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Peter2010

nice anim as usual Neven, and curious timing.
the ol saying springs to mind, great minds think alike.

its looks like another 3 days of reverse flow if the Russians have it right
http://www.aari.nw.ru/clgmi/forecast/show_drift.asp?fign=0&lang=0

indicates stronger reverse flow for today and tomorrow (10th,11th,12th), compared to yesterday reverse flow start.
should be interesting to see its affect on the region.

Neven

Peter2010, if it's okay with you I'm reposting your comments on this matter that you posted on the SIE update thread:


Andrew, I believe that large chuck off Alert is due to the flow reversal in the Nares Straits that started yesterday.

http://www.bing.com/maps/?v=2&cp=82.042~-61.548&lvl=9&cid=4AF6474AAB468769!116&eo=0

The speed of reverse flow of much warmer water from the Straits back into the Arctic basin is 14km a day (point 16 to point 17). Each day this continues, I would expect significant melting within 30km radius from the mouth of the Straits, growing each day as roughly 500km2 area of water is pushed back into the Arctic.

Alert is within 20km of the Straits entrance. and this is first time I've see a reverse flow this year(it may have occurred I just haven't spotted it, no buoy data to verify it)

Will the Flow End date be the same as 2009?, my own prediction is that this will be extended by at least a week due to the thinner ice now permeating in the Arctic basin around north of Greenland.

note - reverse flow has a bigger impact on ice extent in Arctic basin then normal out flow at this time of year due to the pumping of 500km2 of warm water back into the basin region. how to quantify 'bigger impact' will be seen over coming days.

Neven

nice anim as usual Neven, and curious timing.

What a coincidence, eh?

the ol saying springs to mind, great minds think alike.

What does that have to do with us? :-B


On-topic: I didn't even know this was possible. This is one crazy melt season so far.

Nick Barnes

What drives the Nares Strait current? Is it the Beaufort Gyre? In which case, maybe this is simply the result of the Gyre stalling and reversing.

andrewt

My guess had been the strong southernly winds of previous days probably pushed that large chunk of sea ice off the shore at Alert, maybe with their warmth assisting by producing some surface melt at the shoreline.

Maybe their local effect is sufficient to reverse the ice flow in Nares Strait?

Evilreductionist.blogspot.com

This has been a very bizarre melt season. There is no way that I would have expected these kinds of things. And have you seen the roos graph and the surge in area? Weird. Could it be that Goddard is correct? Have we and groups like PIOMAS and NSIDC misread things?

Steve Bloom

Never forget that Goddard is the proverbial stopped clock when it comes to these things, ER. He'll be right occasionally, but it will always be for the wrong reasons. Regardless, it's always a mistake to draw conclusions from trends of a few days.

Anu

@ Evilreductionist.blogspot.com | July 12, 2010 at 03:03

Greenland has 44,000 km of coastline - the 'coastline' of Arctic sea ice now is probably about 100,000 km. Ice floes drifting a few km one way or another on a few of these coastlines can change the "30% sea ice extent" number pretty easily one way or another.

Look at the actual sea ice area:
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Area.png
(download to zoom in if you want to see it better)
2003,2004,2005, 2007 and 2008 all had a horizontal stall in sea ice area loss - 2007 even went up in late June. But then, all the years recovered and went on to plunge pretty directly to their summer minimums.

Note that 2010 is 2nd lowest, in the measured satellite era, for this date.
And plunging right along with 2007 in sea ice area.

I've been predicting since Spring a summer minimum below 2009, based mainly on the trends:
http://nsidc.org/images/arcticseaicenews/20091005_Figure3.png

The day to day and week to week events are interesting to watch unfold, but there are 2 more months to melt season, and I would be very surprised if the summer minimum is above that of 2009.
Not so surprised if below 2008, too.
Somewhat surprised if below 2007.

Anu

Neven,

Looking at the big picture as the final two months of melt season are about to unfold, I've been looking at Arctic Sea Surface Temperatures as shown here:
http://ocean.dmi.dk/satellite/index.uk.php
(geographical domain 'Arctic Ocean', or click on the North Pole in the lower left)

They also archive about 30 days of previous plots here:
http://ocean.dmi.dk/satellite/plots/
For example, here's 7/1/10, as of now:
http://ocean.dmi.dk/satellite/plots/satsst.arc.d-10.png

I don't know how accurate these maps are - they seem to miss some open water in the Laptev Sea that I've noticed. But otherwise, it gives an interesting view of the open water heating up (sunlight, or perhaps currents from the Pacific and Atlantic for some Seas), the sea ice coast melting (cooling the water next to the sea ice coastline), then the water heating up again. It seems to happen in successive waves.

