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Stratosphere Temperature Watch


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#1 chionomaniac

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Posted 29 October 2010 - 21:48

Hi all,

With winter not too far ahead, it is worth keeping an eye on the stratosphere once again to see how the conditions there may influence the tropospheric conditions below.

As usual, it is worth giving a brief explanation of the stratosphere and how it influences the troposphere for those who are not familiar with the concept.


The stratosphere is the layer of the atmosphere situated between 10km and 50km above the earth. It is situated directly above the troposphere, the first layer of the atmosphere that is directly responsible for the weather that we receive. The boundary between the stratosphere and the troposphere is known as the tropopause. The air pressure ranges from around 100hPa at the lower levels to around 1hPa at the upper levels. The middle stratosphere is often considered to be around the 30hPa level.

Every winter the stratosphere cools down dramatically as less solar UV radiation is absorbed by the ozone content in the stratosphere. The difference in the temperature between the North Pole and the latitudes further south creates a strong vortex – the wintertime stratospheric polar vortex. The colder the stratosphere, the stronger this vortex becomes. The stratospheric vortex has a strong relationship with the tropospheric vortex below. The stronger the stratospheric vortex, the stronger the tropospheric vortex becomes.

The strength and position of the tropospheric vortex influences the type of weather that we are likely to experience. A strong polar vortex is more likely to herald a positive AO with the resultant jet stream track bringing warmer wet southwesterly winds. A weaker polar vortex can contribute to a negative AO with the resultant mild wet weather tracking further south.



Last year the start of the stratospheric winter saw the stratosphere cool down far less than recent years. This was probably due to an enhanced Brewer-Dobson Circulation (BDC) which resulted in more ozone being transported from the tropical stratosphere to the polar stratosphere and a warmer polar stratosphere as a result.

One of the reasons the BDC was enhanced was because the solar minimum coincided with an easterly or negative QBO. The Quasi-Biennial Oscillation (QBO) is a major influence on the stratosphere. This is a tropical stratospheric wind or gravity pulse that has a rough two year cycle. This wind descends from the top of the stratosphere towards the troposphere in an either westerly or easterly direction. This year the QBO is in a westerly phase. The westerly phase flows in the same direction as the polar vortex circulation which does nothing to inhibit the flow, and the BDC is also reduced in a westerly phase. Therefore this year the polar vortex is likely to be stronger than last and as a result high latitude blocking is less likely.

We are already entering the start of the stratospheric winter and the temperature of the polar stratosphere will need careful monitoring in the coming weeks.

We are at a junction that can be seen from the following link that could already influence December. Looking at last year we see that the stratosphere was at record warm levels for the month of November which set the pattern of winter. We are already cooler than at any point during last November.

http://acdb-ext.gsfc...90n_30_2010.pdf

My guess is that we will see the stratosphere cool more in line with average this November, and it will be difficult to get any sustained northern blocking this December.

One thing that we can hope for though is a Sudden Stratospheric Warming (SSW) or also known as Major Midwinter Warmings (MMW).These are caused by large-scale planetary waves being deflected up into the stratosphere and towards the North Pole, often after a strong mountain torque event. These waves can seriously disrupt the stratospheric vortex, leading to a slowing or even reversal of the vortex. This can occur by the vortex being displaced off the pole – a displacement SSW, or by the vortex being split in two – a splitting SSW.

The effects of a SSW can be transmitted into the troposphere as the propagation of the SSW occurs and this can have a number of consequences. There is a higher incidence of northern blocking after SSW’s but we are all aware that not every SSW leads to northern blocking. In January 2009 we experienced a record breaking splitting SSW that was responsible for the pulse of easterly snow some areas received in February (directly from the split) but it did not lead to any major northern blocking. Last year we received much northern blocking and split polar vortices as a result of the warmer early season stratosphere. This created numerous splits in the lower stratospheric and tropospheric vortex, which displaced the vortex off the North Pole allowing pressure to build in this region. I remember Steve Murr commenting how we never see pressure rises over Svalbard in early December, only for one such split to occur and create these conditions soon after.

For those interested in further reading on the stratospheric polar vortex, here is some excellent further reading which is very comprehensive.

http://www.columbia....Volume-2010.pdf


Other essential sites

CPC- http://www.cpc.ncep....ere/strat-trop/

ECM (from 1/11 hopefully) - http://strat-www.met...n/diagnostics?1

JMA - http://ds.data.jma.g...x.html#monit_nh

NCEP data- http://acdb-ext.gsfc...t/ann_data.html

The sudden stratospheric warming site - http://www.appmath.c.../ssws/index.php


My main hope for the stratosphere this winter is that we may get a SSW that may lead to sufficient vortex disruption such as we saw in Feb 2009.

Fingers crossed.

c

Edited by chionomaniac, 29 October 2010 - 21:58 .

