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sebastiaan1973

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Everything posted by sebastiaan1973

  1. sebastiaan1973
    Thanks Matt for this overview. Altough not an expert, I suspect we have to wait a little longer. Chio showed us the theory of Cohen with his Snow Advance Index. In that perspective things look quite well in Siberia. The effect of this snowfall will become clear in the coming weeks.
  2. sebastiaan1973
    This is the current Ozon situation. Not looking good right now.
  3. sebastiaan1973
    Steve, not just Scandinavia, but lot's of snow too in western parts of Siberia. If all things work out well, we can come close to 2009!
  4. sebastiaan1973
    SIberia seems to become 1 big low pressure area. Excellent news. In the coming days there will (too) snow fall in area's which hadn't receive snow yet.
  5. sebastiaan1973
    I found this piece about the SAI. Mid-month October update on Eurasia snow cover. The plot shows snow cover from 0 to 180 E, 25N to 60N. This matches the domain in Judah Cohen's 2011 paper. The red line is 2009 (which had a -AO the following winter) and the blue line is 2007 (which had a +AO the following winter). Cohen's 15 year data set has a correlation of 0.86 between snow advance and the following winter's AO. This year, in green, has had what I believe to be an ideal start. If snow cover explodes in the second half of the month, then I'm on the bandwaggon for a deep -AO this winter. Most of the snow cover this year has been in eastern Eurasia. However, the GFS ensembles show a great deal of storminess in western Eurasia toward the end of the month which would be fantastic for anomalous snow extent. http://www.americanw...25#entry1791017
  6. sebastiaan1973
    Quick answer: no.
  7. sebastiaan1973
    This is the difference in two weeks time. At the first of october we had a large negative anomaly. Right now it's around normal (both not shown). So logical thinking brings me to the conclusion that the Snow Advance Index has a rapid increase.
  8. sebastiaan1973
    Good morning. EC 216. Look at these 850 temperatures around Alaska.
  9. sebastiaan1973
    Chio, if I understand well, the pushing of warmer air into the northpole around Alaska is a good thing?
  10. sebastiaan1973
    That's a nice experiment Chio! Interesting. They refer to Cassou's article in Nature. http://www.nature.co...ature07286.html In 2008 Cassou made a presentation with this subject, which can be found here: http://www.cerfacs.f...cassou_2008.pdf In my opinion it's an excellent presentation. Nicely illustrated and clearly written.
  11. sebastiaan1973
    Very good developments. Excellent for the Snow Advance Index.
  12. sebastiaan1973
    http://www.eps.jhu.edu/~cig4/mjosswv6.pdf thanks to Karel for this suggestion The effect of the Madden-Julian Oscillation (MJO) on the Northern Hemisphere wintertime stratospheric polar vortex and major, midwinter stratospheric sudden warmings (SSWs) is evaluated using a meteorological reanalysis dataset. The MJO influences the tropospheric North Pacific, and in particular the region in the North Pacific most strongly associated with a SSW. Consistent with this, SSWs in the reanalysis record have tended to follow certain MJO phases. The magnitude of the influence of the MJO on the vortex is comparable to that associated with the Quasi-Biennial Oscillation and El NiËœno. The MJO could be used to improve intra-seasonal projections of the Northern Hemisphere high latitude circulation, and in particular of the tropospheric Northern Annular Mode, at lags exceeding one month.
  13. sebastiaan1973
    Please take a look overhere. http://www.wzforum.de/forum2/read.php?27,2519981 German written forecast for this winter, including SSW (most chance in January). If you don't read German, you can use google translate.
  14. sebastiaan1973
    Please take a look overhere. http://www.wzforum.d....php?27,2519981 German written forecast for this winter.
