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Author Topic: Atmospheric connections, structure, and long range weather forecasting  (Read 50513 times)

oren

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #450 on: December 02, 2020, 03:48:48 PM »
Quote
Thus the climatology estimate was a 33.3% chance of each.
Great post Glen.

However - in a trending climate, perhaps beating the climatology has a chance higher than 33%? Predicting upper third might explain why temp forecasts have some skill.

Glen Koehler

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #451 on: December 02, 2020, 04:48:42 PM »
    Correction to previous post - the comparison was to the most recent 30-year average, not "ca. 100 years in the historical record".  But your point still applies.  You would not lose much money by always betting on the warmer tercile.
« Last Edit: December 02, 2020, 05:01:15 PM by Glen Koehler »

El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #452 on: December 02, 2020, 05:42:15 PM »
That is why I showed the study on the main thread which filtered out the basic warming effect. Once you get rid of that these seasonal forecasts are not really good for anything, a simple persistence (bet on the prevailing anomaly to stay) model beats them...

One somewhat usable skill is in NE Europe according to the study where based on the late winter snowline you can draw good conclusions on how warm spring is going to be

vox_mundi

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #453 on: December 03, 2020, 04:57:53 PM »
Is Arctic Warming Behind a Monster Saharan Dust Storm?
https://phys.org/news/2020-12-arctic-monster-saharan-storm.html

The June 2020 dust storm set records in terms of its geographic size and its aerosol optical depth—essentially a measure of its thickness determined by the ability of satellites to see through it. It reached an altitude of 6,000 meters (19,600 feet). In certain locations over the Atlantic Ocean, its thickness was double what had ever been recorded during the month of June during the history of the satellite record, which dates back to 1995.

The researchers analyzed what made it happen in a study appearing today in the journal Geophysical Research Letters

.Evan, lead author Diana Francis of Khalifa University of Science and Technology in the United Arab Emirates, and colleagues attributed the dust storm's magnitude to conditions set up by the development of a type of high-pressure system called a subtropical high off the coast of the Sahara. This increased the north-south pressure gradient over West Africa leading to record-strength, persistent northeasterly winds. The intensification of the northeasterly winds over the Sahara generated continuous dust emissions over several days in the second half of June 2020.

The researchers found that the subtropical high was embedded in a circumglobal wavetrain, a chain of wind patterns that extended around the planet, and was present in the Northern Hemisphere for most of June 2020. This wavetrain may have been caused by record-low Arctic sea ice extent observed in June 2020 as well. The warming of the Arctic region is believed to be altering the course of wind patterns in the mid-latitudes and subtropics and causing severe weather events, though there is controversy among scientists about this concept.

"The development of the subtropical high off the African coast had a deterministic role in both dust emissions and rapid westward transport of the airborne dust across the tropical Atlantic," said Francis. "The clockwise circulation associated with the high, intensified the African Easterly Jet, a jet stream present over the Sahara around five kilometers (3.2 miles) in altitude, which rapidly transported the dust towards the Caribbean and southern United States."

The study also touches on a controversial topic within the science community. Though not the main focus of study, the wavetrain pattern that set the Godzilla dust storm in motion looked very similar to one observed in 2010 when sea ice in the Arctic Ocean was substantially diminished, Francis' team noted.

"As the Arctic sea-ice cover was rather low in June 2020, around the lowest on record in the period of satellite observations, it may have contributed to the observed large-scale anomaly pattern," the study concludes. "Thus, if such patterns become more common in a warmer world, it is plausible that these extreme dust outbreaks will increase in frequency in the future."

Diana Francis et al. The Atmospheric Drivers of the Major Saharan Dust Storm in June 2020, Geophysical Research Letters (2020)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL090102
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Glen Koehler

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #454 on: December 14, 2020, 11:35:06 PM »
    RE: 2020 global average surface temperature.
    Hansen speaks.  All should listen.  Excerpt below.  Full message at     http://www.columbia.edu/~jeh1/mailings/2020/20201214_GlobalWarmingAcceleration.pdf

El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #455 on: December 15, 2020, 08:59:40 AM »
    RE: 2020 global average surface temperature.
    Hansen speaks.  All should listen.  Excerpt below.  Full message at     http://www.columbia.edu/~jeh1/mailings/2020/20201214_GlobalWarmingAcceleration.pdf

