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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456, I think some have said "wave " as in "that thing out there ". I think you and others made it clear earlier that it was not a Tropical Wave.
seen
My bad; I didn't check the charts before I posted. It does, however, strongly resemble a wave/tropical wave disturbance at first glance at a satellite image.
Usually Moderate risks out three days have a good chance of eventually being upgraded to High risk.
Exerpt from tomorrow's outlook:
A FEW
TORNADOES...SOME STRONG...WILL ALSO BE POSSIBLE AS THE LOW-LEVEL
FLOW IS PROGD TO REMAIN SSELY BENEATH STRONGLY VEERING PROFILES
BETWEEN SFC-1KM. THE SVR RISKS WILL CONTINUE WELL INTO THE
NIGHT...LIKELY EXPANDING N AND E WITH AN ADDITIONAL RISK OF DMGG
WIND GUSTS ACROSS NCNTRL/NE TX INTO CNTRL/ERN OK AND PSBLY WRN
AR/SWRN MO.
Excerpt from Thursday's outlook:
...A HIGH SRH ENVIRONMENT AND MOIST BOUNDARY
LAYER WILL SUPPORT AN APPRECIABLE RISK FOR TORNADOES...SOME OF WHICH
COULD BE STRONG/LONG TRACKED. OTHERWISE...WIDESPREAD DAMAGING WINDS
AND LARGE HAIL ARE LIKELY.
whatever happens with this (nothing!), blob-watching season '08 is officially underway!!
..but I don't think it has any implications for the season. Even if it becomes a tropical storm (yeah right), it won't signal anything bad. Monster seasons are foreshadowed by such occurances as Cat 5s in July.
THE ITCZ IS PRETTY ACTIVE E OF 20W. IT AXIS IS CENTERED ALONG
4N10W 2N20W...THEN ALONG THE EQUATOR BETWEEN 30W AND 40W INTO NE
BRAZIL. A SFC TROUGH IS ANALYZED ON THE 12Z MAP ALONG 14/15W
WHERE SATELLITE IMAGERY SHOWS AN AREA OF MODERATE TO STRONG
CONVECTION. ANOTHER SFC TROUGH IS INTRODUCED ALONG 36W FROM 5N
TO 10N. VIS SAT PHOTOS REVEAL A WELL DEFINED CYCLONIC TURNING
ALONG THE TROUGH AXIS NEAR 8N. SCATTERED MODERATE CONVECTION IS
WITHIN 200 NM E OF TROUGH AXIS. MOISTURE ASSOCIATED WITH THIS
FEATURE IS FORECAST BY THE COMPUTER MODELS TO MOVE WWD REACHING
50W LATE FRIDAY OR SATURDAY.
And storm dude your welcome. Check out my site and subscribe if you wish.
If there is any cyclonic turning associated with the wave, it will be transient in nature. This won't develop this far out in April. If anything, it should serve as a reminder that the hurricane season is fast approaching.
hehehehe
And I notice how pottery and Weather456 said that it wasn't a tropical wave. My bad. I'll listen to them before listening to myself. I may know a lot about tropical weather, but I trust them more than I do myself.
Even so, it should still serve as a reminder the season is fast approaching.
into its normal preseason position thats it
fun to watch test out all the old sat links
I think I'm gonna set my hair ablaze....
You can catch a good view from this loop.
in which iam hoping the cloud cover will cool it a little sst wise
ATLANTIC OCEAN...
A RIDGE/TROUGH/RIDGE PATTERN IS OBSERVED ACROSS THE DISCUSSION
AREA. THE RIDGE AXIS EXTENDS NWD ALONG 65W CROSSING BERMUDA. A
BROAD UPPER LEVEL TROUGH IS OVER THE E ATLC WHILE ANOTHER RIDGE
DOMINATES WEST AFRICA AND THE IBERIAN PENINSULA. A JET STREAM
BRANCH WITH CORE WINDS OF 90 TO 110 KT IS ALONG THE BASE OF THE
UPPER TROUGH EXTENDING FROM 29N33W ALL THE WAY NE OVER PORTUGAL
AND SPAIN. ANOTHER WIND MAXIMA UP TO 90 KT IS SEEN BETWEEN THE
CANARY AND THE CAPE VERDE ISLANDS. BROAD E/W UPPER RIDGE COVERS
THE TROPICAL BELT WITH AN UPPER LEVEL ANTICYCLONE NEAR 10N18W.
lol
I will step off the soap box now.
long time no see.
New space station crew rockets into space
By Clara Moskowitz, SPACE.com Link
W456 - What is the difference between African Easterly Wave and a Tropical Wave? Does one have different characteristics than the other?
I'm confused...is this a tropical wave or not?
At this moment, its not a wave.
Extreme. Just because June is the official start of the hurricane season that doesent mean that Nothing can happen untill then. The only reason June-November is hurricane season is because tropical cyclones dont usually form in the months before or after that.
I absolutely agree. If this wave-like feature was occuring during hurricane season when the environment was more favorable this thing would have more of a chance. I wouldn't rule anything out though.
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