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Author Topic: Atmospheric connections, structure, and long range weather forecasting  (Read 25594 times)


sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #301 on: December 13, 2019, 03:26:51 AM »
https://www.cpc.ncep.noaa.gov/products/intraseasonal/z200anim.shtml

A five year rolling average gives out some outline as to the looks of this thing.  We can look at it anyway.  Look at the emergence of smaller scales at 500mb :x

*(Click to run the second image, it's a GIF)*

We've come a long way to get where we are.  The trend is your friend.  The stratospheric winter PV is a strong force.  And the atmosphere is an exquisite balance.

However

May-Oct '19 is #1 highest geopotential over the Arctic in the archives, 2016 in 2nd place

2016 re-takes the title for May-Nov, as does Jan-Nov.  Tropopause will be higher though.

PV splits it all the time so it can go back together... but the Arctic is too warm NOW.  What happens upstream at the vortex core?  well it unravels

Weather will still "work" like usual, and probably be unblocked as there are no real blocks, just breaks, with vortex interaction spooling the temps North & South at 850mb fast & furious and from all angles.  Jet stream is obviously tilting out exhibiting banding or a Lundgren spiral. 

I've gotten the sense that the big game out here is atmospheric superrotation.  There was a very high AAM in early 2018, so after a year with such geopotential heights we have seen spikes in +AAM.

But who knows what will happen next?
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #302 on: December 13, 2019, 04:09:02 AM »
Now here is the archive at 1000mb of temperatures for the past month. 

What you see is a minor -AO perturbance starting in early November and then a long recovery which scored the highest AO strength since Mid-April.  And then it sets up for the super block

https://www.esrl.noaa.gov/psd/data/animation/

+/- 25C temp 1000mb works well at any time of the year.  You can see everything. 

our deterministic model guidance is showing in such fine detail something that doesn't exist in the archives.  a butterfly of 500mb anomalies constructed *about* the North Pole

* the US is to the LEFT (sorry)
« Last Edit: December 13, 2019, 01:35:25 PM by sark »
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #303 on: December 13, 2019, 01:26:05 PM »
This is from an obsolete GFS op det where we see pairs of tiny lows occurring at a sort of simultaneous merger of high latitude blocking from Siberian high, Beringian block and Scandinavian block.  Onset of polar shear.  IMHO this is a modeled instance of vortex core divergence.

Run is GFS OP DET 00Z 12DEC2019 36-276h
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #304 on: December 13, 2019, 05:23:04 PM »
November 25th - December 25th *2016*

potential temperature 1000mb +/- 25C

I am looking for any record of tiny vortexes within a few hundred km of the pole, at points in this animation ... right around Dec 10 and 22 2016

Not exactly at sea level but would be visible at 500mb
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #306 on: December 14, 2019, 06:51:06 AM »
this is the bad moment when packets fold in simultaneously over the pole.  shear across the pole up until this moment.  once it fills with slack air, the vorticity collapses

look at jet stream after

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=uv250&runtime=2019121400&fh=360
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #307 on: December 14, 2019, 06:56:52 AM »
Lundgren Spiral at 10hPa, already visible and banding up over the next 5 days

https://earth.nullschool.net/#2019/12/19/0000Z/wind/isobaric/10hPa/orthographic=90.00,90.00,274
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #308 on: December 14, 2019, 10:28:52 AM »
I think the key development in recent GFS guidance deterministic models is a shear induced across the North Pole, which is beginning now.  From where I'm sitting, looks like model runs show both a ripple (dark) and shear (light) lines across the North Pole in the troposphere.  This can be seen in a number of ways but presenting 330K cyclonic PV

Ripple: https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=pv330K&runtime=2019121400&fh=18

Shear: https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=pv330K&runtime=2019121400&fh=36

Once the two packets of anticyclonic air reach the pole simultaneously at about hour 198 (Dec 22 2019) the vortex core collapses.  Everything blocks up after.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #309 on: December 28, 2019, 09:28:02 AM »
Posting this which has reached positive for the 2nd time only since July. 

Here we are again, with strength in the Arctic Oscillation, strength in the vortex, and zonality in winds.  The forecast is for a strong polar vortex situation, positive Arctic Oscillation

Can it hold?  That is and has been my only concern.  I don't know what this stuff all means, I just know 2019 sucked.  It looks bad.  I know it has been -AO and -AAM in the extreme.  The reason it sucked?  Not necessarily.

who knows.  it could do anything.

