Stratosphere Temperature Watch

[cheeky_monkey]

i hate to sound like a bore..but to me reading the last few posts or so..thers is still a habit of manipulating timings of cold events to fit in with a ssw event..sometimes its 6-8weeks then it can 4 weeks and also an immdiate effect is argued for..if the two are liinked there must be other causes that effect the timing of a cold event from 8weeks down to an nstant.

or is it just trying to fit the culperit to the crime??

[Guest North Sea Snow Convection]

I'm not being funny at all; as I find this thread of great interest...I was just wondering how we know that the cold spring of 2006 was caused by that particular event?

I know I'm old and all, but could those 'events' have been unrelated?

PS: I learn from asking stupid questions...

No problem Pete

The lag times of that event fitted the blocking episodes of late Feb/early March and it was shown to be a good propagator event. It is this factor that differentiates whether an MMW relates to a cold spell or not. For blocking to arise and be sustained it requires westerly energy in the atmosphere to be suppressed as much as possible and the stratospheric winds to turn anticlockwise (easterly) to provide the negative zonal winds which in turn, depending on the potency of the event either propagate to the troposphere fully enough, or not sufficiently as the case maybe to slow the polar westerlies down enough and then reverse them to provide the high latitude blocking which can in turn displace polar air to our latitude.

Based on the effects of previous MMW 's in this way, and noting the scale of propagation of those events, we can in turn make comparisons with the current one and then try and gauge the liklihood of blocking based on how well this event is doing. This event is unprecedented strength with very good propagation so there are very good grounds to believe that knock on effects will surpass previous episodes such as winter 2006 as one most recent case example. And indeed last winter whereby there were three warming waves before sufficient propagation occured and effects were finally noticed at the surface - but only after winter had finished.

i hate to sound like a bore..but to me reading the last few posts or so..thers is still a habit of manipulating timings of cold events to fit in with a ssw event..sometimes its 6-8weeks then it can 4 weeks and also an immdiate effect is argued for..if the two are liinked there must be other causes that effect the timing of a cold event from 8weeks down to an nstant.

or is it just trying to fit the culperit to the crime??

read my post to PT and you will how some apply to cold spells and others don't so easily

Edited February 12, 2009 by North Sea Snow Convection

[johnholmes]

i hate to sound like a bore..but to me reading the last few posts or so..thers is still a habit of manipulating timings of cold events to fit in with a ssw event..sometimes its 6-8weeks then it can 4 weeks and also an immdiate effect is argued for..if the two are liinked there must be other causes that effect the timing of a cold event from 8weeks down to an nstant.

or is it just trying to fit the culperit to the crime??

the reason I've tried to approach the matter in a scientific and rigorous fashion, I use to values, 10 days and 15 days, outside that then I question it. I am not sure if that is correct but at least it gives a framework to start and try and test the theories.

[Guest North Sea Snow Convection]

Maybe this belongs more in the political thread, but if this is the route we're heading, just think how our present governments and the UN departments (IPCC) will be viewed in terms of using AGW and "carbon taxes" to fill their coffers for their short term ideological gains... when the funding would have been better spent on working out how to cope with food production in a global cooldown!

I feel many of these phenomena (e.g. HALE winters, solar minima and SSW's) are related in a cyclical way - that is the way nature tends to work. Purely my opinion and of course there are many examples to the contrary, but it's a gut instinct for me.

Yes , we need the whole research thing based on looking at all potential causation factors. The interest that CH thread has attracted should naturally provide a cross over into climate trend analysis, and I hope it does, as I am sure most people will agree.

This thread of course is just devoted for monitoring the progress of the current MMW and trying to learn more in the process about the stratospshere/troposphere relationship. It is 'live work in progress' - and the best way to learn IMO

[chionomaniac]

i hate to sound like a bore..but to me reading the last few posts or so..thers is still a habit of manipulating timings of cold events to fit in with a ssw event..sometimes its 6-8weeks then it can 4 weeks and also an immdiate effect is argued for..if the two are liinked there must be other causes that effect the timing of a cold event from 8weeks down to an nstant.

or is it just trying to fit the culperit to the crime??