  15. sebastiaan1973
    I didn't do the research. Someone who calls himself skiervermont did
  16. sebastiaan1973
    Over seas they are also interested in the stratosphere. Please take a look over here http://www.americanwx.com/bb/index.php/topic/34743-winter-2012-2013/page__st__2590 I have a question based on the following: 'Of course there are other factors, but the stratospheric correlation is the strongest I've seen to date, except perhaps ENSO (depending on location). Almost all cold stratospheres in November average +AO for Dec-Jan. You can always find exceptions. As a reminder of how strong this correlation is, for the 10 coldest Nov+Dec stratospheres, there has NEVER been an AO below -.2. 8/10 had a +AO, 7 strongly +AO, and the AO averaged 2.81 higher than following the 10 warmest stratospheres. A cold stratosphere is essentially a guarantee of a that you will not get a -AO, and nearly a guarantee of a significantly +AO. It is the November and December stratosphere temperatures that matter the most. Also, it is really not the whole stratosphere that should be cold. A +AO is usually preceded by a warm stratosphere over Greenland. ' http://www.americanwx.com/bb/index.php/topic/34743-winter-2012-2013/page__st__2590#entry1782546 And 'There has never been a significantly -AO January following a top 10 cold stratosphere. November stratosphere -The December AO was 1.09 higher following the 10 coldest than the 10 warmest. -The January AO was 1.75 higher following the 10 coldest than the 10 warmest. -The December AO was .63 higher following cooler than average than warmer than average -The January AO was 1.71 higher following cooler than average than warmer than average November + December stratosphere -The December AO was 1.82 higher following the 10 coldest than the 10 warmest -The January AO was 2.81 higher following the 10 coldest than the 10 warmest -The December AO was .72 higher following cooler than average than warmer than average -The January AO was 1.41 higher following cooler than average than warmer than average - 8/10 coldest had +AO Dec, only 1 below -.1 - 8/10 coldest had +AO Jan, none below -.2 -9/10 warmest had -AO Dec, none above +.2 -9/10 warmest had -AO Jan, none above +.3' http://www.americanwx.com/bb/index.php/topic/24854-and-we-begin-part-deux/page__st__385#entry1127279 I wonder is this true?
  17. sebastiaan1973
    According to GFS there will be a massive expansion of snow. According to Cohen it is important to have a rapid expansion (SAI-index, snow advance index) especially to the more sourthern parts of Siberia. In my opinion things look well. Thanks to Karel for the charts from over here http://forum.vwkweb.nl/viewtopic.php?f=2&t=13188&start=60 (dutch website)
  18. sebastiaan1973
    I was under the impression the forecasts by UKMO were getting better http://www.ecmwf.int/newsevents/meetings/workshops/2011/MOS13/presentations/Hewson.pdf Or is it a another model?
  19. sebastiaan1973
    Thanks Matt. Latest ozon map. Seems to me it's going in the right direction.
  20. sebastiaan1973
    Well I have more trust in the UKMO seasonal forecast http://www.ecmwf.int...ions/Hewson.pdf Some excellent forecast were made by them. I would say, we have to wait until november. E.g. the snowfall in Siberia is important in october.
  21. sebastiaan1973
    Those MetOffice charts are from 21-9. So there are not new. We have to wait until the 10th of october.
  22. sebastiaan1973
    Based on GFS, I expect some more snow in the more sourthern parts of Siberia. http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=2&carte=1
  23. sebastiaan1973
    Abstract With extreme variability of the Arctic polar vortex being a key link for stratosphere–troposphere influences, its evolution into the twenty-first century is important for projections of changing surface climate in response to greenhouse gases. Variability of the stratospheric vortex is examined using a state-of-the-art climate model and a suite of specifically developed vortex diagnostics. The model has a fully coupled ocean and a fully resolved stratosphere. Analysis of the standard stratospheric zonal mean wind diagnostic shows no significant increase over the twenty-first century in the number of major sudden stratospheric warmings (SSWs) from its historical value of 0.7 events per decade, although the monthly distribution of SSWs does vary, with events becoming more evenly dispersed throughout the winter. However, further analyses using geometric-based vortex diagnostics show that the vortex mean state becomes weaker, and the vortex centroid is climatologically more equatorward by up to 2.5°, especially during early winter. The results using these diagnostics not only characterize the vortex structure and evolution but also emphasize the need for vortex-centric diagnostics over zonally averaged measures. Finally, vortex variability is subdivided into wave-1 (displaced) and -2 (split) components, and it is implied that vortex displacement events increase in frequency under climate change, whereas little change is observed in splitting events. http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-12-021.1
  24. sebastiaan1973
    http://icdm2012.csp.escience.cn/dct/attach/Y2xiOmNsYjpwZGY6Mjc0NTE= Nice presentation by Adam Scaife. More can be found here http://icdm2012.csp.escience.cn/dct/page/65537 SUMMARY NAO/AO are single largest source of variability in NH regional climateVariability occurs on all timescales and is eddy drivenNAO/AO patterns govern the frequency of extreme eventsThe same patterns appear in response to a variety of forcings (degeneracy) and present a particular problem for detection/attribution studiesStrat-trop interaction important in many casesNew sources of conditional predictability are emerging but always limited by internal chaotic fluctuations
  25. sebastiaan1973
    http://icdm2012.csp.escience.cn/dct/attach/Y2xiOmNsYjpwZGY6Mjc0NTE= Nice presentation by Adam Scaife. More can be found here http://icdm2012.csp.escience.cn/dct/page/65537
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