Because of what it looks like to me, have to say I expect to have the polar cell cracking open again Jan 16-19.  I would hope I'm wrong and the AO is able to trend outside of neutral for a long time, instead of a dynamic wipeout situation with regular large disturbances at the tropospheric level.

and if true,  it could be solar minimum and ENSO and all that.  But, you would start to expect huge changes in global weather patterns to kick in eventually eh?

Tons and tons of ideas out there.  After well over a year of researching, I don't know if it's merely the IPCC scenario or if it's out of control runaway.  Neither ideas matter.  What is it?  Somewhere in between probably.

Don't know what to hope for but the positive global AAM can help.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #310 on: December 29, 2019, 08:45:33 AM »
ECMWF operational quite dramatic this morning.  As the most likely time nears for a stratospheric polar vortex disruption, the lastest 10 day gives a very strong signal for a major wave 2 split.

GEPS and GEFS all have it losing strength and the Euro has been showing signs of warming of the strat PV for the past day.

Hype winter stuff

https://twitter.com/PvForecast
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vox_mundi

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #311 on: January 09, 2020, 04:35:49 PM »
Connection Found Between Arctic Oscillation and Increased Risk of Fire in Siberia
https://phys.org/news/2020-01-arctic-oscillation-siberia.html

A team of researchers from the U.K., South Korea and Japan has found evidence that in positive phase years, the Arctic Oscillation can boost late winter temperatures in Siberia, resulting in more forest fires in the spring. In their paper published in the journal Science Advances, the group describes studying a 20-year global weather period and their findings.

... Prior research has shown that due to opposing patterns of air pressure in the middle latitudes and the Arctic, air circulation patterns emerge in the northern hemisphere. These patterns, known as the Arctic Oscillation, can have a dramatic impact on weather in the areas below them. During what is known as its positive phase, air pressure in the Arctic drops below that over the Atlantic and Pacific Oceans, pulling warm air masses north in some parts of the northern hemisphere and pushing some south. Air masses are pushed north in Siberia, resulting in warmer late winters. And warmer late winters mean earlier snowmelt. And that earlier snowmelt, the researchers have found, can lead to an increase in forest fires. To learn more about the impact of the Arctic Oscillation on weather patterns, the researchers studied weather and fire statistics in Siberia from information in global databases over the years 1997 to 2016. They found a pattern—when there was a positive phase in later winter, there tended to be an increase in forest fires in Siberia in the spring.

The findings indicate that if weather forecasters in Siberia keep tabs on the Arctic Oscillation, they can warn residents of an impending early snow melt and a subsequent increase in forest fires—this would allow the population to take proactive action to protect themselves.


Fire activity over southeastern Siberia. (A) Mean burned area fraction (% year−1) over mid- and high latitudes in the Northern Hemisphere. Hatched areas indicate permafrost regions. The black box indicates the study area in southeastern Siberia (100°–150°E, 45°–55°N). (B) Monthly burned area (Mha month−1) in southeastern Siberia for 1997–2016 in each year (gray), mean (thick black), composite for February to March AO index > 0.5 SD cases (red), and AO < −0.5 SD cases (blue). (C) Mean burned area according to February to March AO index (orange) and 850-hPa geopotential height anomaly over southeastern Siberia (red). Bins on the x axis indicate <20%, <40%, <60%, <80%, and <100% rank ranges.

Open Access: Jin-Soo Kim et al. Extensive fires in southeastern Siberian permafrost linked to preceding Arctic Oscillation, Science Advances (2020)
« Last Edit: January 09, 2020, 05:09:06 PM by vox_mundi »
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vox_mundi

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #312 on: January 09, 2020, 05:08:47 PM »
El Niño-Southern Oscillation Heat Engine Shifts Eastward Under Global Warming
https://phys.org/news/2020-01-el-nio-southern-oscillation-shifts-eastward.html

In a study recently published in Science Advances, an international team from China, the U.K. and the U.S. proposes a new mechanism to understand the eastward shift and extension of ENSO-induced precipitation anomalies under global warming. The researchers analyzed a large ensemble climate change simulation conducted by the Met Office in the U.K.

