The climate is changing: the Arctic Dipole emerges
The dramatic loss of Arctic sea ice in recent years has created a fundamental new change in the atmospheric circulation in the Northern Hemisphere that has sped up sea ice loss and is affecting fall and winter weather across most of the Northern Hemisphere, according to several recent studies. Arctic sea ice loss peaks in September and October, exposing a large area of open water that heats the air above it. This extra heat has helped drive September - November air temperatures in the Arctic to 1°C (1.8°F) or more above average over about half of the depth of the lower atmosphere (Figure 1). This deep layer of warm air has grown less dense and expanded, pushing the top of the troposphere (the lower atmosphere) higher. The result has been a decrease in the pressure gradient (the difference in pressure) between the North Pole and mid-latitudes. With not as much difference in pressure to try and equalize, the jet stream has slowed down in the Arctic, creating a major change in the atmospheric circulation for the Northern Hemisphere.
Figure 1. Cross section of Arctic temperature anomaly from 1000 mb (the surface) to 300 mb (roughly, the height of the top of the lower atmosphere or troposphere). Cross section is taken along the Date Line (180°W), from 60°N latitude (left side) to the North Pole (right side), for September - November for the 12-year period 1998 - 2009. Three year averages were done to reduce the amount of year-to-year noise associated with natural variation. Other cross sections along different lines of longitude show similar results, though typically with more warming aloft and less warming at the surface. Image credit: NOAA/ESRL.
A new atmospheric pattern emerges: the Arctic Dipole
In a 2008 article titled, Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system Zhang et al. show that the extreme loss of Arctic sea ice since 2001 has been accompanied by a radical shift of the Arctic atmospheric circulation patterns, into a new mode they call the Arctic Rapid change Pattern. The new atmospheric circulation pattern has also been recognized by other researchers, who refer to it as the Arctic Dipole (Richter-Menge et al., 2009). The old atmospheric patterns that controlled Arctic weather--the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO), which featured air flow that tended to circle the pole, now alternate with the new Arctic Dipole pattern. The Arctic Dipole pattern features anomalous high pressure on the North American side of the Arctic, and low pressure on the Eurasian side. This results in winds blowing more from south to north, increasing transport of heat into the central Arctic Ocean. The Arctic Dipole pattern occurred in all summer months of 2007 and helped support the record 2007 summer reduction in sea ice extent (Overland et al., 2008). Overland et al., 2010 also found that the Arctic Dipole pattern tended to create an increase in easterly winds in the lower half of the atmosphere of 40% in fall, between 2002 - 2008. Fall 2008 through spring 2009 featured the old AO pattern. The new Arctic Dipole pattern re-appeared in June - July 2009, but the old AO pattern dominated in August - September, resulting in greater sea ice extent than in 2007 and 2008. The Arctic Dipole pattern was active again in October, inactive in November, and reasserted itself this December. As a result, Arctic sea ice reached a new record minimum for a 10-day period in early November, increased above record lows during late November and early December, and appears poised again to reach a new record minimum later this December (Figure 2).
Figure 2. Sea ice extent in the Arctic for this year (blue line) compared to the record low year of 2007 (green line) and 1979 - 2000 average (gray line). One could make the ice loss looks less significant by using the full satellite data record from 1979 - 2008 for the average. Image credit: National Snow and Ice Data Center.
Arctic Dipole blamed for colder winters in East Asia
It turns out that the new Arctic circulation patterns help to intensify the Siberian High, a large semi-permanent region of surface high pressure prevalent in winter over Siberia. According to Honda et al. (2009), this results in increased flow of cold air out of the Arctic in early winter over eastern Russia, Japan, Korea, and eastern China, causing colder temperatures. By late winter, the pattern shifts, resulting in colder than average temperatures from East Asia to Europe.
