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Stratosphere Temperature Watch 2012/2013


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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Quick question to anyone who knows, what's the difference between a positive and negative mountain torque event? I understand what MT's are and how they can effect Rossby waves (deflection towards the polar strat and possible wavebreaking, or just dispersion at lower latitudes), but what is the significance of positive and nagative values?

    Thanks.

    Great paper that I have found here which helps explains.

    http://www.reading.a...on_Driscoll.pdf

    Firstly torque definition:

    2.2 Torque

    A Torque, deï¬ned as T, is given by

    T = r × F (2.5)

    If a torque, or a ‘turning force’, is applied to a rotating object it will slow down or

    speed up the object’s rate of rotation about the origin, or even change its direction of

    rotation. Through friction and pressure the atmosphere applies these rotational forces to

    the solid Earth which cause the rotation rate of the solid earth to either speed up or slow

    down, and in doing so the atmosphere’s angular momentum decreases or increases as it

    imparts or receives angular momentum to or from the earth, thus torques represent the

    flux of angular momentum across the surface of the earth.

    Mountain torques:

    Mountain Torque is a function of pressure and orography and is the ‘turning force’ exerted

    due to a difference in pressure across any raised surface on the earth, but most signiï¬cantly,

    mountains or mountain massifs. Consider a mountain with a high pressure on the west side

    of a mountain and low pressure on the east. The pressure system will exert an eastward

    torque that causes the earth to increase it’s rate of rotation, imparting angular momentum

    from the atmosphere to the solid earth. The opposite case, where there is higher pressure

    on the east side of the mountain, will slow the earth’s rotation down, reducing the solid

    earth’s angular momentum, and imparting it to the atmosphere.

    The first above is a positive MT as I understand it.

    Edited by chionomaniac
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    Steve whilst I agree to a certain extent, more especially with regards to the difficulty in forecasting exact placement of tropospheric synoptics (particularly with regard to the UK in the overall sch

    Posted Images

    Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)

    Great paper that I have found here which helps explains.

    http://www.reading.ac.uk/web/FILES/maths/Simon_Driscoll.pdf

    Firstly torque definition:

    2.2 Torque

    A Torque, deï¬ned as T, is given by

    T = r × F (2.5)

    If a torque, or a ‘turning force’, is applied to a rotating object it will slow down or

    speed up the object’s rate of rotation about the origin, or even change its direction of

    rotation. Through friction and pressure the atmosphere applies these rotational forces to

    the solid Earth which cause the rotation rate of the solid earth to either speed up or slow

    down, and in doing so the atmosphere’s angular momentum decreases or increases as it

    imparts or receives angular momentum to or from the earth, thus torques represent the

    flux of angular momentum across the surface of the earth.

    Mountain torques:

    Mountain Torque is a function of pressure and orography and is the ‘turning force’ exerted

    due to a difference in pressure across any raised surface on the earth, but most signiï¬cantly,

    mountains or mountain massifs. Consider a mountain with a high pressure on the west side

    of a mountain and low pressure on the east. The pressure system will exert an eastward

    torque that causes the earth to increase it’s rate of rotation, imparting angular momentum

    from the atmosphere to the solid earth. The opposite case, where there is higher pressure

    on the east side of the mountain, will slow the earth’s rotation down, reducing the solid

    earth’s angular momentum, and imparting it to the atmosphere.

    The first above is a poitive MT as I understand it.

    Thanks for clearing that up, and thanks for the link, really fascinating stuff! :)

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    Posted
  • Location: Near Bromley, Kent
  • Weather Preferences: Heavy snow, lots of it.
  • Location: Near Bromley, Kent

    Hi VL,

    Yes you are right - a SSW is different to a Canadian Warming. Whereas a lot has been written about SSW's, there is less information in the literature about Canadian warmings.

    To recap a SSW is characterised by a reversal of mean zonal mean winds in the stratosphere at a level of 10 hpa at 60ºN. This requires a rather pronounced warming.

    A Canadian warming is a less pronounced warming seen over the Canadian sector in November or December. There is no reversal of the mean zonal winds. The stratospheric polar vortex is displaced towards Siberia and weakened somewhat. I suspect that this is a result of increased wavenumber 1 activity.

    Still no significant warming in the mid stratosphere forecast.

    Many thanks Chio. I have been doing some very basic research and I think I'm right in saying that there is more frequency of an SSW event in an easterly QBO. I also read that SSW events occur on average every 2 years but not necessarily in sequence, IE: none occurred for a period during the late eighties and early nineties but there have been 9 SSW's since 2000. I wonder what the link is to the frequency of theses SSW events since 2000 and the QBO. I think I need to go back over yours and GP's posts to try and understand as much as I can about teleconnections, causes and the triggers. I do find this a fascinating aspect of meteorology.

