Our extreme weather: Arctic changes to blame?

By: Dr. Jeff Masters , 9:50 PM GMT on December 16, 2011

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"The question is not whether sea ice loss is affecting the large-scale atmospheric circulation...it's how can it not?" That was the take-home message from Dr. Jennifer Francis of Rutgers University, in her talk "Does Arctic Amplification Fuel Extreme Weather in Mid-Latitudes?", presented at last week's American Geophysical Union meeting in San Francisco. Dr. Francis presented new research in review for publication, which shows that Arctic sea ice loss may significantly affect the upper-level atmospheric circulation, slowing its winds and increasing its tendency to make contorted high-amplitude loops. High-amplitude loops in the upper level wind pattern (and associated jet stream) increases the probability of persistent weather patterns in the Northern Hemisphere, potentially leading to extreme weather due to longer-duration cold spells, snow events, heat waves, flooding events, and drought conditions.


Figure 1. Arctic sea ice in September 2007 reached its lowest extent on record, approximately 40% lower than when satellite records began in 1979. Sea ice loss in 2011 was virtually tied with the ice loss in 2007, despite weather conditions that were not as unusual in the Arctic. Image credit: University of Illinois Cryosphere Today.

Summertime Arctic sea ice loss: 40% since 1980
The Arctic has seen a stunning amount of sea ice loss in recent years, due to melting and unfavorable winds that have pushed large amounts of ice out of the region. Forty percent of the sea ice was missing in September 2007, compared to September of 1980. This is an area equivalent to about 44% of the contiguous U.S., or 71% of the non-Russian portion of Europe. Such a large area of open water is bound to cause significant impacts on weather patterns, due to the huge amount of heat and moisture that escapes from the exposed ocean into the atmosphere over a multi-month period following the summer melt.


Figure 2. The extent of Arctic sea ice loss in the summer July - August - September period in 2007 was about 1.4 million square miles (3.6 million square kilometers) greater than in 1980, according to the University of Illinois Cryosphere Today. For comparison, the lost ice coverage (orange colors) was equal to an area about 44% of the size of the contiguous U.S., or 71% of the non-Russian portion of Europe.

Arctic sea ice loss can slow down jet stream winds
Dr. Francis looked at surface and upper level data from 1948 - 2010, and discovered that the extra heat in the Arctic in fall and winter over the past decade had caused the Arctic atmosphere between the surface and 500 mb (about 18,000 feet or 5,600 meters) to expand. As a result, the difference in temperature between the Arctic (60 - 80°N) and the mid-latitudes (30 - 50°N) fell significantly. It is this difference in temperature that drives the powerful jet stream winds that control much of our weather. The speed of fall and winter west-to-east upper-level winds at 500 mb circling the North Pole decreased by 20% over the past decade, compared to the period 1948 - 2000, in response to the extra warmth in the Arctic. This slow-down of the upper-level winds circling the pole has been linked to a Hot Arctic-Cold Continents pattern that brought cold, snowy winters to the Eastern U.S. and Western Europe during 2009 - 2010 and 2010 - 2011.


Figure 3. West-to-east jet stream wind speeds at 500 mb (approximately 18,000 feet or 5,600 meters) in the mid-latitudes (40 - 60°N) over North America between 1948 and 2010. During fall (October - November - December) and winter (January - February - March), jet stream winds weakened by about 20%, from 13 - 14 m/s to 10.5 - 11 m/s. Spring (AMJ) and summer (JAS) winds changed little during this time period.

