Stratosphere Temperature Watch 2012/2013

[-uksnow-]

hi, i am just wondering what, if any signals to look out for that maycause a SSW event, or are they something that are hard to predict and effectivrly just happen ?

[bobbydog]

It does, especially when there is a strong strat vortex or weak one. I got the impression from your original post that you were thinking the trop pressure pattern would influence the strat conditions but its pretty well always the other way around when relevant. Sure the trop can affect the strat via wave breaking but that would take some time to propagate up to the 30hpa level we see on the chart referred to, if indeed it managed to have an effect. And when it comes to the strat, we are all still learning.

now you mention it, - from Chiono's first post in the thread-

"One noticeable aspect of the recent previous winters is how the stratosphere has been susceptible to wave breaking from the troposphere through the lower reaches of the polar stratosphere - not over the top as seen in the SSWs. This has led to periods of sustained tropospheric high latitude blocking and repeated lower disruption of the stratospheric polar vortex. This has coincided with a warmer stratosphere where the mean zonal winds have been reduced and has led to some of the most potent winter spells witnessed in recent years."

not beyond the realms of possibility then, as has recently been proven!!

[beng]

I have a question for the Stratospheric gurus - there's been some chatter on here about the lack of ozone above the Arctic at the moment - is this actually relevant at this stage of the season? My understanding is that for ozone to help with a warming event, then it would require warming by direct sunlight - so if that's correct, then I'd expect Ozone to be more relevant from January on-wards as currently any solar heating would be rapidly decreasing; or is the primary driver behind the warming due to Ozone acting as a greenhouse gas in the stratosphere and preventing heat escaping?

Also assuming that Ozone needs direct UV to be important to trigger a warming, then I would anticipate that it's a lot less relevant in the case of any early season warmings - e.g. where we see disruption of the vortex from below?

Thanks to all for a really fascinating thread.

Edited October 21, 2012 by beng

[chionomaniac]

Matt.

Hi Matt,

I agree with all of that and can't wait for that cold front as well!

hi, i am just wondering what, if any signals to look out for that maycause a SSW event, or are they something that are hard to predict and effectivrly just happen ?

Hi eded,

SSW's are hard to predict but don't just occur - they are more the result of a chain of events. My first post in the thread explains why but we also know that conditions in Autumn can precipitate more conducive conditions.

Rapid growth of Eurasion snow cover increases the risk as shown below:

Increased autumnal North Atlantic heat flux also has an effect as shown in the diagram below:

http://www.agu.org/j...o03-tn-350x.jpg

We also know that we are more likely to see a SSW in an ENSO year rather than a neutral year.

I have a question for the Stratospheric gurus - there's been some chatter on here about the lack of ozone above the Arctic at the moment - is this actually relevant at this stage of the season? My understanding is that for ozone to help with a warming event, then it would require warming by direct sunlight - so if that's correct, then I'd expect Ozone to be more relevant from January on-wards as currently any solar heating would be rapidly decreasing; or is the primary driver behind the warming due to Ozone acting as a greenhouse gas in the stratosphere and preventing heat escaping?

Also assuming that Ozone needs direct UV to be important to trigger a warming, then I would anticipate that it's a lot less relevant in the case of any early season warmings - e.g. where we see disruption of the vortex from below?

Thanks to all for a really fascinating thread.

Hi Ben,

The ozone amounts are critical as part of the process. Ozone can absorb UV radiation in the stratosphere in the NH latitudes around the pole - critical in warming throughout all levels of the stratosphere. The ozone is transported from the tropical stratosphere by the BDC and wave activity to the polar stratosphere. It looks like the SH has nabbed all the ozone earlier this autumn though!

Edited October 21, 2012 by chionomaniac

[knocker]

I posted this in another thread recently but it may be of interest here.

Stratosphere targets deep sea to shape climate

North Atlantic 'Achilles heel' lets upper atmosphere affect the abyss

SALT LAKE CITY, Sept. 23, 2012 – A University of Utah study suggests something amazing: Periodic changes in winds 15 to 30 miles high in the stratosphere influence the seas by striking a vulnerable "Achilles heel" in the North Atlantic and changing mile-deep ocean circulation patterns, which in turn affect Earth's climate.

"We found evidence that what happens in the stratosphere matters for the ocean circulation and therefore for climate," says Thomas Reichler, senior author of the study published online Sunday, Sept. 23 in the journal Nature Geoscience.

Scientists already knew that events in the stratosphere, 6 miles to 30 miles above Earth, affect what happens below in the troposphere, the part of the atmosphere from Earth's surface up to 6 miles or about 32,800 feet. Weather occurs in the troposphere.

Researchers also knew that global circulation patterns in the oceans – patterns caused mostly by variations in water temperature and saltiness – affect global climate.

