Paul123
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Posts posted by Paul123
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The warming of 22-24 November will lead to a Canadian Warming and a wave 1 of exceptional magnitude for the time of the year. As a consequence the SPV will be displaced to the Russian side of the North Pole. That's where it begins to be really interesting. By the end of the month and the Russian High (troposphere) will intensify again (mainly because of the long lasting AO+). For the beginning of December a huge heat flux is being calculated, due to the all known wave breaking.
I would like to know something more about this wave breaking. Is this wave breaking taking place in de troposphere, over East Siberia (picture 2)? Secondly: is it purely a coincidence that the heat flux in the stratosphere shows itself at the transition of the Canadian wave1 and the Russian wave2. What kind of mechanism is taking place?
The early December heat flux leads to a wave2 at the upper levels of the statosphere over East Siberia (Picture 3). West of this second wave is an area of intense heat flux, but at the east side of the Candadian wave also strong heat flux is taking place. Is this second one a downward heat flux?
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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.
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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.
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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.
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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.
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On 24-1-2018 at 10:03, Paul123 said:
Sorry guys, double post. I don't know how to remove it.
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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.
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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.
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On 4-10-2017 at 16:21, phil nw. said:
Just my simplified view based on many years of following the charts.Having said that we appear to be in a better place this year with the E-QBO and heading closer to Solar minimum.
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.
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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.
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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
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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.
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1 hour ago, Gael_Force said:
From the late Karin Labitzke's definitions ....
http://www.atmosp.physics.utoronto.ca/SPARC/News15/15_Labitzke.html
Canadian Warmings often happen in early winter. They take place when the Aleutian stratospheric high intensifies and moves poleward. The Canadian warmings can reverse the meridional temperature gradient and sometimes briefly change the zonal wind direction over the polar cap, but nevertheless they do not lead to a breakdown of the cyclonic polar vortex.
So, no, does not seem reversal of zonal winds always to be expected. IMO, we've already reached the criteria to call it a Canadian warming. The fact they are looking at standardising all the different definitions may change this but as it stands, good enough for me.
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.-
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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.
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3 hours ago, Recretos said:
But thats exactly what it is. Everybody make the same mistake of looking and emphasising the temperature, like its THE alpha and the omega of the strat. All we always hear about is the temperature. But like this year when the warming has a negative effect, people cant seem to understand how and why that is possible "if like the strat warming is like the most certain thing to like make two months of cold shots and like a big greenland block".
Those meters per second have a lot more meaning than people give it credit for. Even proffesionals like Judah Cohen Phd.
I remember back in my strat beginings 4 years ago I was already emphasizing the importance of the heights when everybody was looking at temperature. Unless it was a split forecasted. Then it gets some attention.
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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On 5-2-2016 at 10:04 PM, lorenzo said:
Last conversation I had with Amy Butler
For now we are not re-classifying beyond the WMO definition of 10 hPa 60N reversal but more work will be done on that soon...
Hope that helps- yes I agree definitely scope for more categories / definitions. Each year the study of the stratosphere takes on new layers, over summer I think it will evolve up a notch again.
Great warming going on - and probably the best example of the two extremes - warming and brutal vortex equalling no guarantees...
Measuring (determining) a warming in (by) meter per second is asking for trouble. Sooner or later someone will come up with a more plausible alternative, resulting in even more confusion.
To use one line in space also is far from elegant, when defining a warming for the whole of the polar stratosphere.
Everwhere on forums, and when talking to people, I notice incomprehension concerning the used method of classification.
This definition should be adjusted sooner or later, I think.
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We are very close to a SSW now. The warming is impressive.
Is there anyone who can tell me what kind of wave breaking we are seeing?
https://www.jstage.jst.go.jp/article/jmsj/86/5/86_5_613/_pdf
I would say a sheared wave breaking in poleward direction, but is it cyclonically or anti-cyclonically?