I think Tamara has explained the stratospheric/tropospheric interelationship a number of times this winter. Are you dubious about this particular MMW event or do you question whether the stratosphere can influence the troposphere and vice versa per se?

c

[Nick B]

Yes , we need the whole research thing based on looking at all potential causation factors. The interest that CH thread has attracted should naturally provide a cross over into climate trend analysis, and I hope it does, as I am sure most people will agree.

This thread of course is just devoted for monitoring the progress of the current MMW and trying to learn more in the process about the stratospshere/troposphere relationship. It is 'live work in progress' - and the best way to learn IMO <_<

Absolutely, wrt the purpose of this thread. It's been exemplary in general in terms of the quality of input from most members and I am doing my best to keep up, join dots and learn as much as possible. Certainly your posts, C's and GP's (though his take a bit of fathoming!) have been very enlightening.

To try to add a question that may be of interest, are there any main potential factors that could scupper this type of MMW from leading to a blocking scenario? If so, what type of event do you anticipate might be strong enough to overcome the warming and the negative zonal wind anomalies? This is regardless of exactly where the blocking might occur, since I assume that can vary in placement and affect local areas in dramatically different ways?

I sort of anticipate you saying that's jumping the gun, really, and best to wait until after winter when we can study the findings properly. However, I'm just curious to know if there are any niggly doubts about propagation being overcome by any overlooked factors. Maybe you don't have any!

[Guest North Sea Snow Convection]

Absolutely, wrt the purpose of this thread. It's been exemplary in general in terms of the quality of input from most members and I am doing my best to keep up, join dots and learn as much as possible. Certainly your posts, C's and GP's (though his take a bit of fathoming!) have been very enlightening.

To try to add a question that may be of interest, are there any main potential factors that could scupper this type of MMW from leading to a blocking scenario? If so, what type of event do you anticipate might be strong enough to overcome the warming and the negative zonal wind anomalies? This is regardless of exactly where the blocking might occur, since I assume that can vary in placement and affect local areas in dramatically different ways?

I sort of anticipate you saying that's jumping the gun, really, and best to wait until after winter when we can study the findings properly. However, I'm just curious to know if there are any niggly doubts about propagation being overcome by any overlooked factors. Maybe you don't have any! <_<

You are absolutely right to raise the question. But unfortunately it will only really be time that tells. However, as has been oft repeated there is good agreement from members who are contributing to this thread that the magnitude of the event in comparison to previous one's, combined with its progress in terms of propagation, again in comparison to previous episodes,means that perhaps wholesale effects will take place in phases over the coming weeks on the polar field and the attendant strong rises of pressure in association. There was reference to a 'laddering' effect earlier which means that the negative zonal winds in association with the polar easterlies will come in wave anomalies with pauses in between. Therefore maybe a sequence of corresponding cold periods with milder interludes is a possibility? We will have to see what happens.

There are signs that the net zonal winds higher up in the stratosphere may turn westerly again, but I would think that this will simply just provide a forcing mechanism to further push a backlog weight of easterly anomalies to the surface. We should remember that the process is lagged and there are nigh on two three weeks of 'backlogged' polar easterly winds in the pipeline before any predicted westerly winds in turn impact the surface (and they are lagged too). These aren't due for a few more days yet with all the previous negative pattern still to feed through first. So plenty of time for other surface weather pattern factors to play ball and allow further cold shots.

Plenty to look out for - but a wait and see policy as always .

[Methuselah]

Thank you for your reply NSSC...It does make interesting reading; and, afterall something must cause the blocking.

[Nick B]

You are absolutely right to raise the question. But unfortunately it will only really be time that tells. However, as has been oft repeated there is good agreement from members who are contributing to this thread that the magnitude of the event in comparison to previous one's, combined with its progress in terms of propagation, again in comparison to previous episodes,means that perhaps wholesale effects will take place in phases over the coming weeks on the polar field and the attendant strong rises of pressure in association. There was reference to a 'laddering' effect earlier which means that the negative zonal winds in association with the polar easterlies will come in wave anomalies with pauses in between. Therefore maybe a sequence of corresponding cold periods with milder interludes is a possibility? We will have to see what happens.

