Stratosphere Temperature Watch

[bongo]

Chionomaniac - please forgive me but I barely keep up with what you are describing at the best of times.

So for a dullard like me could you spell out the ????? !

[bluearmy]

Chionomaniac - please forgive me but I barely keep up with what you are describing at the best of times.

So for a dullard like me could you spell out the ????? !

i think ???? = 'sypnotic nirvana' (too many letters i know but you get the gist)

[brogdale]

Hi Brogdale

I hope you are well.

I have posted on the other site but have real difficulty posting up charts and links for some reason.

I am sad enough to have already read the links and viewed the presentations from the latest middle Atmosphere convention. I noticed that you had homed into the same presentations that had caught my eye!

c

Latest update.

The start to this stratospheric winter has already been very interesting with episodes of record breaking warmth over the North Pole contrasting with very cold stratospheric conditions over the equatorial stratosphere. This has led to the very disturbed stratospheric vortex conditions that we are seeing presently.

There appears to be another episode of warming about to occur that I have mentioned previously:

This may have been caused by an increase in recent wavenumber 1 activity which I mentioned a few days ago. This has been extremely prominent during November and activity can be viewed here.

http://www.cpc.ncep....ALL_NH_2009.gif

It appears that another wave is in the process of propagating down the stratosphere.

However that is not what is grabbing my attention currently. What is grabbing my attention is a forecast split of the polar vortex from the base of the stratosphere/troposphere that is propagating upwards. It is this split vortex that is behind the interesting wave patterns that are being forecast by the tropospheric models. The last time we saw a split vortex like this was cough ahem back in January.

This split is being forecast by both the GFS and ECM but is more pronounced on the GFS and extends further up the stratosphere.

100 hPa level at T+240

30 hPa level at T+240

Could this just be?????

c

Hi Chionomanic

Thanks for the swift reply (and over on the other side).

You've given the TWO brethren a very clear, succinct account of the season so far and the inticing prospects. As yet not many over there appear very keen on Straty matters, but a bit of splitting in the offing should raise the level of engagement.

I have to say I'm very impressed with the thread you've got going here, and I'm in the process of working through the links, papers and graphics that have been posted already.

WRT to the Middle Atmosphere lectures I was certainly drawn to Newman's decadal cyclical analysis, but a bit disappointed with Long's consideration of the impact of the Jan event. I'd have liked a little more of the Japanese type research into propogation factors...but hey, I suppose you had to be there.

Anyway, its good to chat again, and keep up the good work...I'll certainly be a regular visitor this way from now on.

[chionomaniac]

Hi Chionomanic

Thanks for the swift reply (and over on the other side).

You've given the TWO brethren a very clear, succinct account of the season so far and the inticing prospects. As yet not many over there appear very keen on Straty matters, but a bit of splitting in the offing should raise the level of engagement.

I have to say I'm very impressed with the thread you've got going here, and I'm in the process of working through the links, papers and graphics that have been posted already.

WRT to the Middle Atmosphere lectures I was certainly drawn to Newman's decadal cyclical analysis, but a bit disappointed with Long's consideration of the impact of the Jan event. I'd have liked a little more of the Japanese type research into propogation factors...but hey, I suppose you had to be there.

Anyway, its good to chat again, and keep up the good work...I'll certainly be a regular visitor this way from now on.

Thanks, and I forgot to say welcome to Netweather! Any input from you will be very welcome.

c

[Typhoon John]

This may have been caused by an increase in recent wavenumber 1 activity which I mentioned a few days ago. This has been extremely prominent during November and activity can be viewed here.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_WAVE1_MEAN_ALL_NH_2009.gif

It is indeed very strong. It's hard to tell but it looks like there are browns and possibly a bit of grey in there; very similar to last year.

100 hPa level at T+240

30 hPa level at T+240

Could this just be?????

c

It's almost too good to be true, and it's exactly where blocking will be encouraged later in the month once we see a progression of the GWO towards the MJO. If we get this warming as forecast then it would seem harder to miss than hit.

[brogdale]

Thanks, and I forgot to say welcome to Netweather! Any input from you will be very welcome.

c

Thanks

OK, I'll try a little input, but bear with me ....marking, reports and real ale are taking their toll of the old cognitive processes!

Here's the really interesting Japanese paper that got me thinking about propogation last winter:-

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

Now in their summary they appear to be suggesting that for propogating events we would need to be looking for Wave 2 flux? Do you think i've got that right? So how much notice should we take of the Wave 1 anaysis?

