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Andreas Muenchow
Newark, DE
Sea-going physical oceanographer
Interests: Greenland, gardening, table tennis, dining
Recent Activity
Nares Strait is indeed a fascinating story with many facets. Here is one that relates to both the ice arches of Nares Strait and those of gothic cathedrals, it is a marvelous Open University video
http://podcast.open.ac.uk/oulearn/mathematics-and-statistics/podcast-mst209-arch-never-sleeps#!238ba3834b
Erase and rewind
I don't know what the most interesting forum thread on the planet was last week, but this week it's definitely the Nares Strait thread, over on the Arctic Sea Ice Forum. All who regularly follow Arctic events, know that one of the coolest places in it is Nares Strait, the waterway between Elles...
@Terry: I agree with your sentiment, but the connection may be on longer than annual time scales. The 2006/07 winter season had no icebridge in Nares Strait at either its northern or southern entrance. The 2007/08 winter season only had a southern bridge for less than 60 days while the 2008/09 winter in Nares Strait saw lots of open water and thin ice because a solid northern ice bridge was in place from Jan.-17 through July-7 of 2009. The strange period ended with the 2009/10 season when the northern bridge only formed for less than 30 days. Since the 2010/11 season, we had the "normal" solid northern and southern ice arches in place for well over 150 days in each winter. So, almost free ad almost year-round flux of thick Lincoln Sea ice through Nares Strait took place in 2006/07 and 2009/10 only.
2014 Nares Strait ice bridges
This remains one of my favourite fascinating events in the Arctic. University of Delaware professor in oceanography Andreas Muenchow, the Nares Strait go-to guy, posted the following on his Icy Seas blog: Formation of Nares Strait Ice Bridges in 2014 Darkness and cold covers North Greenland, El...
The USCGC Healy in 2003 entered Nares Strait from the south, as did every other surface vessel (we do not know about submarines). All data from this 2003 expedition are public and posted in easy-to-use ASCII format at http://www.udel.edu/CATS/index.html ... use as you see fit. The first ship to enter the northern reaches was HM Discovery in 1875 commanded by Sir George S. Nares. The last ship to enter the same waters was the CCGS Henry Larsen who reached its farthest north in 2012 near 82 degrees and 15 minutes north.
Open Thread February 2013
The previous open thread has gotten full enough, so here's a new one. We might want to kick off with this animation made by commenter A-Team: His comment: Don't miss this -- it's happening right now, by the hour -- so head on over to 80N 150W. A huge fracture has been opening a bit east of B...
Just added a new perspective as I just learnt how to access NASA's IceBridge data which includes laser altimeter and ice-penetrating radars that scan the underbelly of both Greenland's and Antarctica's ice-sheets, glaciers, ice-shelves, and much more. Happy times ...
First Petermann Ice Island photos
REMEMBER: There are two days left to vote on the poll widgets in the right hand bar, one is for Cryosphere Today minimum daily sea ice area, the other for NSIDC minimum September/monthly sea ice extent. You can also re-vote if you like by going to the polls directly (here for NSIDC minimum month...
The Gulf Stream is NOT changing direction unless you count or pick the right time and the right spot of the many wiggles, meanders, and eddies that are all a normal part of it. Once the Gulf Stream reaches the Grand Banks off Newfoundland (all the fog there is the meeting of the sub-polar Labrador waters inshore and the sub-tropical waters offshore) the tightly focused Gulf Stream becomes the more diffuse North-Atlantic Drift current. If you average long enough in time over a large enough regions, you will get the net heat flux that keeps northern Europe's climate so mild. It is not correct to talk about this broader more diffuse drift to the north-east (yes, it has on occasion southward elements here and there) as the Gulf Stream. I think Neven a few weeks ago summarized all this very eloquently .
Oh, and the "deepest" connection of the Arctic to the Atlantic is Ocean to the west of Greenland is indeed, as Terry points out, the 200-220 meter deep sill in Nares Strait where it is winter already with new ice forming.
PIOMAS October 2012 (minimum)
We already knew a few weeks ago that the PIOMAS sea ice volume record had been broken, but with the latest data release by the Polar Science Center at the University of Washington we now know the minimum sea ice volume for 2012, as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation...
Nice find of a paper, Espen. I had not seen it, but always love to read what people were thinking 40-50 or 100-150 years ago as it often puts the present into a larger perspective. If only the day had more hours or one could get by with less sleep ... to read more or to apply new edge detection codes to quantify motion and change while also account for mountain shadows. Devils and details.
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
Sorry for double posting, the Santer et al (2011) non-paywalled version is at
http://muenchow.cms.udel.edu/classes/MAST811/Santer2011.pdf
Tom Wagner of NASA explains
Hat-tip to Climate Denial Crock of the Week: He's good!
