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Brigantine

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Re: What the Buoys are telling
« Reply #1850 on: April 17, 2018, 01:52:22 AM »
That ARGO Float north of Svalbard has finally surfaced again, and transmitted data from 5 profiles stretching back to April 4.

On April 1 - before the wind blew ice over that location - the water was a uniform ~2.3C ~34.95 PSU to ~350m depth. Then there's a thermocline down to ~1.6C at 500m depth, with no data below that.
(though per the GPS location the water is ~1500m deep, ~100km NNW of Nordaustlandet in the middle of a steep slope which drops from ~800m in the East to ~2200m in the West)

The next profile on April 4 had a new ~50m deep minty (presumably ice-related) layer on top, ~34.5 PSU and temp somewhere between freezing and +1C. The Atlantic layer was barely changed - still uniform temp & salinity from 50m to 320m depth. (Typical stratified layers for the Arctic, but maybe saltier than usual?)

Then on April 7, the Atlantic layer is no longer uniform. The density is similar, but there are large areas of minty water scattered through. My interpretation is that the minty water mixed up from below, as the buoy drifted further away from the continental shelf flooded with saltier Atlantic water, and out into a proper Arctic Ocean thermocline. There's also a gradual halocline from ~20m depth (~34.35 PSU) to ~150m (~34.95 PSU still).

After that, the spicy and minty patches in the Atlantic layer start to mix away and the profiles look more and more like a typical profile from ITP 95 did last year, peaking at ~2.0C and ~34.92 PSU at ~300m depth.

The co-ordinates of the profiles from April 4 to April 13 look like they're interpolated, but the profile on April 16 is in ~2500m deep water in the middle of a small deep basin to the North of Spitsbergen, connected in the NE to the Eurasian Basin.
(April 1: 81.310N 016.726E on the slope; April 16: 81.600N 014.320E in the basin)

be cause

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Re: What the Buoys are telling
« Reply #1851 on: April 17, 2018, 11:30:55 AM »
spicy and minty ?
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

Brigantine

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Re: What the Buoys are telling
« Reply #1852 on: April 17, 2018, 11:56:59 AM »
colder water is denser, and saltier water is also denser... so you can have comparatively cold fresh (minty) water and then warm salty (spicy) water, both at the exact same density.

So it's an axis transformation. Instead of using temperature and salinity to describe the water, you can describe it in terms of density and spiciness.
(the relationships between temperature, salinity and density are not quite linear, but at least conceptually it's useful)

Basically I just mean that some water is warmer/saltier/colder/fresher without implying anything about the relative buoyancy.
« Last Edit: April 17, 2018, 12:03:01 PM by Brigantine »

Tor Bejnar

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Re: What the Buoys are telling
« Reply #1853 on: April 20, 2018, 03:53:25 PM »
Just noticed this January post on Andreas Muenchow's Icy Seas Blog.  Just-retrieved moorings from near the NE corner of Greenland (Fram Strait) show currents coming from the south dominate and are stronger at depth.  Winds at the NE corner of Greenland (map) are usually from the north.
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Re: What the Buoys are telling
« Reply #1854 on: May 06, 2018, 07:49:12 PM »
Just came across this - a small update on O-Buoy 14
"Hunters found OB-14 near Gates Head island in the west Victoria Straits while Polar Bear hunting recently (March 2018)"
There is a picture at the link - http://www.o-buoy.org/

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Re: What the Buoys are telling
« Reply #1855 on: May 06, 2018, 08:23:19 PM »
great find, just before i was reading your post i was somehow pissed of that we don't have that and other buoys anymore. i'm not usually tending to fanboyism but i was kind of fan of those buoys of which the last one died last fall.