So, what he says is that aerosol effects are stronger than presumed by IPCC and as humanity quickly reduces aerosols (my addition:  the global shipping industry drastically reduced sulphur content of shipping oil from jan 1 this year)  this shows up in bigger than expected warming. He says that so far Co2 was somewhat counterbalanced by aerosols but now that aerosols are reduced we are in trouble, especially as a new solar cycle has just started.
He's probably right on all

Glen Koehler

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #456 on: December 16, 2020, 05:21:38 PM »
    Hansen posted a short Q&A to reply to questions he got from yesterday's post about acceleration.  Not trying to turn ASIF into a climate blog, but it's all connected and it's Hansen talking, not Joe down at the local bar.  Q&A is at http://www.columbia.edu/~jeh1/mailings/2020/20201216_Twittering.pdf

El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #457 on: December 29, 2020, 08:43:48 AM »
OK, so here comes your SSW (sudden stratospheric warming). See attached picture of T+2 and T+6 days.
We will have a strong warming over Siberia in the stratosphere by T+2 which will churn and turn and push around the polar vortex. It might split into two eventually, we don't know yet... GFS has been changing its mind in the latest runs as for the longer term outcome. This might bring some cold weather into NH mindlatitudes during mid Jan-end Feb

blu_ice

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #458 on: January 01, 2021, 11:34:35 PM »
OK, so here comes your SSW (sudden stratospheric warming). See attached picture of T+2 and T+6 days.
We will have a strong warming over Siberia in the stratosphere by T+2 which will churn and turn and push around the polar vortex. It might split into two eventually, we don't know yet... GFS has been changing its mind in the latest runs as for the longer term outcome. This might bring some cold weather into NH mindlatitudes during mid Jan-end Feb
It’s gonna get cold in Europe after mid-January, says ECMWF extended forecast. Especially Scandinavia, the Baltics and Northwest Russia will be freezing if/when temps will go below average during the coldest time of the year.

El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #459 on: January 02, 2021, 08:41:59 AM »
GFS shows that the SSW is already under way and also shows the polar vortex splitting into two in 2 days' time (shown). After that GFS shows that the polar vortex tries to reform over C/E Europe, but stays weak until the end of the forecast period (Jan 18). This could really bring unseasonally cold, Arctic air into Europe...

be cause

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #460 on: January 02, 2021, 03:38:51 PM »
very first words I hear on bbc radio 4 this morning .. 'Sudden stratospheric warming' ..
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

Bruce Steele

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gerontocrat

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #462 on: January 02, 2021, 06:46:16 PM »
Environment Canada says its going to be a warm (as in not quite so perishing cold) Canadian winter

https://weather.gc.ca/saisons/image_e.html?img=mfe1t_s
https://weather.gc.ca/saisons/index_e.html
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El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #463 on: January 03, 2021, 09:18:18 AM »
As we have discussed before, these long term forecasts (Canada, Europe, or US models all the same) have hardly any predictive skill.

Besides, since on average winters are significantly warmer now than in the past (see picture), if you forecast warm(er than average) winters, you will likely be right 70-80% of the time.

I even bet one of my friends that this winter (in Hungary) will be warmer than the average of the last 12 years. With AGW (and the late refreeze of the Siberian Seas) I think I have a slight edge, but definitely not 70-80% probability. I subjectively put my chances at cca 65%. This is not skill, it is just a trend. And I rarely bet against trends.

gerontocrat

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #464 on: January 03, 2021, 04:24:19 PM »
As we have discussed before, these long term forecasts (Canada, Europe, or US models all the same) have hardly any predictive skill.

Besides, since on average winters are significantly warmer now than in the past (see picture), if you forecast warm(er than average) winters, you will likely be right 70-80% of the time. ..... I rarely bet against trends.
But.... La Nina is associated with a cool North America

https://blogs.ei.columbia.edu/2017/11/15/how-will-la-nina-affect-winter-in-the-u-s/
Quote
Broadly speaking, La Niña gives us winters with cooler temperatures and more precipitation than normal in the northern U.S., and warmer, drier conditions in the south.


https://gripped.com/gripped-outdoors/winter-2020-in-canada-big-snow-and-more-ice-thanks-to-la-nina/
Quote
La Niña brings above-average precipitation and colder-than-average temperatures throughout Canada.

So Environment Canada's forecasts for above average temperatures are a bet against the trends?
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gerontocrat

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #465 on: January 03, 2021, 04:33:16 PM »
Meanwhile - SSW

Two images attached that even I can understand from From the Tokyo Climate Centre at http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

All sorts of other stuff there (but a mystery to me)

"Para a Causa do Povo a Luta Continua!"
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El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #466 on: January 03, 2021, 04:47:07 PM »

So Environment Canada's forecasts for above average temperatures are a bet against the trends?

