Stratosphere Temperature Watch

[Mr Plough]

Thanks for updating us on Xmas day Chino, I really look forward to these updates

Merry Christmas

[chionomaniac]

Thanks for updating us on Xmas day Chino, I really look forward to these updates

Merry Christmas

Cheers, Mr P.

I am loving this chart this morning:

A fully displaced lower vortex towards Siberia with a split towards Scandi thrown in for good measure too. Also note the Greenland height rises.

Watch the tropospheric models start to throw up some great output for around the end of the first week in January.

It is all dictated by this warming higher up the stratosphere which is placing considerable pressure on the vortex.

Enjoy the mild reprieve whilst it lasts.

[cooling climate]

I must admit my first reaction when I viewed the stratospheric charts was WOW.

As you say enjoy the milder couple of days because these charts would soon

have us back in the freezer. Lets hope these varify as the GFS is not quite on

board this morning, playing catch up perhaps.

[chionomaniac]

I must admit my first reaction when I viewed the stratospheric charts was WOW.

As you say enjoy the milder couple of days because these charts would soon

have us back in the freezer. Lets hope these varify as the GFS is not quite on

board this morning, playing catch up perhaps.

GFS certainly looks better today. The warming is predicted to reach the 30hPa level now. I would be surprised not to see a SSW out of this.

[knocker]

I wonder whether chino or cc could clarify something for me. Just read the following.

The polar vortex is a wintertime feature of the stratosphere. Consisting of winds spinning counterclockwise above the pole, the vortex varies in strength on long timescales because of interactions with planetary waves generated in the troposphere. The polar vortex acts like a big flywheel. When it weakens, it tends to stay weakened for a while. A strong connection has been noted between periods when the polar vortex is weak and outbreaks of severe cold in the northern hemisphere

When the vortex is strong, the westerlies descend all the way to Earth's surface. This carries more warm air from the ocean onto the land. When the vortex is weak, then the really deep cold occurs. Such correlation could prove useful for weather forecasting.

The polar vortex does not create new modes of variability in the troposphere. It stimulates preexisting modes that are fundamental to the dynamics of the lower atmosphere.

Source: Stratosphere Troposphere Interactions, K. Mohanakumar.

I think I'm okay with the strong PV but perhaps not with the weakening. I take it that a split or elongation is a sign of weakening but does signifant warming at say, 10mb, signify this as well? Also does a signal indicate weakening have to appear at more than one level? I ask because having a quick look at the 70mb level, to my inexperienced eye this would appear fairly weak but on the other hand it could be normal.

Sorry to be a pain but this is not an easy subject to get to grips with.

Edited December 26, 2010 by weather ship

[chionomaniac]

I wonder whether chino or cc could clarify something for me. Just read the following.

The polar vortex is a wintertime feature of the stratosphere. Consisting of winds spinning counterclockwise above the pole, the vortex varies in strength on long timescales because of interactions with planetary waves generated in the troposphere. The polar vortex acts like a big flywheel. When it weakens, it tends to stay weakened for a while. A strong connection has been noted between periods when the polar vortex is weak and outbreaks of severe cold in the northern hemisphere

When the vortex is strong, the westerlies descend all the way to Earth's surface. This carries more warm air from the ocean onto the land. When the vortex is weak, then the really deep cold occurs. Such correlation could prove useful for weather forecasting.

The polar vortex does not create new modes of variability in the troposphere. It stimulates preexisting modes that are fundamental to the dynamics of the lower atmosphere.

Source: Stratosphere Troposphere Interactions, K. Mohanakumar.

I think I'm okay with the strong PV but perhaps not with the weakening. I take it that a split or elongation is a sign of weakening but does signifant warming at say, 10mb, signify this as well? Also does a signal indicate weakening have to appear at more than one level? I ask because having a quick look at the 70mb level, to my inexperienced eye this would appear fairly weak but on the other hand it could be normal.

Sorry to be a pain but this is not an easy subject to get to grips with.

The polar vortex is fuelled by the temperature gradient between the Arctic stratosphere and latitudes further south. Therefore the cooler the Arctic stratosphere compared to the tropical stratosphere, the stronger the polar vortex is likely to be. So, when a warming occurs, for instance by a wave breaking event, this will reduce the gradient and the strength of the polar vortex as a result. The strength of the polar vortex ranges from an incredible 80m/s at the 1hPa level to a still impressive 15m/s at the 100hPa level. Whenever the polar stratosphere warms then we will see a corresponding reduction in the vortex strength which can be passed from level to level right down to the troposphere.

