Stratosphere Temperature Watch 2012/2013

[cooling climate]

I wonder how much if any the meteorite explosion during mid February impacted on the

stratosphere. A large amount of energy and heat was released (roughly the size of a small

A-bomb). Also remember several days later we had the start of the large mountain torque

over Asia.

Therefore the tanked AO that we have seen could very well be a combination of three

events....

1) The SSW in January

2) The downwelling of energy and heat from the meteorite explosion combined with

3) The very large mountain torque event over Asia that started around the 25th of Feb.

[Interitus]

I wonder how much if any the meteorite explosion during mid February impacted on the

stratosphere. A large amount of energy and heat was released (roughly the size of a small

A-bomb). Also remember several days later we had the start of the large mountain torque

over Asia.

Therefore the tanked AO that we have seen could very well be a combination of three

events....

1) The SSW in January

2) The downwelling of energy and heat from the meteorite explosion combined with

3) The very large mountain torque event over Asia that started around the 25th of Feb.

There was a thread discussing the meteorite - http://forum.netweather.tv/topic/76074-russian-meteorite-and-weather-patterns/

It would seem logical to have an effect on the atmosphere with the release of 3.75 x 10e14 Joules, but on the balance of things the incoming solar radiation is 173 petawatts which is the equivalent to 461 of this meteorite every second so on a global scale the influence is probably negligible.

[cooling climate]

There was a thread discussing the meteorite - http://forum.netweat...ather-patterns/

It would seem logical to have an effect on the atmosphere with the release of 3.75 x 10e14 Joules, but on the balance of things the incoming solar radiation is 173 petawatts which is the equivalent to 461 of this meteorite every second so on a global scale the influence is probably negligible.

We are not taking about global scale. This was in a relatively localised area but cheers I did

not realise there was a seperate thread on this.

[chionomaniac]

Comparing last year mean zonal winds to this year we see a vast difference in the mean zonal wind speeds at both 10 hPa and 30 hPa.

Last year at this point we were close to a reversal and final warming with the wintertime stratospheric polar vortex no longer having a meaningful input and influence on tropospheric weather patterns.

But this year we have seen a steady increase in the mean zonal wind speeds in the middle stratosphere since the SSW. These are now upto 20m/s+ and have yet to downwell to the troposphere. It is my belief that these will have an influence with a late downwell from mid April until mid March and that this can have an effect of a late strengthening of the tropospheric vortex.

With a stronger late polar vortex we should see a waning of HLB's until later on in summer and with that an increased chance of any Azores high extending over southern areas in a stronger westerly flow. The big if in this case is will the trough placement be favourable to keep the unsettled weather to the north? MJO amplitude should help with the positioning here, though the stratospheric signal may dampen and override any strong meridional MJO signal.

[Supercell 89]

Hi Chino, thanks for the informative post as always

I have a couple of questions though, how does a late strengthening of the polar vortex allow for less northern blocking during the summer? Wouldn't the stratosphere undergo a late final warming as a result and allow the pattern to default back to northern blocking, assuming there are no other factors allowing for the northern blocking to weaken.

Or is it because that the final warming will be more gradual therefore the northern blocking would take longer to gradually rebuild?

Many Thanks

[chionomaniac]

Hi Chino, thanks for the informative post as always

I have a couple of questions though, how does a late strengthening of the polar vortex allow for less northern blocking during the summer? Wouldn't the stratosphere undergo a late final warming as a result and allow the pattern to default back to northern blocking, assuming there are no other factors allowing for the northern blocking to weaken.

Or is it because that the final warming will be more gradual therefore the northern blocking would take longer to gradually rebuild?

Many Thanks

Firstly, I should have said that the tropospheric response to the late downwelling will be likely to have an effect until mid May ( not mid March as originally posted). From what happens after this we will have to wait and see. From the moment of the Final warming, which will be late this year, then we will see the stratosphere enter summer conditions - where weak easterly mean winds predominate. The Summer tropospheric polar vortex is still westerly due to the temerature difference induced baroclinicity combined with the coriolis effect. However, it is much weaker due to the reduced summer thermal gradient and lack of stratospheric driver.

Because of this we cannot use the stratospheric conditions to help guide any forecasting for the summer months. (Or probably not yet, though I am sure that there will be a knock on effect to southern hemisphere stratospheric conditions and feedback mechanisms due to ENSO conditions).

There has been a preponderance of late ( after April 9th) summer strat conditions in the last 20 years and therefore I feel that there is little to be gained looking at this in isolation as a guide to summer months.

http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/northpole/index.html

Another thing of note is the QBO profile towards the end of last year:

http://www.geo.fu-berlin.de/met/ag/strat/produkte/qbo/qbo_wind_pdf.pdf

The westerly QBO extended in the lower reaches of the stratosphere right up until the end of the year- it wasn't until the start of 2013 that the easterly QBO propagated down to the troposphere. Now the QBO is a tropical stratospheric wind - ie well away from the polar stratosphere - but when it does reach the lower regions of the stratosphere it does tend to spread more polewards and therefore this will have been very beneficial in helping reduce the lower stratospheric polar vortex when combined with the SSW over the last few months. As ever with these types of situations it is a combination of all factors occurring at the same time that leads to the preponderance of easterly winds seen over the UK.

[Interitus]

We are not taking about global scale. This was in a relatively localised area but cheers I did

not realise there was a seperate thread on this.

Well if considering an effect on the AO we are looking at a hemispheric scale at least. Consider the energy input in another way, from numerous sources it was less than the estimated energy released in 1 second by a tropical cyclone, or alternatively possibly an order of magnitude less than by a single thunderstorm - bear in mind that there maybe 2000 of these occurring at any particular moment or around 20,000 per day. Doubt either of these single events would be considered significant enough to cause wide scale change in northern hemisphere circulation.

[cooling climate]

Well if considering an effect on the AO we are looking at a hemispheric scale at least. Consider the energy input in another way, from numerous sources it was less than the estimated energy released in 1 second by a tropical cyclone, or alternatively possibly an order of magnitude less than by a single thunderstorm - bear in mind that there maybe 2000 of these occurring at any particular moment or around 20,000 per day. Doubt either of these single events would be considered significant enough to cause wide scale change in northern hemisphere circulation.

Don't really know what thunderstorms have to do with it at all. The impact occured between the

5 and 10mb level which would then downwell and 10 days later a very large mountain torque

event over Asia. I guess we may never know but I would certainly not rule it out.

Chionomaniac apologies for being off topic but I thought I would pop this in here as I know

you will see it.

My query regarding the temperatures on Sunday 24.03.13. I e-mailed the Met and they

responed as below.

(enquiries@metoffice.gov.uk)

Add to contacts (enquiries@metoffice.gov.uk)

Add to contacts

02/04/2013

From: 'Enquiries' (enquiries@metoffice.gov.uk) 02April 2013 08:36:51

Dear Declan,

Please see below the response from our Forecast Service Delivery Team:

Declan

Thank you for your email.

The reason the 24th was so cold, is as Netweather.tv suggested some very low level cold air over the continent moved east during the day.

In winter, the temperature at 850mb can sometimes be a poor reflector of whether it is colder or warmer at the surface and this was one such occasion.

I hope this helps.

Kind regards,

James

Edited April 3, 2013 by cooling climate

[chionomaniac]

Cheers for that, cc. As I suspected then.

[Supercell 89]

Firstly, I should have said that the tropospheric response to the late downwelling will be likely to have an effect until mid May ( not mid March as originally posted). From what happens after this we will have to wait and see. From the moment of the Final warming, which will be late this year, then we will see the stratosphere enter summer conditions - where weak easterly mean winds predominate. The Summer tropospheric polar vortex is still westerly due to the temerature difference induced baroclinicity combined with the coriolis effect. However, it is much weaker due to the reduced summer thermal gradient and lack of stratospheric driver.

Because of this we cannot use the stratospheric conditions to help guide any forecasting for the summer months. (Or probably not yet, though I am sure that there will be a knock on effect to southern hemisphere stratospheric conditions and feedback mechanisms due to ENSO conditions).

There has been a preponderance of late ( after April 9th) summer strat conditions in the last 20 years and therefore I feel that there is little to be gained looking at this in isolation as a guide to summer months.

http://www.geo.fu-be...pole/index.html

Another thing of note is the QBO profile towards the end of last year:

http://www.geo.fu-be...bo_wind_pdf.pdf

The westerly QBO extended in the lower reaches of the stratosphere right up until the end of the year- it wasn't until the start of 2013 that the easterly QBO propagated down to the troposphere. Now the QBO is a tropical stratospheric wind - ie well away from the polar stratosphere - but when it does reach the lower regions of the stratosphere it does tend to spread more polewards and therefore this will have been very beneficial in helping reduce the lower stratospheric polar vortex when combined with the SSW over the last few months. As ever with these types of situations it is a combination of all factors occurring at the same time that leads to the preponderance of easterly winds seen over the UK.

Thanks for replying Chino

That's helped with the questions i had about the stratosphere

In regards to the QBO my i always thought (although my knowledge on it isn't great) that generally a Negative QBO causes the the Polar Jet to be weaker and the Postive QBO causes the Jet to be stronger throughout any point in the year or Is this only the case when either the Westerly winds or Easterly winds reaches as you said the lower part of the stratosphere and able to be spread out to the polar regions?

Also If this is the case then what caused the jet to be so amplified last summer other than the PDO being negative?

Sorry for all the questions, i'm trying to understand how all the jigsaw pieces of all the different variables fit together

[Interitus]

Don't really know what thunderstorms have to do with it at all. The impact occured between the

5 and 10mb level which would then downwell and 10 days later a very large mountain torque

event over Asia. I guess we may never know but I would certainly not rule it out.

The point is that the energy released was miniscule compared to the atmospheric energy fluxes that are occurring continually. Furthermore, the nature of the energy release took place in a matter of seconds with dissipation as light and soundwaves from between seconds to a few hours (infrasound waves were recorded in Antarctica) meaning that it didn't represent a long term affect on the atmosphere.

It's not a matter of ruling it out, it's looking at the evidence and balance of probability as far as it is known rather than just going on a hunch.