"We found under global warming, the weakened easterly trade wind over the tropical Pacific would weaken the meridional overturning circulation of the subtropical cell, and further cause the narrowing of the meridional span of ENSO," said the corresponding author Dr. Bo Wu from Institute of Atmospheric Physics at Chinese Academy of Sciences. "It means that the sea surface temperature (SST) anomalies associated with the ENSO are more concentrated toward the equator. Tighter ENSO becomes more powerful in driving moisture convergence over the equatorial central-eastern Pacific, which leads to the eastward shift and extension of the precipitation anomalies, even if ENSO intensity stays unchanged under global warming."

The eastward shift of the ENSO heat engine under global warming would not only lead to remarkable changes in global climate variations during ENSO years, but also accelerate the decay of El Niño events after their peak phase, thus shortening their duration.


Schematic diagram illustrating the physical processes responsible for the eastward shift and extension of ENSO-induced tropical precipitation anomalies under global warming

Open Access: Zixiang Yan, et.al. "Eastward shift and extension of ENSO-induced tropical precipitation anomalies under global warming" Science Advances (2020)


Global climate impacts caused by the changes in the ENSO-driven precipitation anomalies.
(A) Ensemble mean of ENSO-related D(0)JF(1)-mean 500-hPa geopotential height anomalies (m) for the historical (contour) and RCP8.5 simulations (shading). Black dots and red crosses denote the centers of geopotential height anomalies in historical and RCP8.5 simulations, respectively. (B) As in (A), but for 200-hPa velocity potential anomalies (106 m2 s−1). (C) Simulated changes in ENSO-driven precipitation anomalies (shading; mm day−1) and 925-hPa wind anomalies (vector; m s−1) under global warming. Values reaching 5% significance level are dotted. (D) Temporal evolutions of Niño3.4 indices for El Niño events in the historical (black) and RCP8.5 (red) simulations. Thick lines denote ensemble means. Shadings denote 5th to 95th percentiles. Thin vertical lines denote the timing when Niño3.4 index transforms from positive to negative.
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Glen Koehler

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #313 on: January 10, 2020, 12:29:31 AM »
This bit about the Australian fire season seems relevant to this thread

"Another contributing factor has been a “rare phenomenon called sudden stratospheric warming (SSW) that took place in Antarctica”, noted the Times. Back in September, “winds circling the South Pole about 30km high in the stratosphere went into reverse causing the temperature of the stratosphere to rocket by 40C”, the article explained.

This “added to the hot dry conditions by shifting the westerly winds, which usually lurk over the Southern Ocean, up onto the continent”, said ABC News.

SSW events, which also occur in the northern hemisphere, are “rare in the southern hemisphere with only one major event ever identified, in 2002”, noted another ABC News piece."

Source:   CarbonBrief.org, 7 January 2020
Media reaction: Australia’s bushfires and climate change
https://www.carbonbrief.org/media-reaction-australias-bushfires-and-climate-change

Gray-Wolf

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #314 on: January 17, 2020, 12:02:35 PM »
Talking of SSW's, GFS is now punting for an SSW of our Vortex after Jan 30th

This could bring some cold airs down into our temperate regions with the 'beast from the east' still fresh in the minds of many of us!

Watch this space!
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #315 on: January 17, 2020, 03:02:02 PM »
There is NO split in the GFS forecast. There is stratospheric warming on jan 29 but no split forecast. Without a split, no beast from the east, sorry

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #316 on: January 17, 2020, 03:10:48 PM »
Hi El Cid!

I'm certainly not looking for any 'Beast from the East'.... enjoying the mild winter so far thank you very much!.... but if the Polar Night Jet is disrupted this late into the season will it have time to recover before the final warming?

If what occurs is a weak and unruly PNJ for the rest of its life then will it not drive impacts across the Arctic Basin?

I'm taking it that the various high temp records we've been seeing around our hemisphere is partly due to an orderly PNJ keeping the cold trapped where it ought to be and not 'plunging' into lower lats?

With the Sun on the rise in early Feb (for most of the basin?) any swapping out of the cold for a Warm Air Advection could aid an early start to the melt season there?