Arctic Dipole blamed for drier winters in Northern Europe
Francis et al. (2009) found that during 1979 - 2006, years that had unusually low summertime Arctic sea had a 10 - 20% reduction in the temperature difference between the Equator and North Pole. This resulted in a weaker jet stream with slower winds that lasted a full six months, through fall and winter. The weaker jet caused a weaker Aleutian Low and Icelandic Low during the winter, resulting in a more negative North Atlantic Oscillation--a pattern that usually brings reduced winter precipitation over Alaska and Northern Europe and increased precipitation over Southern Europe. A more negative NAO also tends to bring cold winters to eastern North America and Europe. Though it was not mentioned in the article, reduced Arctic sea ice may also cause dry early winter conditions in the U.S. and the Caribbean (Figure 3). The authors noted that strong La Niña or El Niño events can have a much larger influence on the wintertime atmospheric circulation, which will overshadow the changes due to Arctic sea ice loss.
Figure 3. Difference in early winter precipitation (November - January) between five years that had low Arctic sea ice (2005, 2006, 2007, 2008, and 2009), and five years that had unusually high Arctic sea ice extent (1981, 1984, 1986, 1989, 1993). Note that low sea ice may be responsible for dry conditions in early winter for the Caribbean and most of the U.S.
Commentary
Arctic sea ice loss appears to have created a new atmospheric circulation pattern that brings more warm air in the Arctic, creating a positive feedback loop that causes even more sea ice loss. This feedback loop increases the likelihood that an ice-free Arctic in the summer will indeed come by 2030, as many Arctic experts are predicting. It's worth noting that such an atmospheric circulation shift was not predicted by the climate models. Indeed, the loss of Arctic sea ice over the past three years exceeds what any of our models were predicting (Figure 4). While we can rightly criticize these models for their inaccuracy, we should realize that they are just as capable of making errors not in our favor as they are of making errors in our favor.
Figure 4. Arctic sea ice extent from observations (thick orange line) and 13 model forecasts used to formulate the 2007 IPCC report (light lines). The thick black line is the multi-model ensemble mean, with the standard deviation plotted as a dashed black line. Image has been updated to include the observed 2008 and 2009 measurements. None of the models predicted the record 2007 sea ice loss. Image credit: Arctic sea ice decline: Faster than forecast by Stroeve et al., 2007.
References
Francis, J.A., W. Chan, D.J. Leathers, J.R. Miller, and D.E. Veron, 2009, "Winter Northern Hemisphere weather patterns remember summer Arctic sea-ice extent", Geophysical Research Letters, 36, L07503, doi:10.1029/2009GL037274.
Honda, M., J. Inoue, and S. Yamane, 2009. Influence of low Arctic sea - ice minima on anomalously cold Eurasian winters, Geophys. Res. Lett., 36, L08707, doi:10.1029/2008GL037079.
Overland, J. E., M. Wang, and S. Salo, 2008: The recent Arctic warm period, Tellus, 60A, 589.597.
Overland, J. E., and M. Wang, 2010: Large-scale atmospheric circulation changes associated with the recent loss of Arctic sea ice. Tellus, 62A, 1–9.
Richter-Menge, J., and J.E. Overland, Eds., 2009: Arctic Report Card 2009, http://www.arctic.noaa.gov/reportcard.
Simmonds, I., and K. Keay (2009), Extraordinary September Arctic sea ice reductions and their relationships with storm behavior over 1979.2008, Geophys. Res. Lett., 36, L19715, doi:10.1029/2009GL039810.
Wu, B., J. Wang, and J. E. Walsh, 2006: Dipole anomaly in the winter Arctic atmosphere and its association with sea ice motion. J. Climate, 19, 210-225.
Zhang, X., A. Sorteberg, J. Zhang, R. Gerdes, and J. C. Comiso (2008), Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system, Geophys. Res. Lett., 35, L22701, doi:10.1029/2008GL035607.
Jeff Masters
Reader Comments
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It has to be atleast cool in Dec
Depends what am I trading for LOL?