Eli81

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Re: What the Buoys are telling
« Reply #1856 on: May 07, 2018, 06:41:05 AM »
Just came across this - a small update on O-Buoy 14
"Hunters found OB-14 near Gates Head island in the west Victoria Straits while Polar Bear hunting recently (March 2018)"
There is a picture at the link - http://www.o-buoy.org/

And they didn't hit the reset button?!   :o :-\  >:(  :'(

 ;D

JayW

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Re: What the Buoys are telling
« Reply #1857 on: May 17, 2018, 11:14:23 AM »
"To defy the laws of tradition, is a crusade only of the brave" - Les Claypool

uniquorn

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Re: What the Buoys are telling
« Reply #1858 on: May 17, 2018, 01:11:23 PM »
ITP100.
http://www.whoi.edu/page.do?pid=160116
Edge of the chukchi plateau is one of my favourite spots. I didn't know there was a buoy there.
https://forum.arctic-sea-ice.net/index.php/topic,2278.msg153075.html#msg153075
It hasn't been quite so cloud free recently.

edit: That's quite a temperature spike. Found a bit of open water maybe?
Worldview terra/modis may16, 78N 150W
« Last Edit: May 17, 2018, 04:40:54 PM by uniquorn »

Hyperion

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Re: What the Buoys are telling
« Reply #1859 on: May 20, 2018, 06:08:47 PM »
Ta brigs for that Argo link. Couldn't find them when you mentioned they before.

Latest from you one nth of Svalbard 19 may. At 82.2 nth 17.6 east must be into the ice now.
Seems there's a lot of
Quote
minty
melt cooled water plummeting beneath the
Quote
spicy
warmer stuff. Half a PSU is not a stable haloclinic stratifier

http://www.usgodae.org/cgi-bin/argo_profplot.pl
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Brigantine

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Re: What the Buoys are telling
« Reply #1860 on: May 20, 2018, 11:18:11 PM »
Thanks for the tip. I'd given up on that buoy, thought it would have been toast already. (Or at least mummified?). A whole month of nothing, and then it wakes up again!

Except that colder water beneath ~400m was already present back when ITP95 was in that area. (some of the time, esp. this time last year).

I don't think it's been newly created at the halocline, but rather that it has remained there and the buoy has drifted there and re-discovered it. It's now in more typical Arctic water and ~2200m deep - less affected by the continental shelf and that ridge. (even though it's currently close to the (~800m) deep end of that ridge - per this map).

I agree that half a PSU is not exceptionally stable, when there's an almost 4C temp gradient - but if that colder water had originated from interaction with the halocline, I would expect it to be at least marginally fresher. (more like how it was mid-April, actually). And in the case of ITP data, I would expect higher dissolved oxygen.

[But I'm no expert - just an armchair observer trying to make sense of things I don't really understand]
« Last Edit: May 20, 2018, 11:56:43 PM by Brigantine »

JayW

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Tor Bejnar

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Re: What the Buoys are telling
« Reply #1862 on: July 11, 2018, 04:37:10 AM »
Cross post
The Arctic cyclone last week passed over the only ITP buoy working this year.  It did register a small
.4 degree jump in Sea Surface temperature and a contemporaneous jump in salinity down to ~ 10 meters. The effects are short lived as conditions are currently returning to those before the little GAC.

http://www.whoi.edu/page.do?pid=160136
See ITP T/S contours
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Bruce Steele

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Re: What the Buoys are telling
« Reply #1863 on: July 11, 2018, 05:03:38 AM »
Tor Bejnar, I should have put buoy data here but it's been kinda quiet without cameras , ice mass buoy data or other tethered profilers. I think the little blip in the Temperature / Salinity data from ITP 108 is one of the best cyclone disturbance signals I have seen in seven years of watching the ITP WHOI data.

Neven

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Re: What the Buoys are telling
« Reply #1864 on: July 18, 2018, 09:20:20 PM »
Hydro International:

Quote
XTP Sensors Deployed on UpTempO Buoy

An experimental drifting buoy equipped with eXpendable Temperature and Pressure (XTP) sensors from Soundnine Inc (USA) was deployed for the UpTempO project. The UpTempO project, headed by Dr. Mike Steele of the University of Washington, Polar Science Center, uses inexpensive buoys to measure the Upper layer Temperature of the Polar Oceans. The buoy was deployed in northern Hudson bay on 14 June 2018 by Canadian research icebreaker CCGS Amundsen. It transmits real-time temperature and conductivity data to 25 metres deep, enabling scientists to measure the rate of surface warming as Arctic sea ice increasingly thins and retreats each summer.

Pacific Gyre Inc. (USA) integrated Soundnine’s inductive modem and seven XTP sensors into a modified drifting buoy. The XTP sensors are accurate to 0.005°C; 10 to 20 times more accurate than temperature sensors on previous UpTempO buoys. The sensors are clamped to a jacketed wire rope tether. They communicate with the buoy through the wire rope using Soundnine’s inductively coupled telemetry. The small size and streamlined shape of the XTP sensors should improve the survivability of the system through winter freeze-up (ice ridging) and allow this buoy to provide data throughout spring break up and the following summer.

