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#1434157 - 16/09/2017 09:44 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
I don't have twitter but I often follow Amy H Butler who quite often brings up things to do with Antarctica. I find her feed interesting at times. See below her latest comments.

https://twitter.com/DrAHButler/status/907726755984805888



Edited by CoastalStorm22 (16/09/2017 09:44)

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#1434204 - 16/09/2017 21:15 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
Posts: 105
Thanks greatly for that CS22 - I might try and put together a note and see of she can confirm if there's anything to my thoughts on southern vortex activity in 2014.

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#1434304 - 18/09/2017 10:59 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
Snowbaby, Dr Butler has made a few more interesting comments overnight. Due to near record heat fluxes the ozone hole appears to be elongating which is unusual. Most of the records for heat flux were set in 2002 during that first documented SSW over the SH.

Interesting times!

https://ozonewatch.gsfc.nasa.gov/monthly/SH.html

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#1434342 - 18/09/2017 21:28 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
Posts: 105
Thanks for that as well - I have trouble connecting to her page off my machine at home(antiquated OS)- I'll have a look via my local library.

Yeah it looked to me like something was happening with that giant spike showing on JMA charts

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#1434413 - 19/09/2017 21:36 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
Posts: 105
Invaluable reading here
https://doi.org/10.1175/JAS-3318.1
on the 2002 split vortex - good visual representation and fairly easy text.

Interesting to look for similarities with current situation.

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#1435074 - 25/09/2017 12:42 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
This years Ozone Hole is currently looking very elongated and small for the time of year.

Sea Ice around Antarctica also currently on lowest in record territory I believe. Very unusual year were having down there.

At the moment the stratosphere above about 50mb is very warm, however, lower down say from about 100-700mb it's cooler than normal so hence the high SAM were currently experiencing, I'd say once the lowers warm the SAM should drop. IMO.










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#1435116 - 25/09/2017 22:29 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
Posts: 105
Thanks for that CS22. I'm having difficulty accessing some sites. Interesting that the hole is currently smaller.

From limited charts it looks to me like temp at 50hPa in the polar vortex is just above the temp for polar stratospheric cloud formation, but is forecast to fall near to or below the threshold in near future.

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#1435634 - 01/10/2017 10:27 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
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Here is fairly recent sizing of the polar vortex. This chart has been updated since I posted - there is a bit of variation from time to time - best to check on cpc site.


The area capable of supporting psc formation fell dramatically early September, right outside the range of the last 10 years by mid month.Apologies- cant seem to get the pic up - direct link to cpc
http://www.cpc.ncep.noaa.gov/products/stratosphere/polar/gif_files/psc_sh.png

How close is the final warming(and the onset of the summer pattern?).
The large quasi-stationery anti-cyclone in the 90E-180 quadrant(same location as the warming) is usually associated with the stripping out of pv from the vortex at the beginning stage of the final warming process.



Note the date stamp on the chart - would be pretty much on time in the seasonal vortex evolution, though since this forecast chart Iíve noticed the large cell has broken down somewhat and a procession of smaller high pressure cells resumed an easterly migration around the vortex - typical of an earlier stage in the annual life cycle.

The deformation of vector streamlines towards the centre of the pole may be suggestive of strong wave activity resuming.

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#1435638 - 01/10/2017 12:48 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
Kino Offline
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Registered: 10/08/2017
Posts: 1013
Loc: Wollongong, NSW, Aus
Fascinating, thanks, any reasons why the activity is so focused/intense over us and no where else? Is it due lack of monitoring sites or associated with Hadley Cell activity?

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#1435756 - 02/10/2017 11:05 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
Posts: 105

Couple of things - only ways Iím looking at it generally - not specific answers as such -havenít really thought about role of Hcell or the teleconnections to the troposphere much.

Highest concentrations of 03 in the SH collar region just outside the PSV(PolarStratosphericVortex) are roughly in the quadrant mentioned. As polar night retreats hydrostatic balance requires anti-cyclonic development following any warming.

Perhaps it can be argued that there was a slight shift westward from the area of highest frequency of blocking in the SH, towards 90E -180 in September.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/blocking/real_time_sh/real_time_index_nrm.shtml

I visualise blocking as an important component in planetary wave driving which may be guided into the interior of the PSV and cause it to weaken as seems to have happened this year.

The PSV rotates on its axis it seems independently from the parameter fields(and the anti-cyclone) in the collar region.

But at other times, the cells in the collar region suddenly begins to circle in concert with the PSVís rotation - that part at least might describe in some mechanical way, the eastward migration of these cells -they usually decay over mid-pacific at the earlier stage,rather than coalesce into a single intense high cell prior to the initiation of the final warming.

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#1435760 - 02/10/2017 11:58 Re: Stratospheric sudden warmings (SSWs) [Re: snowbooby]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
Originally Posted By: snowbooby

Couple of things - only ways Iím looking at it generally - not specific answers as such -havenít really thought about role of Hcell or the teleconnections to the troposphere much.

Highest concentrations of 03 in the SH collar region just outside the PSV(PolarStratosphericVortex) are roughly in the quadrant mentioned. As polar night retreats hydrostatic balance requires anti-cyclonic development following any warming.

Perhaps it can be argued that there was a slight shift westward from the area of highest frequency of blocking in the SH, towards 90E -180 in September.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/blocking/real_time_sh/real_time_index_nrm.shtml

I visualise blocking as an important component in planetary wave driving which may be guided into the interior of the PSV and cause it to weaken as seems to have happened this year.