Back to the reports......

Edited December 1, 2009 by brogdale

[chionomaniac]

Thanks

OK, I'll try a little input, but bear with me ....marking, reports and real ale are taking their toll of the old cognitive processes!

Here's the really interesting Japanese paper that got me thinking about propogation last winter:-

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

Now in their summary they appear to be suggesting that for propogating events we would need to be looking for Wave 2 flux? Do you think i've got that right? So how much notice should we take of the Wave 1 anaysis?

Back to the reports......

This is where I start to get bogged down. I think both waves are important and propagation will occur with both. I can't remember which presentation shows this from the Middle Atmosphere presentations but it is in there somewhere.

On TWO you posted a link to Olivia Martius presentation regarding blocking precursers to SSW's. The paper from this presentation can be found here and also looks at the type of planetary wave that influences displacement or splitting SSW's.

http://www.columbia.edu/~lmp/paps/martius+polvani+davies-GRL-2009.pdf

Note the increase in wave number 1 with displacement SSW's. Look at the displacement 1987 event ( low solar conditions, easterly QBO El Nino year) and how this evolved prior to the SSW to get an idea of what can be achieved this winter.

A list of all Polvani's papers can be found here: http://www.columbia.edu/~lmp/pubs.html

You may want to stick to the marking!

[chionomaniac]

I am just copying this post that I made in the model thread in order to add a couple of extra charts.

What we are essentially seeing is the polar vortex splitting at around T+200. This is no transient feature and has been modeled for some time. The split extends right up into the middle stratosphere. This is significant suggesting that once the split forms, it will not disappear overnight. The split leaves two main sections of daughter vortices - one over Canada the other over Siberia. Current modeling suggests that the Canadian daughter vortex will be the stronger. Now this is where it gets interesting. The position and strength of these vortices, alongside any reducing residual vortex left elsewhere, will be critical in determining whether or not an Easterly will occur. The models are throwing up differing solutions to height rises between the two vortices. One thing that has been consistent is the suggestion of height rises over Alaska and the Pacific region. What we have to hope for is that we can see similar height rises to out north allowing the jet to undercut and bring us our easterly. With this type of set up we have a good a chance as any.

Look at the negative zonal wind anomalies for 60-90ºN and how far they extend into the stratosphere due to the split at T+192.

Here is the latest ECM split forecast at the 100 hPa level

And up into the middle stratosphere at the 30 hPa level

I suspect that the vortex will reform after this as the upper levels are cooling down and zonal winds look set to strengthen. I do not (presently) think that we are seeing a SSW type of event as we have not seen a major warming propagating down from the upper levels of the stratosphere, but rather we are seeing a split vortex developing from the bottom upwards. However it should be noted that SSW's are far more common early in the season in low solar east QBO years so something bigger could still develop early yet.

c

Hopefully update the GFS later

[karyo]

I am just copying this post that I made in the model thread in order to add a couple of extra charts.

I suspect that the vortex will reform after this as the upper levels are cooling down and zonal winds look set to strengthen. I do not (presently) think that we are seeing a SSW type of event as we have not seen a major warming propagating down from the upper levels of the stratosphere, but rather we are seeing a split vortex developing from the bottom upwards. However it should be noted that SSW's are far more common early in the season in low solar east QBO years so something bigger could still develop early yet.

c

Hopefully update the GFS later

Thank you for the update and explanation! It sounds promising!

I have to say, I hope we do see a SSW soon so that we can benefit in the heart of winter! I find the current cooling at the upper levels a bit discouraging after such a good start to the stratospheric season!

Karyo

Edited December 2, 2009 by karyo

[chionomaniac]

GFS update

Firstly we are still seeing a strong amplitude wave number 1 event propagating from the top of the stratosphere. It remains to be seen how this may affect the stratosphere lower down as it propagates.

The vortex at the 100 hPA level currently looks like this:

Pretty much as would be expected for this time of year. However the split forecast is getting into a closer timeframe now.