Looking at the first chart below one can see the dramatic drop in mean zonal wind at the 1hPa level which has been caused by the predicted warming event mixing in with the cooler elements of the stratosphere. This kind of reduction is likely to displayed throughout the whole stratosphere as the projected warming occurs at lower levels.

With the amount of warming forecast there is a fair chance of complete disruption of the vortex that a SSW will bring.

c

[Kentish Kiwi]

An SSW would be particularly remarkable would it not? At the beginning of the winter it was noted that it is extremely rare to get such occurrences during La Nina (or maybe it was +QBO's?) and they were almost completely ruled out... Wasn't 2009 the first such SSW recorded during a La Nina, or at least something along those lines? And if so, could we not see a similar atmospheric reaction to the event ie. it not being as favourable for cold in the UK as initially forecast?

(Sorry for all the questions Chiono, appreciate the effort you put into this thread, especially given the time of year. The prospects are certainly very exciting. If we saw a complete disruption of the vortex, this winter as a whole could turn out to be historic/memorable, not just December.)

[knocker]

The polar vortex is fuelled by the temperature gradient between the Arctic stratosphere and latitudes further south. Therefore the cooler the Arctic stratosphere compared to the tropical stratosphere, the stronger the polar vortex is likely to be. So, when a warming occurs, for instance by a wave breaking event, this will reduce the gradient and the strength of the polar vortex as a result. The strength of the polar vortex ranges from an incredible 80m/s at the 1hPa level to a still impressive 15m/s at the 100hPa level. Whenever the polar stratosphere warms then we will see a corresponding reduction in the vortex strength which can be passed from level to level right down to the troposphere.

Looking at the first chart below one can see the dramatic drop in mean zonal wind at the 1hPa level which has been caused by the predicted warming event mixing in with the cooler elements of the stratosphere. This kind of reduction is likely to displayed throughout the whole stratosphere as the projected warming occurs at lower levels.

With the amount of warming forecast there is a fair chance of complete disruption of the vortex that a SSW will bring.c

Thanks very much for taking the trouble to reply in detail. Light is appearing at the end of the tunnel. I shall ignore anything to do with the Eliassen-Palm flux.

Edit;

Not relevant to the PV but talking of wind speeds when we were flying high level balloons at Camborne we did on occasion record winds of 200kts in the stratospheric jet. The highest the balloons reached was between 2 and 3mb.

Edited December 26, 2010 by weather ship

[pyrotech]

SSW is not unusual in La Nina years, and we are currently in a deep solar minimum. When stratospheric warming occurs in the polar regions it is always associated with cooling of the tropical stratosphere. Occurring in conjunction with a deep solar minimum, an event of this magnitude is an observational rarity. However, it seems to be associated with La Nina conditions in the tropics because significant events occurred in 1999, 2001, 2004, 2006 and 2009. A large event of this type also occurred in the transition between solar cycle 21 and 22 in 1987. This was an odd to even number transition, a reversion of the suns magnetic orientation that usually yields a reduction in the impact of the solar wind on the Earths magnetosphere

[Kentish Kiwi]

Apologies, it must be the +QBO I was thinking of that usually limits the potential for SSW's not the ENSO

[Stu_London]

SSW is not unusual in La Nina years, and we are currently in a deep solar minimum. When stratospheric warming occurs in the polar regions it is always associated with cooling of the tropical stratosphere. Occurring in conjunction with a deep solar minimum, an event of this magnitude is an observational rarity. However, it seems to be associated with La Nina conditions in the tropics because significant events occurred in 1999, 2001, 2004, 2006 and 2009. A large event of this type also occurred in the transition between solar cycle 21 and 22 in 1987. This was an odd to even number transition, a reversion of the suns magnetic orientation that usually yields a reduction in the impact of the solar wind on the Earths magnetosphere

i cant vouch for the rest of your post but we are not in a deep solar minimum - Sunspots were present on over 85% of the days in 2010

[NorthNorfolkWeather]

i cant vouch for the rest of your post but we are not in a deep solar minimum - Sunspots were present on over 85% of the days in 2010

Moot point, the number of sunspots expected at this point of the cycle would mean the sun would have an average count of 50 spots, it has been much lower than this and we had some blank days this month, which is pretty well unheard of at this stage in a cycle.

The 10.7 flux is also well down compared to normal, no one really knows the effect that these factors, as well as extreme UV, have on the upper atmosphere. There is evidence of the atmosphere being 'thinner' due to less excitation.

I personally have no idea how that then propagates down, but everything is interlinked

[Uncle_Barty]

i cant vouch for the rest of your post but we are not in a deep solar minimum - Sunspots were present on over 85% of the days in 2010

Agree - solar flux and sunspot levels are significantly above 'rock bottom' values, even if they are still well below the levels seen at recent (most 20th century) solar maxima.