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Brigantine

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Re: What the Buoys are telling
« Reply #1865 on: July 30, 2018, 05:13:20 AM »
The latest profile from the West Spitsbergen Current:

jdallen

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Re: What the Buoys are telling
« Reply #1866 on: July 30, 2018, 08:51:08 AM »
The latest profile from the West Spitsbergen Current:
Thats... alarmingly hot.
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Phil.

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Re: What the Buoys are telling
« Reply #1867 on: July 30, 2018, 01:13:56 PM »
The latest profile from the West Spitsbergen Current:
Thats... alarmingly hot.

And rather salty!

Brigantine

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Re: What the Buoys are telling
« Reply #1868 on: August 17, 2018, 08:35:48 AM »
There are no less than 3 ARGO floats north of Fram Strait which have been reporting data this month.

~5.7C at depth 20m near the NW corner of Svalbard (on Aug 4),
~2.8C at depth 200m further to the NE (on Aug 14)
and the furthest NE float (82.8N 22.1E) is showing a typical arctic water profile, peaking at ~1.8C at 200-300m depth (on Aug 14), with a healthy halocline above that.

Jim Hunt

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Re: What the Buoys are telling
« Reply #1869 on: August 24, 2018, 02:23:35 PM »
The shiny new CRREL-Dartmouth Ice Mass Balance Buoy web site is up and running at long last:

http://imb-crrel-dartmouth.org

Unfortunately the "Live Data" page still states:

Quote
Website under construction. We are working to finish it as soon as we can. Please visit again!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

oren

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Re: What the Buoys are telling
« Reply #1870 on: August 24, 2018, 04:12:09 PM »
The shiny new CRREL-Dartmouth Ice Mass Balance Buoy web site is up and running at long last:
Thank you Jim. I found this sentence notable:
Quote
We are current collaborating with the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) program to deploy ice mass balance buoys in the fall of 2019.

Jim Hunt

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Re: What the Buoys are telling
« Reply #1871 on: August 24, 2018, 06:43:23 PM »
CRREL deployed some buoys earlier this year. We just can't see the acquired data yet!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

oren

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Re: What the Buoys are telling
« Reply #1872 on: August 24, 2018, 06:55:13 PM »
Do you know if these are buoys with cameras and the whole deal?

Jim Hunt

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Re: What the Buoys are telling
« Reply #1873 on: August 25, 2018, 12:02:39 AM »
Do you know if these are buoys with cameras?

Not that I know of, but that doesn't prove much!

From Don Perovich at the end of March:

Quote
We do have some deployment plans for this year.
 
1.       Beaufort Sea – deployed last week.
2.       Just north of Prudhoe Bay – deployed on Monday
3.       Two deployed in  Beaufort Sea in conjunction with WARM buoy – to be deployed later this week.
4.       Three in Eastern Arctic – to be deployed in September
5.       Two in Beaufort Sea – to be deployed in September.

No mention of cameras, though the WARM buoys generally start life with one.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Rod

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Re: What the Buoys are telling
« Reply #1874 on: August 29, 2018, 05:10:16 AM »
This is a stupid question, but since it is specifically related to ITP108, I though this would be the best place to ask.

It appears that the ITP108 drift has stalled during the last few days (I know the profile data is not any good any more, but I like watching its location to get an idea of how the currents are moving).  The position map has not shown its position changing in any significant way recently.   

I can think of three possible reasons, but I'm guessing one of you knows the correct answer:

1) it has stopped transmitting its location data,

2) its 700 meter cable got tangled up on something, or

3) it is still transmitting, and moving, but the currents have not been moving it around much the last few days. 

There might very well be other possibilities that I have not thought of.  If anyone has some insight on what is going on with ITP108 I would love to hear your comments. 

Thanks.

Brigantine

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Re: What the Buoys are telling
« Reply #1875 on: August 29, 2018, 08:56:05 AM »
It still has a location reported for 2018-08-29, so it's not 1).