The PSV rotates on its axis it seems independently from the parameter fields(and the anti-cyclone) in the collar region.

But at other times, the cells in the collar region suddenly begins to circle in concert with the PSVís rotation - that part at least might describe in some mechanical way, the eastward migration of these cells -they usually decay over mid-pacific at the earlier stage,rather than coalesce into a single intense high cell prior to the initiation of the final warming.


Would you say were headed for a later or earlier breakdown of the vortex this year?

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#1435942 - 03/10/2017 11:12 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
Posts: 105
Earlier or later I'd be doing little more than guessing at this stage.

The large anti-cyclonic cell (@10hpa)dominating our quadrant is forecast to break down somewhat as mentioned( representing a slight fall off in temps) and to circle to about the 90W position, while another cell establishes at 90E.

I think there is some warming that seems to be working it's way down into the lower polar stratosphere - but dont know that it's part of final warming process. More warming probably required from wave driving.

If the two developing cells "squeeze" and elongate the PSV, the formation, which favours wave 2, is thought to make the PSV more vulnerable to splitting (though a rare event in our backyard).




Edited by snowbooby (03/10/2017 11:21)

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#1436141 - 05/10/2017 13:59 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
Smallest September Ozone hole since the freakish 2002 vortex split!

https://atmosphere.copernicus.eu/news-and-media/news/smaller-ozone-hole-observed-september-2017

If we remove 2002 then smallest since the late 80's I believe. Polar vortex looking weaker than normal as well. A weaker vortex will be more susceptible to any warming which could mean an even earlier end to it than last year, which I believe was earlier than normal.

Sea Ice still well below average as it has been all year.







We also still have the fascinating Weddell Polynya phenomenon going on in Antarctica.

https://twitter.com/kryosat/status/914554108396351488

In all a very interesting year going on for us.

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#1436145 - 05/10/2017 15:02 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
Kino Offline
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Registered: 10/08/2017
Posts: 1013
Loc: Wollongong, NSW, Aus
Well, that's interesting (for those like me who didn't know what it was: it's an open area of sea surrounded like by ice).

Weren't they supposed to be suppressed because of you-know-what. #awkward #breakingthenarrative

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#1436157 - 05/10/2017 17:15 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
In the 1970's they had one(much larger than this year and last) appear three years in a row 74,75 and 76 and until last year they had not observed one since. It's interesting that we have another one this year(in addition to last years) and it will be interesting to see if like the 70's one appears again next year.

Perhaps a symptom of the record low sea ice?

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#1436533 - 10/10/2017 11:58 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
GEFS showing what looks to be some planetary wave forcing putting the squeeze on the PV over the next 10 days.

Final warming not far off? Vortex already well below average in size making it more susceptible to such forcing. Interesting times!








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#1436559 - 10/10/2017 16:53 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
snowbooby Offline
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Registered: 11/05/2016
Posts: 105
Nicely done.

I think it could be close. That warming seems to involve lower levels of the PSV whereas many of the earlier episodes were more confined to middle PSV - and this time it looks smack bang over the centre of the continent - at 30hPa and above at least.

Check out this forecast http://db.cger.nies.go.jp/gem/stras/en/forecast_20171009_S_675.html you can see evidence of the concentrations of PV being stripped out of the vortex at each day.

There are quite a few threshold parameters about the place which are used to signify the event as having occurred - probably you'd want to see a reversal of perimeter westerlies?

Not sure how early a FW would be in next little while climatologically - but early for recent years. It was anticipated with the recovery of ozone which seems to have occurred fairly substantially this season


Edited by snowbooby (10/10/2017 17:00)

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#1438577 - Yesterday at 12:56 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2680
Loc: Lane Cove, Sydney, NSW
Looks to me like the final warming is not far off?

What do the more knowledgeable posters think?

Zonal winds at 60s look set drop well below normal!




Big warm up coming in the strat if GFS is correct!

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#1438607 - Yesterday at 16:06 Re: Stratospheric sudden warmings (SSWs) [Re: CoastalStorm22]
snowbooby Offline
Weather Freak

Registered: 11/05/2016
Posts: 105
Originally Posted By: CoastalStorm22
Looks to me like the final warming is not far off?

What do the more knowledgeable posters think?

Zonal winds at 60s look set drop well below normal!




Big warm up coming in the strat if GFS is correct!


That forecast looks like you'd imagine it.

One measure Iíve seen about the place for final warming is Zonal wind 10ms-1(pardon meant as superscript) @ 50hPa. There are others which are a lot more obtuse and beyond my capacity to work out.Using climate composites at esrl the winds at 50 hPa are in the range ~ 37 ms at present. Last week of Sept it was ~55ms. It doesnít fall at a constant rate of course - my guess is it varies with wave activity but if it lags temperature changes or not I dont know. Havenít had time to play about with any correlations.

The rate from top to bottom Iíve seen bandied about is anywhere 10-40days, something like that- about day 265 to about day 305 on that chart. That's 40 days spot on.

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#1438625 - Yesterday at 18:05 Re: Stratospheric sudden warmings (SSWs) [Re: crikey]
Kino Offline
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Registered: 10/08/2017
Posts: 1013
Loc: Wollongong, NSW, Aus
Given the forecast SAM and still quite mobile cold pools where is the warming at?

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