There are signs that the net zonal winds higher up in the stratosphere may turn westerly again, but I would think that this will simply just provide a forcing mechanism to further push a backlog weight of easterly anomalies to the surface. We should remember that the process is lagged and there are nigh on two three weeks of 'backlogged' polar easterly winds in the pipeline before any predicted westerly winds in turn impact the surface (and they are lagged too). These aren't due for a few more days yet with all the previous negative pattern still to feed through first. So plenty of time for other surface weather pattern factors to play ball and allow further cold shots.

Plenty to look out for - but a wait and see policy as always .

Thanks! All makes good sense. Especially the phrase I put into bold. This would seem to me to be the way in which your freight train analogy would work - I would have thought its effects would be shown in the models as a relatively immediate about-turn, particularly if they have been showing synoptics other than blocking.

On a slightly mischievous note, if it does indeed occur favourably for snow- and cold-lovers in the UK, it could be fun watching the models blindsiding a few of the posters who perhaps watch each and every run a bit too closely! Ah well, they should have had enough warnings about it by now!

[cheeky_monkey]

I think Tamara has explained the stratospheric/tropospheric interelationship a number of times this winter. Are you dubious about this particular MMW event or do you question whether the stratosphere can influence the troposphere and vice versa per se?

c

i understand the theory and the physics as well as anyone,,but how it transfers into cold events IMHO is still up for debate..hence the reason for my questioning of punters shoe horning cold outbreaks into MMW events..nobody for my mind as adequately explained why one event would result in a cold outbreak 8 weeks down the line yet another would be instantaneous?

correct me if im wrong but some posters a week 10 days ago were stating that the cold we were suffering was seperate to the MMW event and that would propergate into an even colder outbreak around about now....however we now have people saying the cold outbreak just gone must have been down to MMW event after all..it cant be both??

[pottyprof]

however we now have people saying the cold outbreak just gone must have been down to MMW event after all..it cant be both??

It could well be the case. An instant reaction and a delayed reaction.. I think thats why Tamara is saying wait and see.

Super thread guys and gals..

[Glacier Point]

i understand the theory and the physics as well as anyone,,but how it transfers into cold events IMHO is still up for debate..hence the reason for my questioning of punters shoe horning cold outbreaks into MMW events..nobody for my mind as adequately explained why one event would result in a cold outbreak 8 weeks down the line yet another would be instantaneous?

correct me if im wrong but some posters a week 10 days ago were stating that the cold we were suffering was seperate to the MMW event and that would propergate into an even colder outbreak around about now....however we now have people saying the cold outbreak just gone must have been down to MMW event after all..it cant be both??

It could be.

This is embyonic research, and the definitive answer at the moment is that we simply don't know the lag times and understand troposphere-stratosphere interactions fully. However, wave number 2 may have had the immediate impact seen mid to late Jan, especially as the atmosphere was perhaps more primed to react to the wavelength change:

http://www.cpc.ncep.noaa.gov/products/stra...JFM_NH_2009.gif

A more sustained impact may be traced through downwelling zonal wind propagation - currently at about 150 hPa bordering 200 hPa.

http://www.cpc.ncep.noaa.gov/products/stra...JFM_NH_2009.gif

[Methuselah]

i understand the theory and the physics as well as anyone,,but how it transfers into cold events IMHO is still up for debate..hence the reason for my questioning of punters shoe horning cold outbreaks into MMW events..nobody for my mind as adequately explained why one event would result in a cold outbreak 8 weeks down the line yet another would be instantaneous?

correct me if im wrong but some posters a week 10 days ago were stating that the cold we were suffering was seperate to the MMW event and that would propergate into an even colder outbreak around about now....however we now have people saying the cold outbreak just gone must have been down to MMW event after all..it cant be both??

I share your scepticism, CM...It is embryonic research; so is a case of 'maybe yes, maybe no', IMO...A lot more data is required too.

