Barrow Sea Ice Break-up: Dark Open Water In Late April

Barrow Sea ice break-up late April

(Image source: Barrow Sea Ice Cam.)

The warming trend that we provided predictive analysis for yesterday has barely even begun and we already have visible dark, open water off Point Barrow, Alaska as of late Tuesday evening on April 29.  A large polynya that had opened up off the northern Alaskan coast has now extended well past Barrow and landward toward the near-shore waters. By late evening, the open water had invaded to within about 200 yards of shore along and past the Point Barrow coastline.

In broader summary, the open water polynya stretches from Cape Lisburne to past Point Barrow and measures between 20 and 50 miles in width. General trends show this large polynya continuing to expand northward into the Chukchi Sea, a motion that is likely to continue for at least the next few days.

Some cooling will likely return after the currently building Arctic heatwave, but it is questionable if it will be enough to result in a refreeze given the prevailing and much warmer than usual conditions.

Sea ice break-up at Point Barrow typically begins in mid-to-late June. It often involves both the formation of open water offshore as well as sea ice motion near-shore. Though the polynya removed ice from the off-shore waters of Point Barrow today, the near-shore ice still remains grounded, so this admittedly impressive event cannot technically be considered a break-up. That said, it appears that we are seeing a very early initiation of melt conditions for the Barrow region.

With warmer weather settling in, heat stresses to the local and regional sea ice will likely continue to ramp up. So, in other words, this early season melt event has only just begun.

large polynya April 28

(Large polynya extending from Cape Lisburne to about 80 miles past Point Barrow on April 28. The polynya continued to enlarge even as it invaded the near-shore regions of Point Barrow on April 29th. Image source: LANCE-MODIS.)

Links:

Barrow Sea Ice Cam

LANCE-MODIS

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Barrow, Alaska: Near-Shore Ice Rapidly Melting, Off-Shore Ice — Gone

Offshoreicebarrowjune25Gone

(Image Source: Barrow Ice Cam)

Barrow’s sea ice has borne a number of pretty severe insults over the past week. First, an Arctic heatwave sent Alaskan temperatures soaring to 98 degrees (F) in the interior, the highest temperatures ever recorded for the state. This heat pulse extended far above the Arctic Circle pushing temperatures at Barrow as high as 65 degrees (F) even as flows of warm water flooded into the Chukchi Sea from Alaska’s baked center. These high temperatures spurred an early break-up of Barrow sea ice last week. A break up that proceeded about three weeks ahead of schedule. Then, an ice-melting rain settled in, pelting the sea ice over the past three days.

Now the offshore ice is simply gone.

As you can see in the image above, huge sections of near-shore ice are melted and broken with large areas dominated by dark Arctic water. But offshore is were the greater effects have occurred. Over the past 24 hours, the off-shore ice has shrunk back and now only open ocean is visible on the horizon.

Ice break-up at Barrow occurs when off-shore ice at distances greater than 200 meters from shore begins to move. This event usually occurs on about July 8th. This year it happened on June 20th. Now, less than a week later, the ice that first broke has disappeared.

It will take a little longer for the near-shore ice to melt out. But the most important ice off Barrow — the sea ice — is now departing, retreating into a pack that is rapidly receding from the Chukchi Sea.

You can view the retreat of off-shore ice in the radar sequence below:

Note the ongoing parallel motion to shore and then the lifting away of sea ice during the last sequence.

These radar shots were taken on June 24. So final recession of sea ice occurred only four days after break-up.

Today’s radar shots from Barrow show only small chunks of sea ice remaining from a once-large pack.

Barrow Ice Radar June 25

(Image source: Barrow Ice Cam)

We can now say farewell to significant sea ice at Barrow, Alaska for the rest of this summer. Melt will now begin to proceed past the Chukchi Sea and into the Beaufort and East Siberian. This will likely have significant impacts once Beaufort ice begins to break as a Gyre in the center of the Sea begins to increase ice mobility and melt. Already, anchors have been weakened by both rapid melt in the Chukchi and by a large pulse of warm floodwater flowing out of Alberta via the Mackenzie Delta. This pulse of water is a direct result this week’s Canadian floods. So we’ll have to see what impact these warm flood waters have on the shore area of the Beaufort over the coming week.

Last of all, it is worth mentioning that this year’s Persistent Arctic Cyclone has tended to push more ice into the Beaufort. Over past years, the Beaufort has been much more vulnerable to melt come late July through mid-September. With early melt rapidly proceeding from the Chukchi and with areas in Canada and Alaska vulnerable to floods and heatwaves, this critical region of buffering ice will increasingly come into play as melt season progresses. The new dynamic of a PAC hollowing out the central ice as Beaufort melt and ice motion begin to crank up raise the potential for a number of volatile outcomes.

So eyes will shift to the Beaufort as these new potentials emerge.

Links:

Barrow Sea Ice Webcam

Alaskan Heatwave Sends Temperatures to 94 Degrees

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