Note the Beaufort Sea, Chukchi Sea, Kara Sea, and Baffin Bay seem to be warming and ready for a new pulse of rapid sea ice melt.

You can choose Time step "30 days ago" and step through (>) or press Animation "Play" to see 30 days of these warming Seas eat away at the central Arctic Basin sea ice (and some outliers, like in Baffin Bay) .
http://ocean.dmi.dk/satellite/index.uk.php

If somebody ambitious, like yourself, grabbed these archived plots as they became available, you could animate 90 days at the end of the summer :-)

I really don't understand why sites like DMI don't archive things longer - disk space is so cheap these days, and it seems citizen/scientists are getting more interested in playing with online data... if they just saved all these plots for 2009, 2008 and 2007, I could see how the surrounding Seas warmed and melted sea ice at each stage of the summer melt, and how it varies from year to year. One image is only 123 KB - 10 years of these images would only be 438 MB. I think archive policies at sites like http://arctic.atmos.uiuc.edu/cryosphere/
and
http://ocean.dmi.dk/arctic/icecover.uk.php
should be reconsidered in the era of cheap Terabyte disks.

Lord Soth

It is interesting that this slowdown in extent has kept up for almost two weeks now, but it is the volume that counts. And everyday that goes by, that ice is getting thinner and is becoming more fragmented. Those Century melts are coming back, and they will be fast and furious, when they do.

Neven

I have said from the very start of this blog that the record would be broken if weather conditions approached those of 2007. Obviously they have been the opposite of 2007 conditions for the last two weeks. It's as simple as that.

It's still relatively early in the season, so if the AO and especially DA become positive again, I would also expect another series of heavy melt. If that doesn't happen, regardless of the optimal weather conditions for melting, we might start to conclude that the ice in the Arctic Basin was particularly thick this season.

But at this moment I say that it would defy all logic.

Neven

Anu, thanks for those links. I might do an animation of those some time soon. I totally agree that it would be great if we could download graphs and maps from the past, because then you could really start comparing (like I did for instance with the Uni Bremen ice concentration maps).

Nick Barnes

Look at the quality of the ice in the central arctic, as pointed out by Lord Soth a couple of days ago, and clearly visible again today: http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r04c04.2010193.terra.250m

The lower-left corner of the image is the north pole. The lower edge is 90E, the left-hand edge is 180E. So this is the central arctic pack ice, which Goddard assures us is thick, solid, impregnable, guaranteed to survive this melt season. Right?

Pan down the left-hand-side of the image, from top to bottom, scanning over approximately 1000 kilometres of ice, across (on my screen) about a 250km front. I've had cocktails with more ice in than this. The pole itself is obscured by cloud, but we have no reason to think that the ice there is intact. Even 200km from the pole (i.e. north of 88N) there are huge leads, and concentrations of maybe 80%.

Peter Ellis

Anyone have any idea what's happened to North Pole webcam #1? It's not sent any pictures since the 7th. The colocated buoy seems to be still transmitting location data / temp / pressure etc. Wonder if the webcam's fallen over into a melt pond (or even sunk?)

Peter2010

The Nares Strait flow reversal continued at increased speed yesterday(11/7 flow +50% compared to 10/7)
With 21.7km reversal flow speed recorded by Boey 7440 yesterday. (fastest daily flow recorded by Boey 7440)

Thats a total 35km in 2 days, or in water volume terms
Area of water : 1,330 km(squared)
volume of water : 38km(width) X35km(length) x.4km(dept) = 532km(cubed)

I like the analogy of plunger on a sink hole,

I'm still trying to get a basic understanding of the strait hydro dynamics, lots of facters involved such as salinity, currents, tides, winds etc.

One draft paper called 'Nares Strait Hydrography and Salinity Field From a Three-Year Moored Array' yet to be approved for publication in journal of geophysical research,
is illuminating regarding the complex interaction of fresh water coming out of the basin and more saline deep water going in.

http://www.earth.ox.ac.uk/~helenj/work/publications/Berit1.pdf

I like the sink plunger analogy to describe the effect of the this flow reversal, causing increased turbulence in the Roberson channel, and the straits entrance, shifting and breaking up of multi-year land-fast ice and shelves.


Sunday reverse flow - pin 17 to pin 18
http://www.bing.com/maps/#JnE9LjgyJTQwMjIwNSsrKystNjAlNDAyNzgzJTdlc3N0LjAlN2VwZy4xJmJiPTgyLjQ4NTkwNzgyMDgxMTQlN2UtNTUuMDk0OTA1NTE3NTc4MSU3ZTgxLjM5MjIzOTkwMTglN2UtNjcuNzczMTI4MTczODI4MQ==

Neven

Thanks, Peter! It's great that you're keeping an eye on this and keeping us up-to-date.

