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#1274069 - 22/08/2014 17:57 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
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Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
Iím probably reading a little too much into the ďdistortionsĒ in the various parameter fields within the vortex, because, as you hint, they usually turn out to be part of an oscillation - just the extremes in an onging cycle - whatever driving forces are involved.

I always hope there will be a chance to read signs of an imminent threshold event - either a sudden split in the vortex or a displacement. Given that the only split that I know of in the SH was 2002 , it might be a faint hope.

The maths in most of the papers on the subject make it doubly difficult for an enthusiast like myself to get a handle. I can see the benefit of collecting a database of charts as a sort of observational record - but that will take an extended period of time to be of much use.

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#1275674 - 07/09/2014 18:39 Re: Stratospheric sudden warmings (SSWs) [Re: snowbaby]
snowbaby Offline
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Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
7 Sept

Chart of where the temp field@10hPa is progged to finish 14th Sept.



Quite remarkable sudden shift away from antartcic continent begins about 12th. Cant recall seeing the central node of the temperature field so offset from the continent.At same time a warming trend looks set to spread from the antarctic littoral directly to the south of us.
Temp fields below 10hPa arenít quite as offset. Reminded of the stack of plates analogy, with the topmost plate sticking way out.

Iím not sure where this is leading.Perhaps a dramatic warming within the vortex if we're lucky?


Also a momentum in movement of entire gph field@10hPa in same direction after the 12th, though not quite matching that of of the temperature field.



Sorry not up to posting animation on my present set-up but link below has it- just follow menus if of interest.

http://weather.uwyo.edu/models/fcst/index.html?MODEL=gfs003

Again, at lower levels thereís a more muted movement(of gph field) in same direction with a lot more elongation and stretching evident especially at 100hPa (below).



At present there is negligible planetary wave activity in the vortex but some dynamic at play.

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#1275676 - 07/09/2014 18:59 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
apologies for the size of pics...a bit slow with the edit and got timed out..something I'll watch in future..

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#1276587 - 16/09/2014 09:06 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
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Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
Hereís obs from esrl which tend to confirm that movement of the core of cold vortex temps away from its position over the antarctic continent is underway - as gfs forecasts suggested(my post above).



At the present thereís the accompanying sudden appearence of strong EP flux activity within the vortex @10Mb. JMA charts below(incidentally wave1 generally regarded as most often associated with vortex splitting) - amplitude of wave1 now underway looks massive also first indications of sudden spike in temps@10Mb.(black line right of chart just beginning)



Looking ahead from here gfs progs some pretty hefty warming occuring. Something around the 270K mark would represent a major warming event.



Perhaps we might expect that anomalous weather patterns will emerge in spring - but the caveat of course is that at this stage nothing is certain, though I am encouraged by the sudden appearence in Gfs progs of the first decent cold pools since late June(for w.a).

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#1276683 - 16/09/2014 20:16 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 6600
Loc: Maffra, Central Gippsland, Vi...
Well posted observations SB. Thanks smile

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#1276691 - 16/09/2014 22:30 Re: Stratospheric sudden warmings (SSWs) [Re: snowbaby]
Cutofflow Offline
Weather Freak

Registered: 14/08/2009
Posts: 94
Loc: North Central. VIC
SB,

I have observed that, generally, elnino years produce a decrease in Antarctic Sea Ice Extent. It is quite possible that your observations of a potential upcoming resonance event is likely given we are in a similar setup to that of 12 years ago.

I have been expecting a sharp decline in sea ice extent over western Antarctica since the beginning of this year (an area that currently has a large positive extent due to recent lanina episodes) ( Link ). The warming predicted by GFS could be the catalyst for a reduction in sea ice extent, declining from all time satellite-recorded highs. This is poor timing for southern Victoria as our winter fronts are slipping the slide by this time of the year..

Fore the sake of posterity here is the 2002 resonance event. (10mb and 70mb) (Temps)

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#1276733 - 17/09/2014 16:55 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
MOUNTAIN h2o Offline
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Registered: 23/03/2012
Posts: 682
Loc: Hobart Lenah Valley Tas 198 as...
Originally Posted By: crikey
Thanks for keeping this thread alive 'snowbaby' . There does appear to be a vertical oscillation over the winter. The max on the 28th July 2014

https://picasaweb.google.com/110600540172511797362/Stratosphere2014#6049933733184782498

and the minimum of the wave about now. 21st aug 2014
That is a period of one month. If that oscillation continued the next warming max would be about 21 st Sept. Pure speculation of course. As the SH warms the oscillations weaken


current animation
http://www.cpc.ncep.noaa.gov/products/intraseasonal/temp10anim.gif


Great work again crikey smile We are going from snow today and tomorrow in Hobart to a significant warming event on the 21'st onwards. Just when you thought it may happen , amazing stuff , keep up the great work .