Arctic sea ice loss may increase the amplitude of jet stream troughs and ridges
The jet stream generally blows from west to east over the northern mid-latitudes, with an average position over the central U.S. in winter and southern Canada in summer. The jet stream marks the boundary between cold polar air to the north and warm subtropical air to the south, and is the path along which rain and snow-bearing low pressure systems ride. Instead of blowing straight west-to-east, the jet stream often contorts itself into a wave-like pattern. Where the jet stream bulges northwards into a ridge of high pressure, warm air flows far to the north. Where the jet loops to the south into a trough of low pressure, cold air spills southwards. The more extreme these loops to the north and south are--the amplitude of the jet stream--the slower the waves move eastward, and consequently, the more persistent the weather conditions tend to be. A high-amplitude jet stream pattern (more than 1000 miles or 1610 km in distance between the bottom of a trough and the peak of a ridge) is likely to bring abnormally high temperatures to the region under its ridge, and very cold temperatures and heavy precipitation underneath its trough. The mathematics governing atmospheric motions requires that higher-amplitude flow patterns move more slowly. Thus, any change to the atmosphere that increases the amplitude of the wave pattern will make it move more slowly, increasing the length of time extreme weather conditions persist. Dr. Francis discovered that during the early 1960s, a natural pattern in the atmosphere called the Arctic Oscillation increased the amplitude of the winter jet stream pattern over North America and the North Atlantic by more than 100 miles, increasing the potential for long-lasting weather conditions. The amplitude of the winter jet fell over 100 miles (161 km) during the late 1960s, remained roughly constant during the 1970s - 1990s, then increased by over 100 miles again during the 2000s. This latest increase in wave amplitude did not appear to be connected to the Arctic Oscillation, but did appear to be connected to the heating up of the Arctic due to sea ice loss. A warmer Arctic allows ridges of high pressure to build farther to the north. Since temperatures farther to the south near the bases of the troughs are not changing much by comparison, the result is that the amplitude of the jet stream grows as the ridges of high pressure push farther to the north. Thus it is possible that Arctic sea ice loss and the associated increases in jet stream amplitude could be partially responsible for some of the recent unusual extreme weather patterns observed in the Northern Hemisphere. This is preliminary research that has yet to be published, and much more work needs to be done before we can confidently link Arctic sea ice loss with an increase in extreme weather, though.


Figure 4. A high-amplitude jet stream pattern observed over the U.S. on December 13, 2011. Instead of blowing straight west-to-east, the jet was contorted into a southward-bulging trough of low pressure that brought cold temperatures and a snow storm to Southern California, and a northwards-bulging ridge of high pressure that brought record warm temperatures to portions of the eastern 2/3 of the country. The axis of the jet stream is marked by the strongest winds (green and light blue colors) at the top of the lower atmosphere (200 - 300 mb pressure level.)

Earlier snow cover melt on Arctic land also increases the amplitude of jet stream troughs and ridges
As Earth's climate has warmed over the past 30 years, the Northern Hemisphere has seen a dramatic drop in the amount of snow cover in spring (April, May, and June.) Spring is coming earlier by an average of three days per decade, and the earlier arrival of spring has significantly reduced the amount of snow on the ground in May. Less snow on the ground means the land surface can heat up more readily, and May temperatures in Arctic have increased significantly over the past 30 years. Dr. Francis found that the upper-level wave amplitude has increased by over 100 miles (161 km) in summer over the past decade, and this change appears to be connected to the decline in May snow cover. Thus, reduced May snow cover due to global warming may be causing higher-amplitude jet stream patterns, potentially leading to slower-moving weather patterns that favor extreme weather in summer, such as heat waves, drought, and flooding. Note that significant changes to the upper-level atmospheric circulation in spring were not observed, so springtime extreme weather events like the 2011 flooding and tornadoes in the U.S. cannot be connected to changes in the Arctic sea ice or high-latitude snow cover using this research.

Related posts
Florida shivers; Hot Arctic-Cold Continents pattern is back
Jet stream moved northwards 270 miles in 22 years; climate change to blame?

Jeff Masters

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hmmmmmm it's very quiet right now....
Member Since: September 3, 2011 Posts: 13 Comments: 3466
Washi was a catastrophic storm in the Philippines:
UPDATE 4-Typhoon kills more than 436 in southern Philippines

* Local governments declare state of calamity

* Dozens of bodies washed ashore in nearby towns

* Houses swept into the sea while people slept
Member Since: July 7, 2010 Posts: 0 Comments: 5521
Here we go:

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Quoting TropicalAnalystwx13:
Lol..



Dang it, it won't let me upload it!
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Lol..

Member Since: July 6, 2010 Posts: 108 Comments: 30245
Quoting TropicalAnalystwx13:
Go to Google and type in, "Let it snow".


Neat :)
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Quoting CybrTeddy:
All I want for Christmas is sub 40 degree weather in Florida for once this year. Tired of T-shirt days in December.
That's what you get for living in lorida :).Right now we're in the 40's here in D.C.
Member Since: August 14, 2010 Posts: 10 Comments: 15707
Quoting TropicalAnalystwx13:
Go to Google and type in, "Let it snow".