No, the trend is for ever warmer temperatures. Keep forecasting warm temperatures every year and you will be mostly right (or at least not very wrong).
I took a look at Canadian temperatures during winter (eyeballing on gisstemp vs 1970-2000 averages)

very warm: 2012,13,16,17,20
mixed: 2011,15,18,19
Cold: 2014

La nina years: 2011,12 ,18, (17 very weak)
of those, 2 were hot and 2 mixed
The only definitely  cold year was 2014, neither nina or nino
We had a nino in 16 and a weak one in 19
ENSO data:
https://ggweather.com/enso/oni.htm

Shared Humanity

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Bruce Steele

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #468 on: January 03, 2021, 06:06:37 PM »
Shared Humanity, Born from the Void did an article predicting a developing SSW a couple weeks ago. His article talked about a Ural blocking high pressure that sets up conditions for a SSW to develop. So if you get a chance to read his article it is a perfect primer for the other link I posted yesterday.

https://www.netweather.tv/weather-forecasts/news/10610-arctic-amplification-and-winter-weather---whats-the-connection

I liked this explanation from BFTV’s article


“Capturing the Ridge
When a jet stream ridge reaches eastern Europe/western Russia, the added atmospheric thickness in the Barents/Kara region can amplify it. The amplified ridge creates a stronger high-pressure system to its east. In this case, it promotes a stronger Siberian high pressure, pulling colder air south and enhancing snowfall.
Secondly, the amplification also slows down eastward progression of the Rossby waves, encouraging blocking high pressure around the Ural Mountains, otherwise known as Ural Blocking. This is where we come back to the stratosphere! This Ural Blocking is positioned in such a way that when the eastward moving Rossby waves encounter the block, the waves can break. This results in energy being driven both poleward (towards the Arctic) and vertically into the stratosphere. Picture it like a wave breaking against a cliff, with water shooting vertically and horizontally. The net result being disruption of the Arctic stratospheric vortex. A reduction or reversal of the dominant westerly winds then occurs, which can propagate down through the atmosphere, disrupting weather patterns at the surface and allowing cold air to spill south out of the Arctic.“

« Last Edit: January 03, 2021, 06:21:04 PM by Bruce Steele »

Bruce Steele

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #469 on: January 05, 2021, 09:19:33 PM »
The JMA 10hPa temp. at the North Pole has jumped 50 degrees in less than a week.

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

gerontocrat

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #470 on: January 05, 2021, 09:55:09 PM »

So Environment Canada's forecasts for above average temperatures are a bet against the trends?

No, the trend is for ever warmer temperatures. Keep forecasting warm temperatures every year and you will be mostly right (or at least not very wrong).
I took a look at Canadian temperatures during winter (eyeballing on gisstemp vs 1970-2000 averages)

very warm: 2012,13,16,17,20
mixed: 2011,15,18,19
Cold: 2014

La nina years: 2011,12 ,18, (17 very weak)
of those, 2 were hot and 2 mixed
The only definitely  cold year was 2014, neither nina or nino
We had a nino in 16 and a weak one in 19
ENSO data:
https://ggweather.com/enso/oni.htm
Could the current developing SSW disturb the polar vortex in such a way that warm North Pacific storms could invade the Bering sea and the Arctic Ocean via the bering Strait? If Bering Sea Ice replicates the events of Feb March 2019 maybe Central Canada will get really really cold.

file:///C:/Users/Gw/Downloads/climate-07-00087.pdf
Quote
Abstract: In February 2019, central Canada, and especially the province of Saskatchewan, experienced extreme cold weather. It was the coldest February in 82 years and the second coldest in 115 years....

The increased storm activity over the Bering Strait in February 2019, due to the shift in the jet stream, forced the storms and transport of heat deeper into the Arctic. In the process of increased storm activity (15 storms between 27 January and 3 March) and enhanced heat flux and gusty winds, the Bering sea lost 373,000 sq. km of sea ice between 27 January and 3 March and had the lowest recorded sea ice in March (Figure 11). The extended open water further contributed to the heat fluxes into the lower troposphere. Thus, the storm activity over the North Pacific triggered a series of changes in atmospheric circulation indirectly linked to the extreme cold event over the Prairie region of Canada.