What about cold spells that do not follow any stratospheric warming episodes, for example? A lot of questions.

[Nick B]

i understand the theory and the physics as well as anyone,,but how it transfers into cold events IMHO is still up for debate..hence the reason for my questioning of punters shoe horning cold outbreaks into MMW events..nobody for my mind as adequately explained why one event would result in a cold outbreak 8 weeks down the line yet another would be instantaneous?

correct me if im wrong but some posters a week 10 days ago were stating that the cold we were suffering was seperate to the MMW event and that would propergate into an even colder outbreak around about now....however we now have people saying the cold outbreak just gone must have been down to MMW event after all..it cant be both??

Rather a bold assertion to make, surely? The physics of this are complicated in the extreme, surely, otherwise we would all already know the outcome of this warming event. I don't pretend to understand this stuff anywhere near as well as GP, for instance, and senior forecasters such as JH and those who have obviously done a good deal of background research such as NSSC and the instigator of this thread, C, defer many times to the depth of GP's research in this field and that of Global Angular Momentum etc. You must have studied this in great detail over a number of years, then?

[tundra]

The reason we saw such a quick reaction to the warming event (ie the easterly biginning of Jan) was due to its strength, even so the easterly still occurred two weeks after the warming started.

The warming in 85 began late December and again was very strong hence a short lag time this warming then rotated east to west in the northern hemisphere bring another bout of bitter weather to northwest Europe in February.

Because the warming this time is even stronger and more sustained i don't think we will have to wait as long for the next bout of very cold air.

Apparently from what i have been reading over on TWO on the strato warming thread after a split in the vortex the canadian vortex normally perishes of moves towards the Siberian vortex which was at first forcast to happen, but instead the Canadian vortex although weak and weakening all the time started to move towards Greenland. I believe this is why we have seen the strange behavior in the models.

The vortex is forcast to weaken further and some of the energy is expected to travel back towards Siberia so i think we can expect to see northern blocking start to appear in the models shortly.

Global warming if there really was such a thing was only caused by a more energetic sun hence the warming of other planets in the solar system. With a much quieter sun the Earth will cool along with the rest of the solar system,if it carries on as it is now with virtually no solar activity then the Earth will cool significantly.

A colder northern hemisphere winter was always more likely for these reasons. A warmer stratosphere is just another sign of the Earth entering a cooling cycle

A met office spokesman even said last week that the effects of this warming would be felt for several weeks.

Edited February 12, 2009 by tundra

[matt44myst]

hi all, this is my first post ever! I am new to netweather, although i have been following a few threads such as this one for most of the winter. anyway i have a few questions for the experts, particuarly NSSC or GP...if the current model outlooks of a slightly milder pattern are based on a downwelling of slight westerly zonal winds, when do you expect the subsequent easterlies to appear over the polar field? is it likely that model outputs will change dramatically, over a relatively short period of time, when these are picked up? in other words how long will this preceding westerly downwelling last before easterlies propagate right through the trophosphere? hope that makes sense and that my understanding isnt too flawed.

matt

[full_frontal_occlusion]

It could be.

This is embyonic research, and the definitive answer at the moment is that we simply don't know the lag times and understand troposphere-stratosphere interactions fully. However, wave number 2 may have had the immediate impact seen mid to late Jan, especially as the atmosphere was perhaps more primed to react to the wavelength change:

Interesting observation GP.

My scientific background is in electronics and aerospace application not meteorology, but the maths for wave propagation is pretty much identical

Haigh and Blackburn (8/06, Space Science Reviews V125, N1-4, Pgs 331-334) used an AGCM to investigate the response of the troposhere to thermal perturbations in the stratosphere. They found heating weakens the sub-tropical jets and the tropospheric mean meridional circulations.

The distribution of stratospheric heating directly impacted the scale of Hadley cells and the positioning of the jets with uniform heating displacing them towards the equator.

They found stability at the tropopause is initially reduced by eddy (Foucault) flux convergence in this region within 12 days. A vertical transfer of the momentum follows forcing anomalous mean circulation to the surface and they concude by suggesting thermal stratospheric changes is a key mechanism affecting Rossby wave propagation.