[chionomaniac]

Latest ECM forecast is still very promising. I would just like to say that presently we have no SSW or one forecast. It is important not to mislead people who I have seen suggesting that we are in the middle of a SSW event. We are not. However, the pattern of projected stratospheric warming witnessed so far could very well lead to one. Even if it doesn't, I am confident that there would be enough disruption of the PV to lead to further northern blocking.

The 1hPa level is forecast to undergo a very serious warming event first with temperatures rising to 37K above average and the vortex strength cut in half.

The 10 hPa level is following this pattern nicely.

Even though as KK correctly identified that SSWs were none existent in wQBO years until 2009, I wouldn't be surprised to see this occur again.

Watch the temps at the 10 and 30 hPa levels spike sharply in the next few days for this to occur.

The early impact of this event on the troposphere is likely to be any mid latitude high slowly extending to Greenland with a Scandi trough developing and heading further south. Iexpect this to be showing in the models for around 10 days time.

Just to add very significant projected warming seen at the 10hPa and 30hPa GFS Strat forecasts. I can't wait to see the vortex get blown to bits.

My main thought on this is split or displacement SSW if it is to occur?

[pyrotech]

i cant vouch for the rest of your post but we are not in a deep solar minimum - Sunspots were present on over 85% of the days in 2010

DEEP SOLAR MIN

DEEP - as in long length and low minimums

Take a look at the length of the solar minimum then take a look at the number of spotless days in the minimum. Thanks

The Sunspots were evident thru 2010 and at a level equal to 2007/2008 which some thought was MINIMUM. Except it wasnnot we went on and on.

Plus do not get confused by the two accounting methods, the modern account is useless for comparing historic data. Use layman

Lets hope we are in towards solar minimum rather than solar max, if not and this is YOUR solar max im off to buy an ice breaker.

IF you want to see the Cycle 24 forecasts from the last 3 years i will provide them and the actual so far.

Does Solar energy effect SSW well it would seem so but i think the Jury is still out on that one with different so called experts saying differently.

My opinion is that yes it does, but i have no real data to prove that either way.

[cooling climate]

Warming can clearly be seen on the 30mb graph below and considering

the extended range models NAEFS etc were showing blocking to re- emerge

over Baffin Island and Greenland then it is possible we could very well see the

AO and NAO drop through the floor.

Very, very interesting times ahead.

Time series of 30-hPa Temperature over the North Pole

[Rollo]

I would be the first to admit that despite reading and rereading Chino' and Cooling Climates posts I still do not fully understand how the assesments are made but there is no doubt in my mind that they are onto something,whether each SSW means a large High cell over Greenland is not in itself important to me ,what is,is that they have proved to be correct in nearly if not all cases.Well done guys.

[Mark Bayley]

The 10hpa is now forecast to reach above average with the 30hpa continuing to climb. If I'm reading CH right we should see this rise continue over the next few days. I will be following the updates in this thread with great interest!

I'm guessing the GFS's idea of a strong PV over the Arctic is unlikely then?

Edited December 28, 2010 by Mark Bayley

[chionomaniac]

Latest update.

I think today that it will be worth looking at the top of the stratosphere and working our way down. So lets start at the 1Hpa level. Here we are seeing forecast a very significant warming event after an increase in wave number 1 activity. It also looks like a two phased event with an initial moderate warming followed by an even stronger one. By T+240 this is very dramatic.

This will have the effect of reducing the polar vortex at this level from 83.2m/s today to 25.2m/s by T+240.

What we need from here is to see the warming way propagating down the stratosphere causing a knock on vortex reduction as it does so. Remember the warming comes first, followed by the disruption of the polar vortex. The warm area travel around the vortex center create a pressure differential before becoming engulfed in the vortex. If the net warmth of the polar vortex increases greater than latitudes further south, then we will see the vorex reduce and reverse as it is the temperature differential that drives the vortex (Effectively that is what a SSW is).

So looking down at lower levels, we still continue to see warming forecast out to T+240 and that this is increasing every day.

At 10 hPa

And at 30 hPa

The initial warming is creating some displacement of the vortex and to see how this may affect us it is best to look down at he tropopause level (the closest reading we can get is the 100 hPa level). Here we see that there is a slight difference between the GFS and ECM. The ECM suggests a displaced vortex to the Siberian sector allowing Mid Atlantic height rises to drift north. The GFS goes along with the same theme but also with a split leaving a small amount of energy towards the Canadian sector.