That was actually written by our friends at the NOAA/NCEP, not myself. They were stating that computer models past 7 days are basically useless. My 3 year old grand daughter, Lilye, could probably do a better job of forecasting the weather for Christmas :0)!!
Snoopy expressing his frustration at the latest GFS models for 12-21 through 12-28-09
The main factor if you ask me attributing to these summer like temps is the location of the jet stream relative to south Florida.The core of the jet stream has extended from northern Mexico across the northern Gulf of Mexico to the mid-Atlantic and northeast United States. The location of the jet stream typically marks the approximate track of winter storm as they move from west to east across the nation. The southwest-to-northeast orientation of this jet stream across the Gulf coast is significant in that it prevents cold fronts and their associated cold air masses from penetrating too far south into Florida. As a result, recent cold fronts have either stalled right over south Florida or not made it this far south, keeping the region mainly on the warm side. Another contributing factor is an area of high pressure in the middle and upper levels of the atmosphere that has been nearly stationary over the Greater Antilles and Bahamas .The northern edge of the dome of high pressure area has extended far enough into south Florida to help keep cold fronts north of our region.
Although El Niño winters usually bring wetter and cooler than normal temperatures to south Florida, they are also marked by a stronger than normal southern jet stream.Till now the jet stream has stayed far enough to the north to keep the cooler and wetter weather just to our north. In fact, much of the southeast United States has been cooler and wetter than normal. Even within south Florida, slightly cooler and wetter conditions have been observed along the southwest Gulf coast and Lake Okeechobee region compared to southeast Florida as fronts have been able to barely clear those areas before stalling over southeast Florida. A slight shift in the jet stream pattern and an eastward retreat of the high pressure over the Greater Antilles and Bahamas is all that it would take to bring the cooler air masses down to south Florida. As the winter progresses, look for the possibility of these southward shifts in the jet stream pattern which could bring periods of wetter and cooler conditions forecast for this winter.
Adrian
ROFLM"B"O: Oh, gee, it would be such a pity to get banned -- let's wait for a CC/AGW discussion! I'm so sorry, I think I'm too old to even qualify as "Cougar."
On a semi-serious note, only semi-...modest home in DC suburbs, not too far from 3 metro stations...comes with 2 ankle-biters, hubby will prob. stay in his "man-cave"...how inviting is that (NOT)! Suggest you wait 'til Cherry Blossom season! Still LOL'ing...
That's good, too! Spring & Fall here good...the rest is "eh" -- and I know you know that, for a fact!
Would not doubt that one bit! When I read some of the the weather bulletins or statements, I wonder what they are thinking when the are writing. I have come to the conclusion, they are not thinking at all that much.
NCEP's full statement, for your laughing pleasure!!
Statement on the Use of GFS Output Beyond Day 7
There is some concern about NCEP model variability from run to run, particularly at extended ranges beyond 7-8 days. The American Meteorological Society Statement adopted on January 14, 2001, titled "Statement on Seasonal to Interannual Climate Prediction" (Bull. Amer. Met. Soc., 82, 701), states, in part, the limit of predictability for day-to-day weather changes for deterministic forecasts is "in the range of 1-2 weeks." NCEP agrees with this statement and notes that for current state-of-the-art models, the limit of "useful skill" is about 7-8 days. Beyond that range, deterministic numerical weather predictions are characterized by little or no skill and suffer from large run to run variability. However, ensemble or probability forecasts may offer improved predictive skill.