    Regards

    VL

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    Posted
  • Location: Thornton Heath, Croydon
  • Location: Thornton Heath, Croydon

    Hi Chio,

    I have been watching the 10 and 30 hpa temps and the temps are rising. What do you say about this

    http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/gif/pole10_nh.gif

    http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/gif/pole30_nh.gif

    Thanks

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    Posted
  • Location: Ashford, Kent
  • Weather Preferences: Anything
  • Location: Ashford, Kent

    Has anyone got a link to historical versions of this chart below. Specifially the last few years or so? Much obliged!

    Posted Image

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Hi Chio,

    I have been watching the 10 and 30 hpa temps and the temps are rising. What do you say about this

    http://ds.data.jma.g...f/pole10_nh.gif

    http://ds.data.jma.g...f/pole30_nh.gif

    Thanks

    There was a small warming forecast previously which is now showing up. I would expect a small rise above average from this before dipping below average again.

    see posts around post no 193.

    and 60 -90N well below average still.

    Edited by chionomaniac
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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Has anyone got a link to historical versions of this chart below. Specifially the last few years or so? Much obliged!

    Posted Image

    Not this chart but similar

    http://acdb-ext.gsfc.nasa.gov/Data_services/met/ann_data.html

    or

    http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/

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    Posted
  • Location: Thornton Heath, Croydon
  • Location: Thornton Heath, Croydon

    I am going to trial a prediction for the next month in order to see how possible it is to predict stratospheric events. Here it is:

    I am going to suggest strong wave activity will lead to a Canadian Warming(CW) middle to last third of November.

    This will follow the snow cover growth in October leading to the stratospheric feedback. The analogue years when this has happened previously are good, and this October's Eurasian snow cover will be promising and tropical ozone levels will have recovered somewhat.

    I suspect any warming will follow on from MT activity prior to the waves entering the stratosphere in around 2 weeks time.

    We haven't seen a CW for over 10 years.

    Good luck chio.. Posted Image

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    Posted
  • Location: Netherlands
  • Location: Netherlands

    Chio thanks for the update. I suppose you mean this one? http://mls.jpl.nasa....ng_GRL_2001.pdf

    Here you can find the peak of november 2000.

    http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/archive/30mb9065_2000.gif

    post-10577-0-71820700-1351161827_thumb.p

    post-10577-0-83372500-1351161837_thumb.p

    Edited by sebastiaan1973
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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    I am going to trial a prediction for the next month in order to see how possible it is to predict stratospheric events. Here it is:

    I am going to suggest strong wave activity will lead to a Canadian Warming(CW) middle to last third of November.

    This will follow the snow cover growth in October leading to the stratospheric feedback. The analogue years when this has happened previously are good, and this October's Eurasian snow cover will be promising and tropical ozone levels will have recovered somewhat.

    I suspect any warming will follow on from MT activity prior to the waves entering the stratosphere in around 2 weeks time.

    We haven't seen a CW for over 10 years.

    Hi Ed

    What are the analogue years for this?

    cheers

    BFTP

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Hi Ed

    What are the analogue years for this?

    cheers

    BFTP

    Novembers 62 and 68

    November CW's are predominantly an easterly QBO event.

    Edited by chionomaniac
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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    Novembers 62 and 68

    November CW's are predominantly an easterly QBO event.

    68 is of particular interest to me, cheers and good luck with experiment

    BFTP

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    Posted
  • Location: E Lancs, 900ft asl
  • Weather Preferences: Snow, blizzards, cold, thunderstorms, frosts, fog, general extreme weather
  • Location: E Lancs, 900ft asl

    I am going to trial a prediction for the next month in order to see how possible it is to predict stratospheric events. Here it is:

    I am going to suggest strong wave activity will lead to a Canadian Warming(CW) middle to last third of November.

    This will follow the snow cover growth in October leading to the stratospheric feedback. The analogue years when this has happened previously are good, and this October's Eurasian snow cover will be promising and tropical ozone levels will have recovered somewhat.

    I suspect any warming will follow on from MT activity prior to the waves entering the stratosphere in around 2 weeks time.

    We haven't seen a CW for over 10 years.

    Nice prediction and if it were to actually happen would most certainly aid in producing a far different December this year than was evident last year, but obviously it's got to happen. At the present time it's all pretty 'quiet' really, not a great deal to discuss, the forecast and analysis charts look very similar almost daily and the lack of ozone is still a concern, for now.

