Stratosphere Temperature Watch 2011/2012

[VillagePlank]

Quick question.

Is the absolute temperature change more important than the difference in temperature? What I mean by this is that the polar front is caused by the difference in temperature at 300hPa+ between the Mid-Latitude Cell and the Polar Cell; that is to say that the jet stream is a representation of the difference in temperatures between the warmer lower latitudes and polar regions. My presumption is that if the polar part warms, the jet stream is caused further south as that is where the temperature gradient is steepest - in this sense the jet stream doesn't actually move anywhere - it is simply caused by temperature differences wherever they might occur.

If this is correct, is it not the case that a cool mid-latitude cell will do the same job as a warming polar cell? Subsequently, if we are warm, say, over the UK, we'd expect the jet-stream to occur to the north of us; conversely, if we are cool over the UK, we'd expect the jet stream to occur to the south of us. Is it therefore the case that we can look for mid-latitude cooling at 30hPa on the assumption that polar air at 30hPa is stable and not in much flux.

... and if that's the case, is it simply the difference in temperature - and nothing to do with absolute temperature at all? In which case, numerically, can we simply add both factors together and reason that if a 5C rise over the polar region is sufficient, it is therefore sufficient for only a 2C rise over the polar region as long as the mid-latitude air falls by 3C - thus equalising the temperature gradient between the polar and mid-latitude cells, with the jet stream and it's encumbered low pressures having to occur (if at all) over Spain instead of Scotland.

(I hope that lot made sense - not even sure if half of it's right: coffee break reasoning and all that)

EDIT: Alas, there is data to test the idea, http://www.metoffice.gov.uk/hadobs/hadrt/, so I can find out for myself ...

Edited December 9, 2011 by Boar Wrinklestorm

[chionomaniac]

The transition of the QBO from west to east allied to an uptick in solar activity and interfrence of the Brewer Dobson Circultation during the summer (following a strong final warming of the polar stratosphere in April have all lead us to where we are now, something that was anticipated back in October.

However, green shoots starting to emerge. This is not a forecast of a stratospheric warming.

Mean zonal winds have decreased in the last 48 hrs to average levels in the middle and upper stratosphere. We also see the ECM continuing to toy with the idea that 10hPa tempeatures are trending back towards normal (this might be of interest to monitor the impacts of a relative increase from such a low base). Heat flux at 60N 30hPa is approaching a medium level and 30hPa temperatures whilst forecast to remain static, relative to the cooling mean, will actually show a slight increase.

When we next get a westerly wind burst in the troposphere (estimated at latter 1/3 of December), and potential Asian Mountain Torque off the back of it, this will be the time to take advantage of any lessening of the cooling trend.

Agreed with this potential (love the capitals). Already seeing a large increase in the wave 1 and 2 heat and momentum fluxes at 10 days. Add this to the cooling ceasing then things setting up as expected.

Still no end to the tropospheric zonal conditions and less chance of a deflecting UK ridge with a possible reversal of the MJO back to phase 4. So no end to the increased strength PV into Jan now - but we will have to see what occurs stratospherically in the meantime.

I think the recent rising of the temperature is just temporarily (like Chio stated earlier in this page) and he uses not this picture, but a more broader view.

Anybody a clue why this year the atmosphere is so extremely cold?

Ozone depletion following from last winter's record low.

I could be wrong but I was under the impression that it was generally the thermal gradient between the polar and tropical stratosphere that determined (in part or in whole) the strength and positioning of the PV. The smaller the gradient, the weaker the vortex.

On that theme, are there any graphs out there to show the state of the tropical stratosphere? As i suppose in theory even an average polar stratosphere could lead to a disrupted vortex should the tropical stratosphere be cooler than average.

SK

Yes, that is important but with a very cold Arctic stratosphere I guess it is less important this year.

Data here: http://www.cpc.ncep....re/temperature/

Quick question.

