Stratosphere Temperature Watch

[Rollo]

I continue to read your posts with great interest C and hope that one day I fully understand them-keep up the good work and thanks.

[Guest North Sea Snow Convection]

We still have great mean zonal wind forecasts which are now negative into the reliable timeframe.

http://strat-www.met...ecast=all&var=u

We have a lovely strat 100hPa profile at T+192 - the kind that I would have liked to see after last winters MMW- the only annoying thing is that the ECM forecasts are delayed a day so things may have changed by the time we look at them!

Looking further afield I am looking for evidence that the strong amplitude wave 1 may be ready to cause another warming. There are signs, with a severely distorted vortex shape at the 10hPa level that this could occur. Even though the mean zonal winds are forecast to increase dramatically I feel that the stratospheric vortex is there for the taking!

It's like a squeezed balloon ready to pop!

I have been thinking this too - we need another warming to come along and slay the foe before it regroups. The ingredients are certainly there this winter for such a favourable event to happen.

[brogdale]

We still have great mean zonal wind forecasts which are now negative into the reliable timeframe.

http://strat-www.met...ecast=all&var=u

We have a lovely strat 100hPa profile at T+192 - the kind that I would have liked to see after last winters MMW- the only annoying thing is that the ECM forecasts are delayed a day so things may have changed by the time we look at them!

Looking further afield I am looking for evidence that the strong amplitude wave 1 may be ready to cause another warming. There are signs, with a severely distorted vortex shape at the 10hPa level that this could occur. Even though the mean zonal winds are forecast to increase dramatically I feel that the stratospheric vortex is there for the taking!

It's like a squeezed balloon ready to pop!

Hi Chionomanic

Shucks those report and assessment deadlines have really been stopping me from paying enough attention to matters straty. As ever, thanks for the updates. What's happening with those zonal wind forecasts? It looks as though there's very little reversal forecast up within the strat, but quite a lot down with us in the Trop...is that right?

So we've got those trop reversals without a preceeding SSW/MWW?

BTW have you seen the encouraging poleward burst of EP flux shown here:-

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/ep_12z_nh.html

now that is a good sign for your 'ripe' strat

[chionomaniac]

Hi Chionomanic

Shucks those report and assessment deadlines have really been stopping me from paying enough attention to matters straty. As ever, thanks for the updates. What's happening with those zonal wind forecasts? It looks as though there's very little reversal forecast up within the strat, but quite a lot down with us in the Trop...is that right?

So we've got those trop reversals without a preceeding SSW/MWW?

BTW have you seen the encouraging poleward burst of EP flux shown here:-

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/ep_12z_nh.html

now that is a good sign for your 'ripe' strat

Hi Brogdale,

My taking on the situation is that we have had a series of minor warmings during November which has seriously weakened the stratospheric vortex. This has allowed a split in the vortex to occur from the troposphere radiating upwards into the middle stratosphere - a completely different type of split to those caused by a MMW. However I feel that we could still see a MMW. The flux charts that you highlight are suggestive of poleward energy transfer to the top of the stratosphere- perhaps from the large wave number 1 event - and as I see it this could trigger another warming. And if one does occur, as Tamara and I say I don't think the vortex will survive. We shall see!

c

Ps. Thanks Rollo

[Jack Wales]

I have been thinking this too - we need another warming to come along and slay the foe before it regroups. The ingredients are certainly there this winter for such a favourable event to happen.

And right on cue you can see the warming just starting to show its hand...

[chionomaniac]

And right on cue you can see the warming just starting to show its hand...

Hi Jack,

This latest warming looks like an upper based minor warming going on the latest forecasts.

Still good to see. I hope to see a bigger warming towards the end of the month.

c

[Guest North Sea Snow Convection]

And right on cue you can see the warming just starting to show its hand...

Hello Jack

I think that very regular minor warmings are going to be a feature continuing this winter, and very possibly there is a SSW to follow sooner or later. And we hope so certainly!

The factors that GP and CH have documented so well, including solar min, stratospheric ozone state which is especially good in terms of many recent winters are all good ingredients for a very different set-up this winter. As ever things need to fall into place for our maritime climate - but as we know, there is plenty of interest already at the end of only the first week of December

Edited December 7, 2009 by North Sea Snow Convection

[Glacier Point]

Re. question from JH -

What has caused 30mb temperatures to be above average for all of November ?

I would say the impacts of enhanced Brewer Dobson Circulation tied into the east QBO / low solar minima resulting in increased ozone concentrations over the polar stratosphere John.