......We conclude that the record cold event in the Prairie region of Canada is indirectly linked to the record low sea ice event in the Bering Sea through the changes in storm activity over the North Pacific and a pattern shift of the jet stream.
"Para a Causa do Povo a Luta Continua!"
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El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #471 on: January 05, 2021, 10:08:23 PM »
Could the current developing SSW disturb the polar vortex in such a way that warm North Pacific storms could invade the Bering sea and the Arctic Ocean via the bering Strait? If Bering Sea Ice replicates the events of Feb March 2019 maybe Central Canada will get really really cold.

Well, that's an interesting idea. An SSW usually "disturbs" the vortex, which obviously heavily influences stratospheric winds, so that they get weaker and/or change direction from the usual N.Pole-centered counterclockwise movement. We know that very often heavy Arctic air outbreaks happen in the aftermath of an SSW (with warm intrusions at other places), so I guess the above could happen. We'll see.

All we know now is that the vortex has broken down, and the models have it slowly re-forming  in cca 2 weeks' time. Nasty things could happen in Jan/Feb (or they won't) :)

Bruce Steele

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #472 on: January 07, 2021, 05:34:24 AM »
From JMA  “ A major stratospheric sudden warming (SSW) started in the Northern Hemisphere at 30-hPa around 4 January 2021. ”

El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #473 on: January 07, 2021, 08:05:27 AM »
Even more interesting (I don't know if this is unprecedented or not - someone with more knowledge about this could chip in), that GFS is showing a SECOND SSW starting T+4 and reaching its high by T+11 days (shown)!


dnem

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #474 on: January 15, 2021, 08:28:23 PM »
This is one of the best non-technical pieces I've read on SSW, the PV and effects in the mid-latitudes.

https://www.cbsnews.com/news/stratospheric-warming-winter-weather-coming/

gerontocrat

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #475 on: January 17, 2021, 04:13:45 PM »
The data seems to say an SSW happened around the 4 Jan, started to fade and is reinvigorated, and can be called a major SSW.

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/
http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/readme.html
The warming is called a "Minor Warming", when the polar temperature increases more than 25 degrees in a period of a week or less at any stratospheric level.
If the zonal mean temperature increases poleward from 60 degrees latitude and the net zonal mean zonal winds become easterly at 60 degrees latitude at 10 hPa (32 km) or below, it is classified as a "Major Warming".
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #476 on: January 20, 2021, 11:46:28 PM »
A somewhat heavy GIF but I hope it is worthy.  Frames are from here: https://acd-ext.gsfc.nasa.gov/Data_services/met/qbo/anim.html

New type of wave seems to be crashing in it.  The QBO is fairly powerful... heads up





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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #478 on: January 24, 2021, 11:24:27 PM »
Earth's rotation has been speeding up for the past 5 or 6 years.  2020 was enough to create a need for a negative leap second.  https://www.timeanddate.com/time/earth-faster-rotation.html

Data from:  https://hpiers.obspm.fr/eop-pc/index.php?index=realtime&lang=en
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #479 on: January 25, 2021, 12:03:41 AM »
"The projected delay in SFWs suggest a later seasonal transition from the climatological wintertime to summertime circulation in both hemispheres. In the Southern Hemisphere (SH), essentially all of the delay in the SFW occurs in the era with strong ozone depletion (1980–2040)"

https://link.springer.com/article/10.1007%2Fs00382-021-05647-6
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #480 on: January 25, 2021, 12:09:30 AM »
"Why is this #PolarVortex disruption different from all other polar vortex disruptions? First are the twirls & loop-de-loops in this event's polar cap geopotential height anomalies. Yellow arrows show where they go up & blue arrows where they go down. Normally they only go down"

https://twitter.com/judah47/status/1352625178090631172
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El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #481 on: January 25, 2021, 08:08:01 AM »
Even more interesting (I don't know if this is unprecedented or not - someone with more knowledge about this could chip in), that GFS is showing a SECOND SSW starting T+4 and reaching its high by T+11 days (shown)!

Well, noone had the answer to that question, but Judah Cohen says it IS unprecedented:

"To just show how unprecedented this may be, there is the possibility of two separate MMWs this winter separated by about a week based on the most recent EPS weeklies.  There have been two MMWs in one winter before but usually they are separated by months and not a week or two.  As far as I know this has never happened before."

Not only that, but we still see no re-forming of the vortex even on the T+10 forecast! It is thought to be coming back by Feb 10, but that forecast is very far out...Quite interesting. We lost the vortex at the very end of last year/beginning of Jan, and it is still nowhere...

