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Stratosphere Temperature Watch 2012/2013


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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

    an all amps H5 anomaly would be useful as a 'control', perhaps to smooth out inherent variability and to compare against ENSO state.

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    Steve whilst I agree to a certain extent, more especially with regards to the difficulty in forecasting exact placement of tropospheric synoptics (particularly with regard to the UK in the overall sch

    Posted Images

    Posted
  • Location: Slovenia, Central Europe 1050m ASL
  • Location: Slovenia, Central Europe 1050m ASL

    I really hope that once the special thread is created, all these posts are going to be moved there, because they are offtopic. Posted Image But until then, I hope people dont mind if we share a word or two in here. Posted Image

    @GP: I understand now. How about AMP below 1? Also required I assume? Posted Image

    Edit: About amps: Are talking above 1, or above & equal to 1? and the same for below.

    Edited by Recretos
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    Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

    I would go all amplitudes (control) and high amplitude (>1SD) to see if there is a meaningful difference between the two. We have an excellent case in point right now. Really strong phase 8 projection which is in part driven by a stratospheric coupling through forcing of tropical convection.

    H5 anomaly in the next few days: post-2478-0-37101800-1359841269_thumb.jp

    Is this more amplified because of a more amplified GWO signal ?

    Edited by Glacier Point
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    Posted
  • Location: Slovenia, Central Europe 1050m ASL
  • Location: Slovenia, Central Europe 1050m ASL

    Ok so no extra composites with amp below 1.

    I have already completed the basic extraction for all phases for all months.

    Here is a composite of Phase 8 in February, all amps and all ENSO phases. In total 113 days in the composite.

    Posted Image

    Maybe the signal would be even better, if amp>1 would be applied and only ENSO neutral years.

    EDIT:

    This is again phase 8 for February, but I quickly applied the AMP>1 filter. In total 77 days in the composite. A bit better match, but still with all ENSO phases. Maybe an even better match would come put if I would apply the ENSO filtering, but that would take some time, and as I have just find out, that will be the most time consuming part.

    Posted Image

    EDIT2: Just for the sake of curiosity and to make the post less offtopic, here is the 10mb anomaly plot, with a negative 11 day lag applied. So 11 days before the H500 anomaly above. The 10mb mean is basically useless, because only the anomalies show the actual "tendencies" at this height, with so many days in the mix. For a comparison, I added the ECM analyse.

    Posted ImagePosted Image

    Edited by Recretos
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    Don't want to put a dampener on this composite project but might it be worth doing some statistical research on the data beforehand?

    If there is no significance in the correlations then the composites won't actually be particularly meaningful and serve little forecasting potential.

    I would go all amplitudes (control) and high amplitude (>1SD) to see if there is a meaningful difference between the two.

    If there was a negligible effect with amplitudes <1SD then you are autocorrelating >1SD with itself (albeit diluted) and there would be no meaningful difference.

    Edited by Interitus
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    Posted
  • Location: Slovenia, Central Europe 1050m ASL
  • Location: Slovenia, Central Europe 1050m ASL

    If there is no significance in the correlations then the composites won't actually be particularly meaningful and serve little forecasting potential.

    Well, I think that is what we are going to find out, once we put the composites into practical use. Posted Image

    I am already doing the ENSO filtering, and February is now 100% completed, and ready for coding the data files for upload.

    And here is the finished Phase 8 (0.5) for February, in ENSO neutral phase, and with AMP>1

    Posted Image

    P.s.: The MEI dataset goes till December 2012, so that is why I also decided to use the dataset for GWO Jan 1970-Dec 2012. So no 2013 dates included.

    EDIT:

    Just for fun, I did the same thing as yesterday. Taking the Phase 8 (0.5) which is now corrected with Neutral ENSO and AMP>1, and I plotted 10mb anomaly, with a 12-day negative lag applied. So before the onset of the phase. And I added the anomaly of this year for a similar period, around 12 days before the onset of the phase 8. Of course the anomaly of this year is much greater in the reanalysis, because it contains much less days than the GWO phase composite. Now I am not really trying to make a specific point here. Only trying to say that it should be quite interesting to experiment with all this data. Posted Image

    Posted ImagePosted Image

    Edited by Recretos
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    Posted
  • Location: Eccles, Greater manchester.
  • Location: Eccles, Greater manchester.

    Hi Graham,

    I highlighted briefly yesterday in the MOD thread the strat support from the GFS, and to a lesser extent the ECM, for height rises to the NE and this has grown today.

    Firstly, it is worth pointing out that following the SSW we are now seeing a return to 'normal' conditions at the top of the stratosphere. The polar vortex is increasing in strength and this is slowly working its way down the stratosphere.

    Mean zonal winds are now at 60+m/s at 1 hpa and this is slowly descending.

    post-4523-0-59621200-1359793216_thumb.gi

    The forecast for the mid stratosphere still only increases the mean zonal wind to less than 10m/s at 10 hPa (whereas 20+m/s could reasonaably be expected) so these are still weak by day 10.

    post-4523-0-77062000-1359793337_thumb.gi

    Down to the most variable level at 100 hpa close to the troposphere and we see the disrupted vortex that could ( I will repeat this for those who fail to grasp - COULD) lead to some form of height rises to the NE. Today the ECM paints a far better picture than the GFS due to the extent that the Euro trough is forecast to head south, rather than slightly east as per the GFS.