Is the absolute temperature change more important than the difference in temperature? What I mean by this is that the polar front is caused by the difference in temperature at 300hPa+ between the Mid-Latitude Cell and the Polar Cell; that is to say that the jet stream is a representation of the difference in temperatures between the warmer lower latitudes and polar regions. My presumption is that if the polar part warms, the jet stream is caused further south as that is where the temperature gradient is steepest - in this sense the jet stream doesn't actually move anywhere - it is simply caused by temperature differences wherever they might occur.

If this is correct, is it not the case that a cool mid-latitude cell will do the same job as a warming polar cell? Subsequently, if we are warm, say, over the UK, we'd expect the jet-stream to occur to the north of us; conversely, if we are cool over the UK, we'd expect the jet stream to occur to the south of us. Is it therefore the case that we can look for mid-latitude cooling at 30hPa on the assumption that polar air at 30hPa is stable and not in much flux.

... and if that's the case, is it simply the difference in temperature - and nothing to do with absolute temperature at all? In which case, numerically, can we simply add both factors together and reason that if a 5C rise over the polar region is sufficient, it is therefore sufficient for only a 2C rise over the polar region as long as the mid-latitude air falls by 3C - thus equalising the temperature gradient between the polar and mid-latitude cells, with the jet stream and it's encumbered low pressures having to occur (if at all) over Spain instead of Scotland.

(I hope that lot made sense - not even sure if half of it's right: coffee break reasoning and all that)

EDIT: Alas, there is data to test the idea, http://www.metoffice...k/hadobs/hadrt/, so I can find out for myself ...

Yes, I think I understand what you are getting at, BW. Effectively if the Arctic stratospheric is warmer than latitudes further south then we get no vortex setting up and no polar night jet. However, isn't this exactly what occurs in the Arctic stratospheric summer? Or have I missed the point completely?

Ps I regularly check the temperatures further south just to watch for this having an effect and there is normally around a 10C difference between 90-65 and 65-25. This year the difference is increased at around 13-14C so this helps drive the vortex.

Edited December 9, 2011 by chionomaniac

[cooling climate]

The transition of the QBO from west to east allied to an uptick in solar activity and interfrence of the Brewer Dobson Circultation during the summer (following a strong final warming of the polar stratosphere in April have all lead us to where we are now, something that was anticipated back in October.

However, green shoots starting to emerge. This is not a forecast of a stratospheric warming.

Mean zonal winds have decreased in the last 48 hrs to average levels in the middle and upper stratosphere. We also see the ECM continuing to toy with the idea that 10hPa tempeatures are trending back towards normal (this might be of interest to monitor the impacts of a relative increase from such a low base). Heat flux at 60N 30hPa is approaching a medium level and 30hPa temperatures whilst forecast to remain static, relative to the cooling mean, will actually show a slight increase.

When we next get a westerly wind burst in the troposphere (estimated at latter 1/3 of December), and potential Asian Mountain Torque off the back of it, this will be the time to take advantage of any lessening of the cooling trend.

There is no such thing as the BDC in the summer it is a late Autumn and winter phenomenon

only. Plus I see no reason to suspect the very cold stratosphere is down to the QBO switching.

[chionomaniac]

There is no such thing as the BDC in the summer it is a late Autumn and winter phenomenon

only. Plus I see no reason to suspect the very cold stratosphere is down to the QBO switching.

Perhaps GP meant to use the word suspension instead of interference, cc.

I am sure he will thank you for so kindly pointing it out.

[summer blizzard]

There is no such thing as the BDC in the summer it is a late Autumn and winter phenomenon

only. Plus I see no reason to suspect the very cold stratosphere is down to the QBO switching.

The cold stratosphere is partially a result of the QBO not switching completely yet.

The QBO is an up-welling or down-welling wave and while we have weak to moderate easterlies at some levels, the QBO as a whole was marginally positive still during November due to westerlies at 50hpa (December likely to be negative overall). A -QBO does seem to correlate well with a warmer than normal statosphere (winters 06 and 10 for example).

[chionomaniac]

Todays update.