:OO
Member Since: October 22, 2011 Posts: 0 Comments: 2179
Quoting CybrTeddy:
All I want for Christmas is sub 40 degree weather in Florida for once this year. Tired of T-shirt days in December.


I second this. It hasn't even hit the 40s at all this year in PBC and this time last year we were in the mid 20s for lows.
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TropicalAnalystwx13 gasps!

You can draw on it (:
Member Since: July 6, 2010 Posts: 108 Comments: 30245
Uploaded by Nasawhatonearth on Sep 15, 2011

Watch as sea ice in the Arctic ocean declines from its near-maximum state in early spring 2011 through the summer and up until Sept. 9, 2011, in this visualization of data collected by the AMSR-E instrument on NASA's Aqua satellite.

Sea ice goes through this shrink-and-swell rhythm every year, but since consistent satellite observations began in 1979, both the annual minimum at the end of summer and the annual maximum at the end of winter continue to decline in area and thickness. Consistent with rising temperatures globally and specifically in the Arctic, climate scientists are concerned with this trend both as an indicator of climate change and as a feedback mechanism. As the white, highly reflective ice disappears, darker ocean waters appear.

This darker surface absorbs more solar radiation and acts as a positive feedback to the warming that is already occurring and causing the change in the first place.

Visualization courtesy of NASA's Scientific Visualization Studio, Goddard Space Flight Center.



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137. wxmod
Dr Masters blog was belittled by someone who posted a map of the arctic showing sea ice in December this year. The September ice cover map shows not only an alarming loss of sea ice, but also an alarming loss of ice thickness. Next year or the year after I expect there will be no ice in September, so, throughout the arctic, the December ice will only be a few feet thick. If you don't think this will affect your lifestyle, consider drinking your martini without ice next time.
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Go to Google and type in, "Let it snow".
Member Since: July 6, 2010 Posts: 108 Comments: 30245
twitter.com/NSIDC

(NSDIC is down for routine server maintenance today till 4pm EDT)
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Quoting BahaHurican:
Geez... what'd I type in 111?

Something about the north pole??? violates community standards?

Weird.

it came back....?
Member Since: October 22, 2011 Posts: 0 Comments: 2179
Quoting PensacolaDoug:
I see post 111.

The other day some admin removed the "Twelve Days Of Christmas Wunderground version". But about 10 others had already re-posted it. That was a very funny/entertaining post and I don't don't understand how anybody (except for maybe a troll) could have found it offensive. Bizarre.

It kinda talked bad about the admins. here.
Member Since: July 6, 2010 Posts: 108 Comments: 30245
MODIS true Color, Gulf Coast
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Quoting PensacolaDoug:
I see post 111.

The other day tho some admin removed the "TwelveDays Of Christmas" WU Style post. But about 10 others had already re-posted it. That wss a funny post and I don't don't understand how anybody (except for maybe a troll) could have found it offensive. Bizarre.
I find it offensive that anyone finds anything offensive in Christmas!
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I see post 111.

The other day some admin removed the "Twelve Days Of Christmas Wunderground version". But about 10 others had already re-posted it. That was a very funny/entertaining post and I don't don't understand how anybody (except for maybe a troll) could have found it offensive. Bizarre.
Member Since: July 25, 2006 Posts: 0 Comments: 519
Only white Chritmas here is the sand at the Beach!! Warmer the better.
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Quoting SPLbeater:


been there. comment removed for no reason
What was scary was I couldn't even remember what I had posted at first, it was so innocuous... lol... I was like... what, u don't want I should post on the site anymore, eh?

Anyway, it now seems that all is love. I am currently wondering if that ITCZ disturbance currently on track for the central American coast has even the slightest chance of impacting wx above 20N.... naw... I doubt it...
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting BahaHurican:
Geez... what'd I type in 111?

Something about the north pole??? violates community standards?

Weird.


been there. comment removed for no reason
Member Since: August 4, 2011 Posts: 46 Comments: 4481
Quoting Ameister12:

Awww. No white Christmas for me. :(
Yippee!!! No white Christmas for me!!!

