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Author Topic: What the Buoys are telling  (Read 441758 times)

ghoti

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Re: What the Buoys are telling
« Reply #1750 on: August 13, 2017, 01:23:48 AM »
Pavel's animation of Obuoy 14 photos http://forum.arctic-sea-ice.net/index.php/topic,1834.msg125028.html#msg125028 seems to show the buoy has been liberated - the ice in view appears to be drifting away from the camera.

abraca

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Re: What the Buoys are telling
« Reply #1751 on: August 13, 2017, 01:35:10 AM »
Pavel's animation of Obuoy 14 photos http://forum.arctic-sea-ice.net/index.php/topic,1834.msg125028.html#msg125028 seems to show the buoy has been liberated - the ice in view appears to be drifting away from the camera.

The horizon moves up also, and adequately, so this seems like it is a pitch change only - the ice around the buoy seems gone to let it have some space to move, but it doesn't seem like it's free, like on open water.

ghoti

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Re: What the Buoys are telling
« Reply #1752 on: August 13, 2017, 02:21:37 AM »
Pitch and roll are shown on the GPS tab for the buoy. The changes are there but quite small. I guess we'll have to wait a few more days to see how the relative positions turn out.

JayW

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Re: What the Buoys are telling
« Reply #1753 on: August 13, 2017, 04:16:25 AM »
I was looking at ITP95.  It appears to me that the buoy is heading north from looking at the drift track.  Doesn't that imply that warm, salty water is also moving north?  Or am I oversimplifying?


Edit: mainly below 100m

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Tor Bejnar

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Re: What the Buoys are telling
« Reply #1754 on: August 13, 2017, 05:53:51 AM »
Pavel's animation certainly shows melting happening by the hour!
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greatdying2

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Re: What the Buoys are telling
« Reply #1755 on: August 13, 2017, 07:30:18 AM »
I was looking at ITP95.  It appears to me that the buoy is heading north from looking at the drift track. 

Isn't it drifting south (and into shallower waters)?

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Rob Dekker

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Re: What the Buoys are telling
« Reply #1756 on: August 13, 2017, 07:37:09 AM »
At this point, I'd like to point out a remarkable consistency between IMB (Ice Mass Balance) buoy 2017A and co-located WARM buoy 6 when it comes to ice bottom melt.

IMB buoy 2017A shows this melting profile :

Note that over July, that amounts to about 2 cm/day of bottom melt.

WARM buoy 6 records this profile of in-ice and under-ice PAR irradiance :



which suggests PAR irradiance (light between 400 nm and 700 nm) was some 30 W/m^2 over July.
We know that sunlight holds some 43% of its energy between 400 and 700 nm, so we can reasonably expect that some 30 * 1/0.43=70 W/m^2 of sunlight made it through the ice in July.
70 W/m^2 is enough heat to melt 2 cm/day of ice, very consistent with the 2 cm/day we see recorded by 2017A. Other WARM buoys (such a WARM 3) suggest that this level of irradiance is common, and lasts July through Aug.

This is telling although not quite unexpected. It suggests that light that makes it through the ice is THE main source of bottom melt in the Arctic sea ice pack.

It also tells a lesson, since this should be happening all through the Arctic : Even without external influence, simply the Arctic light that shines through the ice can account for 2 cm/day bottom melt through July and August. That's 120 cm right there. Add 30 cm of top melt and we can conclude that any ice that is 1.5 meter of ice thickness or less at the start of the melting season is at risk of melting out in-situ.

oren

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Re: What the Buoys are telling
« Reply #1757 on: August 13, 2017, 07:44:21 AM »
Pavel's animation certainly shows melting happening by the hour!
Yes, the lower left corner shows it beautifully.

JayW

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Re: What the Buoys are telling
« Reply #1758 on: August 13, 2017, 09:37:21 AM »


Isn't it drifting south (and into shallower waters)?

Latest location (triangle)


Look closer. It might have been at one time, but it's not moving south lately.

Here's a gif of the last 3 days.  I'd make it longer, but only have these days saved.