[NorthNorfolkWeather]

Re. question from JH -

What has caused 30mb temperatures to be above average for all of November ?

I would say the impacts of enhanced Brewer Dobson Circulation tied into the east QBO / low solar minima resulting in increased ozone concentrations over the polar stratosphere John.

Hi GP (and all the other experts)

AAquestion about the effect of the deep solar minimum and it's possible effect on the Stratosphere.

As I understand it, due to the low solar wind as part of the slumber that the sun is in, our atmosphere is actually thinner than is is at solar max, or even when the solar wind is 'faster' and more energetic than it is now.

Firstly, is there a measurable difference now in the 30mb height at the Poles compared to say 2003/2004 when the sun was active?

secondly same question for the tropics?

thirdly are there any known teleconnections between any height differences om the first two questions?

I understan also that, also due to the low power level of the solar wind we have a incidence of Galactic Cosmic rays, is there any known effect that this increase in very high GCR's other than there may be an increase in cloud cover and therefore also an increase in the albedo

I hope they are sensible questions

Edited December 8, 2009 by NorthNorfolkWeather

[Glacier Point]

Hi GP (and all the other experts)

This paper provides an excellent reference to most of your questions. It will take some reading (and re-reading) but it's well worth the effort.

http://strat-www.met.fu-berlin.de/labitzke/summary/JASTP-Labitzke-2005.pdf

In theory, the order of preferential warming / +ve height anomaly is as follows:

east QBO / low solar

west QBO / high solar

east QBO / high solar

west QBO / low solar

Hope that helps.

Edited December 8, 2009 by Glacier Point

[NorthNorfolkWeather]

This paper provides an excellent reference to most of your questions. It will take some reading (and re-reading) but it's well worth the effort.

Thanks, a liitle light reading then

[Typhoon John]

Regarding Galactic Cosmic Rays, I think they actually destroy Ozone. But we have more Ozone and more GCR than usual this year. So it's interesting that even though the low solar is causing GCR that are having a negative effect on ozone, it's causing something else which is having a much bigger positive effect.

[leroys35]

We still have great mean zonal wind forecasts which are now negative into the reliable timeframe.

http://strat-www.met.fu-berlin.de/cgi-bin/ecmwfzm?alert=1&forecast=all&var=u

We have a lovely strat 100hPa profile at T+192 - the kind that I would have liked to see after last winters MMW- the only annoying thing is that the ECM forecasts are delayed a day so things may have changed by the time we look at them!

hi do you think when the next warm wave enters the strat if it collapes is it possible that we could end up with a 1963 or a 1947 with sustained cold any ideas

Looking further afield I am looking for evidence that the strong amplitude wave 1 may be ready to cause another warming. There are signs, with a severely distorted vortex shape at the 10hPa level that this could occur. Even though the mean zonal winds are forecast to increase dramatically I feel that the stratospheric vortex is there for the taking!

It's like a squeezed balloon ready to pop!

[chionomaniac]

leroys I have just noticed your question in the middle of my post.

I don't think you should get too concerned re whether we are going to get another 1947 or 1963 type winter. No one will know that for sure, but it has to be said that even though it is not impossible to get a 1947 or 1963 type winter, it is highly unlikely. We can only deal with what we know presently, and that is that we are now likely to see a period of northern blocking which substantially increases the likelihood of cold weather. In effect we are going to get a 2009/2010 event!

Regarding the warm wave that you mention, I assume that you are referring to the possibility of MMW/SSW. The possibility of a MMW occurring is certainly there and if a warming occurs then I feel that the chances of zonal wind reversal throughout the whole of the stratosphere would be quite high. The stratosphere repsonds to wave breaking caused by tropospheric events such as mountain torque events. There appears to be a large planetary wave number 2 event forecast for the next 10 days that can also be a precursor to a SSW - but there is no way of knowing for sure.

The stratosphere is currently cooling and the vortex strength appears to be increasing, as the vortex regroups, following the split.

The possibility of deep cold in the coming weeks shows what an important part that the stratosphere plays in tropospheric weather and I feel that this cannot be stressed enough. Without the weakened polar vortex during November, it is highly unlikely that the lower stratospheric and tropospheric polar vortex split would have occurred. One of the reasons that myself, Tamara, GP etc got so excited following the vortex split MMW last winter was because of the possibilities that can occur following this type of event. Alas, even though we may have had the best snowfalls in some areas for many a year, the true northern blocking that I had envisaged didn't materialise to affect us, for reasons previously explained. However it now appears that we have a 'bonus' event (whether or not we get long lasting deep cold or not) on our hands even without a SSW! Many of us stressed prior to this winter how important an easterly QBO would be and GP suggested how important the enhanced Brewer Dobson circulation would be, but I never thought that we would see an event this soon into winter. I know that we have not seen any snow yet, but the event for me is the vortex split - remember how important this is - it was stressed earlier in the thread.