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2 hours ago, John (Netherlands) said:
http://www.aer.com/science-research/climate-weather/arctic-oscillation
According to Cohen SSW likely......
"The models are now coming into better consensus for a stronger pulse of energy transfer beginning next week that is predicted to initiate a sudden stratospheric warming (SSW) at the end of the month"
Of course we will have to wait and see what the consequences will be for the weather in Western Europe.
Thank you John, for posting this update from Cohen.
I would like to add some images from his blog, to make matters clear. Firstly the observed and predicted dailly vertical component of the WAFz, say the vertical energy transport over the polar region. This will increase significantly towards the end of the month.
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The impact of the increased vertical energy input from the troposphere to the stratosphere is seen in figure 8. This warming should, according to Cohen, lead to a SSW.
The warming of the stratosphere is being accompagnied by a cooling of the polar troposphere (see below, the picture of the mean polar cap height), causing a rise of the AO. Initially this will cause a warming of the temperatures of Western Europe, some time after the SSW a cooling trend is to be expected.
Quote from Cohen:
'Therefore we are more confident that a troposphere-stratosphere-troposphere coupling event is underway (Cohen et al. 2007). The current strong negative AO is a tropospheric precursor that will initiate a strong burst of vertical energy transfer from the troposphere into the stratosphere the last week of January as seen in the vertical wave activity flux (WAFz) plot (Figure 7). More recent model runs have trended stronger with this energy burst and are indicating this energy burst will be of sufficient amplitude to initiate a SSW during the last week of January. And as can see from Figure 8, a dramatic warming of temperatures is now predicted at the Pole the fourth week of January as much warmer air floods in from Siberia. As we have discussed previously in the blog, the vertical transfer of energy from the troposphere to the stratosphere warms the polar cap heights in the polar stratosphere and forces a negative AO trend in the stratosphere. And for the first time this cold season, the models are predicting the cold polar cap geopotential height anomalies (PCH) or the strong polar vortex in the stratosphere to be erased (Figure 9). However the energy burst forces the opposite in the troposphere resulting in a cooling polar cap height and a positive AO trend, which can be seen with a weakening of the warm PCH in the troposphere. However following the SSW, the associated circulation anomalies of positive geopotential height anomalies and warm temperatures over the Arctic and negative geopotential height anomalies and cold temperatures in the mid-latitudes propagate down from the stratosphere to the troposphere.'
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The stratospheric vortex remains strong despite hammering of wave 1 and 2.
Nice displacement and elongation of the vortex, though.
After wave impuls of 5th of January a new one follows, from the 10th onwards.
I wonder what the results will be in the long run.
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5 minutes ago, KyleHenry said:
The signal is faint but in the outer reaches of GFS at 384z on 7th January 2016 could be the beginning of the elusive SSW. More runs needed.
This is consistent with yesterday's Cohen blog.
'We have been discussing the polar vortex model developed here at AER that predicts the strength of the polar vortex one month in advance. As we discussed in the blog for the past month, the model was predicting the polar vortex to become disturbed the third week of December, which is predicted by the weather models to occur this week. The polar vortex model also predicts a similar perturbing of the stratospheric polar vortex in the first week of January, which again is now being predicted by the weather models. And as we have been discussing, the polar vortex model predicts an even bigger event the second week of January. As we discussed above the predicted atmospheric circulation is nearly optimal for the vertical transfer of energy from the troposphere to the stratosphere that results in weakening of the polar vortex. Therefore, based on the polar vortex model and the upcoming atmospheric circulation pattern, we are anticipating more upward pulses of WAFz. If the predicted atmospheric circulation pattern is correct and our expectations of more upward pulses of WAFz is correct, this should be sufficient to force a sudden stratospheric warming (SSW) sometime in January. And if our expectations of a weakened polar vortex verify, this will likely favor an increased likelihood of severe winter weather across the continents of the Northern Hemisphere. One ongoing inhibiting background factor is the westerly phase of the quasi-biennial oscillation (QBO) that favors a strong vortex over a weak vortex. If this prevails and our expectations of an active period of WAFz is incorrect, then the polar vortex will strengthen and likely the AO will remain positive and the weather pattern mild for the Eastern United States, Northern and Western Europe and East Asia. However we are becoming increasingly confident in the first solution of a weakening polar vortex and an increasing bias towards a negative AO.'