We are seeing some slight warming still skirting the vortex at the 30hPa level which is consistent with the ozone build up in this area. Whereas this is only slight it is better than none at all.

It also appears that strong stratospheric wave activity is forecast in the next 10 days. The likely effects on the vortex could lead to a disturbance of the whole tropospheric vortex pattern with more defined Rossby waves setting up across the whole northern hemisphere as both the troposphere and stratosphere interact together.

These kind of patterns feedback on to themselves, larger amplitude Rossby waves increase the likelihood of mountain torques as they interact with landmasses which then feeds back again and so on and so forth. The larger amplitude Rossby waves create a more meridional flow until eventually the pattern is large and disturbed enough to lead to northern blocking.

So one to watch in the coming weeks to see if this occurs.

[Rollo]

So some hope for the future Chino ,but for the moment the wait continues.

[chionomaniac]

So some hope for the future Chino ,but for the moment the wait continues.

Exactly Rollo.

[sebastiaan1973]

Altough I would rather see some snow or low temperatures so I can skate, I do like the quietness of being patience and knowing there's nothing special on the short term. Last year was a rollercoaster of emotions. It's such a clear picture of the current state of the atmosphere.

[chionomaniac]

Something to keep an eye on.

[Fozfoster]

Something to keep an eye on.

Can you explain these charts to a numty like me please C.

[chionomaniac]

Can you explain these charts to a numty like me please C.

These temperature charts are taken from the 1hPa and 10 hPa levels. They indicate that there is a warming event at the top of the stratosphere that is showing signs of propagation to lower levels. Not a SSW, but the first signs that the increased wave activity may be having an effect.

[BLAST FROM THE PAST]

These temperature charts are taken from the 1hPa and 10 hPa levels. They indicate that there is a warming event at the top of the stratosphere that is showing signs of propagation to lower levels. Not a SSW, but the first signs that the increased wave activity may be having an effect.

And what's the difference on effect Ed? I mentioned that there is a train of thought of a SSW around the 3rd week of Dec and thus could lead to blocking for January. Maybe its SW but leads to same/similar evolution.

BFTP

[chionomaniac]

And what's the difference on effect Ed? I mentioned that there is a train of thought of a SSW around the 3rd week of Dec and thus could lead to blocking for January. Maybe its SW but leads to same/similar evolution.

BFTP

The greater the warming the greater the reduction in vortex strength. A warming limited to the top of the stratosphere won't have too much affect on the strength of the lower vortex. The greatest warmings (SSW's) totally reverse the vortex, but we still want this reversal to propagate to the troposphere.

I suspect that we will see one or two lesser warmings before a SSW (60% chance). I think that I will start to see something in the models early January.

The westerly QBO remnants have almost dissipated and should have gone by then.

[Fozfoster]

These temperature charts are taken from the 1hPa and 10 hPa levels. They indicate that there is a warming event at the top of the stratosphere that is showing signs of propagation to lower levels. Not a SSW, but the first signs that the increased wave activity may be having an effect.

Cheers C,

Every day I look in here for signs of a warming, no guarantee for cold but a start.

I think I need to get out more!

[chionomaniac]

Certainly more to keep me interested at the moment. We are seeing an increase in momentum flux with wavenumber two breaks into the top of the stratosphere. This occurs a number of times over the season but these wave can propagate further down into the stratosphere disturbing the cold vortex.

The first chart here so the increase in the momentum flux but that this is limited to the top of the stratosphere.

Already this is causing a warming forecast at the 1 hPa level. The high of 24ºC is some 20ºC higher than today's high.

There are signs that this warming is filtering down to lower levels so at last we are seeing some pressure forecast on the vortex.

We even see at tropopause level the forecast elongated vortex remains with two distinct centres.

One can imagine the wave activity on the periphery of the vortex from troposphere to the top of the stratosphere that causes this. Will the warmer zone enter the heart of the vortex and propagate?