And we still have the possibility of a SSW to come - I wonder was GP alluding to this in this morning's post when he hinted at mid Jan - it would certainly help.

c

[cooling climate]

This explanation for SSW from Wikipedia is a compacted and fairly simple

explanation of the processes involved for those of us that get lost in the technical jargon.

Dynamics of sudden stratospheric warming

In a usual northern-hemisphere winter, several minor warming events occur, with a major event occurring roughly every two years. One reason for major stratospheric warmings to occur in the Northern hemisphere is because orography and land-sea temperature contrasts are responsible for the generation of long (wavenumber 1 or 2) Rossby waves in the troposphere. These waves travel upward to the stratosphere and are dissipated there, producing the warming by decelerating the mean flow. This is the reason that major warmings are only observed in the northern-hemisphere, with one exception. In 2002 a southern-hemisphere major warming was observed. This event to date is not fully understood.

At an initial time a blocking-type circulation pattern establishes in the troposphere. This blocking pattern causes planetary zonal wave number 1 and/or 2 to grow to unusually large amplitudes. The growing wave propagates into the stratosphere and decelerates the mean zonal winds. Thus the polar night jet weakens and simultaneously becomes distorted by the growing planetary waves. Because the wave amplitude increases with decreasing density this easterly acceleration process is not effective at fairly high levels. If the waves are sufficiently strong the mean zonal flow may decelerate sufficiently so that the winter westerlies turn easterly. At this point planetary waves may no longer penetrate into the stratosphere (due to the Charney-Drazen criteria). Hence further upward transfer of energy is completely blocked and a very rapid easterly deceleration and the polar warming occur at this critical level, which must then move downward until eventually the warming and zonal wind reversal affect the entire polar stratosphere.

The dynamics of the stratosphere and mesosphere by H.R Holton

There exists a link between sudden stratospheric warmings and the quasi-biennial oscillation: If the QBO is in its easterly (westward) phase, the atmospheric waveguide is modified in such a way that upward-propagating Rossby waves are focused on the polar vortex, intensifying their interaction with the mean flow. Thus, there exists a statistically significant imbalance between the frequency of sudden stratospheric warmings if these events are grouped according to the QBO phase (easterly or westerly).

Edited December 10, 2009 by cooling climate

[tcc]

And we still have the possibility of a SSW to come - I wonder was GP alluding to this in this morning's post when he hinted at mid Jan - it would certainly help.

c

I think it might be in connection to the fact that El Nino is forecast to become strong now, with the effects hitting us about mid Jan? Hopefully it won't be fully east based although isn't more blocking possible with a typical El Nino signal?

[jonboy]

Regarding Galactic Cosmic Rays, I think they actually destroy Ozone. But we have more Ozone and more GCR than usual this year. So it's interesting that even though the low solar is causing GCR that are having a negative effect on ozone, it's causing something else which is having a much bigger positive effect.

I think there was a paper posted not long ago which suggested thatlow sunspot activity led to high cosmic rays which help in the developement of ozone which helps with a warmer stratosphere and possibly why we are now begining to see a strong northern block develope etc etc. I would go as far as to say that I think that the hole / depletion of the ozone inthe 80's/90's was probably in a large part down to the very high level of sun spot activity

[picog]

I think there was a paper posted not long ago which suggested thatlow sunspot activity led to high cosmic rays which help in the developement of ozone which helps with a warmer stratosphere and possibly why we are now begining to see a strong northern block develope etc etc. I would go as far as to say that I think that the hole / depletion of the ozone inthe 80's/90's was probably in a large part down to the very high level of sun spot activity

Do you mean that CFCs had no role to play in the depletion of the ozone layer?

[jonboy]

Do you mean that CFCs had no role to play in the depletion of the ozone layer?

I wouldn't say 'had no part to play' but again I think greater external influences where at play. I'm sure this will stir a hornets nest!!!!!!!

[brogdale]

leroys I have just noticed your question in the middle of my post.

I don't think you should get too concerned re whether we are going to get another 1947 or 1963 type winter. No one will know that for sure, but it has to be said that even though it is not impossible to get a 1947 or 1963 type winter, it is highly unlikely. We can only deal with what we know presently, and that is that we are now likely to see a period of northern blocking which substantially increases the likelihood of cold weather. In effect we are going to get a 2009/2010 event!