It is a very slippery slope to claim that "denialists" are 95% wrong or misleading in their claims while "alarmist" are only 35% wrong or misleading. I do not like labels and refuse to enter this slippery slope making "predictions" that are little more than "educated guesses."
More on topic, please be careful when you argue with the North Atlantic Oscillation Index. It describes variations only, it contains no trends, the average of the NAO is ZERO. So, everytime someone argues with strong NAO+ phases does this, there are NAO- phases which do the opposite. More formally, the NAO is the first and dominant principal component of atmospheric pressure that explains no more than 1/3 of the variance in winter. Variance explained is lower in other seasons.
And finally, also on-topic, a 10-year record is too short to make statements related to warming as this Los Alamos press release https://www.llnl.gov/news/newsreleases/2011/Nov/NR-11-11-03.html and the Santer et al (2011) paper indicates (non-paywalled manuscript is at http://muenchow.cms.udel.edu/classes/MAST811/Santer2011.pdf)
Tom Wagner of NASA explains
Hat-tip to Climate Denial Crock of the Week: He's good!
This is a very good interview indeed, because it is nuanced, detailed, and explains the physics and their implications real well without resorting to drama or manipulation-by-omission. Sadly, such tactics are found too often on both sides of the political argument that bends data and analysis to a pre-conceived notion that (a) all change is "unprecedented," (b) global warming is the culprit of all change, or (c) climate change and global warming is a hoax. The ice-ocean-air-land global system is way too complex and nonlinear for any discipline of science to come up with a definite answer. This does NOT invalidated Richard Alley's concise statement that "If the earth warms more, Greenland is going to melt more ..." And yet, I feel, we have to be careful to not over-hype each weather event, even if it is a rare weather event that occurs only every 80-250 years or so. The melt reported by NASA this week was a rare weather event, as Dr. Wagner explains rather well.
Tom Wagner of NASA explains
Hat-tip to Climate Denial Crock of the Week: He's good!
River discharge from Watson River, Greenland:
It appears that best estimates of annual averages are perhaps closer to 250 m^3/s which is slightly smaller than the discharge from the Delaware River (330 m^3/s). This does not mean that peak discharges cannot reach much larger values, but a short pulse may not reflect the importance of this element in the mass balance of Greenland. My source is http://www.the-cryosphere.net/6/199/2012/tc-6-199-2012.pdf that I still have to read more careful than a 10 minute browse. I wonder if there are other gauged rivers around Greenland and if a scaling law exists that relates catchment area (and/or temperature and/or something) to discharge for land-based glaciers or ice sheets. I know such laws exist for mid-latitude rivers as well as Alaska's many streams and rivers ... but Greenland?
Unprecedented Greenland Ice Sheet Surface Melt
This just in from NASA (hat-tip Apocalypse4Real): Satellites See Unprecedented Greenland Ice Sheet Surface Melt July 24, 2012: For several days this month, Greenland's surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire...
Geostrophic dynamics (Coriolis balancing pressure gradients) only work away from boundaries or when friction is negligible. At boundaries (such as the ice or the ocean or the bottom of the ocean or atmosphere) friction enters. If friction is balanced by the Coriolis force, then you get an Ekman spiral. So, lets put this together (Neven is right, largely):
Low pressure system atmosphere, counter-clockwise (geostrophic) flow aloft, friction between air and ice/ocean results in convergence of air (bottom boundary layer atmosphere) and upward motion (like in hurricanes), counter-clockwise winds force ice and/or surface ocean at an angle to the right of the winds (northern hemisphere) which gives a divergence in the ocean boundary layer, the divergence lowers sealevel (ocean) causing pressure gradients to which then the ocean currents below the boundary adjusts geostrophically, that is, low pressure atmosphere, low pressure ocean, counter-clockwise circulation in both. Boundary layer flux, however, is in opposite directions in atmosphere (bottom boundary) and the ocean (surface boundary).
Search Ekman pumping ... this is how most of the oceans are forced by the winds, indirectly via pressure gradients due to convergences or divergences in boundary layers ... all physics is beautiful ... geophysical fluid dynamics even more so ;-)
Peeking through the clouds
When low-pressure areas take over the Arctic, they do two things: make the ice pack diverge and increase cloudiness. The diverging of the pack is hidden by the clouds, but we can sometimes see the holes in the ice pack through holes in the cloud cover on the LANCE-MODIS satellite images. We saw...