All of this bears striking similarities for eddy currents within electromagnetic domains and much can be read across. Within these systems intial perturbations result in magnetic field disruption almost instantaneously (propagation velocity dependent on dielectric medium) followed by sustained vortices with preserved momentum dissipating over a much longer time frame. Boundary features now play an important role in energy dissipation.

The analogue to tropospheric weather can clearly be seen with the set up of eddy's from stratospheric forcing having an initial effect and then unrelated surface height rises within the troposphere protruding into the stratosphere subsequently causing the major lagged energy dissipation back into the troposphere. A sort of transmission reflection effect. I can feel a paper coming on!

ffO.

[Nick B]

Interesting observation GP.

My scientific background is in electronics and aerospace application not meteorology, but the maths for wave propagation is pretty much identical

Haigh and Blackburn (8/06, Space Science Reviews V125, N1-4, Pgs 331-334) used an AGCM to investigate the response of the troposhere to thermal perturbations in the stratosphere. They found heating weakens the sub-tropical jets and the tropospheric mean meridional circulations.

The distribution of stratospheric heating directly impacted the scale of Hadley cells and the positioning of the jets with uniform heating displacing them towards the equator.

They found stability at the tropopause is initially reduced by eddy (Foucault) flux convergence in this region within 12 days. A vertical transfer of the momentum follows forcing anomalous mean circulation to the surface and they concude by suggesting thermal stratospheric changes is a key mechanism affecting Rossby wave propagation.

All of this bears striking similarities for eddy currents within electromagnetic domains and much can be read across. Within these systems intial perturbations result in magnetic field disruption almost instantaneously (propagation velocity dependent on dielectric medium) followed by sustained vortices with preserved momentum dissipating over a much longer time frame. Boundary features now play an important role in energy dissipation.

The analogue to tropospheric weather can clearly be seen with the set up of eddy's from stratospheric forcing having an initial effect and then unrelated surface height rises within the troposphere protruding into the stratosphere subsequently causing the major lagged energy dissipation back into the troposphere. A sort of transmission reflection effect. I can feel a paper coming on!

ffO.

In my opinion, an excellent and very interesting comparison. Good post.

[Paul]

hi all, this is my first post ever! I am new to netweather, although i have been following a few threads such as this one for most of the winter. anyway i have a few questions for the experts, particuarly NSSC or GP...if the current model outlooks of a slightly milder pattern are based on a downwelling of slight westerly zonal winds, when do you expect the subsequent easterlies to appear over the polar field? is it likely that model outputs will change dramatically, over a relatively short period of time, when these are picked up? in other words how long will this preceding westerly downwelling last before easterlies propagate right through the trophosphere? hope that makes sense and that my understanding isnt too flawed.

matt

Welcome to the forum Matt, I'm sure one of the experts will be along soon to answer your questions :lol:

[cheeky_monkey]

Rather a bold assertion to make, surely? The physics of this are complicated in the extreme, surely, otherwise we would all already know the outcome of this warming event. I don't pretend to understand this stuff anywhere near as well as GP, for instance, and senior forecasters such as JH and those who have obviously done a good deal of background research such as NSSC and the instigator of this thread, C, defer many times to the depth of GP's research in this field and that of Global Angular Momentum etc. You must have studied this in great detail over a number of years, then?

my understanding is in laymans terms..no i havnt done years of research..i got better things to do with my time but i understand the theory perfectly well..you dont have to be pele to understand football do you?

[Nick B]

my understanding is in laymans terms..no i havnt done years of research..i got better things to do with my time but i understand the theory perfectly well..you dont have to be pele to understand football do you?

Good discussion for the pub, that one! (but probably not this thread!) No offense meant at all, I was poking a bit of fun really, but I reckon those who do spend a lot of time with this research probably have a fair grasp of detail that most of us wouldn't even know was relevant...