Regarding the warm wave that you mention, I assume that you are referring to the possibility of MMW/SSW. The possibility of a MMW occurring is certainly there and if a warming occurs then I feel that the chances of zonal wind reversal throughout the whole of the stratosphere would be quite high. The stratosphere repsonds to wave breaking caused by tropospheric events such as mountain torque events. There appears to be a large planetary wave number 2 event forecast for the next 10 days that can also be a precursor to a SSW - but there is no way of knowing for sure.

The stratosphere is currently cooling and the vortex strength appears to be increasing, as the vortex regroups, following the split.

The possibility of deep cold in the coming weeks shows what an important part that the stratosphere plays in tropospheric weather and I feel that this cannot be stressed enough. Without the weakened polar vortex during November, it is highly unlikely that the lower stratospheric and tropospheric polar vortex split would have occurred. One of the reasons that myself, Tamara, GP etc got so excited following the vortex split MMW last winter was because of the possibilities that can occur following this type of event. Alas, even though we may have had the best snowfalls in some areas for many a year, the true northern blocking that I had envisaged didn't materialise to affect us, for reasons previously explained. However it now appears that we have a 'bonus' event (whether or not we get long lasting deep cold or not) on our hands even without a SSW! Many of us stressed prior to this winter how important an easterly QBO would be and GP suggested how important the enhanced Brewer Dobson circulation would be, but I never thought that we would see an event this soon into winter. I know that we have not seen any snow yet, but the event for me is the vortex split - remember how important this is - it was stressed earlier in the thread.

And we still have the possibility of a SSW to come - I wonder was GP alluding to this in this morning's post when he hinted at mid Jan - it would certainly help.

c

Well after the exhausting business of model watching, its good to get back to the 'sanity' of the strat threads

I've really been trying to get my head around this piece from two Japanese researchers, that attempts to establish why some SSW events propagate downwards to affect the troposphere and others don't.

http://center.stelab...mazaki_koji.pdf

Now do forgive me if I make any glaring errors with this attempt at simplification, but here we go:-

Nakagawa & Yamazaki looked at 51 SSW events from 1957 to 2002 and defined 28 as downward propgating events (affecting the tropopause) and 23 as non-propagators. (They actually described them as Trop 'warm' and Trop 'cold' respectivly indicative of whether polar warm anomalies reached down below 500hPa).

They used the normal 'key day' definition of max rate warming ' 10 hPa, with -days before the key day and +ive days after.

So as we approach the point in the year when we might expect to witness the 'growing stage' of another SSW what signs should we be looking for if we are to get a downward propagator?

To start with both types appear to be characterised by preconditioned +ive anomaly winds above 10hPa, with the propagator type perhaps showing more intense +ive anomaly preconditioning till day -5. Both types also see a decrease in (50 - 80N) zonal winds @ the key day, and -ive zonal wind anomalies by day +5. But crucially it appears that the propagator type is determined in the growing phase (-10 to key day) with propagators having reduced zonal wind velocity in the high trop to the key day, and the non-propagators seeing high trop zonal velocities increase.

Also in this growing phase the propagators see Wave 2 > Wave 1 with EP flux exhibiting poleward propagation, whereas the non-propagators see Wave1 stronger and equatorward EP.

So there you have it ( ) What we need to be looking out for if we hope to see a Splitting SSW capable of driving some cold our way later in the season is the following:-

a) Increasing Wave 2 energy

:lol: Less strong wave 1 energy

c) Poleward EP flux

d) Decreasing zonal wind velocity in the high trop.

Shall we have a look?

a) & B) http://ds.data.jma.g..._12z_wn_nh.html

looks promising with the Wave 2 rising, and wave 1 declining.

c) http://ds.data.jma.g.../ep_12z_nh.html

looks like there's a healthy poleward element to the EP flux?

d) http://strat-www.met...cast=f192&var=u

some encouraging signs of decreasing/reversing high trop zonal winds there.

So all in all looking rather interesting for those of us keen to see another SSW this year, and hopefully one capable of producing effects way down into the trop for up to 40 days after the key day!

Edited December 10, 2009 by brogdale

[karyo]

[quote name='chionomaniac' date='09 December 2009 - 15:36 ' there and if a

The stratosphere is currently cooling and the vortex strength appears to be increasing, as the vortex regroups, following the split.

c

Edited December 11, 2009 by karyo

[chionomaniac]

This explanation for SSW from Wikipedia is a compacted and fairly simple

explanation of the processes involved for those of us that get lost in the technical jargon.