Nick Barnes

(a) what is the depth of the Nares Strait? (b) surely the movements of sea ice only provide information about the surface waters? I see no reason to suppose that any deep water currents which might exist in the Strait are affected by whatever is causing these reversals.

Glacierchange.wordpress.com

A good view of the Physical Oceanography and also your depth question is contained in the Munchow and Melling (2008) paper

Nick Barnes

A fascinating paper which I don't have time to read in detail. Sections 4 and 5, and figure 9, seem to apply: over longer timescales channel flow averages 0.57+-0.09 Sv, mostly geostrophic (i.e. Coriolis), but at short timescales - from tidal up to weekly - reverse flows are possible across the whole depth; these may be driven by wind friction.

logicman

The prevailing wind in the Nares Strait is a low level strong wind that drives ice into Baffin Bay. The 'reversal' appears to me to be a strong wind driving the ice to the Greenland coast. That wind has been blowing for some time and has strengthened, blowing more diagonally from Ellesmere Island to Lincoln Sea. This has pushed ice into the Petermann Glacier outlet bay and Lincoln Sea, but the flow from Kane Basin remains fairly normal.

Take a look at the MODIS image for July 11. There is a vee-shaped line of algal bloom, and two curved areas of open water. This appears to be caused by strong winds from top left corner blowing about 45 to 50 degrees to right of image.
http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010192.terra.1km

The clouds in the adjacent image show that the wind is localised: other ice flows are normal.
http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c02.2010192.terra.1km


As I noted in a comment in my blog, a large area in Lincoln Sea and beyond is covered with meltwater pools. As soon as the flow normalises there will be a very dramatic loss of ice from that area.

Factor in the incredibly open state of the ice near the pole, as noted by Lord Soth and Nick Barnes and the ice volume is headed for a nose-dive.

Account Deleted

Buoy 7440 has moved out of the Nares strait
http://iabp.apl.washington.edu/maps_daily_naresstrait.html

David Klein

Lord Soth | July 10, 2010 at 16:23

I am not so concerned about 2010 crossing of the 2007 graph, because the extent will probably be somewhere between 2007 and 2008. After 2007 the arctic gained ½ million KM2 in 2008 and another ½ million KM2 in 2009 approx.
The first year ice in 2008 became 2nd year ice in 2009. The late melt start of 2010 (26 days compared to 2009) did not basically alter the extent; 13.96 KM2 on March 5 and 14.41 KM2 on March 31 i.e. 45,000 KM2.
Both 2009 and 2010 started with an extent of 14.41 million KM2 but by the time 2010 started its melt, 2009 had melted 440,000 KM2 at a rate of 17,000 KM2/day, which gave 2009 a head start of 440,000 KM2 on March 31.
Between 31 March and 12 July, 2010 has dropped from 14.41 million KM2 to 8.16 million KM2, a drop of 3.44 million KM2 @ 61,000 KM2/day.
For the same period 2009 dropped from 13.97 million KM2 to 8.69 million KM2, a drop of 5.28 KM2 @ 51,000 KM2/day. (103 days)
So far, 2010 has had 9 100K+ days and 2009 had 7. After today, 2009 had another 7 100K+ days, of which 5 sequentially, starting 21 July.
Between July 12 and September 13, 2009 melted an additional 3.44 KM2 @ 55,000 KM2/day.
Assuming that 2010’s remaining melt season will average 2009, including 5-7 100K breaks, averaging 55,000 KM2/day and assuming the same end date of 13 September, then 2010 will come out similar to 2008 and likely less.
I think that Lord Soth is right, we are likely to see some spectacular melts. In my view, 2010 quickly disposed of all 1 year ice and a lot of 2 year ice. Even though the extent rate of decrease has slowed, the loss in volume is not, which will predict the near future scenario. If there is no spectacular collapse this melt season, then 2011 is bound to have. I'm less optimistic but still do not rule out breaking the 2007 record.

andrewt

Fractures opening west of Ellef Ringnes Island
http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r04c02.2010193.aqua.500m
I guess by the strong Southerly winds recorded at Isachsen:
http://text.weatheroffice.gc.ca/forecast/24_hour_conditions_e.html?wic&unit=m
Alert has simialr winds:
http://text.weatheroffice.gc.ca/forecast/24_hour_conditions_e.html?ylt&unit=m

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