Not long to go before the new strat thread appears........ Winter must be coming. Its here! - http://forum.netweat...4/#entry2806873

 

Links to previous strat threads - http://forum.netweat...80#entry2445171

Burgess Hill.


#2 Gavin P

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Posted 29 October 2010 - 21:56

Thanks Chiono

Given we're going to have a La Nina near or at record levels, I think a very cold stratosphere and resulting positive AO is just something we're going to have to deal with winter.

If this is a "double dip" La Nina, as I suspect it might be, we could be in for two winters of raging positive AO's and very intense PV's.

Edited by Gavin P, 29 October 2010 - 21:58 .

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#3 Isolated Frost

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Posted 29 October 2010 - 22:00

Another interesting year, though you'd think It'll be considerably cooler than last year.
November @ Durham University (to the 8th)
9.3° (-0.1°) | 1.7° (-1.7°)|5.5° (-0.9°) | 11.6° (1st) | -1° (1st/4th)

#4 chionomaniac

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Posted 29 October 2010 - 22:02

Thanks Chiono

Given we're going to have a La Nina near or at record levels, I think a very cold stratosphere and resulting positive AO is just something we're going to have to deal with winter.

If this is a "double dip" La Nina, as I suspect it might be, we could be in for two winters of raging positive AO's and very intense PV's.

I am less concerned for next winter (2011/12) than this. One thing that will be worth watching though for this winter, is the Eurasion snow cover in the hope for some stratospheric feedback come January.

Not long to go before the new strat thread appears........ Winter must be coming. Its here! - http://forum.netweat...4/#entry2806873

 

Links to previous strat threads - http://forum.netweat...80#entry2445171

Burgess Hill.


#5 AtlanticFlamethrower

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Posted 29 October 2010 - 23:56

Great post, as always. Will look forward to following stratospheric events this winter. J.B. (Accuweather) thinks we will get an average temperature but a drier than average winter. That forecast doesn't rule out a cold week because drier than average conditions necessitate that high pressure isn't far from the UK. My expectation is for repeating 'toppler' highs, period of Euro high sitting over the UK, and one hit or miss Easterly event from a loaded continent in January or February if we get a helpful Sudden Stratospheric Warming.

Edited by AtlanticFlamethrower, 29 October 2010 - 23:58 .

Notable snow depths for my location: 1985 (Jan): 2 ins. 1986 (Feb): 2 ins. 1987 (Jan): 8 ins. 1991 (Feb): 12 ins. <<< 18 years >>> 2009 (Dec) 2 ins. 2010 (Jan) 3 ins. 2010 (Nov/Dec) 8 ins. 2010 (Dec) 2ins. 2012 (Feb): 7 ins. 2013 (Jan): 3 ins.

Netweather CET Competition: 2007-8: 1st. 2008-09: ?th. 2009-10: 4th. 2010-11: 8th. 2011-12: 42nd. 2012-13: 45th.


#6 Eugene

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Posted 30 October 2010 - 07:49

Given we're going to have a La Nina near or at record levels, I think a very cold stratosphere and resulting positive AO is just something we're going to have to deal with winter.

If this is a "double dip" La Nina, as I suspect it might be, we could be in for two winters of raging positive AO's and very intense PV's.



The earliest winter is over post ever recorded even saying winter 2011/12 is already over :lol:

Sorry but i buy your reasoning at all, if it was that easy to forecast upcoming seasons then why do even the big organisations like the met office get it wrong so many times, humble pie for you come March i feel ;)

Edited by Eugene, 30 October 2010 - 08:27 .

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#7 Isolated Frost

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Posted 30 October 2010 - 07:51

The earliest winter is over post ever recorded even saying next winter is already over :lol:

Sorry but i dont buy your reasoning at all, if it was that easy to forecast upcoming seasons then why do even the big organisations like the met office get it wrong so many times, humble pie for you come March i feel ;)


Eh? He was just giving his insight into the next 2 winters. We don't live in the stratosphere, you know.
November @ Durham University (to the 8th)
9.3° (-0.1°) | 1.7° (-1.7°)|5.5° (-0.9°) | 11.6° (1st) | -1° (1st/4th)

#8 Eugene

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Posted 30 October 2010 - 07:57

We actually live in the here and now but that doesn't stop him forecasting a season over a year away.







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#9 Isolated Frost

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Posted 30 October 2010 - 08:09

We actually live in the here and now but that doesn't stop him forecasting a season over a year away.



The stratosphere is a whole new ball game, I'd think it's easier to forecast it, all he was saying is, there could be a double-dip La Nina and 'Raging AO's and Intense PV's', stating good probabilities.

Can you stop this though, since I joined you seem like the one person who goes round the Weather Discussion, and tries to belittle and criticize others.

