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Author Topic: 'implausibly stationary ice' as a method of shoal discovery  (Read 17031 times)

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #50 on: January 26, 2020, 09:12:33 PM »
A new row of candidates in the ESS further south.

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #51 on: January 31, 2020, 11:06:05 AM »
S1 close up of the lower candidate in the above post. The small island in blue, something just visible in the possible shoal area (marked, top left).  cffr

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #52 on: February 18, 2020, 08:54:13 PM »
Another candidate (seen before) further east of NSI. 2 are visible on these images. ctr

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #53 on: March 20, 2020, 12:36:20 PM »
ESS-4S, 72.77N 161.30 is visible again. https://go.nasa.gov/3a59ov2

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #54 on: April 10, 2020, 11:20:04 PM »
using rammb to verify anchored ice.  https://col.st/U5EeI
2 in this image
« Last Edit: April 10, 2020, 11:27:00 PM by uniquorn »

Freegrass

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #55 on: May 19, 2020, 09:14:11 PM »
Blum just told me about this thread, so I'll duplicate my message from the newbie thread here.

Last year we had a small discussion here about grounding icebergs in the Arctic ocean, because I thought that one got stuck on the seafloor in the ESS.

This year I'm seeing that bottom-fast ice again (bottom right corner), and it's doing something weird. It seems to be blocking a whole lot of ice inbetween it, and another bigger piece of fast ice.

I noticed it yesterday already, but waited another day to see if that very little piece of ice against that little round piece of BFI would be able to hold that entire icebridge in place. And it seems it was. Quite amazing...  :o

Ocean depth there is around 15 meter according to this GMRT map tool, and I haven't found prove yet that this ice is stuck on an underwater island. Although I do believe that's what it is that this fast ice is stuck to. Maybe someone should take a dive there to update the bathymetry charts?

Anyway...
What do you think is happening here?
90% of the world is religious, but somehow "love thy neighbour" became "fuck thy neighbours", if they don't agree with your point of view.

WTF happened?

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #56 on: May 19, 2020, 10:39:50 PM »
what is the lat/lon?

Freegrass

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #57 on: May 19, 2020, 10:58:08 PM »
It's in the moose head in the ESS. Worldview.
Is there an easy way to copy those Lat/Lon numbers from Worldview?
The little one is 73°14.000'N, 151°04.000'E
90% of the world is religious, but somehow "love thy neighbour" became "fuck thy neighbours", if they don't agree with your point of view.

WTF happened?

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #58 on: May 19, 2020, 11:26:16 PM »
Please see post#34. Thanks for confirming their reappearance this year. There are some suggestions for causes upthread also.

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #59 on: May 23, 2020, 03:28:51 PM »
3 or 4 large areas of anchored ice in the Laptev.
uni-hamburg amsr2-uhh, may1-22.

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #60 on: June 12, 2020, 12:01:56 AM »
cross postinghttps://forum.arctic-sea-ice.net/index.php/topic,2417.msg268267.html#msg268267
https://www.mdpi.com/2072-4292/8/1/4/htm
Sea-Ice Wintertime Lead Frequencies and Regional Characteristics in the Arctic, 2003–2015
by Sascha Willmes and Günther Heinemann
Quote
and in the East Siberian Sea, some less known features exhibiting high lead frequencies are indicated north of the Kolyma Gulf (D).

« Last Edit: June 12, 2020, 12:09:16 AM by uniquorn »

blumenkraft

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #61 on: July 20, 2020, 03:12:45 PM »
Due to a request from Freegrass. i repost the GIF i posted in the Melting Chatter thread.

Location: ESS. Band: Day&Night via RAMMB-SLIDER.


Freegrass

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #62 on: July 20, 2020, 03:23:39 PM »
Thanks Blum. I'm sure Uniquorn will appreciate this.
Can we call this The New Siberian Islands Barrier Reef?
90% of the world is religious, but somehow "love thy neighbour" became "fuck thy neighbours", if they don't agree with your point of view.

WTF happened?

blumenkraft

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #63 on: July 20, 2020, 03:52:33 PM »
I'm not in the naming business but go ahead. The maker is always right. ;)

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #64 on: July 20, 2020, 08:26:39 PM »
Thanks. The anchored ice has been quite spectacular with such quick melt. Not sure if this paper was linked to before. This year may pose problems for subsea permafrost.

Understanding the Permafrost–Hydrate System and Associated Methane Releases in the East Siberian Arctic Shelf
https://www.mdpi.com/2076-3263/9/6/251/htm
Quote
2.2. Current State of Subsea Permafrost
ESAS permafrost stability is the key to whether pre-formed CH4 sequestered in hydrate deposits escapes to the overlying strata. Warming of the ESAS began >12 thousand years (kyr) ago at the beginning of the Holocene after the ESAS was inundated by sea water due to rising sea level. Terrestrial permafrost in the Holocene Arctic experienced a change in its thermal regime caused by a 6–7 °C mean annual air temperature increase since the last glacial maximum [31]. Subsea permafrost has been subjected to additional warming induced by sea water; in the ESAS, sea water is much warmer than air (mean annual air temperature of −10 °C vs. mean annual sea water temperature of −1 °C). Consequently, the subsea permafrost has warmed by up to 17 °C during the last 12 kyrs [23,32]. It has been suggested that the following factors determine the evolution of subsea permafrost after inundation: duration of submergence compared to duration of previous exposure above the sea surface; thermal state and thickness of permafrost before inundation; coastal morphology and hydro- and lithodynamics; shoreline configuration and retreat rate; pre-existing thermokarst (thermokarst is the process by which characteristic landforms result from the thawing of ice-rich permafrost or the melting of massive ice) accompanied by formation of thaw lakes; bottom water temperature and salinity; and sediment composition, including ice content

added JayW's ani for reference
« Last Edit: July 20, 2020, 08:45:33 PM by uniquorn »

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #65 on: November 13, 2020, 11:51:16 PM »
shoal hunter  ;)

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #66 on: February 04, 2021, 12:03:25 PM »
Possible shoal sightings. amsr2-uhh ess, jan28-feb3
Ice to the north and west of NSI looking fragile.