:)

[Sorry, couldn't resist...]
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Member Since: August 9, 2009 Posts: 10 Comments: 4498
Quoting GeoffreyWPB:

Awww. No white Christmas for me. :(
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Quoting sar2401:


Without getting into the issue of melting Artic ice, your understanding of sea ice and the sea water beneath it is deficient. I've done scuba diving through three feet of ice in Baffin Bay. Bad idea if you're claustrophobic. :) The air temperature was about 42F. Sea water, because of it's increased salinity over freshwater, doesn't begin to freeze until it reaches about 28F. The water under the ice is rarely below 27F, and the lowest I saw was 25F. The ice acts as an insulator, keeping the water at just below the freezing point, but not allowing it to turn to ice because of the pressure of the ice cap above it. The thickness of the ice increases during the long Artic nights and melts during the long Artic summers. However, it takes a lot of sun to melt three or four feet of ice, and many places have ice more than 30 feet deep. There are many thinner spots along the edges of the ice pack and due to local topography. I would think the main issue with more open water is that it will take much longer for the absorbed heat to turn back to ice during the winter. If the ice isn't at least a couple of feet thick by summer, it will melt again. This heats the exposed sea water, and thins the ice at the edges of the open water. Over the long run, enough open water will make it impossible to regain the lost sea ice unless we have unusually cold summers for an extended period of time.


Not quite correct. Due to the rapid melting in the arctic you will find very very very few places where the ice is 30 ft thick. The arctic survey team that went up there were drilling holes through the oldest ice areas and they were having problems finding areas deeper than 3 meters. There is very little old ice left. Warmer water temps combined with warming arctic temps have pretty much decimated the old thick ice.

New ice is ice less than 3 meters in thickness, almost all of which melts off every summer. As you noted, without thick ice around this opens up larger expanses of water, which in turn absorb a lot more energy. This makes it harder for the ice to refreeze, which in turn leads to fewer "freeze" days, and so on and so on.

The arctic has lost a lot of areal extent, but it pales in comparison to how much ice volume has been lost. If ideal melting conditions like 2007 were to happen consecutively for a few years in a row, then the arctic would be practically ice free in the summer (there would always be ice in the winter).
Member Since: October 31, 2009 Posts: 0 Comments: 1224
Quoting CybrTeddy:
All I want for Christmas is sub 40 degree weather in Florida for once this year. Tired of T-shirt days in December.


Wanna trade? I'd kill for a T-shirt weather!
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Never get into an argument with Grother about pronunciations. You will lose.

[and you deserve to, for not recognising the master's voice in this matter.... lol]
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting Grothar:


It is pronounced EYE-gor.


Froederick :)
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Can't imagine to many polaar bears mad about this
Member Since: June 17, 2011 Posts: 11 Comments: 6439
Geez... what'd I type in 111?

Something about the north pole??? violates community standards?

Weird.
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting CybrTeddy:
All I want for Christmas is sub 40 degree weather in Florida for once this year. Tired of T-shirt days in December.
Good luck with that... lol

Actually, I'm hoping that the sub-40s hold off until New Year's, when I'm likely to be back home. I'm likely to be in the S FL area between Christmas and New Year's, and I don't want to freeze my patooties... or my toes for that matter... :o)

I haven't looked at long range forecasts for a while, but I'd be surprised to see a major change before next weekend.

However, anything's possible in S FL... just about.
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting Skyepony:
I was looking at the monsoonal trough down there in the SW Caribbean. It does at times get to be a semi-ingrained feature this time of year, flooding Columbia...especially when La Niña is in play.

Looking at 850 vort the CAtl swirl is much more prominent. Attached to a front, surface map has it at 1007mb. A bunch of sinking air is threatening it..Shear is closing in..it's in a hostile spot.

Caribbean blob is living on La Nina enhanced divergence aloft. If it stays shallow shear is light..above that, looks pretty hostile.

No surprise the enhanced divergence either.. ESPI fell .20 the last few days to -1.02. this tells La Nina is strengthening again.. Columbia has been feeling it all week with landslides. Shouldn't be long til TX dries out again.
Yeah... poor TX... another year of hot dry weather is sure enough not going to help the farming there.....
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting presslord:
Can Santa's sleigh land on water?! Can his elves swim?!?!
This is a serious question for those savvy 4-8 year olds who understand exactly where the North Pole is.... maybe Santa is going to have to invest in some convertible submarine launch equipment for that sleigh....