    Here is the ECM 10 day forecast at 100 hPa with NE height rises indicated.

    post-4523-0-36925500-1359793615_thumb.gi

    Compare this to the latest GFS in respect of Euro trough.

    post-4523-0-33403500-1359793653_thumb.pn

    One thing to note though on both 100 hPA charts is the slight waning of our Canadian friend. Could it just possibly leave residence. We know what that could lead to if it does.........

    Any way Graham - no particular focus on the NW with these synoptics, but as ever get the cold in place and then see what happens.

    Really thankyou.I appreciate your ever present willingness to help others in an open manner which does not hinder the purpose the expression of ideas[ie showoffs who have knowledge but like to not share their knowledge by being purposely overly complicated]Again ,thanks for the time out a lot,Graham. Edited by greybing
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    Posted · Hidden by General Cluster, February 4, 2013 - Crap!
    Hidden by General Cluster, February 4, 2013 - Crap!

    Really thankyou.I appreciate your ever present willingness to help others in an open manner which does not hinder the purpose the expression of ideas[ie showoffs who have knowledge but like to not share their knowledge by being purposely overly complicated]Again ,thanks for the time out a lot,Graham.

    People who have the knowledge do not directly have the ability to explain. And if they do have that ability, its not always simple to explain something complicated. ;)
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    Posted
  • Location: Dublin
  • Location: Dublin

    Can anybody link me to a paper on the model thread a few weeks ago. Stratospheric Warming Paper which gives Height anomalies at different points before and after historic warming events.

    Can anybody remember the author or a link to the paper?

    I would be really grateful if you could help me with this!

    Thanks

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    Can anybody link me to a paper on the model thread a few weeks ago. Stratospheric Warming Paper which gives Height anomalies at different points before and after historic warming events.

    Can anybody remember the author or a link to the paper?

    I would be really grateful if you could help me with this!

    Thanks

    Sounds interesting, was it Cohen & Jones? Looks at a few heights and SLP patterns and anomalies - http://web.mit.edu/~...dJones_JC12.pdf

    The next question is when the final warming takes place? On average, when that does that occur?

    Can start in late March but typically the middle of April. This paper looks at them in some detail and shows that they vary, characterised by warming from the top of the strat downwards, or from the middle stratosphere - the latter leading to a more -NAO in April http://elib.dlr.de/7..._et_al_2011.pdf

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    Posted
  • Location: Irlam
  • Location: Irlam

    Can start in late March but typically the middle of April. This paper looks at them in some detail and shows that they vary, characterised by warming from the top of the strat downwards, or from the middle stratosphere - the latter leading to a more -NAO in April http://elib.dlr.de/7..._et_al_2011.pdf

    Thanks :)

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    There are trends however - 7 day running means show that there is on average a cooling response in the 2nd week after SSW, followed by a milder interlude, before a second period of cold about 5 weeks after SSW. Not easy to be precise because there is some variation in the dates used by Cohen and Martineau, and the years obviously don't always follow the same pattern. The first cooling on the graph looks smaller but is often the more dramatic and the anomaly is reduced by the strong positive temperature swings that can occur in some instances.

    post-2779-0-23245700-1357295550_thumb.jp

    Now a month after the SSW is a good time to see how the effects have progressed.

    As before here is a graph of the 7 day running mean CET trends from 55 SSW events with the scaled CET to show the trends from this year. Starting from a week before SSW to a month after, the mean is the 7 days following the date on x-axis, day 0 is 06/1/13 -

    post-2779-0-02449300-1360317993_thumb.gi

    The daily correlation is 0.72, but with daily variation smoothed out, the 7-day running mean correlation of temperature trends shown in the graph of over a month is 0.94.

    Now, there is an element of luck that the response has been typical but there appear to be solid, reproducible trends - remember this is a composite of all SSW and closer matches can be found if selectively choosing analogues.

    At Day 15 after SSW, including this year, 34 times out 56 there has been a negative CET anomaly, or 60.7% which doesn't sound particularly impressive but there is a simple binomial probability of only 4% of there being this many or more colder days by chance.

    This seems to confirm research which hints that far from being harder to forecast tropospheric conditions after SSW it may actually be easier.

    edit: Just double checking the figures and a stupid error means that the correlations are not as high but still impressive 0.63 and 0.91, apologies.

    Edited by Interitus
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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    An interesting post there I.

    Have you done anything for the severe winters, say 1947 and 1962-63, to see how they compared. That is if there is SSW data and again if it showed as well as the chart above?

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    Posted
  • Location: E Lancs, 900ft asl
  • Weather Preferences: Snow, blizzards, cold, thunderstorms, frosts, fog, general extreme weather
  • Location: E Lancs, 900ft asl

    FAO: Longer range boffins...