As an aside how rare is it to have the Southern hemisphere see a SSW followed by the Northern Hemisphere ending its winter on one?
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #317 on: January 20, 2020, 08:36:26 AM »
Global atmospheric angular momentum has gone net U positive for the first time in the record.

https://atlas.niu.edu/gwo/

https://twitter.com/gensiniwx/status/1219077898897850368
« Last Edit: January 20, 2020, 01:24:36 PM by sark »
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Aleph_Null

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #318 on: January 20, 2020, 08:34:31 PM »
Global atmospheric angular momentum has gone net U positive for the first time in the record.

2020/1/19 -- seems a historic date, but I'll admit to being dazzled and mystified by AAM. You've motivated me to send for a book on global circulation, because I find it difficult to grasp how and why the atmosphere would rotate at a different rate than the Earth. In the meantime, these links might be interesting to my fellow strugglers:

https://business.weather.com/blog/atmospheric-angular-momentum-to-drop-this-week-the-driving-mechanism-and-future-implications-this-summer

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/angular-momentum

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #319 on: January 22, 2020, 09:50:56 AM »
Atmospheric superrotation is the endgame for the Earth we recognize.  As such, it's also probably decades off.  We're not at an instantaneous climate change moment, just abrupt.

What's interesting is that after all that time of low winds, it has corked positive with the greatest acceleration we have ever seen.

The atmospheres of Venus and Titan superrotate those planets.  https://journals.ametsoc.org/doi/full/10.1175/JAS-D-15-0030.1

It's expected that Earth, too, will abruptly transition to a superrotating atmosphere.  Angular momentum at zero essentially means that the planet's atmosphere is static relative to the surface with no prograde or retrograde net rotation.  It has no angular momentum to deposit or absorb.  You could say that any time vertical and zonal integral of relative AAM anomaly is positive, the atmosphere is rotating faster than the Earth, but this is not the same as the definition of superrotation applied to other planets.

In order to truly superrotate, you'd have to have the QBO westerly and endless convective plumes from the Tropics lined up just right.  At some point, when that happens, this planet should exhibit a bimodal stability and flip into the true hothouse mode where equatorial temperature differences East to West are eliminated because the Rossby waves flooding poleward introduce enough Westerly momentum equatorward that the Equatorial Easterly winds are reversed.  I was reading that this flip to superrotation occurs with Equatorial ocean temperatures around +33C.  That is... if the stratocumulus deck doesn't evaporate first.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008PA001652

https://journals.ametsoc.org/doi/abs/10.1175/JAS-D-19-0089.1

Either way, the completely Westerly tropical surface winds lately yielded an atmospheric acceleration faster than has ever before been observed.  This would be fascinating if it were happening on Mars.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #320 on: January 22, 2020, 10:22:31 AM »
Global atmospheric angular momentum has gone net U positive for the first time in the record.

https://atlas.niu.edu/gwo/

https://twitter.com/gensiniwx/status/1219077898897850368

This should say relative AAM not total global AAM

Global AAM regularly cycles between positive and negative, but excluding the QBO, all global winds became Westerly yesterday, even in the Tropics, for the first time in the record.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #321 on: January 22, 2020, 10:26:07 PM »
The ocean heat has arrived years ago already.  I'm gonna say high likelihood the Arctic situation is what caused the abhorrent US corn belt conditions during 2019.  New all time record year?  Somewhat disquieting trend wetter over the past 2 years?  This thing splitting right in front of our eyes?  Yeup.

Odds of a repetitious 2020 are rising
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Glen Koehler

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #322 on: January 23, 2020, 03:27:46 AM »
Angular momentum at zero essentially means that the planet's atmosphere is static relative to the surface with no prograde or retrograde net rotation.  It has no angular momentum to deposit or absorb.  You could say that any time vertical and zonal integral of relative AAM anomaly is positive, the atmosphere is rotating faster than the Earth,
-------

Either way, the completely Westerly tropical surface winds lately yielded an atmospheric acceleration faster than has ever before been observed.  This would be fascinating if it were happening on Mars.

Thanks Sark.  I still don't really understand the mechanisms or significance of the AAM stuff, but your post is the most helpful info I've seen about it.

El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #323 on: January 23, 2020, 07:31:09 AM »
Interesting research quoted sark! thx

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #324 on: January 25, 2020, 06:32:31 PM »
The year to date average geopotential heights over the Arctic demonstrate the split that has been visually very striking within the circulation for the past year to three years.  December 2019's "6000 thickness" shows the same.

This 6000 thickness plot shows geopotential meter thickness between 1000-500mb.  This is where the 540 line comes from.  "“The 540 Line” refers to the difference in height between the 500mb pressure level and the 1000mb pressure level (which is roughly the surface).  If the difference between these two pressure levels is 5400 meters…then the 540 Line gets placed there on a weather map" https://cbs3weather.wordpress.com/2011/10/24/the-540-line/

Centering the scale on the 540 line and plotting geopotential heights over time, the emerging split jumps right out.

These are the raw geopotential heights, not an anomaly map.  When this is increasingly split, there has to be an increasing separation of the two rotations, which is visually quite striking over the past 3 years.  It's not the fact of it happening, it's that it has become preferred.

https://doi.org/10.1063/1.2424498

Analysis of corotating vortex interactions is typically found in aerodynamics studies of wake turbulence from aircraft, and not geophysical fluid dynamics.  I would bet this is an unassessed bad feedback in the dynamics.
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kassy

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #325 on: January 25, 2020, 09:15:33 PM »
Interesting. Clearly shows why we have no winter here in Europe.
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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #326 on: January 28, 2020, 01:35:58 AM »
Dwindling Arctic Sea Ice May Affect Tropical Weather Patterns
A new study finds a possible link between Arctic warming and more frequent El Niños in the Central Pacific.
By Bob Berwyn, InsideClimate News   
Jan 27, 2020
https://insideclimatenews.org/news/26012020/arctic-sea-ice-melting-tropical-weather-el-nino-climate-change

"Kennel said it appears the sea ice decline passed a threshold with global consequences about 20 years ago.

"Sea ice reached a kind of tipping point around 1999," he said. "Before that, the seasonal melting from June to October was about the same size (each year). After that, it was much bigger."

"Francis, who was one of the first to propose that declining Arctic sea ice could intensify storm and drought extremes in the mid-latitudes, said that "interestingly, the Arctic connection was weak or non-existent during years before sea ice had declined substantially."

She added, "These authors present multiple lines of evidence that all fit the story that, when it comes to influences on mid-latitude weather, the tropics are no longer the only game in town."

Francis said another recent paper found different types of links between Arctic sea ice and the tropics. In the 2019 report in the journal Nature, the researchers wrote that extensive sea ice around Greenland and the Barents Sea favors El Niño conditions the following winter. "

&
""If this is true, it would mean that the impacts of Arctic sea-ice loss could literally affect the entire planet," she said. "Arctic sea ice melt is by no means only a polar bear problem."  "

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #327 on: January 29, 2020, 10:54:59 PM »
Unbelievable result at 500mb for a January, to say nothing of the preceding 8 months of disruption to the core of the polar vortex.  This is not an anomaly map, this is the straight geopotential heights.

This emerged gradually in the last couple of years and is now becoming a preferred pattern of circulation.

What are the consequences?
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Gray-Wolf

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #328 on: February 20, 2020, 12:09:38 PM »
With the Polar Night Jet (PNJ or 'Polar Vortex') seeming to behave itself this Arctic winter this struck me as interesting;

https://www.exeter.ac.uk/news/homepage/title_778916_en.html

I had mooted, back in 2012, that once the rest of the basin caught up with Barrentsz/Kara then the PNJ would not be being dragged out of shape (leading to the 'polar plunges/WAA') and its impact on the Polar Jet would lessen?

This winter seems to show us this in operation with a strong PNJ most of its residence (still blowing hard and setting date records for its speed?) and the mid latitudes getting a glimpse of where their temps/weathers shouldn't be without being skewed by the rude interruption of polar plunges/WAA as the PNJ threw lobes down into lower Lats?

« Last Edit: February 20, 2020, 12:18:37 PM by Gray-Wolf »
KOYAANISQATSI

ko.yaa.nis.katsi (from the Hopi language), n. 1. crazy life. 2. life in turmoil. 3. life disintegrating. 4. life out of balance. 5. a state of life that calls for another way of living.
 
