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chionomaniac

Stratosphere Temperature Watch

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With the northern hemisphere stratospheric winter beginning to get into full throttle, it is the right time to open a thread dedicated to following the stratospheric temperatures, polar vortex strength and position.

For those who do not know how the stratosphere may influence our weather I will provide a brief guide.

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.

post-4523-1256989521338_thumb.jpg

Occasionally the wintertime stratosphere can undergo dramatic warming events. These are called Sudden Stratospheric Warmings (SSWs) or Major Midwinter Warmings (MMWs). 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 (after last winter) we are all aware that not every SSW leads to northern blocking. Last January 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.

Here is a list of site that stratospheric information can be gained from:

CPC- http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

ECM (from 1/11 hopefully) - http://strat-www.met.fu-berlin.de/cgi-bin/diagnostics?1

JMA - http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/index.html#monit_nh

NCEP data- http://acdb-ext.gsfc.nasa.gov/Data_services/met/ann_data.html

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

One major influence on the stratosphere is the Quasi-Biennial Oscillation (QBO). 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. Presently we are in an easterly phase of this wind which is flowing in an opposite direction to the polar vortex flow. It has been shown that an easterly QBO will lead to warming of the stratosphere and therefore this is more favourable in reducing the polar vortex.

Please remember that the purpose of this thread is to monitor the state of the stratosphere and discuss the implications that this may have on the troposphere and how this may affect us. I politely request that any climate change discussion is kindly left outside of this thread. Many of the charts posted in this thread may be difficult to understand if you have not seen them before, so please do not hesitate to ask if you require an explanation and I will do my best to explain (if I can!).

The cooling of the stratosphere this autumn so far has been far from uniform with some minor warmings along the way when comparing to last autumn. Presently we are slightly above average for this time of year and the stratospheric vortex is correspondingly below average with some slight negative zonal wind anomalies.

post-4523-1256989559837_thumb.gif

http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/30mb9065.gif

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_UGRD_ANOM_OND_NH_2009.gif

c

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Thanks for such an excellent and informative post Chionomaniac. One that I,m sure will be of benefit to many members seeking to understand more about our winter weather patterns.

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thanks again Ch-very informative and simply stated even for numpties like me.

I do hope it can be kept as you request, I'll make a personal plea to admin and mods here, can you simply delete any post that is not in the spirit that Ch has requested please?

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thanks again Ch-very informative and simply stated even for numpties like me.

I do hope it can be kept as you request, I'll make a personal plea to admin and mods here, can you simply delete any post that is not in the spirit that Ch has requested please?

I agree. And thanks again CH!

PS: I'm sure I can delete that which is OT... :)

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Some more information which will provide a good starting point for the winter:

http://www.ccpo.odu..../Chap_6/6_3.htm

http://strat-www.met...bitzke-2005.pdf

I would draw attention to the relationship of the east QBO, solar minima and role of the Brewer-Dobson Circulation with particular reference to this year.

This link is a good one for daily monitoring of ozone:

http://www.cpc.ncep....7_ll_latest.gif

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Some more information which will provide a good starting point for the winter:

http://www.ccpo.odu..../Chap_6/6_3.htm

http://strat-www.met...bitzke-2005.pdf

I would draw attention to the relationship of the east QBO, solar minima and role of the Brewer-Dobson Circulation with partticular reference to this year.

This link is a good one for daily monitoring of ozone:

http://www.cpc.ncep.noaa.gov/products/stratosphere/sbuv2to/gif_files/sbuv17_ll_latest.gif

Thanks GP,

That is a good article on the Brewer-Dobson circulation, and will help my understanding and knowledge of ozone transport and what to monitor in this respect.

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I am pleased to see this thread again C i ,and many others i`m sure, followed this with great interest last Winter.

Thankyou for the very informative opening post and also to GP for the additional links.

I find with so much information it`s a lot to assimilate to start with.

I am an old fashion Weather Watcher who grew up only looking at the Sypnotic Charts on TV and written media-pre Tinterenet, but i will try to move with the times.

There`s so much more Knowledge available to the ordinary observer these days.

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Very true Phil, I had only heard and read passing reference to the NAO and AO in my time as a forecaster, so this is a whole new horizon for me-very interesting and some of it difficult to get hold of. Reading posts from GP and Ch along with others has certainly expanded my understanding of wider meteorological applications.

I too am looking forward to in depth discussions on here.

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Very nice to see you putting the effort in again Ch. Really enjoyed this thread last year although I did'nt contribute. Keep up the fantastic work, here's to a great winter season of lamp post watching :drinks:

Ric

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To kick us off, comparison of ozone concentrations 1st and 30th October:

Ozone conc. more or less translates to ozone temp and height so, so far so good. Watch it build.