    Chaps, just a quick one, but from evidence within any journals looked at or from general knowledge, is there any time lag in relation to the phase of the MJO and the possible synoptic patterns that *may* result from the phase of the MJO?

    Just asking as currently we are in a decent phase 2 and just using the good'ol americanwx chart, this does seem to match quite well to the thinking synoptically that high pressure will become a player across the UK into next week

    http://raleighwx.americanwx.com/MJO/FebruaryPhase2500mb.gif

    http://www.wetterzentrale.de/pics/Rz500m6.gif

    The MJO is certainly on the move and latest EC32 has it quite rapidly heading into phase 3 and then phase 4 within 10 to 15 days, but again, is there any sort of time lag between expected phases of the MJO and resultant synoptic patterns.

    Cheers, Matt.

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    Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

    Morning Matt,

    This is the best paper imo on the MJO and impacts over Europe.

    http://www.cerfacs.f...cassou_2008.pdf

    This page highlights the atmospheric benchmarks and also the lag time in days.

    post-7292-0-77751400-1360655912_thumb.jp

    Conclusions

    post-7292-0-36113100-1360655990_thumb.jp

    Generally 8/10/12 day lags with NAO- preceeded by phase 6-7 of the MJO.

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    Posted
  • Location: E Lancs, 900ft asl
  • Weather Preferences: Snow, blizzards, cold, thunderstorms, frosts, fog, general extreme weather
  • Location: E Lancs, 900ft asl

    Thanks for that Lorenzo, I'll take a read, just what I was after.

    M.

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    An interesting post there I.

    Have you done anything for the severe winters, say 1947 and 1962-63, to see how they compared. That is if there is SSW data and again if it showed as well as the chart above?

    Unfortunately the data doesn't go back to 1947, most starting a couple of years after. Not looked at 1963 in detail but here is a graph of running 7 day mean scaled 1963 CET anomaly vs 54 other SSW years (with day 1 being the 7 days up to the SSW etc)

    post-2779-0-13270400-1360676285_thumb.gi

    The correlation over a two month period is 0.36 and a post SSW temperature signature can be seen quite clearly.

    However it didn't coincide with the severest cold as might be imagined. The SSW was quite late in season on 11/02/63 with most of the cold already passed by the time any effects were felt, as seen in this graph of daily CET anomalies

    post-2779-0-43611400-1360678615_thumb.gi

    It is almost as though the SSW jilted the circulation away from the extreme set up that it was in previously and presaged the return to more normal conditions. The 24th January 2009 SSW was quite similar in this effect also, and the SSW of 27th January 1982 pretty much reversed the extreme conditions triggered by the earlier SSW on 4th December 1981.

    Edited by Interitus
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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    thanks for that work Int-not perhaps what I expected but thanks anyway

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    thanks for that work Int-not perhaps what I expected but thanks anyway

    Yes, there seems to be a general viewpoint with the rise in awareness of the subject that SSW are linked with severe outbreaks. They certainly can be, but to counter some disappointment that has been expressed by many posters in the model forum for example, from looking at the data it becomes clear that they are not a rare circumstance and are part and parcel of a normal northern hemisphere winter, with 'normal' cold spells being more typical.

    Charlton and Polvani http://www.columbia....-JCLIM-2007.pdf state that SSW occur with a mean frequency of 0.62 per winter, however the list I have been using has a mean frequency of 0.9 per winter whilst Nakagawa and Yamazaki http://center.stelab...mazaki_koji.pdf compiled a list with a frequency of 1.13 per winter.

    More than being viewed as a pointer for cold, it has struck me how SSW can be used for timing events and trends. A bit like electric shocking a fibrillating heart, an SSW is a bit like an atmospheric defibrillator - removing quasi-random signals and restarting the atmospheric circulation again for a while.

    Edited by Interitus
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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    thanks for that post Int.

    I have only a very limited knowledge in this field and tend to leave it to those of you who have done a lot of reading about things. I do feel a fair number on the model thread are using it, so to speak, by running before learning to walk. The buzz term which to me is best left to read the conclusions you folk give and to try and read more. Note for summer-bookmark the links various of you have given in this quite first class thread-hopefully a lot of others will do the same!

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    Interesting seeing model output tending towards a period of increased heights to the northwest, which is entirely in line with the historical analogues of NAO trends.

    Here is a chart of NAO anomalies following all SSW (now increased to 60 excluding this year) - day 1 is the SSW.

    post-2779-0-42532100-1360857650_thumb.gi

    Anomalies are used rather than the actual NAO because the CPC/NCEP NAO doesn't average zero as might be expected. We are now on about day 39 so a negative anomaly should be the form horse around now, or in the near future.

    Here is 2013

    post-2779-0-07887100-1360857671_thumb.gi

    Some of the trends are present, but it has been a bit different. The early impact of the SSW on CET has been more reliant on the AO - correlation 0.66 vs 0.4 for NAO.

    So here is a graph of the 5 closest NAO anomalies by correlation to 2013. They are all vortex splits which is highly unlikely to be a coincidence because of the particular resulting pressure patterns. Again a spell of -NAO would appear to be in the offing.

    post-2779-0-87681200-1360858016_thumb.gi

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