Stratosphere discussion 2020

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TonyT
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Re: Stratosphere discussion 2020

Unread post by TonyT »

Another element in the mix is the QBO is heading solidly into its easterly phase, which conventional wisdom suggests is associated with increased westerly airflow in the troposphere, (interestingly also with a tendency to develop El Nino, which is running against the other factors currently being picked up by models tending towards La Nina). Also tends to be associated with more south to southwest airflow over NZ.
Chris W
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Re: Stratosphere discussion 2020

Unread post by Chris W »

GFS continues to generally model the strat vortex as being tightly-confined over the Indian Ocean but more spread-out over the Pacific and South Atlantic. The troposphere does seem to be responding to this overall, with the 1-2 month lag, meaning there’s potential for very cold air to be bottled up but then be released towards Australia/NZ when the tropospheric winds tap into it.
4165874C-ADB5-46AB-9AA5-BC977137A778.jpeg
Interestingly today it is modelling a minor warming in about 2 weeks’ time in the same location as last year’s, which if it verifies would push the vortex towards South America again:
4D91760A-6A58-4C4A-BA48-6AB76BCC65BC.jpeg
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Chris W
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Re: Stratosphere discussion 2020

Unread post by Chris W »

Stratobserve has cut over from NH to SH charts:
https://stratobserve.com/

Some good visualisations there, really interesting narrowing of the vortex down the atmospheric profile - with the wide strat vortex at the top - and hint of 60S zonal wind reversal anomaly lower in the troposphere in a week or two's time but also rapid cooling of the strat vortex through May as you might expect.

GFS is not forecasting that minor warming any more, just the warm area over the Indian/Southern Ocean keeps the vortex more confined there.
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Re: Stratosphere discussion 2020

Unread post by Cyclone Tracy »

Yes, the polar vortex is gaining strength :smile: Only 5 days now until the 11 week astronomical polar night starts over the South Pole.

Initial UAH IR satellite data and method for April is showing the global stratosphere still has a positive temperature anomaly. It came down slightly from March. It will be interesting to see all the satellite datasets from NOAA in the next week or so, including the temperature impacts of the lower troposphere near the surface.
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Re: Stratosphere discussion 2020

Unread post by Chris W »

Looks like the placement of the 10hPa PV and lack of strength of the 70hPa vortex is dragging the westerlies south or weakening them our way, there’s just not much oomph this side to drive the jet and surface winds which is allowing the blocking highs to develop. Anywhere near the mark or not so?

Granted, the PV should intensify but is it too far away?

https://earth.nullschool.net/#current/w ... -86.60,297
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Re: Stratosphere discussion 2020

Unread post by Cyclone Tracy »

PV structure through the layers is still gaining strength.

NOAA have released the global stratosphere numbers for April. Maintaining it's warming and the highest temps high's since 1993. Lower troposphere dropped in April from March, backing up the hypothesis of the 3 month lag between the two. It's now becoming a significant signal and global event.
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Re: Stratosphere discussion 2020

Unread post by Razor »

Interesting side note - Smoke on the Stratosphere https://www.rnz.co.nz/national/programm ... ratosphere
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Re: Stratosphere discussion 2020

Unread post by Chris W »

It’s so interesting to see what’s happening at 10hPa and what trickles down from there over the following couple of months. As the vortex intensifies the position of warm areas of ozone-rich air in the stratosphere over the southern Indian Ocean and the Southern Ocean is going to really influence how tight the vortex is that side and its angle towards NZ.
AD414CC5-950A-4C75-9266-65B87748C7CF.png
Later in the current GFS run the vortex becomes elongated and migrated towards the Ross Sea. Makes me want some popcorn.
:popcorn:

https://www.metcheck.com/SEASONAL/strat ... ecasts.asp
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Re: Stratosphere discussion 2020

Unread post by Chris W »

Looking pretty elliptical in 7 days’ time!
71E5334F-AA99-4AB4-9004-214128806963.png
GFS has higher 10hPa zonal wind speeds and a colder stratospheric vortex than GEFS ensemble members and other models on Stratobserve, but either way the vortex has fired up and zonal wind at 100hPa has leveled off just shy of 30m/s.

https://stratobserve.com/ens_ts_diags
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Re: Stratosphere discussion 2020

Unread post by Chris W »

That warm area I’ve talked about the the PV have an impressive battle ahead of them. The PV is currently losing and as mentioned very elliptical which to me augurs for some interesting colder weather later in winter, but then the PV makes a strong comeback late into the run. Really cool to watch how this develops:

https://earth.nullschool.net/#current/w ... -90.04,297

https://www.metcheck.com/SEASONAL/strat ... ?Region=SH
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Re: Stratosphere discussion 2020

Unread post by Cyclone Tracy »

NASA & EC lining up a sister vortex formation over the Antarctic continent in the lower stratosphere in early July. It's also coupling into the troposphere and impacting the polar Jet. Major mid latitude cold snap is brewing for the 2nd half of July.
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Re: Stratosphere discussion 2020

Unread post by Chris W »

As mentioned in the July thread it seemed that there were early signs of this being modelled the other day, but I haven't really looked since. Interesting that last year there seemed to be a strong rev-up of the vortex before the SSW, and this year it has gone strong early on. Unless I'm reading the 2019 ozone charts wrongly.
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Re: Stratosphere discussion 2020

Unread post by Chris W »