'Only treat others like you'd like to be treated yourself'


November @ Durham University (to the 8th)
9.3° (-0.1°) | 1.7° (-1.7°)|5.5° (-0.9°) | 11.6° (1st) | -1° (1st/4th)

#10 Eugene

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Posted 30 October 2010 - 08:25

You will find i haven't posted much in the past few months and hardly ever to criticise anyone, feel free to private message me any examples of me criticising people in the past few months.

It's too simplistic to say strong La Nina's = winters with very unsettled conditions dominating which is what in layman terms he is saying, there are lots of different factors to take into account.
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#11 Gavin P

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Posted 30 October 2010 - 08:38

Eugene, where did I say winter is over? I simply said a cold stratosphere/strong PV is something we're going to have to live with this winter (and possibly next) given the ENSO state. In a strong La Nina winter the arctic tends to get very cold, unlike an El Nino when the arctic is often warm, relative to average (this is good news for anybody concerned about arctic sea ice and hoping to see a recovery in ice from the 2007-2010 period)

That absolutely doesn't mean winter is over before its begun. There are several things that can still go in our favour. We might get a big blocking high set up over Scandinavia. We might see the jet steram take a southerly track. We might see the NAO go massively negative. We might get a big SSW. All of which is quite capable of producing a prolonged cold spell for us even with an overall positive AO/intense PV winter.

So are we now clear about what I was actually saying rather than just putting our own spin on things? :acute:

Edited by Gavin P, 30 October 2010 - 08:46 .

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#12 Isolated Frost

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Posted 30 October 2010 - 08:38

You will find i haven't posted much in the past few months and hardly ever to criticise anyone, feel free to private message me any examples of me criticising people in the past few months.

It's too simplistic to say strong La Nina's = winters with very unsettled conditions dominating which is what in layman terms he is saying, there are lots of different factors to take into account.


Well, you've just criticised Gavin P for making a long-range prediction, you said GP has pretty much said the chances of a snowy winter are gone, when in-fact he said 'Cold and Dry', which means precipitation can still fall.



End of this though, let's keep it on-topic.
November @ Durham University (to the 8th)
9.3° (-0.1°) | 1.7° (-1.7°)|5.5° (-0.9°) | 11.6° (1st) | -1° (1st/4th)

#13 beng

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Posted 30 October 2010 - 09:06

Worth mentioning that the Oct ENSO forecasts show a more rapid weakening of this event (relative to the Sept forecasts) - there's a good discussion about it in DT's US winter forecast - so we might find that by the time we hit Jan/Feb, La Nina is only moderate and weakening (that doesn't rule out at 2 year event though).

http://1664596.sites...interPUBLIC.htm

Other ingredients to all this are that we now have a tropical volcano erupting (not sure it's big enough to impact though) and a high latitude volcano - SHEVELUCH http://www.avo.alask...hp?view=kaminfo - which if it continues erupting possibly can impact on the polar stratosphere - and might help check the AO somewhat.

Edited by beng, 30 October 2010 - 09:13 .

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Prof Kelly, “(i) I take real exception to having simulation runs described as experiments (without at least the qualification of “computer” experiments). It does a disservice to centuries of real experimentation and allows simulations output to be considered as real data. This last is a very serious matter, as it can lead to the idea that real “real data” might be wrong simply because it disagrees with the models! That is turning centuries of science on its head.”

 


#14 knocker

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Posted 30 October 2010 - 09:44

My question is can last winter be considered a one off because of the Warm Arctic-Cold Continents climate pattern that occured.?
Winter 2009-2010 showed a major new connectivity between Arctic climate and mid-latitude severe weather, compared to the past. Figure A7a

Posted Image

shows normal early winter atmospheric conditions with low geopotential heights of constant pressure surfaces over the Arctic (purples). These fields indicate the tendency of wind patterns: winds tend to blow counter clockwise around the centers of lower heights, parallel to the height contours. In Figure A7a for example, winds tend to blow from west to east, thus separating cold arctic air masses from the regions further south.

In December 2009 (Fig. A7b) andand February 2010 (Fig. A7c)
Posted Image
Posted Image

we actually had a reversal of this climate pattern, with higher heights and pressures over the Arctic that eliminated the normal west-to-east jet stream winds. This allowed cold air from the Arctic to penetrate all the way into Europe, eastern China, and Washington DC. As a result, December 2009 and February 2010 exhibited extremes in both warm and cold temperatures with record-setting snow across lower latitudes. Northern Eurasia (north of 50° latitude to the Arctic coast) and North America (south of 55° latitude) were particularly cold (monthly anomalies of -2°C to -10°C). Arctic regions, on the other hand, had anomalies of +4°C to +12°C. This change in wind directions is called the Warm Arctic-Cold Continents climate pattern and has happened previously only three times before in the last 160 years.

http://www.arctic.no...atmosphere.html

Edited by weather ship, 30 October 2010 - 10:23 .