This is still not guaranteed but I would put it in the highly likely catergory. The forecast split is still forecast to occur up towards the middle stratosphere (around 20 hPa level). I do not know why the split is occurring as it appears not to be a SSW type of event. I can only think that the last months record warmth in the stratosphere and subsequent reduced mid vortex strength has something to do with it. All theories welcome!

c

[BrickFielder]

Stratospheric disturbances can be triggered by blocked patterns in the troposphere. Typically a repeating pattern of weather in the north atlantic or north pacific will trigger a disturbance. The type of disturbance depends on the strength of the disturbance, the timing and current position of the vortex and whether blocking occurs in both the atlantic or pacific. It has been shown that blocking in both the atlantic and pacific will tend to cause a split in the vortex where as a single blocking pattern will tend to shift the vortex. These disturbances show up as a warming in the stratosphere or more importantly the movement of the cold air in the vortex away from the pole.

When we look at the vortex we should perhaps think about it as a low pressure system in the stratosphere or low pressure systems if it is split. These systems have an impact on the height of the tropopause and hence the weather in the troposphere where we live. Let us look at the vorticity chart for 400k which clearly illustrates where the vortex is (Non blue areas show where the vortex or vortexes are).

What I think you will tend to see is higher pressure is more likely under the vortex.

This means the current forecast split in the forecast is happening in exactly the wrong way to break up our current pattern of weather, worse still it sets up a pattern in the troposphere which would trigger a further disturbance in the stratosphere which would result in exactly the wrong type of vortex split that is forecast now.

There is hope however and it relates to which one of the two vortexes becomes dominate when the split decays, because this will change the nature of any subsequent disturbances in the stratosphere. Timing would suggest the form coming blocked pattern should trigger a potential further disturbance(warming) during the later part of January.

[BLAST FROM THE PAST]

Approximate 200 yr Solar cycle with current solar minimum forcing the jetstream on southerly track. This inevitably would lead to split vortex.

BFTP

[chionomaniac]

This means the current forecast split in the forecast is happening in exactly the wrong way to break up our current pattern of weather, worse still it sets up a pattern in the troposphere which would trigger a further disturbance in the stratosphere which would result in exactly the wrong type of vortex split that is forecast now.

There is hope however and it relates to which one of the two vortexes becomes dominate when the split decays, because this will change the nature of any subsequent disturbances in the stratosphere. Timing would suggest the form coming blocked pattern should trigger a potential further disturbance(warming) during the later part of January.

Thanks for your thoughts, BF.

I can understand why you think that the split is unfavourable to us in the UK. I don't think that the polar vortex will ever split leaving us at the favourable end - ie it will always break Canada/Siberia - though we can still get something out of these situations. Our best hopes are for the Canadian vortex to be as west based as possible and for the Siberian segment to retrogress and undercut any block. As I feel that the Siberian vortex will weaken first, I remain with some hope, but I realise that this is going against the dominant flow.

My worst case scenario is that the Canadian residual vortex transfers to south Greenland before eventually returning to the pole. This could prevent any blocking from influencing our weather. Having said that, I still believe that we have a far better chance of cold here, than if we already had a cold stratosphere with a strong Greenland based polar vortex in situ.

c

Edited December 2, 2009 by chionomaniac

[cooling climate]

I would say that the vortex split is ideally suited for our location. if there is any residual energy

from the vortex left on the western side of Greenland then I think a more east northeasterly

pattern will emerge.

One thing we don't want to see as I have mentioned in the model thread is any energy left on

our side of the pole near Svalbard if you like, as this will scupper any height rises to our north.

I think this is classic rosby wave dispersal (wave breaking ) in the stratosphere caused by the pna

ridge.

Edited December 2, 2009 by cooling climate

[azores92]

this is a very fascinating topic imho. it looks as if the upper stratosphere is cooling a little, and itll be interesting to see how far it cools. will it go below average? as a general rule of thumb, if it takes a few weeks for potential effects to propogate down to the uk from a ssw, then surely mid december would be a good place to look for a ssw event in time for january? brickfielders comments dont fill me with excitement exactly, but as we all know, these are forecasts for the stratosphere, and just like the models, they could easily change. surely a ssw will appear rather spontaneously as the name suggests. itll be interesting to see how stratospheric conditions played out during the leadup to the feb 1991 cold spell and jan 1987 cold spell.

Edited December 2, 2009 by azores92

[brogdale]

this is a very fascinating topic imho. it looks as if the upper stratosphere is cooling a little, and itll be interesting to see how far it cools. will it go below average? as a general rule of thumb, if it takes a few weeks for potential effects to propogate down to the uk from a ssw, then surely mid december would be a good place to look for a ssw event in time for january? brickfielders comments dont fill me with excitement exactly, but as we all know, these are forecasts for the stratosphere, and just like the models, they could easily change. surely a ssw will appear rather spontaneously as the name suggests. itll be interesting to see how stratospheric conditions played out during the leadup to the feb 1991 cold spell and jan 1987 cold spell.