http://www.aer.com/science-research/climate-weather/arctic-oscillation
The upward pulses of WAFz are being triggered by the building of a high over Western Russia, which is showing ever more often on the prog charts.
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The geopotential height pattern in the troposphere 100% affects heights in the stratosphere because the geopotential height at any particular pressure level or layer is proportional to the mean virtual temperature in that layer. So the absolute geopotential height is proportional to temperatures all the way down to the surface. This can be seen when vortex splits occur because troposphere vortex is split.
But the height reduction due to the troposphere may be countered by increased geopotential thicknesses in the stratosphere because changes in virtual temperature there. Also tropospheric troughing imprinted on the stratosphere affects the isentropic flow which leads to warming when the vortex is perturbed and not aligned directly over the trough.
Thank you for your affirmation of my trop-strat premise.
Amazing, that a strat split can be caused by a trop split.
Well of course it does. It is all connected, tho the reflection is not 100% as you may know.
Thank you for your explanation. I learn a lot from your animations. Can't wait for the Januari update.
Would you please explain what the upper level of http://youtu.be/r4keByIvhLs is portraying? I remember some time ago you explaining it, but wasn't paying enough attention then and can't trace your posting back now.
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Wind is bound to the pressure gradient force (among some other stuff, but thats besides the point at the moment).
And that brings me to a specific point. I am on here for the third season, and even tho I am trying to make this specific point every year (and one page back actually
), some still dont get it.Write it down, print it, and put it on the fridge or a wall, as long as you see it enough times to remember it:
"Winds reflect the geopotential height pattern, NOT the temperature pattern."
Enough said
This is not the point.
I am still left with the question whether the geopotential height pattern in the troposphere affects the height of the geo's in the stratosphere. It sometimes does, so it seems to me. If (purely hypothetically) over a large area there would be created a vacuum, the pressure would drop. The geo's above this area would be pulled down, as is in a minor way for instance the case with a tropical cyclone or tornado.
Analoguely in the 8 januari case the cold reservoir above northern Canada and Greenland and the associated vast tropospheric low pressure area may have hindered the rising of the stratospheric geo's, thus the forming of a SSW. In some cases, the tropospheric pressure pattern, might hinder the emergence of a ssw , if not prevent it completely. That's my thesis.
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Thank you guys, for your comments, it pretty much makes clear to me why the temperature regime poorly reflected the geopotential height pattern.
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I still don't understand why this 8 januari warming hasn't reversed the 10 hpa wind. It has been quite a substantial warming and leaves behind a very disturbed temperature pattern. Yet it creates only a relatively small change in de stratospheric windfield.
Perhaps it is due to the exteme low tropospheric heights below the warming region or are there any other causes?
), some still dont get it.
Stratosphere and Polar Vortex Watch
in Spring Weather Discussion
Posted
There appears to be a pretty close relationship between max wave1 in November and NAO in December
https://publish.twitter.com/?query=https%3A%2F%2Ftwitter.com%2Fantmasiello%2Fstatus%2F1197347865481404417&widget=Tweet
Maximum wave 1 this November off the chart:
Seeing some real continuation of the wave1 pattern in the upper layers of the stratosphere as new Eddy heat flux is generated over Russia.
Also because of the favorable conditions of the troposphere for blocking because of the solar minimum, we may expect a siginificant blocking signal next month over the Atlantic.
I am wondering if the displacement of the SPV will be enough for an official SSW, later next month.