2) would be an interesting theory if it had been moving consistently in one direction and then just stopped... but it looks like it's last movements have been a bit back and forth in no particular direction, but over a range >> 1.4km.

So 3) seems most plausible to me, but I haven't looked at nearby weather data or anything.

One thing I found interesting, last time I looked the profiler was ~220m deep, in water 200<depth<500. Now it is at 477m in an area close to the 500m isobath. Not just the cable, but probably also the profiler itself is dragging along the sea floor.

RoxTheGeologist

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Re: What the Buoys are telling
« Reply #1876 on: August 29, 2018, 07:05:10 PM »
The latest profile from the West Spitsbergen Current:

Wow - whats going on with that really warm salty layer at 30m depth? That's not a halocline, that's a thermocline! It's the first profile I have seen (of the few I have examined) where the salinity declines with depth over any sort of vertical distance. It's at 4°C and is 0.5 psu more saline than the waters below it. It has to be much warmer than the waters below or it would immediately sink.

Interesting. It shows what complexities of horizontal and vertical mixing are going on east of Svalbard. Is the salinity all recorded instantaneously at every depth, or is it step wise? Could the thermocline simply be an artifact of crossing through the turbulent mixing in the current?


Bruce Steele

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Re: What the Buoys are telling
« Reply #1877 on: September 27, 2018, 04:18:14 AM »
There are two new ITP buoys in the Beaufort, ITP 109 and 110. They both seem to be working and sending out temperature / salinity numbers.

http://www.whoi.edu/page.do?pid=163196

Brigantine

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Re: What the Buoys are telling
« Reply #1878 on: September 27, 2018, 09:11:43 AM »
There are also some ARGO floats in the Chukchi / right at the western edge of the Beaufort.

Brigantine

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Re: What the Buoys are telling
« Reply #1879 on: June 06, 2019, 02:00:10 PM »
Just checked which ITPs seem to still be working... ITP103, 104, 105 and 110 all seem to have functioning profiles from today.

These are in the Beaufort and CAB West of the CAA.

Air temps range from 0.2C to 2.4C, under the ice things seem... pretty normal?

O-Buoy is still dead though. So no cameras!

Can't access ARGO float locations smh.

Brigantine

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Re: What the Buoys are telling
« Reply #1880 on: June 27, 2019, 12:18:39 AM »
Looking closer at active ITPs

Most recent profile from ITP103 has data from just 1 depth level (at 6m). [-1.4791 C   29.5616 PSU]
(so the profiler is stuck and the contour plot is NOT valid)
ITP104 is the same. [-1.5957 C  30.5993 PSU]
ITP 105 also. [-1.5791   30.3429] - I'm guessing these are all at freezing point for that salinity/pressure

ITP 107 just a 6m range from 230m to 236m (~-1.0C)

ITP 110 on the other hand, has data (~0.45C) between 738m and and 760m. (just the very bottom 22m of the tether).

The rest have no data for the last several months.

So there is no single ITP contour plot worth looking at  :(

Now to ARGO...
There is a float in the Chukchi, just east of Wrangel Island. (4902926)
There's a ~10m thick fresh layer at ~2.8C. Below that (only ~65m deep here) is ~-1.7C (near freezing). That was on June 23.

There was a float in the West Spitzbergen Current on June 8 (R3901621_075.nc)
The top 100m were ~4.5C, 35.04 PSU. Right off the northern west coast. It's probably stuck under ice now.
« Last Edit: June 27, 2019, 12:25:29 AM by Brigantine »

uniquorn

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Re: What the Buoys are telling
« Reply #1881 on: June 27, 2019, 12:36:59 AM »
itp103-105 are ok. Look back through the dat files >1kb
itp110  has high drift speed today, recent data here https://forum.arctic-sea-ice.net/index.php/topic,2417.msg208455.html#msg208455 and older analysis here https://forum.arctic-sea-ice.net/index.php/topic,2417.msg205032.html#msg205032
itp107 has been struggling for a while
hoping that itp89 will give new drift locations when the melt comes....
« Last Edit: June 27, 2019, 12:57:10 AM by uniquorn »

oren

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Re: What the Buoys are telling
« Reply #1882 on: July 10, 2020, 04:55:20 AM »
Cross-posted from the questions thread.
That we have no camera buoys doesn't mean we can't learn from buoys past.