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Re: What the Buoys are telling
« Reply #1759 on: August 13, 2017, 11:06:16 AM »
Sure, of course it doesn't take a straight line. There are changes in wind direction, etc. But I thought you were talking about temperature and salinity trends that seem to be over at least the last 20 to 30 days? Maybe I misunderstood what trends you are talking about.
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Andreas T

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Re: What the Buoys are telling
« Reply #1760 on: August 14, 2017, 12:57:50 AM »
At Obuoy14 the narrow bit of ice which separated the water on the near right from the area in the middistance has finally melted through. What this makes more obvious is that the lack of movement of the various areas of ice surface are not moving relative to each other, i.e. it makes it very likely that they are still connected below the waterline. The thin strip of ice would most probably have broken off earlier had it been the only connection holding these parts of the floe together.
In the light of images from last autumn I expected the area on the near left to be thinner, younger ice but so far it has lasted as much as those bits which are remnants of last years melt season. Lets hope the reduction of lightlevels which are now lengthening the periods of insufficient power from the PV panels will allow us to see what happens over the next couple of weeks

ghoti

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Re: What the Buoys are telling
« Reply #1761 on: August 14, 2017, 02:02:22 AM »
What this makes more obvious is that the lack of movement of the various areas of ice surface are not moving relative to each other, i.e. it makes it very likely that they are still connected below the waterline.
Until an hour later!
Everything has moved relative to each other it seems!
Plus buoy speed shows as moving along at a 1m/s clip.

Tor Bejnar

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Re: What the Buoys are telling
« Reply #1762 on: August 14, 2017, 05:06:47 AM »
On August 14 at 2 am, it looks back to normal (sort of) again.  The camera rotated and point elsewhere for an hour or so, and then rotated back and forth.
« Last Edit: August 14, 2017, 05:12:01 AM by Tor Bejnar »
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Adam Ash

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Re: What the Buoys are telling
« Reply #1763 on: August 14, 2017, 08:58:03 AM »
The rapid twiddling (about 40ish degrees right then 100 left then 50ish right in a few hours) would seem to confirm that the buoy is very lightly held in a small floe (one to two metre-scale) which can be subjected to very local current effects.  I would doubt that a comparatively larger more connected floe would twiddle that fast.

So I would imagine that both azimuth and vertical alignment will see more swings soon, before the buoy is bobbing free, even if still in the company of its local friends.  Next up - watch how it behaves in a storm.

Jim Hunt

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Re: What the Buoys are telling
« Reply #1764 on: August 14, 2017, 09:50:32 AM »
Then by 3 AM:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Adam Ash

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Re: What the Buoys are telling
« Reply #1765 on: August 14, 2017, 10:54:39 AM »
Interesting new view.  New orientation in relation to foreground floes.  Greater than 45 degrees from prior view.  Disconnect between buoy and local ice. 

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Re: What the Buoys are telling
« Reply #1766 on: August 14, 2017, 03:53:46 PM »
All change once again:
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woodstea

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Re: What the Buoys are telling
« Reply #1767 on: August 14, 2017, 04:08:11 PM »
Fasten your seatbelts, its going to be a bumpy night.

Tor Bejnar

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Re: What the Buoys are telling
« Reply #1768 on: August 14, 2017, 05:18:09 PM »
If the camera was pointing SSW when the buoy woke up (with Azimuth reading about 160º), now (with a reading of about 240º) is the camera pointing NNW?
Yes, I think so. ...
Therefore: actual direction = Azimuth reading + 40º. 

'highest' reading on Aug. 13 (~290º) the camera was pointing NNW.
'lowest' reading on Aug. 13 (~130º) the camera was pointing just east of S.
'highest' reading on Aug. 14 (~225º) the camera was pointing just south of W.
'lowest' reading on Aug. 14 (so far - ~50º) the camera is pointing due E.

Note: when the Azimuth holds perfectly steady, the power to the GMS unit is probably off.  (I presume the camera is not taking pictures at those times.)
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magnamentis

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Re: What the Buoys are telling
« Reply #1769 on: August 14, 2017, 07:19:57 PM »
if anyone is interested to know what i'm talking about for months now is this what happened withing a few hours around o-buoy 14:

and yes i'm aware that the back could look still difference (probably does) but nevertheless it was not so much open water anywhere during recent rotations of the buoy ;)
« Last Edit: August 14, 2017, 07:25:26 PM by magnamentis »
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magnamentis

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Re: What the Buoys are telling
« Reply #1771 on: August 14, 2017, 07:28:52 PM »
Much like last year:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2016-images/#OBuoy14


exactly and last year ended second extent wise and not sure about area but depending on the source that was even lower, hence we're on a schedule expected by many if not most, nevertheless the poor melting momentum and once the atlantic side will get hit by storms, waves and humid warmth, who knows how it will end, probably second lowest again but this time by far, somewhere in the middle between 2012 and 2016 is well possible.
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Sterks

