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  1. Possibly a DSW. Hence, the new classification classifies SSWs when the ZMZW reversed at a thickness of at least 80 hPa between 10 and 100 hPa for a band between 60 and 70N for at least two days in a 5-day period. Since the new classification method aims at classifying SSWs based on their thickness, it is subsequently referred to as the Deep Stratospheric Warming (DSW) classification. http://bibliotheek.knmi.nl/knmipubIR/IR2018-05.pdf With significantly stronger impact on troposphere (picture shows the 300 hPa anomaly) than an ordinary SSW. Anyway, plenty of downwelling in the long run.
  2. After the heat flux that will cause a Canadian Warming (picture 1) the focus is on the next warming event, which is very likely to take place in the third decade of this month. This new round up is looking to be bigger than the previous one and likely to reduce zonal winds (10 hPa 60N) once again (after a temporary increasement). Everything still is going on track, hopefully enough to deliver that SSW we are all longing for.
  3. The vortex is under attack, indeed. A next heat flux (not visible on the Eddy heat flux plot so far) starting December 12th will likely cause a further displacement towards Siberia and the zonal winds may drop a lot more. It looks like we are heading towards a Canadian Warming, in the second half of December.
  4. Amazing, this SSW, how intens the warming is and how prolonged. It gets another boost in about ten days, over Northern Canada, where the cold pole has been centered for months this winter. It is bound to have some effect on the troposphere and it looks as if there are some signs of it, on the progs. I very well understand the feelings of disappointment concerning the effect of this SSW, but it is hard to knock down a very strong tropospheric vortex in a very persistent winter like this. Let's see how it works out this time.
  5. I found the link to de daily data (https://www.esrl.noaa.gov/psd/data/composites/day/). This is the anomaly for the first three weeks of 2018. It looks as if this is not particularly typical of a La Nina pattern, especially because of the Rocky Mountains high. There should be a low over there. The high stretches out over the North Pole into Northern Russia. The high over Nova Zembla may be linked to the snow cover anomaiies in Russia, in accordance with the findings of Judah Cohen. December also showed this anomaly. Anyway, there seem to be other forcings in play than the La Nina, this year.
  6. Thank you everyone for your posts in this interesting thread about teleconnection science and background signals. If I understand it correctly, the current negative AAM is responsible for the enhancement of the effect of the La Nina (please correct me if I am wrong). I have some remarks on this issue. I performed a quick study of the effect of a La Nina on the winter pattern, since 1950. I considered the 20 strongest La Nina’s, according to the ranking of the NOAA (https://www.esrl.noaa.gov/psd/enso/mei/rank.html), for January and February combined. We see that overall the effect in the Atlantic on the 500 hPa is neutral. Only very strong La Nina’s show an enhanced zonality (ranking 1-4). December had a ranking 20, in January the La Nina seems to be fading a bit. I have my doubts weather the current AAM (still) is enough to account for the lacking of blocking in the Atlantic and over Greenland, so far. Furthermore: the type of La Nina also plays a role in the teleconnection. This winter we have a EP La Nina. This should a least have some weakening effect on the zonality, in the Atlantic (https://www.researchgate.net/publication/271737956_Impacts_of_two_types_of_La_Nina_on_the_NAO_during_boreal_winter) Finallly can anyone show me where to find the NOAA link where I can create composites using daily data, instead of monthly? I would like to check the 500 hPa anomalies for the first weeks of January. Perhaps there are daily records of the ENSO, a possible weakening of the La Nina may be verified.
  7. Simply E-QBO and sunspot number <50 To the right: E-QBO and sunspot number <50, without winters with new cycle W-QBO cycle starting in upper stratosphere. :Look much better than we have had recent years: Hoping the E-QBO won't fade away as has been suggested by the ECMWF.
  8. The European warming in the stratosphere next weekend on 30 hPa (picture 1) may be helpful to enable a change in weather patterns over Europe. The ECMWF run today (picture 2) shows a ridge, that possibly for the first time will not be overrun by the so far very dominant westerlies. Without counteraction of the stratosphere this time, this may be the best opportunity until today to extend the Russian blocking into Scandinavia. http://www.netweather.tv/index.cgi?action=stratosphere;sess= http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=1&type=1&archive=0 Also noticible: the synopsis in East-Asia and the Pacific is encouraging wave2 activity, putting pressure on the stratospheric PV.
  9. I see no hope for any relevant disturbance of the polar vortex within two or three weeks (see picture). I think the stratosphere is playing a significant role in spoiling the potential for cold weather in Western Europe these days. It seems the long term potential for wintery weather is partially a relict of the Canadian warming, end November, early December. There are still vast areas of below normal temperatures (Canada, Siberia), they continue to have a blocking effect on the tropospheric PV. http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=10&carte=1
  10. Tropospheric ridging is oncoming the end of this year. Due to...? No MJO, no stratosphere, simply tropospheric? I suspect that the extreme cold over Siberia (and Canada?) has its effect on tropospheric ridging. However Siberic coldness still is a relict of the stratospheric warmth from November and start of December, especially the Canadian warming. If this is true, Canadian warmings (also SSW's) not only have direct (dripping down) effect on the tropospheric polar vortex. This way their effect can be stretched beyond the original limits. March 2013 cold may be another example of this stretching, reaching beyond the 2 month limit after the SSW. I however do not know whether other factors played any role during that time.
  11. Thank you for answering my questions, so a Canadian Warming it is. It is quite a lot of years ago (16) when the last one occurred! It still is possible, despite the AGW.
  12. On what conditions do we speak of a Canadian Warming, I wonder? Is there a wind reversal required, at 60 N, 10 hPa? If not, will we meet the conditions in the near future, looking at the morning EC progs? http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/northpole/index.html CW data don't always match a SSW.
  13. On what conditions do we speak of a Canadian Warming, I wonder. 
    Is there a wind reversal required, at 60 N, 10 hPa?
    If not, will we meet the conditions in the near future, looking at the morning EC progs?

    http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/northpole/index.html CW data don't always match a SSW.

    CW 1997.PNG

  14. I fully agree. Last four years for example each had strong warming events, but only the winter of 2013 delivered a wind reversal and a really cold continuation of the tropospheric winter combined with a prolonged negative AO. Classifying stratospheric events by its wind reversal always is preferrable , but then call it what it is: a wind reversal. For instance a Winter Stratospheric Wind Reversal (WSWR).
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