It is quite typical that melt pond surfaces freeze over when the sky becomes cloudy and temps go colder. Often it's just a thin layer of floating ice. However, the location of the melt pond remains the most vulnerable and as soon as conditions turn around the pond normally returns right where it was.
To understand what really happens in situ, I strongly recommend watching all the movies archived as part of the O-Buoy project that ran a few years back. Must-see for any sea ice enthusiast.

Try this one first.
http://obuoy.datatransport.org/monitor#buoy14/movie
Best to watch the whole 25 minutes, but if you're in a hurry just watch the 2016 season unfolding in the Beaufort/CAB, with melt ponds appearing in late June and the floe breaking up in August. Lots of occasions where the melt ponds are widening and then refreezing. (05:00 to 08:00). Amazingly the buoy survives until next season in the CAA, with ponds again appearing in late June. (16:00 to 22:00).
Conditions appear to have been mostly cloudy both seasons, but one can discern the quick result of the sun making an appearance. While watching, try to imagine the effects of weather that leads to melt pond formation a month earlier, and mostly sunny skies.

As proof of watching - when do the bear tracks appear?

Other movies:
http://obuoy.datatransport.org/monitor#buoy2/movie
Short, 2011

http://obuoy.datatransport.org/monitor#buoy4/movie
2012, deep CAB and Fram

http://obuoy.datatransport.org/monitor#buoy5/movie
2011, Beaufort/CAB

http://obuoy.datatransport.org/monitor#buoy6/movie
2012, deep CAB and Fram

http://obuoy.datatransport.org/monitor#buoy7/movie
2013, Beaufort, with open ocean and new ice refreeze at the end

http://obuoy.datatransport.org/monitor#buoy9/movie
2014+2015, CAB and Fram

http://obuoy.datatransport.org/monitor#buoy10/movie
2014+2015, Beaufort

http://obuoy.datatransport.org/monitor#buoy11/movie
2015, Beaufort

http://obuoy.datatransport.org/monitor#buoy12/movie
2015, Chukchi/CAB



You should probably modify your post to include a warning about the strobe effects at the start.  When the sun was very low and going down, it was annoying for me.  Some people have conditions that can be triggered by strobe lighting.
« Last Edit: July 14, 2020, 06:30:09 PM by oren »

Bruce Steele

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Re: What the Buoys are telling
« Reply #1883 on: July 10, 2020, 05:46:29 AM »
Oren, 18 hrs. I may have misspoke when I mentioned ice pond draining as an explanation for why white ice would appear. Refreezing seems far more common in the buoy camera. My main point was white ice transmitted less UVR and light than melt ponds and that maybe white ice formation, by wherever means, might explain the spike then drop in 6 meter water temperatures on multiple ITP buoys. Uniquorn said cloudy weather but maybe cloudy weather and some ice pond refreeze also.
 It is interesting having microcat and SAMI data from so many buoys this year. It gives us detail that the ITP temp/ salinity contours never did. To bad we don’t have a good camera on at least one ITP.
 Jim has some data from a mass buoy on his site.
 https://greatwhitecon.info/2020/07/facts-about-the-arctic-in-july-2020/

oren

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Re: What the Buoys are telling
« Reply #1884 on: July 10, 2020, 06:20:29 AM »
I agree Bruce that pond surface freezing (or floe breakup) is much more common than pond draining. This is however different for fast ice that can hold much more meltwater. Here is a clear example of drainage in the CAA yesterday. The sky was clear and sunny and temps in nearby Resolute were 12C to 4C, so no surface freezing took place and no new snow fell, and yet the blue on the ice diminished visibly.

be cause

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Re: What the Buoys are telling
« Reply #1885 on: July 10, 2020, 11:50:02 AM »
the pond drainage and colour change remind me of nothing more than our home-made ice lollies in the '60's .. you could suck all the colour and flavour out of them and still be left with porous ice on a stick that looked just like the ice after drainage .. a crunchy skeleton .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
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Jim Hunt

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Re: What the Buoys are telling
« Reply #1886 on: July 10, 2020, 01:53:16 PM »
Jim has some data from a mass buoy on his site.

Thanks for the mention Bruce!