P-maker

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #482 on: January 25, 2021, 11:41:17 AM »
Goodbye capital Polar Vortex, as also described in this song:

https://m.youtube.com/watch/DDOL7iY8kfo

minor polar vortices are about to come our way, where we live. Watch out and pay attention!
« Last Edit: January 25, 2021, 11:46:23 AM by P-maker »

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #483 on: January 26, 2021, 03:01:37 AM »
https://www.aer.com/science-research/climate-weather/arctic-oscillation/

Dr Judah Cohen just posted to his blog, week 2 of talking about this stratospheric polar vortex disruption, click on Archives to see previous entries.

How I see it

Strat PV disturbances usually come in 2 main types, the displacement and the split.  Split stratospheric PV usually leads to a total collapse of the vortex.  The strat PV spins right back up into a vortex again, unless it is the final warming of the winter pole, but at some point the vortex feature loses all power when there's a good split.  These type of SSW give us our best chance of prolonged cold winters in the US East, for example.  People are looking for Wave 2 split events so they get snow.  So far we have seen more Wave 1.

There's a regularity to these events, a climatology of them, winds and heat & momentum fluxes, as well as a profile of the temperature changes throughout the polar atmosphere.  However, as with anything dynamic, it is hard to define the phenomenon.  10hPa zonal wind reversal at a high latitude is one example of a definition, or a way to locate the events in the archives.  This vortex disturbance has already achieved Major Midwinter Warming and negative zonal winds at 10hPa.

Funny thing is, the warming part:  It has been very loudly anomalous that we see so far 2 SSW status warmings at 10hPa with a third in the forecast.

The vortex feature itself is there.  It splits at lower levels but cannot unzip totally.  Pictured below is the 2nd "split."  Some symmetrical splitting has occurred, but instead of separating into two cores, there's an accelerated merge.  You get what looks like PV pants.

If you page through the isentropic PV and other maps on https://stratobserve.com/tht_pvstr_maps you can go back to January 9th currently and look at hour 0s.  I believe the 1st MMW was the 4th or 5th of January, 2nd about 10 days later, and the 3rd we're looking at hour 300ish from now.

Each time the vortex is displaced and sheeted flat, even splitting/merging and shedding smaller vortices at different levels.  It is creating a challenge for the definition of these meteorological events, in one respect, because the vortex gets strained into such a sheeted flat feature that zonal winds are negative at 10hPa 60N, without that spectacular loss of power that people are hoping for so they get snow.

Regular SSW are normal and kind of like playing Roulette for weenies during winter, they are semi-regular but with a hiatus in the 90's.  A good SSW can fill in ozone over the poles.

Too strong vortex destroys ozone at the poles.

4 posts above is a relevant post from me, about Stratospheric Final Warmings being modeled occurring later by a few days in some WACCM-X style models.

Winter vortex were too strong at lower stratospheric levels late in the past 2 cold seasons, which is how I interpret those two charts

https://stratobserve.com/misc_vort3d

https://www.cpc.ncep.noaa.gov/products/stratosphere/

There is a lot going on in the stratosphere and the race is on to figure it out. 
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #484 on: February 03, 2021, 11:35:25 AM »
Monthly air temperatures 80N-90N at 700mb.  It's like this all the way up to 500mb.

This plot includes all months in the R1 Reanalysis.  The spike at the end that steps so far out of the record is May through September of 2020. 

Whatever sea ice there is in the Northern Hemisphere, it's not enough.  I don't think this is going to retrace next year then throw another spike in a few years, I think this will build year on year now and the atmosphere will just have to be polar blocked every summer.  It may actually get colder in some places if this polar amplification runs away to a change in the general circulation and does so as quickly as it has started.

This chart reminds me of the global sea ice chart in October 2016 when that line crashed.  That wasn't "it".  That line retraced previous years and has hugged the bottom of the range with a few additional departures.

Is the atmosphere different?  It will be seen this summer in the Northern Hemisphere.  May, June, July.  I think summer will be full of high atmospheric height anomalies / high latitude blocking and much of it reaching and maintaining the North Pole, with temperatures not just +5C but even greater.. +7C air temps over the CAB 2021 or bust.

https://psl.noaa.gov/data/timeseries/
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #485 on: February 03, 2021, 11:48:29 AM »
This is a cross section of the Arctic air temperature anomaly of May through September 2020.. 5 months pushing +5C.

https://psl.noaa.gov/cgi-bin/data/composites/printpage.pl
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Glen Koehler

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« Last Edit: February 04, 2021, 01:30:17 AM by Glen Koehler »