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To kick us off, comparison of ozone concentrations 1st and 30th October:

Ozone conc. more or less translates to ozone temp and height so, so far so good. Watch it build.

Hi GP,

I am trying to understand what effect Ozone levels have on the Atmosphere.

Your post seems to suggest the build up of Ozone levels in the Higher Latitudes increases the chances of Stratosphere Warmings.

Have i got this right?

Can you explain more please or correct me if i am wrong.?

The Ozone factor in relation to SSW is new to me.

Thanks,Phil

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Phil,

Ozone concentrations are more or less positively correlated to stratospheric temperature. More ozone equates to warmer stratosphere and, given time, increased probability of warming events.

Ozone molecules and free radicals in the polar stratosphere are more long lived than other parts of the atmosphere. The Brewer Dobson Circulation also acts as a source of ozone, transporting it from the tropics to the pole over the autumn. Free oxygen atoms also combine with oxygen molecules to form ozone. This is an exothermic reaction when ozen is formed - heat energy is released warming the atmosphere.

The most useful aspect of ozone monitoring is that it enables us to gauge the general circulation and transport of tropics to the pole. More transport equates to a reduced thermal gradient and slower polar westerlies.

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Phil,

Ozone concentrations are more or less positively correlated to stratospheric temperature. More ozone equates to warmer stratosphere and, given time, increased probability of warming events.

Ozone molecules and free radicals in the polar stratosphere are more long lived than other parts of the atmosphere. The Brewer Dobson Circulation also acts as a source of ozone, transporting it from the tropics to the pole over the autumn. Free oxygen atoms also combine with oxygen molecules to form ozone. This is an exothermic reaction when ozen is formed - heat energy is released warming the atmosphere.

The most useful aspect of ozone monitoring is that it enables us to gauge the general circulation and transport of tropics to the pole. More transport equates to a reduced thermal gradient and slower polar westerlies.

Thanks for your prompt response GP.

After reading your link earlier re.the BDO i grasped the theory of the transportation of Ozone from the tropics towards the pole but couldn`t find any reference to the effect on Stratosphere temps.

Now i think i have the general idea,cheers again for that.

There are so many different factors involved that affect the Atmosphere it takes some keeping up with.

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Thanks for the positive feedback regarding this thread - it is something I enjoy.

Last winter it took some convincing regarding whether or not SSW's had any effect on the troposphere in respect of colder NH mid latitude weather. I did not post this paper as I lost the link to it, but I have relocated it and it is well worth looking at.

http://www.nwra.com/resumes/baldwin/pubs/Thompsonetal_2002.pdf

Here is a table taken from that paper regarding cold events between strong and weak vortices and comparing west and east QBO phases. I think it shows quite clearly that the most favourable conditions are for an SSW during an easterly QBO phase.

post-4523-1257032545292_thumb.gif

The London figures are very clear.

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thanks again Ch-very informative and simply stated even for numpties like me.

I do hope it can be kept as you request, I'll make a personal plea to admin and mods here, can you simply delete any post that is not in the spirit that Ch has requested please?

JH, If you are a numpty, God help the rest of us.

A question regarding linkage. In the post by Ch it shows that a warmer stratosphere tends to equate to weaker Trade winds, does this then help increase the strength of an El Nino, as I've seen some reports that weaker trades has a linkage to stronger El Nino's. Does this mean that this is another example of a system that has feedback systems that we don't quite understand yet. And before anyone asks, it's not a Climate thing, just trying to see linkages

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Hi NNW

There are studies showing how El Nino may play a part in later NH winter regarding stratospheric feedback but I am unsure about the other way around.

http://www.agu.org/pubs/crossref/2007/2006GL028521.shtml

http://www.citeulike.org/user/AndrewCharltonPerez/article/5866436

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Hi NNW

There are studies showing how El Nino may play a part in later NH winter regarding stratospheric feedback but I am unsure about the other way around.

http://www.agu.org/pubs/crossref/2007/2006GL028521.shtml

http://www.citeulike.org/user/AndrewCharltonPerez/article/5866436

Thanks Ch,

That'll keep me busy for a while.

I find this whole site amazing, a level of knowledge and resources that is fantastic. I think we are all lucky that the internet allows the sharing of such knowledge in a way that even 20 years ago was impossible.

And what it shows me is that the more we know, the less we understand. :whistling:

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I maybe making this to simple, but the number one spanner in the works for our prospects of a cold Winter is a strong East based El Nino?.

Everything else seems to be falling into place?.