I reckon that at least one melt pond has recently drained, at ~74N in the Beaufort Sea:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

uniquorn

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Re: What the Buoys are telling
« Reply #1887 on: July 10, 2020, 03:15:06 PM »
This might help with the detective work, 386840, jun15-jul9. click to run
There is an earlier rise in temp at a similar depth on jun18

Jim Hunt

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Re: What the Buoys are telling
« Reply #1888 on: July 10, 2020, 05:06:58 PM »
There is an earlier rise in temp at a similar depth on jun18

There was indeed, whereupon the buoy apparently decided not to report any more data for the next 4 and a bit days.

Reporting seems to be very intermittent again at the moment too. Suffice it to say that I very much doubt that the currently reported "Ice + Snow Thickness" of 1.624 meters is anywhere near accurate.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

uniquorn

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Re: What the Buoys are telling
« Reply #1889 on: July 10, 2020, 08:51:42 PM »
Irritating. The batteries always start to run out when it is most interesting.

uniquorn

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Re: What the Buoys are telling
« Reply #1890 on: July 12, 2020, 03:08:45 PM »
Some new 386840 data today. Generous thickness estimate would be dtc92 to dtc147, 110cm.

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Re: What the Buoys are telling
« Reply #1891 on: July 12, 2020, 07:36:00 PM »
Some new 386840 data today. Generous thickness estimate would be dtc92 to dtc147, 110cm.
Hycom shows blue tinging on purple so about a meter or just under there.

Bruce Steele

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Re: What the Buoys are telling
« Reply #1892 on: July 13, 2020, 01:34:06 AM »
ITP 105 shows some warm temperatures at 5 and 6 meters. It is only 98 kilometers from the 386840 mass buoy.

Jim Hunt

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Re: What the Buoys are telling
« Reply #1893 on: July 14, 2020, 11:48:30 AM »
Another report from SIMB3 386840.

It looks to be on the threshold of melting out of its hole.

Plus an image of an ancient SIMB from the archives. How I imagine the scene at 74.0 N,   132.6 W as we speak!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Tom

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Re: What the Buoys are telling
« Reply #1894 on: July 14, 2020, 01:55:27 PM »
Another report from SIMB3 386840.

It looks to be on the threshold of melting out of its hole.

Plus an image of an ancient SIMB from the archives. How I imagine the scene at 74.0 N,   132.6 W as we speak!

Hi,  Thanks for posting these graphs/images, could you help confirm/correct my understanding of this data.

I think the x-axis is the vertical position on the buoy of the temp sensor (each sensor marked, 2cm apart), so taking the blue line for the 1st July, it makes sense to me that  0-63 is above ground air temps (pole is sticking ~1.2m in the air), and 145-190 is sea temp, but I am not sure how to interpret the middle section.

Maybe 64-79 is sun-warmed water (melt pond) then 79-121 is ice (so 84cm thick), with 121-145 a pool of warmed fresh melt water sitting between the ice and the colder salty sea water, or is the bottom of the ice at 145 (where temp starts dropping to -1.8 deg)?

Then trying to understand what changed between 1st and 14th July (blue line to red line), my guesses are that:

1. The air temp has dropped significantly, and is now below zero (0-65 now negative temp)
2. Assuming the water/ice boundary is at zero, the ice surface now is at 89 (red line now above blue between 79/89) - so ice has melted 20cm in 13 days
3. The melt pond has been cooled by the lower air temp?  (drop in temp between 65-79), perhaps the melt pond now has a thin ice layer on it's surface?
4. The ice from 81-121 (or 81-145) has warmed further.
5. The lower air-temps has cooled the melt-water making it harder to see where the ice layer begins?
6. How salty would the melt-pond be?  Could it be negative temp and still water?
7. Does the fact that the temp from 69-145 is no colder than -0.4 mean that it could be floating in melt water almost entirely - but then surely if this was the case it would have drained?
8. Looking at the cryosphere link at the mass-balance graph, this seems to show the "snow surface" changing from ~0cm on the 1st July to -17cm on the 14th (which does tie in roughly with my 20cm estimate above).  The bottom of the ice also gets deeper (which I assume is a mistake) The thickness is ~1.5m, which if 145 is the bottom would put the top at 70, so possibly this has been confused by the drop in temp between 70-79 of the red line.

I can see that as time progresses (green->purple->brown->blue->red) the temperature of the middle section has increased, and the data from green->blue shows consistent warming of the ice.

