chiono said, planetary waves are just what the name suggests: a wave on a planetary scale. So it is not hard to recognize the wave pattern if you know what to look for. He has also nicely demonstrated how the typical wave looks like. Personally I prefer the equirectangular view (perpendicular lat/lon grid), because the waves are a bit more defined. Only visually of course. I have made some examples a while back: Now as for the wave 3, things get a bit more complicated. A natural state of the vortex is wave0 , wave 1 and sometimes wave 2 (emphasis on the natural state). Each wave "requires" or induces more dynamics. So a wave 3 and a vortex disruption (intensity varies) do tend to go hand-in-hand. The wave 3 is sometimes basically more of an end result. But nonetheless, if you want to find a decent example, you need stronger amplitudes and a bit more disrupted vortex, which basically points at the upper stratosphere or lower mesosphere, since it wont be easy to find a 200-300m wave on a 10mb level. Wave 3 can also be calculated from smaller g.height fluctuations which do not give the obvious or the expected shape on the charts, but it does appear on the calculations. All this also tends to limit its duration on the time scale. A decent example of a wave 3 pattern was just a year ago. I decided to use the stereographic view this time, because the equirectangular view kinda looses the feeling of it, and most of the charts we look at, have this "top down" look. The vortex got broken up, and it almost looks like a tropospheric pattern (when ignoring that inverted ridge). You could count up to 4 waves, with one having the "wave inside a wave" kinda look. Keep in mind that when the vortex gets disrupted or broken up (or the wave number increases), the min/max height difference can be reduced (or the average wave intensity decreased, which is why the wave amplitude decreases with the wave number increasing), which can also reduce the wave amplitudes. This is a part of the reason why you normally don't see strong wave 1 and strong wave 2 amplitude at the same time. (Boy have I complicated this last paragraph. ) The recent wave 3 does seem to be more of a g.height fluctuation than an actual wave 3 pattern, so its not easy to spot it. In fact you need to go up to the peak, at 0.4mb and even there it looks more like a fluctuation than an actual pattern. And it also has that "wave inside a wave" feel to it. But since the min/max height difference is quite big, it does not look that bad on the GDAS zonal mean graph. Speaking of waves, here is the wave2-ish GEFS that I was talking about before: This is a "ripped off" version of the previous post, because I dont want to take any chances this time (the power just came back ). Regards. Post scriptum: You know, its kinda funny when I think back and I realize that just a little over a year ago, I didnt even know what wave 1/2 actually was or how to interpret the wave charts at FU-Berlin site. You live and learn, as they say.
  17. Recretos
    I was actually just about to post on wave 3 with graphics, but the power just went out. So now I wonder, how long does the post autosave last before it gets erased? P.s. The GEFS looks more and more wave 2-ish. Was planning to add it to the post, but now I cant for obvious reasons.
  18. Recretos
    Not really a reverse at 60N, but a reverse nonetheless.
  19. Recretos
    The "peculiar" scenarios don't want to leave. GEFS 6z GEFS 12z. I am not forecasting anything at this point. Just sharing a more detailed insight into the GEFS. Regards
  20. Recretos
    Thanks, but this comparison is on a level of comparing a home-made volcano to the Yellowstone caldera. Speaking of those "kicks", there are some peculiar perturbations in the latest GEFS. Two examples: If you know what I mean....
  21. Recretos
    In laymans terms, if you want to bring a building down systematically, you first pull the roof down, and then you kick in the walls.
  22. Recretos
    Well, CFS mean is kinda trying to have a go at it, but with no real success in the normal FI. But yes, its the CFS. GEFS is trying to have a go too, and it actually has a pretty beat up looking vortex, when considering the geopotential height and temperature. Not that surprising, when considering what the poor fella went (or is about to go) trough. But that core just doesn't want to give up, no matter how much money you offer it. The models are "peeling" it like an onion, but by the rate of the current trend we will be done just in time for the FW in March. :lol:
  23. Recretos
    I spy, with my little eye,...
  24. Recretos
    To make a quick GFS 12z analysis. I made some cross-sections over latitude and longitude. I was aiming at lines of "points of values". It is meant more as an interesting perspective into the works of the model, and it gives an "in-depth" view of the activity throughout layers. Zonal means are still better overall, but specific lines are sometimes more interesting to watch at least. So first is the 10mb max. temp in the latitude cross section. Added on the right is the location of the cross section (black line). As it is obvious, the warmth is sitting on a big blob of very cold air. So if it wants to go further down, it has to go either east or west, with the east move being a more viable option. Next up is the longitude cross section through the area of max. warming in general in the stratosphere. That is at or around 70°N (look at the black line on the right image). What is most notable, is the strong eastward downward propagation. That is also towards the direction of the high pressure wave, which is of course not a coincidence. Besides, you don't expect the warming to just simply penetrate the mid strat. vortex core from above. Next is the cross section of the max. temperature, which is 49°C at 1mb. Refer to the black line on the right for a better idea of the cross section. Finishing off with the zonal wind. This is the cross section through the 60N latitude circle. The most notable thing is the large amount of zonality and cyclonic energy in the Atlantic sector, pretty much all the way from the troposphere to the upper stratosphere. The vortex being displaced into this region probably has nothing to do with it? Keeping in mind the low accuracy of the tropospheric layers. Next interesting thing is the zonal wind at the same line as the max. 10mb temperature before. A decent poleward reversal from the upper strat down to the upper troposphere. It is pretty likely this is also a part of the GFS strat-trop feedback mechanics, meaning that this 12z run is already calculating the feedbacks. Tho I am not sure about the previous runs, since I havent done the cross-sections. Considering the location of the cross section, this downward oriented zonal reverse does indicate the wave 1 pressing more poleward, pretty much trying to go for a legit SSW try. As for the zonal mean, it looks quite different than the 06z. Notable is a similar feature as on the cross section above, which does tell the story of the wave 1 increasing in strength and pressing poleward (when looking at different times of course). All in all, this post is meant more as an insight into the works of the 12z GFS and as a test run of new perspectives by "slice and dicing" the stratosphere. These kind of products are good when you are trying to pin-point where a model might make the SSW "contact" with the troposphere. To be fully honest, I am testing all these products mainly for the next season (14/15) which should be one bomb of a season of strat. monitoring, and where all of the products I am testing at the moment, might prove if they are actually helpful with forecasting possible SSW induced effects (where and when), if one might occur. Best regards. Edit: Fixed a few typos.
  25. Recretos
    At 60N, the reversal is down to 1,5mb. But it is lower down around. The best run so far this season is still the 06z from 01/01. GFS ran the 00z cycle of 01/01, and then went to the new year model party. And he must've been pretty smashed from the party in the morning when he ran the 06z cycle.
×
×
  • Create New...