Edited December 11, 2011 by chionomaniac

[bluearmy]

the main pressure on the p/v in the trop continues to come from the eastern pacific ridges. we see a 'semi split' later this week as the biggest ridge yet works into the arctic before the higher thicknesses it introduces are shoved towards the siberian high where they are absorbed. one wonders what might be the result of one of these ridges if the vortex is weakened a little. i think we are beginning to see the end of the current strong phase of the p/v. how long it actually takes to get there remains to be seen.

if we do get a strong siberian/eastern canadian split, i assume that leaves the likely position of blocking to be to the north of the uk, probably scandi as has been trailed by so many ??

[chionomaniac]

the main pressure on the p/v in the trop continues to come from the eastern pacific ridges. we see a 'semi split' later this week as the biggest ridge yet works into the arctic before the higher thicknesses it introduces are shoved towards the siberian high where they are absorbed. one wonders what might be the result of one of these ridges if the vortex is weakened a little. i think we are beginning to see the end of the current strong phase of the p/v. how long it actually takes to get there remains to be seen.

if we do get a strong siberian/eastern canadian split, i assume that leaves the likely position of blocking to be to the north of the uk, probably scandi as has been trailed by so many ??

Yes, it certainly wouldn't be a GH in that situation

[Glacier Point]

Quite possibly the beginning of the end of this strong early vortex event..

30hPa zonals showing a notably increase in the middle and lower latitudes as our westerly winds spread out, which should help to dilute the focus around 60N and make it easier for wave breaking later on down the line.

ECM continuing to forecast medium to strong heat flux at 30 hPa 60N.

[Gavin P]

Quite possibly the beginning of the end of this strong early vortex event..

Is this pretty much as you expected, or a few weeks earlier than you thought?

[Glacier Point]

Is this pretty much as you expected, or a few weeks earlier than you thought?

The guidance from the analogues was that January would see a decrease in zonal winds so allowing for some persistence, this evolution looks about right.

I see JB has tweeted something of a warming event in the next 10 days and towards Siberia (mentions 1984/5 !!)

So thinking of possible key dates, plotted below is the mountain torque (MT) anomaly with latest positive MT over Asia centred on 9th December.

Asian mountain torques being of most interest in terms of inducing wave breaking of the stratospheric jet.

I suspect the current MT won't be strong enough to disrupt the vortex. Mountain torques have a periodicity of 10-15 days. That means the next events which could initiate a warming event would be around 19-24 December and subsequently 29 December through 9th January.

From previous events, there would seem to be a lag between mountain torque event and warming events of around 10 days. This puts our earliest possible key warming dates around 29th December through 4th January and 8th Janaury through 19th January. Both are of interest with the MJO likely to be showing some westerly wind tendency and building westerly inertia in the system so period 29th December through 19th January looks to be key.

Edited December 11, 2011 by Glacier Point

[Gavin P]

Thanks GP.

Lots to keep an eye on then?

I must admit I don't really read JB's tweets (I do follow him) as most of them seem to be him ranting and raving about AGW. I'll check out what he's had to say.

[Bolton67]

Yes, it certainly wouldn't be a GH in that situation

Forgive my ignorance Chino, (i'm a noob) but would a Scandi High mean that Eastern areas of the UK would see the Greatest threat of Snowfall under these Circumstances? ie undercutting?

[chionomaniac]

No real surprise to see the Asian MT event as I had suspected that the strat models were responding to something along the likes.

Agree with GP that this will be the start of weakening of the PV, but that it may need a few swings of the axe before it falls.

Forgive my ignorance Chino, (i'm a noob) but would a Scandi High mean that Eastern areas of the UK would see the Greatest threat of Snowfall under these Circumstances? ie undercutting?

That would depend if undercutting were to occur. November shows us what happens with a Scandi High without undercutting!

[kold weather]

Yeah typically takes 2-3 bites of the cherry, hopefully if we were to get at least some decent warming either at the back end of December or early January it'd really help to get things going. Just need to hope that any blocking high forms in a good location.

Have to admit we've been quite lucky with the way the PV has set-up this winter so far, could have been so much worse!