Member Since: October 25, 2005 Posts: 19 Comments: 20686
109. Skyepony (Mod)
Quoting CybrTeddy:
All I want for Christmas is sub 40 degree weather in Florida for once this year. Tired of T-shirt days in December.


It's flannel weather out there right now.. anything less than 76º calls for long sleeves to a true Floridian..


That's awful about Sendong. Feared it when all that white showed up on the Rainbow loop.

Looks like they had atleast a foot of rain in the last week. Looks a little extreme in parts of China too.
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Morning everybody. First free day in simply ages, due to Christmas rush.... lol

Quoting Sfloridacat5:
January trend?
I'm in Southwest Fl. and December has been really warm. It seems like its been 80+ degrees every day this month.
Back in Nov. we had some cold weather (unusually cold for Nov.)
Also, the amount of snow cover across the U.S. is very small for mid December.

I wonder if January will make up for the real warm December we've had down in Fl.
I've been wondering about this absolutely gorgeous weather we've been having, too, and whether we'll see a swing into massive - for Florida - cold weather in January. It would fit patterns seen in previous winters. I'm really enjoying the warm sunny weather now, as I expect it to plunge into the 50s on a regular basis. Reminder to self: look for gloves and scarf not worn for years.... lol

Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting GeoffreyWPB:

NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOO
Member Since: October 22, 2011 Posts: 0 Comments: 2179
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All I want for Christmas is sub 40 degree weather in Florida for once this year. Tired of T-shirt days in December.
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The December update by the ENSO models continue to forecast Neutral conditions by the Summer as the majority of them are in that range by that time.

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Quoting Ameister12:
"Shoulda been" Category 5 Hurricanes

Floyd



I find it interesting that had Floyd been 15 degrees further west, in that picture, it essentially would have been another Katrina. Practically the same size, and with the adjustment in the normal heat concentration between the Gulf and that general part of the Bahamas, essentially the same intensity.

Imo, Katrina was significant, no doubt about it, but it wasn't nearly as much of a meteorological... uniquity.. as people make it out to be. Just one of the more recent ones that people can recall.
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Quoting sar2401:
I find it slightly amusing to see all the back and forth about if a hurricane should have been a 4 or 5. We don't have 4.5 hurricanea, compared to say, a 7.1 earthquake. We know the release of energy much more precisely from earthquakes than we do for hurricanes, but even two earthquakes of the same magnitude won't produce the same amount of damage due to epicentral depth, local landforms, and a whole host of variables. We have had category 3 (maybe it was a 3.9) hurricanes that produced mcuh more damage than some category 4's. Who really cares if it was a 4 or 5? The damage and loss of life is what's important, and that won't change by recategorizing a storm. Seems like a lot of wasted energy for not much return. Of course, I'm willing to enlightened on why this issue is so vital to some of you.


For me, looking back on hurricanes after the fact, an important part of figuring out how they work and studying them scientifically is having the most accurate description as possible.

The category system is an ok metric to say roughly what a hurricane might do, damage-wise, but it really doesn't tell you nearly as much as looking at central pressure, wind speed, integrated kinetic energy, potential storm surge, etc, etc.

Another problem with the past data is that getting accurate measurements (is/was) difficult, with many of the "recorded" results being satellite estimates based on 6 or 12 hour intervals.

And yet another issue with some of the data stems from the fact that the organization generating the data has public safety as a primary goal. The unnamed hurricane (the perfect storm) was intentionally left unclassified to not cause panic in the public. Perhaps other numbers were altered slightly due to public safety considerations? (I'm not saying this is a bad thing in general ... only bad in terms of getting scientifically accurate data).

In summary, I think what you're seeing here is some doubt of the accuracy of past measurements ... which could be for any number of reasons. At least, that's my take on it.
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Quoting sunlinepr:
What a killer storm....Very sad those photos...


I could post more but don't want to give anyone nightmares. Some very shattering photo's coming out via twitter.

I wonder if Dr Masters will do his next blog on Washi/Sendong.
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What a killer storm....Very sad those photos...

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.