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #67 on: July 25, 2021, 10:12:51 PM »
3 shoals east of NSI on jul7, 2 on jul25

https://go.nasa.gov/2UP5295     6.5MB

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #68 on: August 18, 2021, 03:17:52 PM »
Still a few small areas of anchored ice remaining in the ESS, aug9 and 18

SimonF92

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #69 on: August 18, 2021, 06:03:00 PM »
uniquorn, it occured to me that you can use code to highlight differences (or similarities) between images

This needs work, but it could be a way of automating this



from skimage.metrics import structural_similarity as compare_ssim
import argparse
import imutils
import cv2

imageA = cv2.imread('1.jpg')
imageB = cv2.imread('2.jpg')

grayA = cv2.cvtColor(imageA, cv2.COLOR_BGR2GRAY)
grayB = cv2.cvtColor(imageB, cv2.COLOR_BGR2GRAY)

(score, diff) = compare_ssim(grayA, grayB, full=True)
diff = (diff * 255).astype("uint8")
print("SSIM: {}".format(score))


thresh = cv2.threshold(diff, 0, 255,
cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)[1]
cnts = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL,
cv2.CHAIN_APPROX_SIMPLE)
cnts = imutils.grab_contours(cnts)

for c in cnts:
# compute the bounding box of the contour and then draw the
# bounding box on both input images to represent where the two
# images differ
(x, y, w, h) = cv2.boundingRect(c)
cv2.rectangle(imageA, (x, y), (x + w, y + h), (0, 0, 255), 2)
cv2.rectangle(imageB, (x, y), (x + w, y + h), (0, 0, 255), 2)
# show the output images
cv2.imshow("Original", imageA)
cv2.imshow("Modified", imageB)
cv2.imshow("Diff", diff)
cv2.imshow("Thresh", thresh)
cv2.waitKey(0)
Bunch of small python Arctic Apps:
https://github.com/SimonF92/Arctic

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #70 on: July 25, 2022, 12:48:00 PM »
Thanks, might have time for that one day.

A good year for eyeballing southern shoals, many of the northern ones have already melted out.

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #71 on: August 18, 2022, 06:40:24 PM »
anchored ice in the ESS is perhaps more common than we thought. Note the 6 or more small dots, enlarged inset bottom left. There are at least 4 larger examples.
rammb aug15-18         https://col.st/4xg4V

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #72 on: October 14, 2022, 04:57:39 PM »
Wondering if the anchor persists or refreezes upwards from permafrost during the freezing season and becomes a seed for surface ice formation.
awi sic-leads v110, ESS, oct9-13

oren

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #73 on: October 14, 2022, 05:38:58 PM »
I would think it freezes from the top and then catches on the bottom, but I could be very wrong.

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #74 on: October 14, 2022, 08:20:08 PM »
Submarine pingo's are a possibility and the ingredients are all there. Depth is ~20m, if the anchored ice is on shoals, possibly less.

Permafrost of the east Siberian Arctic shelf and coastal lowlands
N.N. Romanovskii, H.-W. Hubberten, A.V. Gavrilov, V.E. Tumskoy, A.L. Kholodov
10.1016/j.quascirev.2003.12.014

extract:
Quote
In the 1990s, the results of joint Russian–German seismo-acoustic sounding and sampling of bottom sediments in the Laptev Sea proved that relic offshore permafrost is widespread all over the shelf. It was also found that the permafrost table has an uneven surface (Romanovskii et al., 1998a, b). The upper acoustic boundary was interpreted as a surface of ice-bearing permafrost. This conclusion was supported by drilling data within the shelf performed in September 2000 (Kassens et al., 2000). Deep seismic sounding on the Laptev Sea shelf (to the north and northwest of Kotel’nyi Island) confirmed the presence of permafrost in this area. The second acoustic boundary was detected at depths from 300 to 700 m; this boundary was attributed to the bottom of the ice-bonded permafrost(Hinz et al., 1998).

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #75 on: October 15, 2022, 01:50:50 PM »
The increase on oct13 looks like a weather front passing over. Southerlies at -3.5C are forecast, see what happens next. If the warm easterlies come after we probably won't see anything.

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #76 on: October 20, 2022, 11:03:47 AM »
update on possible ice formation over ess shoals. The first point persists, the second becomes more prominent. Could be ocean currents.
awi sic-leads v110, oct15-19

uniquorn

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #77 on: May 16, 2023, 12:01:41 PM »
Anchored ice over shallow shoals stick out like a sore thumb this year.
awi sic-leads and terra https://go.nasa.gov/3Muup89 (heavy contrast)

oren

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Re: 'implausibly stationary ice' as a method of shoal discovery
« Reply #78 on: May 16, 2023, 06:30:19 PM »
Nice. Have we ever found out the depths at these locations? I keep wondering what thickness/keeling of ice is needed for the phenomenon to materialize.