Oh boys, The Daily Mail turned Werther's YouTube link into a story:
http://www.dailymail.co.uk/news/article-2177617/Glacier-watchers-bargain-falling-wall-ice-creates-tsunami.html?ito=feeds-newsxml
but we all read it here first ;-)
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
Petermann does NOT work that way, I described the Petermann calving to some media folks as a gentle and very quiet affair similar to a rubber duckie pushed out to sea from the deck of a flat pool.
I wait until your post, Neven, then I can either reference back and find an angle that you did not cover. Humbold Glacier, the next glacier south from Petermann may calve this way, perhaps, as it does not have a floating ice shelf, I think.
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
Werther:
Whow ... and thank you so much for sharing, I'll use this in my future classes as this is oceanography 101 in dramatic action ... and, please, someone tell Neven quickly, if he does not make a blog post on this, I will. This video has all the drama and immediate human impact with very simple physics that the Petermann calvings do not.
It is a dam-breaking problem that has analytical solutions that I blogged about in the link given, but it applies here as well. Physics is both grand and universal, that's why I love it.
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
Espen:
The first paragraph of the original report settles it:
http://muenchow.cms.udel.edu/html/Coppinger1876.pdf
The link above does not work because a stupid "]" got in the way. Notice the very precise description as "On leaving Cape Tyson and Offley Island, which were considered to mark the north-east side of the mouth of the [Petermann] fjord ..."
These are the people who described places and geographies that had not been seen or visited by anyone not an Inuit. Amazing how clear they wrote ... no photography either, they had to paint and sketch ... no GPS, they had to use sextants and the stars to get latitude and keep time very accurately to get longitude. None of these are trivial matters while camping with poor equipment in the wilderness believing that there perhaps was open water at the North Pole.
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
Most welcome, but the name of the island appears to be "Offley" [British Parlimentary Papers from 1877, that I, hopefully legally, posted at http://muenchow.cms.udel.edu/html/Coppinger1876.pdf] This is also the first report that I am aware of that mentions and maps Petermann Fjord and Glacier.
Fun reading and considering how far we all have come in a mere 150 years ... Perhaps, if we'd do our explorations the way it was done then, we'd have more ice now as global warming and climate change would not be a factor impacting ice as it sure does now ...
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
The July-14, 2012 Terra image at 23:15, e.g., http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2012196231500-2012196232000.250m.jpg does show the crack that has been advancing for at least 8 years, but it does not show the crack of the image earlier that day showing clouds or cloud shadows. Sea smoke forms when there is a large temperature difference between the surface ocean at freezng (-1.7 deg.-C) and the air as is common during the winter, but rare in the summer.
I think the island opposite to Joe Island at the entrance to Petermann Fjord is called Offrey Island on NOAA charts, but the spelling may be wrong, especially from a Danish perspective. A bottom pressure sensor to measure tides we deployed there in 2003 was lost and presumably destroyed by ice, as we could not recover it in either 2006 or 2007. We are planing to move an automated weather station from the Canadian Cape Baird to Joe Island in 2-3 weeks from now ... if the ice island stays inside the fjord and/or we can savely get to Joe Island via helicopter from the ship. Exciting stuff either way ...
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
We are about 4 days short of spring tide in adjacent Nares Strait which is forcing the tide in Petermann Fjord as determined by the model of Padman and Erofeeva (2004) which agrees very well with (sealevel and velocity) observations in Nares Strait. A problem in tidal (and other modeling) is that we do not know something as basic as the bottom depth inside the fjord. We had hoped to improve on this for the area where the ice shelf disappeared in 2010, but the new calving may very well prevent such work as no sane sailor will be caught to the north of the new ice island. As it moves towards Nares Strait, we will only be able to survey seaward of the ice island. If it moves into Nares Strait, we will only be able to work to the south of the ice island. So, I hope it stays where it is, but that is unlikely.
Petermann calves again
Petermann Glacier has calved another large ice island, about half the size of the calving of two years ago, which amounts to about two Manhattans. This is what it looks like: This second big calving (spotted this time by Arcticicelost80) is another spectacular event on Greenland this year, fol...
The ice arch at the southern end of Nares Strait extending into Kane Basin is very solid and has been in place since at least Dec.-8, 2011. I thought it was about to collapse when I noticed it change its shape, but it turned out that new ice formed making it look as if it had moved when it did not. Processed and gridded Nares Strait MODIS visible and thermal imagery in a common frame and projections can be found at http://muenchow.cms.udel.edu/MODIS/index.html for almost every day since 2000-present. I expect this ice arch to hold another 3-4 weeks before it collapses. This will allow thick, old, multi-year ice to leave the Arctic via this gate.
ASI 2012 update 5: when graphs agree
During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily IJIS sea ice extent (SIE) and Cryosphere Today sea ice area (SIA) numbers, which I compare to data from the 2005-2011 period (NSIDC ha...
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