Arctic sea ice melting season begins
The annual Arctic melting season has begun. We've just passed the Spring Equinox, so the North Pole is now in 24-hour daylight. Will the melting of Arctic sea ice this year surpass last year's record? Well, we have a greater areal extent of ice over the Arctic this month compared to April of last year, thanks to some cool Arctic temperatures this winter. In particular, the ice in the Bering Straight between Alaska and Russia extends quite a bit further south than in 2007. This extra ice will likely delay the melting season a bit this year, giving some hope that we won't surpass last year's record melt. However, if weather similar to last summer occurs--unusually clear skies and high pressure over the Arctic--this extra ice will not help much, because it is all thin, first-year ice. It is the thick, 2-9 year old ice that is most able to resist summer melting, and the amount of old multi-year ice is only about half of what it was in 2007. This is apparent from images taken by the QuikSCAT satellite, which carries the SeaWinds scatterometer. This instrument emits a pulse of microwave energy that bounces off the ice and returns to the satellite. Old, multi-year ice is thicker, and reflects a different amount of microwave energy back to the satellite than thin ice, resulting in a whiter image. Thin, first-year ice appears a darker grey. It is apparent from Figure 1 that we have only about half of the old, multi-year ice that we had last year. In fact, thin first-year ice extends past the North Pole, raising the distinct possibility that this year's melt will allow one to sail a ship all the way to the North Pole in September, for the first time since humans began testing Arctic waters with ships in 1497. In addition, a large region of the old ice north of Alaska is highly fractured, making it vulnerable to melting.
Figure 1. QuikSCAT images of the Arctic from April 4, 2007 and April 4, 2008. The boundary of old, multi-year ice is marked in yellow, and 2008 has about half the old ice of 2007. Image credit: NOAA/NESDIS/ORA.
How did we lose so much old ice in the past year?
Part of the lost old ice melted during the record-breaking melt season of 2007, which was fueled both by global warming and a natural (but unusual) sunny summer. Another big chunk of old ice was lost due to natural wind patterns between September 2007 and March 2008. An animation of the sea ice available from Environment Canada's sea ice page (click on "Updated QuikScat animation") reveals that strong winds pushed large amounts of old ice out of the Arctic southward along the east coast of Greenland. So, we can't blame the melting of the Arctic sea ice entirely on global warming--natural weather patterns also played a significant role.
The forecast
It's impossible to guess what the dominant Arctic weather pattern will be this summer, and what level of melting we will get. With the loss of so much old ice over the past year, though, even an average summer has the potential to melt much more ice this summer compared to last summer--all the way to the North Pole. There's also a good chance that we'll see the fabled Northwest Passage open up again, since most of the ice along the Passage is young, first-year ice. We'll just have to wait and see how the summer unfolds.
Jeff Masters
Reader Comments
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The big tornado outbreaks are not frequent ... fortunately. The outbreak in early February this year was a scary day.
Is that you or Mo? LOL
".. No! That blob is going to become a CAT 6.."
".. The Blob will become a TD in an hour, its written in stone.."
".. Tis here blob gone an done poofed.."
".. Now you see here, this Blob will do its own thing.."
".. Those clouds are Decressing, its dying!.."
".. Just Durinal Cycles, tonight its going to go strong.."
The Typical Day at Mission Control Center latley during Hurricane Season, apparently the CAPCOM found weatherunderground, and now NASA listens to them only.
that actually doesn't sound to bad
what is this thing in the eastern far atlantic? is this the first wave of the 2008 season? there is some rotation near 10n 35w. if this is a wave then it is an ominous sign for the coming season.
Not wanting to hype anything.......but wow that sure starting to look very tropical in formation......geeessssshhhhhhhhh.
Keep a Jaundiced eye on the Atlantic,
Dissapointments are Probable
Organisation is Possible
Pretty pictures are Planned.
In all seriousness though, a nice formation ?
Not too early to look at the Dust and dry air . In fact, there has been very little of it this year so far. If the Itcz keeps creeping north, then the conditions that allow that may also tend to supress the flow of SAL into the Trop Atl.
I dont recall seeing things quite like they are now, before. ( not that "before " goes back very far ! )
Not looking for a forecast, but rather a brief summary of what may be causing what looks like a moist itcz in April, a little north than usual ?
Thanks.....
The Sahara dust is also interesting because last year as some of that made it over to FL., we notice that horses w/respiratory problems "seemed" to get worse that period of time last year when it was heavy in the air. I never noticed this stuff before, but as I learn more I begin to observe more.
I would have to say that there are some very powerful waves with spin coming off of Africa now.
Good Morning Folks.....The ITCZ has been very healthy for the past few weeks....Still too early to tell what will happen with conditions around August when the Cape Verde season kicks in but we could get a lot of very healthy waves this year (whether they actually develop and make it across the Atlantic is another matter)........
If you notice here there is very little, if any SAL in that region. Also, here you can see the wind shear is not totally unfavorable. Maybe a better visual of this would be in TampaSpin's post 618. Also, if conditions are favorable in Winter, then it will develop. I'm not saying this will, nor am I hinting it. But by the same token, a storm won't develop in September, if conditions aren't right. And as far as the ITCZ goes, I'm not sure either. :-)
MJO stands for.......?
Enjoying my new highspeed connection, so I can keep up with you guys.......
Try this
The Madden-Julian oscillation Link
what is this thing in the eastern far atlantic? is this the first wave of the 2008 season? there is some rotation near 10n 35w. if this is a wave then it is an ominous sign for the coming season.
Its a weak wave or pertubation but I donot know if its a tropical easterly wave. It does consist of a low level trough and vort max near 925 mb mb. TPW loop clearly shows a westward moving wave-like cyclonic feature interacting with upper level southwesterly flow near 35W. Upper vapor winds and divergence show this southwesterly flow is associated with an upper ridge axis extending from West Africa to 50W. Surface divergence is ahead of the "axis" and surface convergence behind. Typical of waves. QuikSCAT show very weak cyclonic (trough) flow at the surface. Given that, I would say the area is just a low level reflection of upper level energy.
This is getting interesting.
Thanks again.
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