A lot of MYI went through the garlic press in 2017
The channels of the CAA have blued notably in worldview over the last ten days (cloudy), accompanied by loss of ice concentration in UH AMSR2 (below), which may prelude an early opening of the main Northwest Passage (northern route).
I haven't chased down all the years and dates of first opening but 1998, 2007, 2008, 2010, 2011, 2012, 2015 and 2016 are among them. The easiest way to do this objectively is with a color picker set on open water blue and a concentration range on a montage of Aug-Sep UH AMSR2 3,125 km.
That would make possible ice export through the garlic press given consistent winds pushing from the north down the basin edge. This would be significant primarily for loss of remaining 3
+MYI, not so much for Arctic Ocean volume.
Last summer, garlic press export ran for some 101 days from August 18th to November 26th as shown in the mp4 below. Export through the Nares and Fram are not notably coordinated with it. It's not possible to foresee when the export route will open nor what the winds will be doing when it is.
The last two months would not have resulted garlic press export even if the passage had been open. Indeed, surface winds have been largely anemic and incoherent for much of the spring, reflecting lack of a persistent MSLP pattern.
Winds flow along pressure contour lines (geostrophically) in proportion to how fast pressure changes with distance between highs and lows (gradient). Ice moves in accordance to the forces exerted on its sails (ridges and edges) by sub-2 m winds which are very inconvenient meteorologically.
We've seen previously that the entire ice edge from Morris Jesup to Banks Island is in motion throughout the year, ie the very thickest CAA basin ice is not attached in any significant way to the shoreline or shelf bottom.
This means at peak peripheral open water in late summer, there is nothing pressing the residual ice pack against the Canadian shore other than the historic air pressure pattern. The residual ice pack could conceivably drift off to the north, ending the season as an island of thick ice surrounded by new FYI.
Neither currents nor tides have much of a role here on floating ice export per Ascat-AB; the thick berg that came down to block the channel above Lowther Island on Nov 6th (day 312 below, discussed way up-forum) may be the rate-limiting step in opening of the passage this year.
[As noted earlier by others, interpretability of UB SMOS as ice thinness in the inner CAA deteriorated rapidly in early June; some value might remain when consistent over several consecutive cold days without passing weather or when trending locally. Piomas and many other tools struggle with low resolution pixels having a foot on both islands and water. Sentinel-1AB rarely images the entire NW Passage even in 3 day composites because of spreading swaths from its orbital inclination.]