I would agree with that cc. Sometimes it is difficult to explain stratospheric processes in a clear and coherent manner. Keep your posts coming - you seem to have a clear idea of the synoptics - makes me think that you have been posting somewhere else previously!

Well after the exhausting business of model watching, its good to get back to the 'sanity' of the strat threads

I've really been trying to get my head around this piece from two Japanese researchers, that attempts to establish why some SSW events propagate downwards to affect the troposphere and others don't.

http://center.stelab...mazaki_koji.pdf

Now do forgive me if I make any glaring errors with this attempt at simplification, but here we go:-

Nakagawa & Yamazaki looked at 51 SSW events from 1957 to 2002 and defined 28 as downward propgating events (affecting the tropopause) and 23 as non-propagators. (They actually described them as Trop 'warm' and Trop 'cold' respectivly indicative of whether polar warm anomalies reached down below 500hPa).

They used the normal 'key day' definition of max rate warming ' 10 hPa, with -days before the key day and +ive days after.

So as we approach the point in the year when we might expect to witness the 'growing stage' of another SSW what signs should we be looking for if we are to get a downward propagator?

To start with both types appear to be characterised by preconditioned +ive anomaly winds above 10hPa, with the propagator type perhaps showing more intense +ive anomaly preconditioning till day -5. Both types also see a decrease in (50 - 80N) zonal winds @ the key day, and -ive zonal wind anomalies by day +5. But crucially it appears that the propagator type is determined in the growing phase (-10 to key day) with propagators having reduced zonal wind velocity in the high trop to the key day, and the non-propagators seeing high trop zonal velocities increase.

Also in this growing phase the propagators see Wave 2 > Wave 1 with EP flux exhibiting poleward propagation, whereas the non-propagators see Wave1 stronger and equatorward EP.

So there you have it ( ) What we need to be looking out for if we hope to see a Splitting SSW capable of driving some cold our way later in the season is the following:-

a) Increasing Wave 2 energy

Less strong wave 1 energy

c) Poleward EP flux

d) Decreasing zonal wind velocity in the high trop.

Shall we have a look?

a) & http://ds.data.jma.g..._12z_wn_nh.html

looks promising with the Wave 2 rising, and wave 1 declining.

c) http://ds.data.jma.g.../ep_12z_nh.html

looks like there's a healthy poleward element to the EP flux?

d) http://strat-www.met...cast=f192&var=u

some encouraging signs of decreasing/reversing high trop zonal winds there.

So all in all looking rather interesting for those of us keen to see another SSW this year, and hopefully one capable of producing effects way down into the trop for up to 40 days after the key day!

Good post Brogdale. It is always difficult picking through these type of papers to get to the bare bones.

I am not as convinced as I was a couple of days ago that the current increased forecast wave 2 activity is going to lead to anything. Hopefully it will, but I am beginning to see signs in the forecasts that the stratospheric vortex is regrouping and regaining strength. Both the ECM and GFS suggest this with no significant warming on the horizon. However we still have a significantly cold tropical stratosphere which in theory should have an limiting effect on the strength of the vortex. In fact, when we look at the tropical stratosphere 30 hPa readings we see that the low temperatures are records for this time of year since the recordings began.

Looking from a stratospheric point of view at the possible breakdown of northern (Greenland) blocking I believe that we are still at least 10 days away judging by the GFS 100 hPa forecasts. At day 10 the vortex is reforming, but still showing signs of a declining Greenland high that may move westwards, with a Scandinavian trough and the UK in a probable northerly airflow.

The blocking forecast still looks good at this timeframe and supports this.

c

Edited December 11, 2009 by chionomaniac

[azores92]

hmmmm not liking that forecast too much chiono, sounds the atlantic could take over once more after a week of potential cool/cold weather? back to square one for christmas

[chionomaniac]

hmmmm not liking that forecast too much chiono, sounds the atlantic could take over once more after a week of potential cool/cold weather? back to square one for christmas

Not necessarily so. As we are all aware the stratospheric influences are only part of the jigsaw. However when this current blocked spell finally subsides I wouldn't be surprised to see a + AO period. How exactly this may affect will depend on the tropospheric teleconnections which I believe (besides El Nino) are not looking too unfavourable.

[azores92]

Not necessarily so. As we are all aware the stratospheric influences are only part of the jigsaw. However when this current blocked spell finally subsides I wouldn't be surprised to see a + AO period. How exactly this may affect will depend on the tropospheric teleconnections which I believe (besides El Nino) are not looking too unfavourable.

surface high condition perhaps?