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Re: What the Buoys are telling
« Reply #1772 on: August 14, 2017, 07:43:43 PM »
if anyone is interested to know what i'm talking about for months now is this what happened withing a few hours around o-buoy 14:

and yes i'm aware that the back could look still difference (probably does) but nevertheless it was not so much open water anywhere during recent rotations of the buoy ;)
In view of the GPS track, and of the satellite images, some here were wondering why we were not watching an image like this before.
I am not sure what you have been claiming since since months but I hope you are not 🍒 picking or utilizing this otherwise expectable image

woodstea

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Re: What the Buoys are telling
« Reply #1773 on: August 14, 2017, 08:01:03 PM »
if anyone is interested to know what i'm talking about for months now is this what happened withing a few hours around o-buoy 14:

and yes i'm aware that the back could look still difference (probably does) but nevertheless it was not so much open water anywhere during recent rotations of the buoy ;)

Go look at this area in PolarView (there's an image from this morning that shows the area just north of the buoy) and you can see that the buoy is near the edge of a lot of ice to the west and open water to the east. We couldn't see it up until now because the buoy wasn't free to rotate. Definitely I think there was a lot of melt and break up this weekend, but it isn't like all that ice we were seeing before has all but disappeared.

magnamentis

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Re: What the Buoys are telling
« Reply #1774 on: August 14, 2017, 08:04:47 PM »
if anyone is interested to know what i'm talking about for months now is this what happened withing a few hours around o-buoy 14:

and yes i'm aware that the back could look still difference (probably does) but nevertheless it was not so much open water anywhere during recent rotations of the buoy ;)

In view of the GPS track, and of the satellite images, some here were wondering why we were not watching an image like this before.
I am not sure what you have been claiming since since months but I hope you are not 🍒 picking or utilizing this otherwise expectable image


i think i pointed out "NO CLAIM" how much clearer can one be ? i have the opinion that due to thinner than usual ice, bottom melt will sooner or later see to some kind of sudden death and this image looks like that. whatever one can say, short ago the buoy was inside a flow on all sides and that has first slowly and now more or less suddenly disintegrated at least on one side.

i wanted to avoid identical double-posts since they're often not welcome, hence read both my posts on the matter, combine them and all is said and clear

http://forum.arctic-sea-ice.net/index.php/topic,1834.msg125274.html#new
« Last Edit: August 14, 2017, 08:16:07 PM by magnamentis »
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magnamentis

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Re: What the Buoys are telling
« Reply #1775 on: August 14, 2017, 08:06:34 PM »
if anyone is interested to know what i'm talking about for months now is this what happened withing a few hours around o-buoy 14:

and yes i'm aware that the back could look still difference (probably does) but nevertheless it was not so much open water anywhere during recent rotations of the buoy ;)


Go look at this area in PolarView (there's an image from this morning that shows the area just north of the buoy) and you can see that the buoy is near the edge of a lot of ice to the west and open water to the east. We couldn't see it up until now because the buoy wasn't free to rotate. Definitely I think there was a lot of melt and break up this weekend, but it isn't like all that ice we were seeing before has all but disappeared.


i think i clearly mentioned that the other side may look different, nevertheless the buoy has till recently been surrounded by ice, sitting inside a floe, visible on the very same sat images you mentioned. of course i can read between the lines, hence nothing new from that side.


i wanted to avoid identical double-posts since they're often not welcome, hence read both my posts on the matter, combine them and all is said and clear

http://forum.arctic-sea-ice.net/index.php/topic,1834.msg125274.html#new
« Last Edit: August 14, 2017, 08:16:30 PM by magnamentis »
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Tor Bejnar

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Re: What the Buoys are telling
« Reply #1776 on: August 14, 2017, 08:29:33 PM »
Obuoy 14 location almost on Aug 14 PolarView
Current O-buoy 14 azimuth reading is 300º, so camera is pointed to 340º or NNW (unless, of course, the camera relation to the GPS azimuth has changed), so the camera isn't likely pointing directly away from the (local) main body of ice.
« Last Edit: August 14, 2017, 08:46:17 PM by Tor Bejnar »
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woodstea