[johnholmes]

The point is that the energy released was miniscule compared to the atmospheric energy fluxes that are occurring continually. Furthermore, the nature of the energy release took place in a matter of seconds with dissipation as light and soundwaves from between seconds to a few hours (infrasound waves were recorded in Antarctica) meaning that it didn't represent a long term affect on the atmosphere.

It's not a matter of ruling it out, it's looking at the evidence and balance of probability as far as it is known rather than just going on a hunch.

a very good explanation-totally agree with your view

[cooling climate]

The point is that the energy released was miniscule compared to the atmospheric energy fluxes that are occurring continually. Furthermore, the nature of the energy release took place in a matter of seconds with dissipation as light and soundwaves from between seconds to a few hours (infrasound waves were recorded in Antarctica) meaning that it didn't represent a long term affect on the atmosphere.

It's not a matter of ruling it out, it's looking at the evidence and balance of probability as far as it is known rather than just going on a hunch.

Have to disagree the effects had it been nearer to the surface would have been greatly reduced

but at between 70,000 to 100,000ft the effects would have been a lot greater. The effects may

well have amplified an already very strong Asian mountain torque and played a part on a already

weakened vortex.

Time to put this to bed now and agree to disagree.

[chionomaniac]

I think that he would see April as a dramatic turnaround month - something akin to the MJO phase 5 for the second half of April.

My guess would be that for the second half of April we will see settled, dry and warmer conditions over the southern half of the country with fronts draped over the far NW.

Well, I am left wondering what GP would have predicted for mid April onwards (we will never know!), but signs are definitely there that if he had have gone for MJO phase 5 scenario then he wouldn't have been too far away from what is likely. Interesting, as ever, that this is one year when we can still use the polar stratosphere conditions as a guide so late on in the season - not often that that occurs.

That positive downwelling (arrowed) will start to fade by the end of the month as the return to summer stratosphere conditions ( blue oval) will start to take place.

Perhaps by mid May we will get an idea of what the summer pattern is likely to be.

[Weather-history]

Is final warming late this year?

[chionomaniac]

Is final warming late this year?

Yes

[Cloud 10]

Temperatures still below normal over the pole at 10 and 30 hpa but are

recovering slowly.

Doesn't look to be any dramatic "catch up" final warming on the cards,so a

slow and steady rise back to normality seems likely.

Perhaps a reasonable second half of spring?

[bluearmy]

a particularly strong trop vortex predicted to take residence north of hudson's in week 2. will the lateness of the winters end and final warming kick through into summer and beyond?

[Interitus]

Is final warming late this year?

The NH final warming can be classified by whether the return of 60°N easterly flow occurs first at either the 10hPa or 1hPa levels. From reanalysis data it appears to occur first at the 10hPa level in about 80% of years, in which case this year would be on the late side, but if this year turns out to be a 1hPa first then it looks about normal at the moment - from http://elib.dlr.de/71036/1/Hardiman_et_al_2011.pdf

[Buriedundersnow]

dont know if this has been posted in here yet

 

this years SSW from the NASA GEOS-5

 

[lorenzo]

Great link BUS, the original NASA page of study is here, link for future reference.

 

http://gmao.gsfc.nasa.gov/researchhighlights/SSW/

 

Link to higher resolution vid

 

http://gmao.gsfc.nasa.gov/researchhighlights/SSW/epv_7mb_20121215_20130128_1080.mov

 

That Canadian segment of vortex clearly spewing energy into the Atlantic from mid Jan on this vid.

Edited April 18, 2013 by lorenzo

[knocker]

I posted this in the climate thread because there are probably more knowledgeable people dwelling here. I'll post it anyway but feel free to disagree.

 

Sudden Stratospheric Warming: Causes & Effects

http://neven1.typepad.com/blog/2013/04/sudden-stratospheric-warmings-causes-effects.html?utm_source=dlvr.it&utm_medium=twitter

Edited April 22, 2013 by knocker

[johnholmes]

fascinating but I will leave an in depth summation of that to the likes of chio perhaps?

[knocker]

fascinating but I will leave an in depth summation of that to the likes of chio perhaps?

 

My feeling exactly John. What I will say is that this bloke has certainly put a great deal of effort into this.

[chionomaniac]

I posted this in the climate thread because there are probably more knowledgeable people dwelling here. I'll post it anyway but feel free to disagree.

 

Sudden Stratospheric Warming: Causes & Effects

http://neven1.typepad.com/blog/2013/04/sudden-stratospheric-warmings-causes-effects.html?utm_source=dlvr.it&utm_medium=twitter

Thanks for posting this knocker.

 

From a quick read, what he is suggesting is something that we are already aware of. That is, that large scale high amplitude planetary waves are deflected polewards by the NH mountain ranges (the 'mountain torque') into the stratosphere - and if these are great enough, they will break the polar vortex rather than deflect off it.

 

And the cause of the increased amplitude of the Rossby waves can be sourced back to the patterns of tropical convection associated with the MJO and ENSO state - all feeding into the GWO.

 

However, it is a great write up of the exact mechanism of the mountain torque process that we should watch out for.