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281c81c43c615177db549fa1fb75da6a.jpeg


#15 cooling climate

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Posted 30 October 2010 - 10:19

The first tentative signs of warming at the 30mb level in the arctic.
Posted Image
Ozone levels in the Arctic are again quite high which could very well be due to the uptick
in stratospheric temperatures as seen above.

It still remains to be seen that if we get any substantial warming in the stratosphere this
autumn and winter whether it will propagate down into the troposphere given that we are
now in a +QBO phase.









#16 knocker

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Posted 30 October 2010 - 10:28

Am I misreading that because it looks likes a tentative sign of cooling. Belay that last pipe my eyesight is worse than I thought.:oops:

Edited by weather ship, 30 October 2010 - 11:23 .

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281c81c43c615177db549fa1fb75da6a.jpeg


#17 beng

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Posted 30 October 2010 - 11:52

The first tentative signs of warming at the 30mb level in the arctic.

Ozone levels in the Arctic are again quite high which could very well be due to the uptick
in stratospheric temperatures as seen above.

It still remains to be seen that if we get any substantial warming in the stratosphere this
autumn and winter whether it will propagate down into the troposphere given that we are
now in a +QBO phase.


Interesting - I wonder if the early snow cover around the globe at lower latitudes is helping here (still enough sun to reflect back into the stratosphere)+ must be some volcanic ash up there still. QBO I believe only becomes a real problem if it goes too positive - if we're around +10, then SSW are still quite possible - we had +10->12 in Jan/Feb 2009. Currently we're at around +6.

http://www.cpc.noaa....s/qbo.u30.index

Even perhaps the first signs of the models latching on to this warming in the latest GFS 6z run - but obviously very early days.

Edited by beng, 30 October 2010 - 11:53 .

Home Location: Reigate, Surrey. 64m asl.
Work Location: Leatherhead, Surrey. 39m asl.

Prof Kelly, “(i) I take real exception to having simulation runs described as experiments (without at least the qualification of “computer” experiments). It does a disservice to centuries of real experimentation and allows simulations output to be considered as real data. This last is a very serious matter, as it can lead to the idea that real “real data” might be wrong simply because it disagrees with the models! That is turning centuries of science on its head.”

 


#18 chionomaniac

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Posted 30 October 2010 - 13:07

The first tentative signs of warming at the 30mb level in the arctic.
Posted Image
Ozone levels in the Arctic are again quite high which could very well be due to the uptick
in stratospheric temperatures as seen above.

It still remains to be seen that if we get any substantial warming in the stratosphere this
autumn and winter whether it will propagate down into the troposphere given that we are
now in a +QBO phase.

Agree with Beng that this is interesting, cc. There are always fluctuations in the temperature as the polar stratosphere cools during autumn. The vortex tends to be centered more towards the Eurasion/Siberian land mass at the beginning of winter before transferring more polewards later. This looks like occurring and as it does so, the door is left open for warming over the Alaskan/Canadian region. When looking at the temperature forecasts for the 10hPa level the GFS is suggesting some kind of warming over this region. This is far better than I would have imagined at this point.

Today


T+192

Edited by chionomaniac, 30 October 2010 - 13:07 .

Not long to go before the new strat thread appears........ Winter must be coming. Its here! - http://forum.netweat...4/#entry2806873

 

Links to previous strat threads - http://forum.netweat...80#entry2445171

Burgess Hill.


#19 cooling climate

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Posted 30 October 2010 - 13:58

Agree with Beng that this is interesting, cc. There are always fluctuations in the temperature as the polar stratosphere cools during autumn. The vortex tends to be centered more towards the Eurasion/Siberian land mass at the beginning of winter before transferring more polewards later. This looks like occurring and as it does so, the door is left open for warming over the Alaskan/Canadian region. When looking at the temperature forecasts for the 10hPa level the GFS is suggesting some kind of warming over this region. This is far better than I would have imagined at this point.

Today


T+192

Yes much more to be encouraged about in the synoptic and stratospheric models.
Below are two charts showing the ozone diviations from normal across the Arctic
for this year and this time last year.



#20 phil nw.

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Posted 30 October 2010 - 16:16

Good to see this thread open again Ch.its always one of the first i view when coming here.
Some good posts already guys and looking at C.C.s post above some signs that things could get interesting as we come in to Nov.
I noticed that it was last Nov.when warming occured which gave us some excitement at the end of Dec.

http://acdb-ext.gsfc...90n_30_2010.pdf

Let`s hope for something similar.

Edited by phil n.warks., 30 October 2010 - 16:17 .

Phil nw.

 

Veteran of the 1962/63 Winter when Snow lay for 66 days ---will we ever see its like again?.