Sorry for all the question, this has gotten a bit longer than I anticipated:

TL/DR - is the ice bottom at 145 or 121?  Is the ice surface currently at ~89?  Does the temp of the ice being so close to zero mean it's closer to melting?

uniquorn

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Re: What the Buoys are telling
« Reply #1895 on: July 14, 2020, 04:14:03 PM »
Mosaic thermistor buoys for comparison, sensors also 2cm apart. jun1-jul14

FishOutofWater

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Re: What the Buoys are telling
« Reply #1896 on: July 14, 2020, 05:14:30 PM »
Melt ponds draining causes surface cooling by exposing the ice surface directly to the atmosphere. That may explain the weird pattern of cooling in recent years on the DMI 80N maps.

Ken Feldman

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Re: What the Buoys are telling
« Reply #1897 on: July 14, 2020, 06:07:21 PM »
Cross-posted from the questions thread.
That we have no camera buoys doesn't mean we can't learn from buoys past.


It is quite typical that melt pond surfaces freeze over when the sky becomes cloudy and temps go colder. Often it's just a thin layer of floating ice. However, the location of the melt pond remains the most vulnerable and as soon as conditions turn around the pond normally returns right where it was.
To understand what really happens in situ, I strongly recommend watching all the movies archived as part of the O-Buoy project that ran a few years back. Must-see for any sea ice enthusiast.

Try this one first.
http://obuoy.datatransport.org/monitor#buoy14/movie
Best to watch the whole 25 minutes, but if you're in a hurry just watch the 2016 season unfolding in the Beaufort/CAB, with melt ponds appearing in late June and the floe breaking up in August. Lots of occasions where the melt ponds are widening and then refreezing. (05:00 to 08:00). Amazingly the buoy survives until next season in the CAA, with ponds again appearing in late June. (16:00 to 22:00).
Conditions appear to have been mostly cloudy both seasons, but one can discern the quick result of the sun making an appearance. While watching, try to imagine the effects of weather that leads to melt pond formation a month earlier, and mostly sunny skies.

As proof of watching - when do the bear tracks appear?

Other movies:
http://obuoy.datatransport.org/monitor#buoy2/movie
Short, 2011

http://obuoy.datatransport.org/monitor#buoy4/movie
2012, deep CAB and Fram

http://obuoy.datatransport.org/monitor#buoy5/movie
2011, Beaufort/CAB

http://obuoy.datatransport.org/monitor#buoy6/movie
2012, deep CAB and Fram

http://obuoy.datatransport.org/monitor#buoy7/movie
2013, Beaufort, with open ocean and new ice refreeze at the end

http://obuoy.datatransport.org/monitor#buoy9/movie
2014+2015, CAB and Fram

http://obuoy.datatransport.org/monitor#buoy10/movie
2014+2015, Beaufort

http://obuoy.datatransport.org/monitor#buoy11/movie
2015, Beaufort

http://obuoy.datatransport.org/monitor#buoy12/movie
2015, Chukchi/CAB

Thanks, that was very helpful.  It's one thing to read about the processes involved with melting and freezing sea ice and another thing to see it happening.

You should probably modify your post to include a warning about the strobe effects at the start.  When the sun was very low and going down, it was annoying for me.  Some people have conditions that can be triggered by strobe lighting.

oren

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Re: What the Buoys are telling
« Reply #1898 on: July 14, 2020, 06:31:12 PM »
Done. Thanks

Jim Hunt

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Re: What the Buoys are telling
« Reply #1899 on: July 15, 2020, 12:30:27 PM »
Could you help confirm/correct my understanding of this data.

Your understanding pretty much coincides with my own. See below for the SIMB's top and bottom sensor readings.

I reckon the indicated "snow surface" should read "melt pond surface", and the indicated "ice bottom" is actually the interface between warm melt water and cold salty sea water.

Quote
TL/DR - is the ice bottom at 145 or 121?  Is the ice surface currently at ~89?  Does the temp of the ice being so close to zero mean it's closer to melting?

I further reckon that the ice bottom is somewhere above 121 by now, and the ice surface below 89. Perhaps 60 cm is left at most?

Bear in mind that SIMBs have a habit of creating a "melt pit" of their very own, so the majority of the floe in the vicinity of the buoy might well be thicker than that.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein