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Author Topic: Atmospheric connections, structure, and long range weather forecasting  (Read 4990 times)

sark

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Dr Judah Cohen has published an update to the AER blog.  Forecast ensemble sees a continued cooling in upper level polar cell with continued troposphere warmth into the first weeks of July.

https://www.aer.com/science-research/climate-weather/arctic-oscillation/

I was really hoping this pattern would break as soon as the snow melted of land
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FishOutofWater

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Ocean heat is impinging on the Arctic from both the Atlantic and Pacific sides. That's what's intensifying the warm Arctic cold continents pattern. Blocking highs tend to form over the oceans at preferred locations near 0 and 180 degrees. This leads to increased heat transfer from the Atlantic and Pacific ocean heat sources to the arctic atmosphere. This situation weakens the polar vortex and  causes WACCy weather. I wouldn't call it the failure of the polar cell, but the polar circulation is increasingly being disrupted by heat advected from the Atlantic and Pacific oceans.

Glen Koehler

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Fish - Is there precedent for Atlantic ocean heat intrusion meeting up with Pacific side?  Any chance of that happening this year?

sark

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I think you are correct but I don't think it's exactly accurate to say the polar cell is failing -- the *single* polar cell system is now changing into a state where we have two smaller continental polar cells centered over North America and Eurasia, with increasing dominance of the NAmerican cell (IMO).

So, yes, the single-polar-cell system is failing, but we still have polar cells, they are just centered in abnormal locations and are now advecting heat into the High Arctic instead of dissipating heat entering the High Arctic (at least, advection is now occurring more often than dissipation).

Pretty much how I see it.  Except there's sort of a third polar cell going on, often over Sea of Okhotsk.

I love this video of a winter PV split


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uniquorn

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Quote
I love this video of a winter PV split
So do I. How do you make one?

Glen Koehler

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RE post #2751 about albedo in the 2019 Melt Season thread

Radiative Heating of an Ice‐free Arctic Ocean
Kristina Pistone Ian Eisenman V. Ramanathan
First published: 20 June 2019
https://doi.org/10.1029/2019GL082914

"During recent decades, there has been dramatic Arctic sea ice retreat. This has reduced the top‐of‐atmosphere albedo, adding more solar energy to the climate system. There is substantial uncertainty regarding how much ice retreat and associated solar heating will occur in the future. This is relevant to future climate projections, including the timescale for reaching global warming stabilization targets. Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year. Assuming constant cloudiness, we calculate a global radiative heating of 0.71 W/m2 relative to the 1979 baseline state. This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years."

Trillion tons CO2, i.e. about 25 years of current annual global emissions.  That's just a theoretical benchmark number of course, we are a long way from Arctic being ice free all summer.  But every portion thereof adds another slice of warming energy. 

Same authors did an earlier, more practical study:
Observational determination of albedo decrease caused by vanishing Arctic sea ice
Kristina Pistone, Ian Eisenman1, and V. Ramanathan
322–3326 | PNAS | March 4, 2014 | vol. 111 | no. 9
www.pnas.org/cgi/doi/10.1073/pnas.1318201111


"The decline of Arctic sea ice has been documented in over 30 y of
satellite passive microwave observations. The resulting darkening
of the Arctic and its amplification of global warming was hypothesized
almost 50 y ago but has yet to be verified with direct
observations. This study uses satellite radiation budget measurements
along with satellite microwave sea ice data to document
the Arctic-wide decrease in planetary albedo and its amplifying
effect on the warming. The analysis reveals a striking relationship
between planetary albedo and sea ice cover, quantities inferred
from two independent satellite instruments. We find that the Arctic
planetary albedo has decreased from 0.52 to 0.48 between 1979
and 2011, corresponding to an additional 6.4 ± 0.9 W/m2 of solar
energy input into the Arctic Ocean region since 1979. Averaged
over the globe, this albedo decrease corresponds to a forcing that
is 25% as large as that due to the change in CO2 during this period,
considerably larger than expectations from models and other less
direct recent estimates. Changes in cloudiness appear to play
a negligible role in observed Arctic darkening, thus reducing
the possibility of Arctic cloud albedo feedbacks mitigating future
Arctic warming."

Note that study period ended in 2011.  After 2019 easy to think that 25% could be up to 30%.

« Last Edit: June 28, 2019, 09:13:30 PM by Glen Koehler »

sark

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Scary storm fires up off thunderstorm activity in the GFS, hour 70-180
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wdmn

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What am I looking at here? Green is rain? Am I looking at the part over the lower Great Lakes St. Lawrence?

sark

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That's the Eastern US and East Atlantic. Click to run gif.  Midlats cyclone headed north up the Eastern seaboard in hour 70+


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b_lumenkraft

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Sark, there is no GIF. :P

jdallen

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Scary storm fires up off thunderstorm activity in the GFS, hour 70-180
I'm just hoping for a Thunderstorm in DC just in time for the parade.
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sark

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vox_mundi

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^ +1 ... LMAO
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

jdallen

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^ +1 ... LMAO

Ditto.  My Schadenfreude meter just pegged itself.  ;D  XD XD XD
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vox_mundi

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Indian Ocean Causes Drought and Heatwaves in South America
https://phys.org/news/2019-07-indian-ocean-drought-heatwaves-south.html

New research has found the record-breaking South American drought of 2013/14 with its succession of heatwaves and long lasting marine heatwave had its origins in a climate event half a world away—over the Indian Ocean.



It all started with strong atmospheric convection over the Indian Ocean that generated a powerful planetary wave that travelled across the South Pacific to the South Atlantic where it displaced the normal atmospheric circulation over South America.

"The atmospheric wave produced a large area of high pressure, known as a blocking high, that stalled off the east coast of Brazil," said lead author Dr. Regina Rodrigues.

"The impacts of the drought that followed were immense and prolonged, leading to a tripling of dengue fever cases, water shortages in São Paulo, and reduced coffee production that led to global shortages and worldwide price increases."

That impact wasn't just felt on land as the high-pressure system stalled over the ocean.

"The result of this blocking high was an unprecedented marine heatwave that amplified the unusual atmospheric conditions and likely had an impact on local fisheries in the region."



... The 2013/14 South American drought and marine heatwave is the latest climate case study to show how distant events in one region can have major climate impacts on the other side of the world.

"Researchers found that Australia's 2011 Ningaloo Nino in the Indian Ocean, which completely decimated coastal ecosystems and impacted fisheries, was caused by a La Niña event in the tropical Pacific," said Australian co-author Dr. Alex Sen Gupta.

"Here we have yet another example of how interconnected our world is.

Regina R. Rodrigues, et.al., Common cause for severe droughts in South America and marine heatwaves in the South Atlantic, Nature Geoscience (2019).

------------------------------------

Summer Eurasian Nonuniform Warming Found Related to the Atlantic Multidecadal Oscillation
https://phys.org/news/2019-07-summer-eurasian-nonuniform-atlantic-multidecadal.html



"Previous studies indicate the Eurasian nonuniform warming since the mid-1990s may be related with the phase shift of the AMO, and we validate this point by using ensemble experiments with three AGCMs [atmospheric general circulation models]," the lead author says. "The overall consistency among the three AGCMs illustrates the robustness of the AMO's influence, although the models are not the most recent updated versions," she adds.

The authors diagnose the underlying mechanism of the AMO's influence on the Eurasian nonuniform warming from the perspective that the boundary forcing modulates the intrinsic atmospheric variability. The results highlight the role of the Silk Road Pattern.

"The AMO-related tropical diabatic heating anomaly excites the Silk Road wave-train over Eurasia with positive geopotential height and anticyclonic circulation anomalies over Europe-West Asia and Northeast Asia, but negative geopotential height and cyclonic circulation over Central Asia. Such opposite circulations lead to opposite changes in temperature advection, precipitation, cloud cover and solar radiation. When these effects overlap the signals of global warming, it causes amplified warming," the authors explain.

Xueqian Sun et al, Simulated Influence of the Atlantic Multidecadal Oscillation on Summer Eurasian Nonuniform Warming since the Mid-1990s, Advances in Atmospheric Sciences (2019)
« Last Edit: July 08, 2019, 11:12:13 PM by vox_mundi »
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late