Another AMS statement adopted January 13, 2002, titled "Enhancing Weather Information with Probability Forecasts" (Bull. Amer. Met. Soc., 83, 450), praises the value of probability forecasts and endorses ensemble model forecasts as a means for improving skill levels in the extended ranges while quantifying the level of certainty (uncertainty) in any forecast. NCEP agrees with this statement. NCEP currently runs a global and regional ensemble of forecasts twice per day which present information on the predictability of a forecast out to day 16 in a more quantitative way. Global Ensemble Products can be accessed at this research website: http://wwwt.emc.ncep.noaa.gov/gmb/ens/
NCEP is working to making these ensemble forecasts products more readily available. In the meantime, we recommend using the GFS, or any global forecast system, with care beyond day 7 and recognizing the inherent variability in long range deterministic forecasts. Also recognize that probability forecasts, while providing much more flexibility and value to the user, require the user be trained to properly understand and use the new product suites based on ensemble model output. Some relevant training material can be found at http://www.hpc.ncep.noaa.gov/ensembletraining/
For ensemble output on shorter time scales with finer resolution see this research web site: http://wwwt.emc.ncep.noaa.gov/mmb/SREF/SREF.html .
The NWS is seeking comments about this web page and access to NCEP's ensemble products. Please send comments to: NCEP Public Liaison
That's ok DC is far too cold for me. Tennessee is my cut off line. Can't live in anything north of there LOL.. It's a cool city though been there twice. Traffic is brutal though..
Here are a few "compiled" excerpts from some high school students writing examples. It reminds me of some statments I have read here of late. I hope you enjoy them. Hope none of them ever become writers for a weather station.
Without the Greeks, we wouldn't have history. The Greeks invented three kinds of columns - Corinthian, Doric and Ironic. They also had myths. A myth is a female moth. One myth says that the mother of Achilles dipped him in the River Stynx until he became intolerable. Achilles appears in "The Illiad", by Homer. Homer also wrote the "Oddity", in which Penelope was the last hardship that Ulysses endured on his journey. Actually, Homer was not written by Homer but by another man of that name.
Socrates was a famous Greek teacher who went around giving people advice. They killed him. Socrates died from an overdose of wedlock.
A dose of "wedlock"!! Ha, ha, ha!! I thought it was a dose of "hemlock".
And none of the high school students are "smarter than a 5TH grader"!!
I'll WU some more to you. I don't want to take up the space on the blog. They are funny, but actually taken from texts.
Yea I cant seem to find it again either...
That name is reserved for another site. Grothar if you please.
I have gone back over the previous posts and can not find it. It was interesting. Perhaps if Drak or xcool come on they might know.
Socrates died from an overdose of wedlock.
And then, there was rich geezer, died with a smile on his face, husband of:
Anna Nicole Smith, a former stripper whose grieving-widow outfit at the funeral of her 91-year-old millionaire husband of a few months included an exposed nipple.
Now that is more like it. Thanks, saved me a lot of time. A friend of mine asked for it from Long Island. Wanted to know if they might have a White Christmas, since they are actually rare on Long Island.
No snow here.... :(
While I'm gone, would somebody please call roll? I wrote Mrs. Floodman, and left a post on her blog (LongStrangeTrip), but no reply yet. I hope the Flood's are still just very busy with Christmas and grandkids, per one of her previous posts. Presslord I think has their phone no.?? Hope.
Also how is NRAAmy doing in California...is TornadoDude actually studying? Are xcool, Patrap surviving NO flooding, MS and TX bloggers, too?
Thanks, BBL! You're great to have on the Blob, er Blog. But I see you've already moved up to the Intermediate Class, dang; I'm going to be in Remedial Weather class forever!
I have been here for years and this in my first model post...LOL...you got me me beat for sure!!!
12z for pat
Where is everyone getting those maps?
Joe who???
Thanx!!!
-0-Z=6 pm CST
18Z=12 NOON
UTC or Z is 6 hrs ahead of CST. It's the official time used when making weather forecasts.
Im definitely liking this scenario
He has been here for YEARS...honestly it seems like decades. We can't get rid of him. We've tried everything- Round-Up, Raid, mothballs, even an angry mob carrying pitchforks and lanterns.
Auburn's posting on DocMaster's blog now...God help us.
Did I mention were 13 and 0 ?
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