ECM

GFS

I don't think that t matters that much wrt these small differences at this stage.

How a stratospheric warming event transfer to the the troposphere depends ultimately in the type of warming and tropospheric influences. We may see Northern blocking position favourably or unfavourably for cold lovers. We may also see after the initial disruption a very weakened jet stream but with no amplification such as we witnessed in Feb 2009! I do expect the initial burst of warming to translate into effects at the surface from around the second week of January in the form of a northerly airstream and would expect more severe ensemble member outputs over the coming days along with the operational runs. What I do not expect to see is anything mild though.

c

[knocker]

Thanks for that interesting update chiono. Will need to read it more carefully later as have to pop out. Been having a look at the AO.

As I understand (using the word loosely) it when the oscillation changes its phases, the srengthening or weakening of the circulation around the pole tends to begin in the stratosphere and work its way down through lower levels of the atmosphere.

The daily geopotential height anomalies at 17 pressure levels are shown for the previous 120 days as indicated, and they are normalized by standard deviation using 1979-2000 base period. The anomalies are calculated by subtracting 1979-2000 daily climatology, and then averaged over the polar cap poleward of 65°N.

The blue (red) colors represent a strong (weak) polar vortex. The black solid lines show the zero anomalies.

Edited December 28, 2010 by weather ship

[yamkin]

Latest update.

I think today that it will be worth looking at the top of the stratosphere and working our way down. So lets start at the 1Hpa level. Here we are seeing forecast a very significant warming event after an increase in wave number 1 activity. It also looks like a two phased event with an initial moderate warming followed by an even stronger one. By T+240 this is very dramatic.

This will have the effect of reducing the polar vortex at this level from 83.2m/s today to 25.2m/s by T+240.

What we need from here is to see the warming way propagating down the stratosphere causing a knock on vortex reduction as it does so. Remember the warming comes first, followed by the disruption of the polar vortex. The warm area travel around the vortex center create a pressure differential before becoming engulfed in the vortex. If the net warmth of the polar vortex increases greater than latitudes further south, then we will see the vorex reduce and reverse as it is the temperature differential that drives the vortex (Effectively that is what a SSW is).

So looking down at lower levels, we still continue to see warming forecast out to T+240 and that this is increasing every day.

At 10 hPa

And at 30 hPa

The initial warming is creating some displacement of the vortex and to see how this may affect us it is best to look down at he tropopause level (the closest reading we can get is the 100 hPa level). Here we see that there is a slight difference between the GFS and ECM. The ECM suggests a displaced vortex to the Siberian sector allowing Mid Atlantic height rises to drift north. The GFS goes along with the same theme but also with a split leaving a small amount of energy towards the Canadian sector.

ECM

GFS

I don't think that t matters that much wrt these small differences at this stage.

How a stratospheric warming event transfer to the the troposphere depends ultimately in the type of warming and tropospheric influences. We may see Northern blocking position favourably or unfavourably for cold lovers. We may also see after the initial disruption a very weakened jet stream but with no amplification such as we witnessed in Feb 2009! I do expect the initial burst of warming to translate into effects at the surface from around the second week of January in the form of a northerly airstream and would expect more severe ensemble member outputs over the coming days along with the operational runs. What I do not expect to see is anything mild though.

c

Hi chionomaniac,

Very interesting read.

The following link is very interesting regarding the shut down of the Gulf Stream etc. Please do let us all know your thoughts http://www.forbiddenknowledgetv.com/videos/meteorology/scientist-gulf-loop-current-is-brokenmini-ice-age-predicted-for-europe.html

Edited December 28, 2010 by yamkin

[cooling climate]

Hi chionomaniac,

Very interesting read.

The following link is very interesting regarding the shut down of the Gulf Stream etc. Please do let us all know your thoughts http://www.forbidden...for-europe.html

Wrong thread.

[chionomaniac]

Not too much more to add today. The ECM still looks very favourable for Greenland height rises. If we are to get a SSW - and I stress again we are not presently forecast one, then I suspect we will be looking at a displacement type which is consistent with the increase in wave number 1 activity. If not, then we will still see enough displacement in the shorter term to warrant favourable cold conditions. So technically achieving a SSW may not be as important as I thought a few years ago.

[geoffw]

when is the warming forecast to take place?

[bluearmy]

when is the warming forecast to take place?

geoff - there will be some significant warming at the upper levels of the strat around the turn of the year. how big and sustained this becomes is unknown. it may not become severe/major at all. for our weather patterns to react to this likely warming, it needs to work its way all the way down to the troposphere. i guess its wait and see.

Edited December 29, 2010 by bluearmy