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Re: What the Buoys are telling
« Reply #1777 on: August 14, 2017, 08:40:55 PM »
Look, it's nothing personal. When someone makes a statement like this:

if anyone is interested to know what i'm talking about for months now

it tends to elicit a kind of reflexive pushback. You make it sound like you've been telling us this all along and all of us were saying "No, no! It can't be that."

woodstea

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Re: What the Buoys are telling
« Reply #1778 on: August 14, 2017, 08:45:21 PM »
Current O-buoy 14 azimuth reading is 300º, so camera is pointed to 340º or NNW (unless, of course, the camera relation to the GPS azimuth has changed)

Tor, I think the offset is greater than 40 degrees, more like 100, though I go back and forth about the exact number. Originally I came up with that estimate based on my best (though very much amateur) attempt at calculating sun position in a photo from last year. The offset could very well change over time (bumped by a polar bear?), though that's not what I would expect.

Tor Bejnar

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Re: What the Buoys are telling
« Reply #1779 on: August 14, 2017, 08:57:22 PM »
Somebody (not me) determined that "40º difference" soon after the buoy woke up in the spring, studying an image with the sun directly behind the camera (and a shadow straight ahead - knowing date, time and location).  I've basically trusted that determination.  Adding 60º would change the current NNW gaze to NE (and definitely away from the main body of ice).
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woodstea

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Re: What the Buoys are telling
« Reply #1780 on: August 14, 2017, 09:04:03 PM »
Adding 60º would change the current NNW gaze to NE (and definitely away from the main body of ice).

Which I think fits what we see in the photo magnamentis posted above from 16:01 UTC. At that time the graph azimuth was 320, plus 40 would be due north. Based on the sun's position it's got be pointing more to the east than that.

ghoti

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Re: What the Buoys are telling
« Reply #1781 on: August 14, 2017, 09:19:31 PM »
The Obuoy 14 movie has updated again (August 14, 2017). Jump to the last 25 seconds to witness the fast melt and breakup. Ice and buoy are moving pretty fast now. Plenty of wind and waves stirring things up.

http://obuoy.datatransport.org/monitor#buoy14/movie

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Re: What the Buoys are telling
« Reply #1782 on: August 14, 2017, 10:01:36 PM »
Fantastic movie! The action in the last 30 seconds reminds me of the climax to the old movie Straw Dogs, it's that dramatic  :o

Based on the movie I'm guessing that the edge of the ice floe has been progressively eaten away until it reached the buoy, which had hitherto faced away from the open water but was then released and swiveled around to view it.

ghoti

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Re: What the Buoys are telling
« Reply #1783 on: August 14, 2017, 11:54:45 PM »
The Obuoy 14 images have been updating every 15 minutes today. ( is that normal?)

There is much more open water than there is ice. Everything appears very mobile. A small sailing yacht might not want to travel this part of the passage at night but they'd have no trouble during the day.

Interesting to note the buoy temperature dropped below 0 C and has remained there since it broke free.

woodstea

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Re: What the Buoys are telling
« Reply #1784 on: August 15, 2017, 12:07:30 AM »
The Obuoy 14 images have been updating every 15 minutes today. ( is that normal?)

It's happened before, including last summer when the buoy broke free. I'm guessing that once things get interesting that they change the frequency of images, either at the buoy itself or the update frequency to the website. I certainly appreciate it!

Interesting to note the buoy temperature dropped below 0 C and has remained there since it broke free.

This may be more a factor of the weather rather than anything about the buoy breaking free. Warmer air came through this past weekend and should again in another day or two. The wind should shift around to the south and send the buoy back in the direction of the Parry channel.

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Re: What the Buoys are telling
« Reply #1785 on: August 15, 2017, 01:10:52 AM »
Worldview shows that the kind of fragmentation we now see in the camera images is widespread in the area. Increased water movement is likely to promote further melting.
As woodstea says winddirection is forecast to change which will stop the flow of ice from the Beaufort into the western end of Parry channel. If that continues the chances of an open Northwest passage at the end of August look reasonable.

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Re: What the Buoys are telling
« Reply #1786 on: August 17, 2017, 09:38:35 PM »
Smoke from above; smoke from below; ice 'all' around (some nice ridging!)
Obuoy - Worldview
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Re: What the Buoys are telling
« Reply #1787 on: August 18, 2017, 05:47:06 PM »
Today's hazy sunshine:
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