Hi Azores 92

Do you know of this site?

http://www.appmath.columbia.edu/ssws/

if you use "View Events" on the blue toolbar you can then select a notable SSW event and explore many aspects of its features.

Unfortunately not many of the featured events tie in neatly with Cold Winter events that we have experienced in the UK, but the Dec 1981 event did preceed our 3rd coldest DJF CET since the war (2.6C).

I think Chiniomaniac will be interested in the wave flux component pattern that preceeded the SSW:-

Hmmm...lots of Wave 1 early on in the season.

If you then use the animations button you can view the event in 2 or 3D.

Enjoy.

[chionomaniac]

Hi Azores 92

Do you know of this site?

http://www.appmath.columbia.edu/ssws/

if you use "View Events" on the blue toolbar you can then select a notable SSW event and explore many aspects of its features.

Unfortunately not many of the featured events tie in neatly with Cold Winter events that we have experienced in the UK, but the Dec 1981 event did preceed our 3rd coldest DJF CET since the war (2.6C).

I think Chiniomaniac will be interested in the wave flux component pattern that preceeded the SSW:-

Hmmm...lots of Wave 1 early on in the season.

If you then use the animations button you can view the event in 2 or 3D.

Enjoy.

My analogue winter to compare to is 1986/87.

More wave 1 before the displacement SSW. I expect (hope) this winters to be sooner than 23rd Jan though.

[azores92]

My analogue winter to compare to is 1986/87.

More wave 1 before the displacement SSW. I expect (hope) this winters to be sooner than 23rd Jan though.

many thanks brogdale. it does certainly seem like the ssw plays a big part in cold weather for us, but it is not always the rule. is it looking unlikely that a major ssw will take place in december then, in your honest opinions? all this talk of a bitter january from many forecasters

Edited December 2, 2009 by azores92

[chionomaniac]

many thanks brogdale. it does certainly seem like the ssw plays a big part in cold weather for us, but it is not always the rule. is it looking unlikely that a major ssw will take place in december then, in your honest opinions? all this talk of a bitter january from many forecasters

I know that some forecasters can work out the timeframes of breaking planetary waves and use this to forecast when a SSW may occur. Beyond me I am afraid. My thoughts on a possible SSW for this winter were for around the end of this month. Guesswork though!

[brogdale]

My analogue winter to compare to is 1986/87.

More wave 1 before the displacement SSW. I expect (hope) this winters to be sooner than 23rd Jan though.

Well if its wave 1 you're after, have you seen the blocking forecast two weeks hence here:-

http://www.cpc.noaa.gov/products/precip/CWlink/blocking/real_time_nh/mrf3.nh.shtml

[chionomaniac]

Well if its wave 1 you're after, have you seen the blocking forecast two weeks hence here:-

http://www.cpc.noaa.gov/products/precip/CWlink/blocking/real_time_nh/mrf3.nh.shtml

Looking good!

[Fozfoster]

Looking good!

Can you explain the blocking forecast to me sorry

[chionomaniac]

Can you explain the blocking forecast to me sorry

Hi foz, the oranges suggest where upper atmosphere level high pressure systems (blocks) are likely to form. We don't often see strong blocks over Greenland!

[Fozfoster]

Hi foz, the oranges suggest where upper atmosphere level high pressure systems (blocks) are likely to form. We don't often see strong blocks over Greenland!

Hi C, Yes it is looking good then, We just need to have a little patience , Ithink!! And cheers.

Edited December 2, 2009 by fozfoster

[Guest North Sea Snow Convection]

I think this can be over analysed and cases 'to and for' a favourable split for this part of the NH hemipshere can ALWAYS be made.

As fed up as I am to the back teeth with this awful cyclonic atlantic pattern, I think that it is (maybe) a case of perhaps losing an initial battle with this one but eventually 'winning the war'. But we dont even know that for sure yet.

As I have said on the model thread a few times recently, what is needed is a full blown warming and death of zonal winds on a seasonal 'permanent basis' and the way that things stack up, with the stratosphere on a full warming time bomb this winter, that is set ticking - and with a LOT of cold air going to stack up to the NE in the meantime, then perhaps a forgettable December is the only thing that stands in the way...

Edited December 2, 2009 by North Sea Snow Convection