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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
Toggle Commented Feb 13, 2015 on Erase and rewind at Arctic Sea Ice
@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.
Toggle Commented Jan 31, 2014 on 2014 Nares Strait ice bridges at Arctic Sea Ice
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.
Toggle Commented Feb 15, 2013 on Open Thread February 2013 at Arctic Sea Ice
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 ...
Toggle Commented Nov 13, 2012 on First Petermann Ice Island photos at Arctic Sea Ice
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.
Toggle Commented Oct 5, 2012 on PIOMAS October 2012 (minimum) at Arctic Sea Ice
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.
Toggle Commented Sep 13, 2012 on Petermann calves again at Arctic Sea Ice
Sorry for double posting, the Santer et al (2011) non-paywalled version is at http://muenchow.cms.udel.edu/classes/MAST811/Santer2011.pdf
Toggle Commented Jul 27, 2012 on Tom Wagner of NASA explains at Arctic Sea Ice
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)
Toggle Commented Jul 27, 2012 on Tom Wagner of NASA explains at Arctic Sea Ice
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.
Toggle Commented Jul 27, 2012 on Tom Wagner of NASA explains at Arctic Sea Ice
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?
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 ;-)
Toggle Commented Jul 24, 2012 on Peeking through the clouds at Arctic Sea Ice
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 ;-)
Toggle Commented Jul 23, 2012 on Petermann calves again at Arctic Sea Ice
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.
Toggle Commented Jul 21, 2012 on Petermann calves again at Arctic Sea Ice
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.
Toggle Commented Jul 21, 2012 on Petermann calves again at Arctic Sea Ice
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.
Toggle Commented Jul 21, 2012 on Petermann calves again at Arctic Sea Ice
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 ...
Toggle Commented Jul 21, 2012 on Petermann calves again at Arctic Sea Ice
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 ...
Toggle Commented Jul 21, 2012 on Petermann calves again at Arctic Sea Ice
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.
Toggle Commented Jul 17, 2012 on Petermann calves again at Arctic Sea Ice
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.
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Jun 19, 2012