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I maybe making this to simple, but the number one spanner in the works for our prospects of a cold Winter is a strong East based El Nino?.

Everything else seems to be falling into place?.

I thought that el nino was weak/mod at best and was mainly west based? dry.gif

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I thought that el nino was weak/mod at best and was mainly west based? dry.gif

I think your right.However the Warmer waters appear to have extended a little further East recently.

This link shows latest

http://www.cpc.ncep....s-fcsts-web.pdf

Although it`s due to update this coming week.

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Guest North Sea Snow Convection

I think your right.However the Warmer waters appear to have extended a little further East recently.

This link shows latest

http://www.cpc.ncep....s-fcsts-web.pdf

Although it`s due to update this coming week.

As per mentioned on the SST thread Phil, there are cold anomalies developing either side of the nino warm anomaly area.

In terms of the stratosphere, we are seeing the traditional intensification of the polar vortex, but we wait to see how and if the favourable QBO state, the solar min, a potential -NAO and (we hope) a contained el nino state can make a difference to our adversary that is oft based in the Greenland region!

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As per mentioned on the SST thread Phil, there are cold anomalies developing either side of the nino warm anomaly area.

In terms of the stratosphere, we are seeing the traditional intensification of the polar vortex, but we wait to see how and if the favourable QBO state, the solar min, a potential -NAO and (we hope) a contained el nino state can make a difference to our adversary that is oft based in the Greenland region!

Hi Tamara,

I`m jumping `tween threads on this. smile.gif

I have posted on El Nino on another thread.

As regards the embryonic PV,yes early signs are not bad according to recent models the lowest 500 hts. are contuinally being modelled over Canada.

Let`s hope that and the "yellow" Hts. over NW Russia keep appearing.

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Guest North Sea Snow Convection

This is another section of text taken from an associated link to the one I posted the other day on the other thread. My computer is still crashing when trying to post links so I am still having to cut,paste and save text to a word document instead!

Anyway, here is info regarding study about the feedbacks processes which are enabled through high amounts of snow cover over Siberia in terms of helping to induce a -AO state and associated troposphere/stratosphere interaction which weakens the polar vortex through a propagating wave flow interaction loop

Good reasons for the recent recovery in snow anonamlies over Siberia to be sustained and keep growing

Journal of Climate</H2>

Article: pp. 3917–3931 | Full Text | PDF (1.36M)

Modeled Northern Hemisphere Winter Climate Response to Realistic Siberian Snow Anomalies

Gavin Gong

· Dara Entekhabi

· Judah Cohen

ABSTRACT

Wintertime Northern Hemisphere climate variability is investigated using large-ensemble (20) numerical GCM simulations. Control simulations with climatological surface (land and ocean) conditions indicate that the Arctic Oscillation (AO) is an internal mode of the Northern Hemisphere atmosphere, and that it can be triggered through a myriad of perturbations. In this study the role of autumn land surface snow conditions is investigated. Satellite observations of historical autumn–winter snow cover are applied over Siberia as model boundary conditions for two snow-forced experiments, one using the highest observed autumn snow cover extent over Siberia (1976) and another using the lowest extent (1988). The ensemble-mean difference between the two snow-forced experiments is computed to evaluate the climatic response to Siberian snow conditions. Experiment results suggest that Siberian snow conditions exert a modulating influence on the predominant wintertime Northern Hemisphere (AO) mode. Furthermore, an atmospheric teleconnection pathway is identified, involving well-known wave–mean flow interaction processes throughout the troposphere and stratosphere. Anomalously high Siberian snow increases local upward stationary wave flux activity, weakens the stratospheric polar vortex, and causes upper-troposphere stationary waves to refract poleward. These related stationary wave and mean flow anomalies propagate down through the troposphere via a positive feedback, which results in a downward-propagating negative AO anomaly during the winter season from the stratosphere to the surface. This pathway provides a physical explanation for how regional land surface snow anomalies can influence winter climate on a hemispheric scale. The results of this study may potentially lead to improved predictions of the winter AO mode, based on Siberian snow conditions during the preceding autumn

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This is another section of text taken from an associated link to the one I posted the other day on the other thread. My computer is still crashing when trying to post links so I am still having to cut,paste and save text to a word document instead!

Anyway, here is info regarding study about the feedbacks processes which are enabled through high amounts of snow cover over Siberia in terms of helping to induce a -AO state and associated troposphere/stratosphere interaction which weakens the polar vortex through a propagating wave flow interaction loop

Good reasons for the recent recovery in snow anonamlies over Siberia to be sustained and keep growing

You have successfully pasted the link, thanks T. (click on full text)

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Guest North Sea Snow Convection

That was a fluke!biggrin.gif

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