"It is not new that the stratosphere impacts the troposphere," says Reichler, an associate professor of atmospheric sciences at the University of Utah. "It also is not new that the troposphere impacts the ocean. But now we actually demonstrated an entire link between the stratosphere, the troposphere and the ocean."

------------------------------------------------------------------------------------------------------------------------------------------------------------

Caption: The simplified artist's conception shows how changes in polar vortex winds high in the stratosphere can influence the North Atlantic to cause changes in the global conveyor belt of ocean circulation.

Credit: Thomas Reichler, University of Utah.

http://www.eurekalert.org/pub_releases/2012-09/uou-std091812.php

[sebastiaan1973]

This is the current Ozon situation. Not looking good right now.

[Methuselah]

Thanks Chio. It's because of what you've been saying that has turned my attention toward Eurasian snow-cover, rather than worrying unduly over SSWs...

Edit: This early in the season...

Edited October 21, 2012 by Rybris Ponce

[gottolovethisweather]

I see a HLB being referred to in the coming week's action. Am I right in guessing this to mean High Level Blocking?

Edited October 21, 2012 by gottolovethisweather

[phil nw.]

I see a HLB being referred to in the coming week's action. Am I right in guessing this to mean High Level Blocking?

High latitude blocking. Edited October 21, 2012 by phil n.warks.

[chionomaniac]

Latitude

[phil nw.]

Latitude

Lol-yes i quickly realised Ed.Sunday afternoon dozyness.

[AWD]

Can i ask is the upcoming northern blocking scenario a result of Stratospheric warming in September or is it too early for the stratosphere to have had an impact on the upcoming HLB?

[chionomaniac]

Can i ask is the upcoming northern blocking scenario a result of Stratospheric warming in September or is it too early for the stratosphere to have had an impact on the upcoming HLB?

The upcoming blocking spell is more about tropospheric factors than stratospheric factors.

[Don]

I wonder what the situation was with the stratosphere at this time in 1985? November was a cold month at 4.1C but it became much milder during December which had a CET of 6.3C and there was a cold snap at the end of the month. January 1986 was slightly below average and then there was February..... I wonder if the stratosphere cooled markedly during November that year but then warmed during December? Any thoughts?

Edited October 21, 2012 by Don

[snowking]

Here you go:

http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/30mb9065_1986.gif

Spot on. Warming in early november, followed by significant cooling until January

SK

[BLAST FROM THE PAST]

I wonder what the situation was with the stratosphere at this time in 1985? November was a cold month at 4.1C but it became much milder during December which had a CET of 6.3C and there was a cold snap at the end of the month. January 1986 was slightly below average and then there was February..... I wonder if the stratosphere cooled markedly during November that year but then warmed during December? Any thoughts?

Don

very interested about this....why you ask re this winter? Its actually along my lines of thinking re this winter

BFTP

[Don]

Here you go:

http://www.cpc.ncep....mb9065_1986.gif

Spot on. Warming in early november, followed by significant cooling until January

SK

Ahh, thanks for the link SK. Very interesting and just goes to show. I imagine it would have been rather negative in here had this forum been around in November/December 1985 based on the stratosphere alone!

Don

very interested about this....why you ask re this winter? Its actually along my lines of thinking re this winter

BFTP

Hi BFTP

It was mainly because of the cold November and mild December that year being followed by a cool down from January onwards. It is indeed interesting that you're actually thinking along the lines of Winter 85/6 for this year. I don't think too many will be disappointed if this comes off! The early signs from the stratosphere could well support your thoughts too. It will be interesting to see GP's early winter thoughts which I believe are due soon.

Edited October 21, 2012 by Don

[Southern Storm]

Hi all

I have a couple of questions for the more knowledgeable people on here, and hope someone would be kind enough to answer them.

First, I know that the stratosphere has a large effect on the the troposphere but can it work in the other direction?

With all this blocking up north at the moment I assume that there is a large easterly component to the atmosphere,

and if so is it be possible for an easterly loaded troposphere to slow a cooling westerly stratosphere?

and my 2nd question is what is the current temperature of the stratosphere around the mid latitudes?

The reason i ask is because i remember a few posts from the end of September stating that the temperature of the stat around the mid latitudes was below normal.

if this is still the case would that give us some sort of a buffer with regard the the temperature differential between the arctic and the equator and with that, the stat not behave as one would expect.

Hope that all made sense .

I just think that some people have jumped on the recant cooling of the stat and think that its a one way street to raging westerly's,

when we all know that its not that simple!

Edited October 21, 2012 by thunderman24

[snowking]

Hi all

I have a couple of questions for the more knowledgeable people on here, and hope someone would be kind enough to answer them.

First, I know that the stratosphere has a large effect on the the troposphere but can it work in the other direction?