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El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #329 on: February 20, 2020, 12:42:44 PM »
I also never bought the warm arctic-cold continents theory because data do not support it, the continents do warm quickly during winter. There have been however many strong cold breakouts during the past years and that is probably due to the uneven loss of sea-ice, especially in the Barents. This year however, the Barents had very stong ice (due to contiuous export), and it was cold and that probably stabilized the PV leading to this very warm winter. But I think the Barents will once again lose its ice and there could be many PV disruptions in the future.
It seems to me that when we have low/uneven ice cover we have a better chance for strong cold breakouts in NH midlatitudes. I think that an even ice distribution stabilizes the atmoshere from the bottom and the PV gets "anchored". If you have big "holes" or "dents" in the Arctic, it has a destabilizing effect.
So all in all, NH midlatitude winters are obviously getting warmer and when the PV behaves, almost all of Europe and a big part of the US becomes something like the Mediterranean for winter...

Gray-Wolf

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #330 on: February 20, 2020, 01:54:37 PM »
I also never bought the warm arctic-cold continents theory because data do not support it, the continents do warm quickly during winter. There have been however many strong cold breakouts during the past years and that is probably due to the uneven loss of sea-ice, especially in the Barents. This year however, the Barents had very stong ice (due to contiuous export), and it was cold and that probably stabilized the PV leading to this very warm winter. But I think the Barents will once again lose its ice and there could be many PV disruptions in the future.
It seems to me that when we have low/uneven ice cover we have a better chance for strong cold breakouts in NH midlatitudes. I think that an even ice distribution stabilizes the atmoshere from the bottom and the PV gets "anchored". If you have big "holes" or "dents" in the Arctic, it has a destabilizing effect.
So all in all, NH midlatitude winters are obviously getting warmer and when the PV behaves, almost all of Europe and a big part of the US becomes something like the Mediterranean for winter...

Makes sense to me El Cid!

When Jen Francis was doing her early work it focussed solely on the low sea ice we began to see ,from 2000 onward, in the Barrentsz/Kara sea areas and the atmospheric anoms over Autumn the 'shedding of heat prior to refreeze' drove.

In 2012 the Pacific side of the basin joined in the fun.

Like putting a lead weight on an unbalanced wheel has this , over time, lead to a 'stabilisation' of the PNJ as it formed in the autumn?

If so we will see rapid changes in the mid lats as mother N. tussles with the new conditions I believe?

Let's see how fast the winter snows go this year and how this , in turn , impacts on the sea ice loss around the coastal areas?

I worry our hemisphere is in for one heck of a Spring/Summer!
KOYAANISQATSI

ko.yaa.nis.katsi (from the Hopi language), n. 1. crazy life. 2. life in turmoil. 3. life disintegrating. 4. life out of balance. 5. a state of life that calls for another way of living.
 
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El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #331 on: February 20, 2020, 03:49:23 PM »
I also noticed that ever since the Bering/chukchi region "joined the fun", NH midlatitude winters are milder. I compared those winters (since 2004) that had very low ice cover, to those that had high ice cover in the Chukchi/Bering region (on 12/01 each year) - eyeballing the NSIDC sea ice spatial comparison tool (http://nsidc.org/arcticseaicenews/sea-ice-comparison-tool/).
High ice years: 2004,5,8,9,10,11,12,13
Low ice years:2006,7, 2014....2019
In my country the "high years' " average winter temp is 1,4 C while the low years' average winter temp is 3,4 C !!!!
So, it seems that truly, the Bering/chukchi counterbalances the Barents, and the PV behaves better.
The conclusion seems to be that NH winters should by and large be mild going forward with a bigger chance of cold winters when the Chukchi ices over early and/or the Barents is very much ice free.

Gray-Wolf

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #332 on: February 22, 2020, 03:36:58 PM »
Again I'd be tempted to agree El Cid

For us in the UK the 80's and early 90's were the times folk were bemoaning the change to the UK winter with the snows of yesteryear a fading memory

The upsets come in the late 90's/noughties when the Polar Night Jet began its 'wobbles' and so impacted upon the Polar Jet and weathers seen in the Northern Hemisphere's temperate zones.

I do wonder what spring/summer will bring to us all this year though?

I tend to worry that whatever arises it will be at the extreme end of those weather 'types'?

I worry that far too many records will be broken before we descend into Autumn?
KOYAANISQATSI

ko.yaa.nis.katsi (from the Hopi language), n. 1. crazy life. 2. life in turmoil. 3. life disintegrating. 4. life out of balance. 5. a state of life that calls for another way of living.
 
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