[johnholmes]

hi all, this is my first post ever! I am new to netweather, although i have been following a few threads such as this one for most of the winter. anyway i have a few questions for the experts, particuarly NSSC or GP...if the current model outlooks of a slightly milder pattern are based on a downwelling of slight westerly zonal winds, when do you expect the subsequent easterlies to appear over the polar field? is it likely that model outputs will change dramatically, over a relatively short period of time, when these are picked up? in other words how long will this preceding westerly downwelling last before easterlies propagate right through the trophosphere? hope that makes sense and that my understanding isnt too flawed.

matt

a very simple answer Matt, and welcome to NW as well, is that the time scale for the next cold spell to show up is probably about 3-7 days from now. I would expect the models to be increasingly showing this by the weekend. The stepped idea commented on by GP may be an explanation of what is happening. Again as he, I, and others have said, its all rather new and far from solid in just what is happening. Certainly the warming from 20-22 January is the largest I've seen since looking at 30mb temperatures. Mixed signals from other teleconnections but it seems very unlikely that some effect will not be felt in the Troposphere before long.

I'm in the middle of trying to write up my observations of 2 relatively minor warming events and one cooling event this autumn-winter which do seem to show a pretty close correlation to the time scales talked of, 15-25 days.

hope that helps but some of the others may be able to give a more detailed answer.

Edited February 12, 2009 by johnholmes

[BrickFielder]

Although we like to think of the stratosphere as a seperate layer to the troposphere rather like air and water are different layers, they are not exactly unlinked. The actual boundary or tropopause is a point where temperatures start to rise with height rather than fall as they do in the troposphere. This boundary has different heights at different points in the year (higher in summer) and depending on whether you are in the walker or hadley cells etc and whether there is high or low pressure in the troposphere.

A change in the temperature above the boundary can have impacts on the boundary heights , but I think the most dominate effect is the winds. With stratospheric winds blowing in the opposite direction to tropospheric winds then in theory both should slow each other down by friction. The question then becomes how long does it take a disturbance at 5hPa to get down to 200hPa (Depends on intensity at a guess) and why might the direction of the QBO matter (probably related to the initiation of the event).

[johnholmes]

anyone interested in the blog I promised on looking at what has happened so far, try below

http://www.netweather.tv/forum/index.php?showtopic=53715

[chionomaniac]

The reason we saw such a quick reaction to the warming event (ie the easterly biginning of Jan) was due to its strength, even so the easterly still occurred two weeks after the warming started.

The warming in 85 began late December and again was very strong hence a short lag time this warming then rotated east to west in the northern hemisphere bring another bout of bitter weather to northwest Europe in February.

Because the warming this time is even stronger and more sustained i don't think we will have to wait as long for the next bout of very cold air.

Apparently from what i have been reading over on TWO on the strato warming thread after a split in the vortex the canadian vortex normally perishes of moves towards the Siberian vortex which was at first forcast to happen, but instead the Canadian vortex although weak and weakening all the time started to move towards Greenland. I believe this is why we have seen the strange behavior in the models.

The vortex is forcast to weaken further and some of the energy is expected to travel back towards Siberia so i think we can expect to see northern blocking start to appear in the models shortly.

Global warming if there really was such a thing was only caused by a more energetic sun hence the warming of other planets in the solar system. With a much quieter sun the Earth will cool along with the rest of the solar system,if it carries on as it is now with virtually no solar activity then the Earth will cool significantly.

A colder northern hemisphere winter was always more likely for these reasons. A warmer stratosphere is just another sign of the Earth entering a cooling cycle

A met office spokesman even said last week that the effects of this warming would be felt for several weeks.

The disintergration of the Canadian segment of the stratospheric vortex at the 100hPa level has indeed been poorly modelled tundra. I have been checking this on a daily basis and have yet to see many consistant forecasts. With the difficulty in forecasting what this weaker Canandian segment will do has led to probable changes subsequently in the troposphere forecasts. As you said it did appear that it was going to merge with its Siberian counterpart but then subsequently left a remnant close to the west of Greenland. I would not be surprised if it was this that has led to the pulses of Shortwaves developing over the Azores high and preventing height rises above Greenland. Here it is today :

The sooner it removes itself the better! The 7 day forecast looks better but I don't entirely trust it!

c