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#1276759 - 17/09/2014 21:39 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A

Yeah that's quite amazing from crikey..thanks for pointing it out again Mh20.

The warming being speculated about though is stratospheric - I dont think there's necessarily a direct link between warm anomaly in the stratosphere and warm anomaly in the troposphere. There's still a lot of work being done on understanding stratospheric-tropospheric linkages - I think it is more usual that the anomaly in one will lead to anomalies of the opposite sign in the other, and there is usually a "lag" factor at play in that as well.

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#1278235 - 30/09/2014 07:42 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
This warming we have just seen in the vortex - a rise of 30C - is a significant event
The overall transformative affect on what happens in the troposphere, may be fairly modest though - for the time being anyway. Iíd like to think that there is connection in the persistence of cold pools(though nothing really spectacular) with fronts into October> for w.a at least that would be a a bit out of the ordinary in recent years. Pure speculation of course.

Interesting to note the distribution of PV on the 600K surface(about 20hPa I think) charted below - shows accompanying erosion of pv about the time/location of the warming.

For the moment, the vortex remains intact but it may be primed for dramatic weakening and there seems likely to be another period of warming later this week - based on gfs prognosis.

Going from this(30/9)

to this(5/10)


Edited by snowbaby (30/09/2014 07:45)

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#1284493 - 17/11/2014 10:36 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
My rap on this.

Warmings in the vortex in recent times - with hindsight, still have to be considered minor events, according to what I can find on the subject . The rapid temps increases @10mb seemed pretty impressive but not really matched by anomalies in the stratospheric zonal winds - something which might be expected for a major event - particularly a reversal of winds (brings very cold siberian blast in some of the northern hemisphere major warming events).

Progression in charts illustrate marked dissipation of the pv which has begun - as the vortex begins annual breakdown?





Think pv circulates dissipates into the troposphere somewhat at this stage - (maybe with exchange with tropospheric air coming the other way?)- elevated pv concentrations intruding via systems which for instance wracked Tas some time back.(Hence the often repeated observation of spring often producing best snowfalls Tasmania) Also, I like to think, perhaps connections with these warming minor events and the brief anomalous spell of winter like conditions we had here last week - only speculation. More to learn and understand yet.


Edited by snowbaby (17/11/2014 10:40)

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#1293991 - 29/12/2014 09:52 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
There does look to have been a split in the vortex around the 13th of December. Havenít been checking pv distribution of late - until recently




Itís a little more dramatic on the 475K surface(lower stratosphere)



Had it occurred a lot earlier, I think things might have been a lot more interesting for us all. JMAís charts show a warming @ 30hPa -perhaps it was confined to mid to lower stratosphere? -beginning early Nov through to early Dec. (btw @10hPa there's no sign of it for that period.)



Its likely that the sudden warming which peaked@10hPa about mid October according to JMA has taken this long to work downward through the mid to lower layers of the vortex. That's what appears to have happened.I am speculating on how this might have worked.

JMA also produced the following which seems to show significant EP flux(wave 2) activity approximating to the time of the split(bottom chart). Wave2 activity is generally associated with splitting while wave1 - though it may play a role in preconditioning the vortex - is usually associated with displacement. (CPCís charts might be a little misleading as they dont show much wave2 amplitude at that time.)



however might be a case of?

ď... following a long period of stable and relatively low-amplitude oscillation, a small (in principle, infinitesimal) change in forcing amplitude leads to a spontaneous vortex split. The small change necessary to cause the split could equally have arisen from a small change in the underlying stratospheric circulation...Ē
[Mathewman& Esler Nov 2011, Stratospheric Sudden Warmings as Self-Tuning Resonances. Part I: Vortex Splitting Events ]

Iím a little reluctant to get too excited - coming at a fairly late stage when the vortex(and pv) had been in decline and already weakened -the affects, if they can ever be tracked, may end up being underwhelming in any of the ways that most of us would notice. Unsure here whether the affects of a split occurring should be anticipated, rather than affects of the scale of the warming which seems to have induced it.

Perhaps there is a period of possible anomalous weather still to come. Baldwin and others, comment that the anomalous affects of warmings last longer in the southern hemisphere troposphere - up to 90 days (which put us into mid January or well into March depending on which episode you track - the mid Oct one @10hPa or this recent one ).