    Good luck with the prediction, always worth having a go and from a "coldies" perspective I hope you're right. It'll be interesting to see what happens in the next 4 weeks as we really begin to firm up on potential 'events' which may affect tropospheric meteorological conditions and patterns for December.

    Cheers, Matt.

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    Posted
  • Location: Near Bromley, Kent
  • Weather Preferences: Heavy snow, lots of it.
  • Location: Near Bromley, Kent

    Well Matt, I wonder what the impact is. Such events seem to me (?) to have little impact at the vortex. Perhaps Chio means it can aid to create a SSW later on.

    I think 1962 just had the one Canadian warming event in November and that turned out to be an epic winter for us if you like severe cold and snow so some impact must have been made on the PV, perhaps driving it to Siberia. I think 1968 had 2 warming events and although it was a cold winter it wasn't as severe as 62 (I assume 68 had a Canadian warming in November and a SSW further down the line). Just going by these 2 years it suggests to me that a Canadian warming is not necessarily a predictor to a SSW warming later on and a combination of warmings does not necessarily make the winter any more severe.

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    Posted
  • Location: st albans
  • Location: st albans

    For the first time this season, mean zonal winds forecast to exceed 20m/s at 30hpa. (T192). Not a trend we want to see become established. Whilst its at day 8, its far enough away to be unreliable. Of course, there is no guarantee that the zonal wind increase will propagate to the lower layers of the strat but its more likely than unlikely. Something else to keep tabs on.

    I could mention some warming at 30hpa on the forecasts to balance this post.

    Edited by bluearmy
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    Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

    Just a quick one, but the overnight update of the EC 32 day model is interesting in terms of variability evident within this particular update. Without question the opening 7 to 10 days of November look to be particularly cyclonic, but towards mid-month and beyond a far more changeable pressure pattern is signaled with perhaps lower pressure to the south of the UK and higher pressure building to the north or north-west once again, which may signal potential cold snaps as the month progresses.

    The updates of late have been lacking consistency which is always a concern, but I do have a lot of faith in this model after using it from a forecasting perspective for over a year now, it has often picked up on trends out to 3 or 4 weeks quite well and this update certainly gives the signal for quite a changeable month once again. What is certainly not evident is a month dominated by zonal conditions either.

    Interesting, time will tell as ever...

    M.

    I'd say that sounds about right. Big swings for November, certainly not a dull month. I'm zoning ahead now as I want to see if the CW develops or not......mustn't wish my life away!!!!

    BFTP

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    For the first time this season, mean zonal winds forecast to exceed 20m/s at 30hpa. (T192). Not a trend we want to see become established. Whilst its at day 8, its far enough away to be unreliable. Of course, there is no guarantee that the zonal wind increase will propagate to the lower layers of the strat but its more likely than unlikely. Something else to keep tabs on.

    I could mention some warming at 30hpa on the forecasts to balance this post.

    It could be quite a battle between the strat and trop later in November. We have the trop teleconnectors battling with northern blocking, whilst the switch for the strat vortex looks like being turned on.

    The MJO forecasts into phase 2 suggest blocking to our NE.

    post-4523-0-32407300-1351237518_thumb.gi

    Question for Matt - are there any ECM 32 day ensemble varieties heading that way?

    Nick, the forecast warming at 30 hPa after the next few days is far away in FI on the GFS runs - is this what you are looking at?

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    Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

    Had a look at mjo plots this morning, whilst mid term phase 2 3 on horizon, looks quite weak.

    Ecm out to 240 still shows trop putting up good interference with PV formation.

    Glaam and mountain torques, Asia into positive just. October really fell off a cliff, no pun intended.

    Liking the prediction C , a CW November way overdue, would go with that.

    Edited by lorenzo
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    Posted
  • Location: st albans
  • Location: st albans

    Straw clutching ed. the small warmings at 30hpa are not at high latitudes. I just wanted to offer something to contrast with the news re the zonal winds. I am aware that glass half empty posts in his thread seem to promote 'winter is over' posts in others.

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Straw clutching ed. the small warmings at 30hpa are not at high latitudes. I just wanted to offer something to contrast with the news re the zonal winds. I am aware that glass half empty posts in his thread seem to promote 'winter is over' posts in others.

    I think that this winter is a lot more difficult to call stratospherically than the last. Just because the forecasts aren't brilliant presently, the rest of the autumn has something of a wild card theme to it imo.

    For coldies, if the strat plays ball then the troposphere is ready for the taking!

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