With all this blocking up north at the moment I assume that there is a large easterly component to the atmosphere,

and if so is it be possible for an easterly loaded troposphere to slow a cooling westerly stratosphere?

and my 2nd question is what is the current temperature of the stratosphere around the mid latitudes?

The reason i ask is because i remember a few posts from the end of September stating that the temperature of the stat around the mid latitudes was below normal.

if this is still the case would that give us some sort of a buffer with regard the the temperature differential between the arctic and the equator and with that, the stat not behave as one would expect.

Hope that all made sense .

I just think that some people have jumped on the recant cooling of the stat and think that its a one way street to raging westerly's,

when we all know that its not that simple!

Im hardly an expert in this field and I would not wish to give the impression that I am, but its interesting for me that you bring up this point (im assuming you mean around the tropical latitudes) as this is something I have been keeping a close eye on

If we take the 30mb level as a mid-stratospheric example:

Polar Strat - http://www.cpc.ncep....re/30mb9065.gif

Tropical Strat - http://www.cpc.ncep....re/30mb2525.gif

So in the tropical strat, where as this time last year we were seeing temperatures nearer -57c, they are cooler at -60c this this year.

So, if we compare the thermal gradient at this time last year to those at present:

2011 - 8c

2012 - 4c

(These figures are approximate)

Now if im honest I dont know whether these figures can really be considered as a significant difference, though in most cases a difference of a factor of 2 could be portrayed as so.

I did a bit of research earlier this month asking the question would a cool tropical stratosphere reducing the thermal gradient play as much of a role in promoting northern blocking (or should I say in reducing the strength of the polar vortex) as sudden polar stratospheric warming episodes do. The conclusion, after scouring through the archives, was that such a situation, based on the data going back as far as 1979, had not arisen, and so it is rather unknown territory.

This upcoming spell is hardly definitive proof of such a hypothesis, but this could be the first time we are seeing such an occurrence.

Incidentally those thermal gradient figures are true through much of the stratosphere at present below 30mb too

Kind Regards

SK

Edited October 21, 2012 by snowking

[Southern Storm]

Im hardly an expert in this field and I would not wish to give the impression that I am, but its interesting for me that you bring up this point (im assuming you mean around the tropical latitudes) as this is something I have been keeping a close eye on

If we take the 30mb level as a mid-stratospheric example:

Polar Strat - http://www.cpc.ncep....re/30mb9065.gif

Tropical Strat - http://www.cpc.ncep....re/30mb2525.gif

So in the tropical strat, where as this time last year we were seeing temperatures nearer -57c, they are cooler at -60c this this year.

So, if we compare the thermal gradient at this time last year to those at present:

2011 - 8c

2012 - 4c

(These figures are approximate)

Now if im honest I dont know whether these figures can really be considered as a significant difference, though in most cases a difference of a factor of 2 could be portrayed as so.

I did a bit of research earlier this month asking the question would a cool tropical stratosphere reducing the thermal gradient play as much of a role in promoting northern blocking (or should I say in reducing the strength of the polar vortex) as sudden polar stratospheric warming episodes do. The conclusion, after scouring through the archives, was that such a situation, based on the data going back as far as 1979, had not arisen, and so it is rather unknown territory.

This upcoming spell is hardly definitive proof of such a hypothesis, but this could be the first time we are seeing such an occurrence.

Incidentally those thermal gradient figures are true through much of the stratosphere at present below 30mb too

Kind Regards

SK

thanks for your fast and detailed reply.

Yes I meant tropical stratosphere, and my post was focusing mostly on the stratospheric vortex which didn't quite make clear enough.

Edited October 21, 2012 by thunderman24

[beng]

Hi Ben,

The ozone amounts are critical as part of the process. Ozone can absorb UV radiation in the stratosphere in the NH latitudes around the pole - critical in warming throughout all levels of the stratosphere. The ozone is transported from the tropical stratosphere by the BDC and wave activity to the polar stratosphere. It looks like the SH has nabbed all the ozone earlier this autumn though!

Thanks Ed.

[minus 9]

just a quick question. is it possible that the pv could set up shop say over siberia or northern canada. or does it usually set up over greenland most of the time. im sure if it set up shop over siberia that would allow stronger heights to build over greenland. is this right?

[Frostbite80]

just a quick question. is it possible that the pv could set up shop say over siberia or northern canada. or does it usually set up over greenland most of the time. im sure if it set up shop over siberia that would allow stronger heights to build over greenland. is this right?

I may be wrong but I believe the normal place of residence for the PV is over Greenland and it is the warming events that can weaken/displace the PV, I may be wrong so if someone more knowledeable can correct me that would be great.

[SteveB]

I alway's wondered why the PV sets up shop over Greenland, is it something that has always happened?

[minus 9]

cheers for the replys.