Edited by snowbaby (29/12/2014 09:56)

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#1294124 - 29/12/2014 21:26 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
adon Offline
Meteorological Motor Mouth

Registered: 19/08/2004
Posts: 5295
Loc: Not tellin!
So does that mean drier or wetter?

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#1294304 - 30/12/2014 21:38 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7166
Loc: Adelaide Hills.
To be honest I donít think we have an adequate grasp of whatís going on [with SSWs] to make longer-term predictions. A paper here also purports there is more to it, influences extending into the Mesosphere.

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#1294387 - 31/12/2014 11:14 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
Adon

The -Cosmic- (naz) stole my thunder.

I have to restrict myself to my observations because I dont understand much yet. I rely on the work of the atmospheric scientists or meteorologists or whatever title applies -

then spin it into a rambling version I can understand without(I hope) taking too many
liberties.

This stuff is fairly new to everyone - I think itís fair to say it wasnít that long ago that it
was thought the stratosphere had little to no influence on our weather. Thatís changing,
but I think itís still a way to anyone being able to reliably forecast from it. Good luck to
you in any case.

..just harking back on the October warming@10hPa for a minute -

Jmaís rise in temp is extreme - from about -55c early Oct to peak -5c about middle of
month



thatís quite staggering and seems in contradiction with noaa's(-20C max?) . .



as it does(to lesser extent) Jmaís other version of 10hPa temperature chart in my earlier post - but since both chart zonal mean temps,perhaps the right assumptionís a smoothing effect at play.(but should the difference be this extreme?)

So far as -55 to -5 goes, I do have a bit of unease ďtemperature over the south poleĒ
doesnít tell a lot about the observation - hope I'm not
missing something.




Edited by snowbaby (31/12/2014 11:21)

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#1294388 - 31/12/2014 11:23 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbaby Offline
Weather Freak

Registered: 05/08/2009
Posts: 295
Loc: Albany, W.A
..apologies for the hatchet job on the editing btw..

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#1294455 - 31/12/2014 15:49 Re: Stratospheric sudden warmings (SSWs) [Re: snowbaby]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7166
Loc: Adelaide Hills.
Originally Posted By: snowbaby
The -Cosmic- (naz) stole my thunder.

Unintentionally smile .
As you indicated:

Originally Posted By: snowbaby
This stuff is fairly new to everyone

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#1386833 - 11/09/2016 18:18 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
Weather Freak

Registered: 11/05/2016
Posts: 108
First evidence I've noticed this year of rapid warming in the S polar vortex region - imagine that further large amplitude wave activity needed to bring on ssw


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#1434131 - 15/09/2017 22:03 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
Weather Freak

Registered: 11/05/2016
Posts: 108
Massive EP flux spike showing extreme right lower chart. Select Southern Hemisphere and then "Temperature & Vertical Components of 100 hPa E-P Flux" from dropdown http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

Temps in polar stratosphere have warmed in recent weeks after periods of wave activity. Sometimes wave activity directed poleward and therefore warming trend linked to easterly phase QBO

Sign of decelerating winds on the vortex perimeter
http://www.cpc.ncep.noaa.gov/products/st...JAS_SH_2017.png

Noticed the polar vortex @ 600k looking elongated since about 12th Sept, especially in last day(about 15th I think). Chart can be found here
http://www.pa.op.dlr.de/arctic/ecmwf.php
Select for Antarctic Polar Vortex, PV@600K

PV and Temp fields - esp the latter shifted right off the polar axis.

Crikey! Where are you?

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#1434136 - 15/09/2017 22:26 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
Weatherzone Addict

Registered: 10/07/2006
Posts: 2704
Loc: Lane Cove, Sydney, NSW
What does that all mean Snowbaby?

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#1434145 - 16/09/2017 07:28 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
Weather Freak

Registered: 11/05/2016
Posts: 108
Wish I had a pat answer CS22. Dramatic, dynamic teleconnections to our part of the world.... possibly.

The southern vortex is currently showing anonymously +ve temps. May mean it is vulnerable to penetration by further wave activity if sufficiently weakened.

Stratospheric warming can be associated with splitting of the polar vortex. 2002 was a major split as you may know. I believe there was another partial split in 2014 possibly close to the time of final warming in that year, though I haven't been organised enough to have this confirmed by anyone with credentials.

Cant say it's near or likely to get to the splitting stage but watching with interest.

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