Decent concentration of Ozone building up, with a thin patch allowing the vortex to distort our way.
0FCB5E01-734E-4EDA-9172-3EBBF696ACD3.jpeg
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Re: Stratosphere discussion 2020

Unread post by Chris W »

SSW south of the Indian Ocean starting Sunday and peaking in 10 days' time?
https://www.metcheck.com/SEASONAL/strat ... ?Region=SH
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Re: Stratosphere discussion 2020

Unread post by Chris W »

SSW still being modelled at 10hPa starting around Saturday, maybe a disturbance coming off the Andes that seems to turn a corner around South Africa:
https://www.weatheronline.co.nz/cgi-bin ... mp;PERIOD=

https://www.weatheronline.co.nz/cgi-bin ... &RES=0

Warming looks to be about 30C so looks like it might meet the 25C criterion that seems to exist for a significant warming.

CT, your thoughts?
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Re: Stratosphere discussion 2020

Unread post by Cyclone Tracy »

Temperature wise, it is still fairly cold and rock solid. GFS & EC are both indicating the vortex is still centred between 80 & 90 degrees south at 10 hPa in the next 10 day to 14 days. Ozone over the cap is also fairly normal. There is a warm anomaly around 30 & 50 hPa closer to the mid latitudes which maybe associated with that ozone spike you have referred to. Below in the troposphere, that coupling with the stratosphere last week is still playing out, so cut off lows might be on the menu near NZ again over the next 2 weeks.
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Re: Stratosphere discussion 2020

Unread post by Chris W »

Yeah I'm not saying it's going to be as big a deal as last year, but it does seem to shunt the vortex in our direction and causes it to contact significantly on the Indian Ocean side. As the elliptical profile you posted shows, it does push the 10hPan wind field around.
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Re: Stratosphere discussion 2020

Unread post by Chris W »

So the warming is still being modelled, but GFS has pulled back the scale a bit. Looking at the wind fields the vortex does get compressed on that side, but revs up at the same time. Seeing wind speeds of 450kmh at 10hPa in a few days’ time. GFS also going for some low temperature anomalies very high up above 10hPa https://stratobserve.com/anom_ts_diags
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Re: Stratosphere discussion 2020

Unread post by Chris W »

Warming now visible on the earth.nulschool GFS map, 10hPa winds up to 490kmh between the warm area and the vortex:

https://earth.nullschool.net/#current/w ... 69,-59.683
https://earth.nullschool.net/#current/w ... 85,-42.788
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Re: Stratosphere discussion 2020

Unread post by Cyclone Tracy »

Monthly global stratosphere temps have been updated by NOAA. The month of June has come back to around 1994 levels but year to date to still well warmer than normal from the last 25 years. I'm starting to see commentary from climate scientists on this subject and it's confused intrigue. No medium to long term climate model forecast this warming of the global lower stratosphere.

Chris W wrote: Mon 29/06/2020 19:36 Decent concentration of Ozone building up, with a thin patch allowing the vortex to distort our way.

0FCB5E01-734E-4EDA-9172-3EBBF696ACD3.jpeg
I think what you spotted at the end of June is some what related to the warmer lower stratosphere after taking a closer look and it comes back to the Australian bush fires and the sudden stratospheric warming from last September.
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Re: Stratosphere discussion 2020

Unread post by Chris W »

The warm area at 10hPa linked to the high concentration of Ozone is firmly in place now, with a gradient of -35C not far form the edge of the East Antarctic Ice Sheet to -85C at the vortex centre. It hasn't really weakened the vortex, just kept it confined on that side:

https://earth.nullschool.net/#current/w ... 21,-56.648

However at 70hPa there is no sign of it so it's definitely an upper stratosphere feature that isn't downwelling.

https://earth.nullschool.net/#current/w ... 44,-55.883

Generally the vortex has been pretty formidable since it fully formed in May.
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Re: Stratosphere discussion 2020

Unread post by Chris W »

GFS modelling a warming at 10hPa concurrent with high ozone concentrations, starting around Friday and working its way around to where last year’s warming was. It has been hinting at something a for a few days, but seems to be coming closer to the more reliable timeframe. What it also does is then model an opposite warming on the other side of the vortex, which ends up very oblong in form towards the end of the current run.

Ensemble members and other models also showing a decrease in zonal wind speeds after a recent spike, and a gradual warming in polar stratospheric temperatures.

All model outputs are linked in other posts, Metcheck/stratobserve/weather online etc.
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Re: Stratosphere discussion 2020

Unread post by Cyclone Tracy »

Well, hello there..... EC now producing a 40c increased warming @ 10 hPa over 25% of the Antarctic continent in 10 days.
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Re: Stratosphere discussion 2020

Unread post by Cyclone Tracy »

2018 (11 Aug image), 2019 & 2020 EC comparison 11th Aug 00Z run for the stratospheric polar vortex temperature @ 10 hPa. :popcorn:
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Re: Stratosphere discussion 2020

Unread post by Bradley »

Cyclone Tracy wrote: Tue 11/08/2020 19:31 2018 (11 Aug image), 2019 & 2020 EC comparison 11th Aug 00Z run for the stratospheric polar vortex temperature @ 10 hPa. :popcorn:
Maybe we will see some extreme events in NZ with this years SSW event, last years event and subsequent flow on effects for NZ was dissapointing to say the least!
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