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Andreas T

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Re: What the Buoys are telling
« Reply #1300 on: May 16, 2017, 03:57:20 PM »
...

So maybe it began with nearly 20 cm of snow but had lost several cm of that by the end?

(Safe) Prediction: that remaining snow isn't going to see out the month!

EDIT: but wait..

Thermal conductivity of ice = 0.005; of water = 0.0014.

So ice has about 3.5 times the thermal conductivity of water.

Conversely, the same depth of water will show about 3.5 times the vertical displacement between the thermistors as ice. There must be some densely packed snow - almost ice but with some trapped air - that shows similar. And maybe that's what we are seeing from 2017A in March? How do we know if it melts? It just gets a little more compact in turning into water, with a similar displacement between thermistors. Perhaps that's what has already happened here - an alternative explanation?

Now I'm uncertain what is going on in that plot, but my apologies for the stream-of-consciousness post!
I am guessing that "vertical displacement" means temperature difference between thermistors. As I said in my earlier comment that  means temperature gradient delta t / delta y (using y as my coordinate perpendicular to the ice surface). With a fixed thermal conductivity of the ice the heat transfer is proportional to that gradient (larger temperature difference between ice bottom and ice top means more heat transferred).
The thermal conductivity of water would only matter if water would remain completely still, which is impossible here because water is cooled at the ice/water interface and sinks. It is also becoming more saline because of the freezing which also increases density and generates convection. Water temperature changes are very small and you call tell which thermistors are in water because they are all showing a temperature very near the freezing point (1.65 from memory)
The discontinuity SIS is pointing out therefore indicates the point where snow above and ice below transfer equal heat fluxes from seawater to atmosphere but because of lower conductivity of snow (air inclusion) that can only happen at steeper temperature gradient.
Of course heat capacity of ice plays a part when ice changes temperature and then the temperature profile deviates from a straight line (constant gradient).

melting is not explicitly shown in that graph. We can  guess it when somewhere that shows the behavior of ice or snow starts to behave like air or water (i.e. shows the flat temperature profile of a convecting fluid.
This is complicated by snow being possibly carried away by wind (mechanically) or sublimating.

vigilius

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Re: What the Buoys are telling
« Reply #1301 on: May 16, 2017, 05:46:37 PM »
Okay, I am still pondering AndreasT's points, in the meantime posting a random image from #14 just for the sake of keeping this thread toward the top. I have high hopes for the heroic buoy in coming weeks. Ummm, does this mean I am not lurking anymore? (I gotta say, when I post stuff in this forum I get real answers which make me think about posts I just scanned on the first run-through, and it's going to make me more careful about reading more thoroughly before I post but I hope I can be forgiven for this one careless comment)

Andreas T

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Re: What the Buoys are telling
« Reply #1302 on: May 16, 2017, 09:09:46 PM »
Not a random image if you connect it with the temperature measurements. 24h sunshine now keeps the buoy powered up without interruptions but IR radiation balance under clear sky is dropping temperatures when the sun angle is lowest.
Nothing to forgive, Vigilius  :)  (in my opinion) I wish some others on the forum were as thoughtful as you!

I have looked at some other buoys (sadly without cameras) but some of the sensors seem to be malfunctioning.
http://data.meereisportal.de/gallery/index_new.php?active-tab1=method&buoytype=all&region=all&buoystate=active&submit3=display&lang=en_US&active-tab2=buoy

edit: replaced the temperature graph with a later one showing more of the 16 May, the thin cloud in vigilius' image contributed to higher temperature I think
« Last Edit: May 17, 2017, 07:56:05 AM by Andreas T »

Andreas T

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Re: What the Buoys are telling
« Reply #1303 on: May 17, 2017, 10:52:03 AM »
I missed the image for midnight but here is the one for 1 hour past local midnight. Again temperature not as low as 24 hours ago. Thin cloud providing some downwelling longwave radiation I think.

Eli81

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Re: What the Buoys are telling
« Reply #1304 on: May 17, 2017, 10:54:47 PM »
Some interesting spikes to ~5C(!) today... Thinking it's anomalous, but humidity spikes at the same time...  Thoughts? Did some 'tropical' air blow through?  ;D



Jim Hunt

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Re: What the Buoys are telling
« Reply #1305 on: May 18, 2017, 02:20:33 AM »
The latest update from IMB buoy 2017A:

http://GreatWhiteCon.info/2017/05/facts-about-the-arctic-in-may-2017/#May-17

Current Buoy Data (05/16/2017):

Pos: 74.33N, 157.57W
Air Temp: -6.4 C
Air Pres: 1006.9 mb
Snow depth : 11 cm
Ice thickness : 119 cm
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Andreas T

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Re: What the Buoys are telling
« Reply #1306 on: May 18, 2017, 09:15:32 PM »
Some interesting spikes to ~5C(!) today... Thinking it's anomalous, but humidity spikes at the same time...  Thoughts? Did some 'tropical' air blow through?  ;D
There have been similar spikes where air temperature jumps abruptly by as much as 10C and drops just as quickly with a second spike shortly after. These are nearly at the same time of day as previous ones.
I find that highly suspicious. The sensors on the obuoy are shaded and should not "catch" the sun as the thermistor strings do on the IMBs but maybe there is some odd reflection heating the sensor?
What surprises me is that the 17th was definitely not sunny and the camera was showing increasing fog before the spikes (I was looking to catch local noon) although the image I saved is taken later

edit:  the camera image now, 20:00 UTC / local 13:00 is looking just the same as yesterday and temperature is at maximum for the year to date, -3C. Once more its not clear sky and sun which brings high surface temperature on snow covered ice.
« Last Edit: May 18, 2017, 10:50:57 PM by Andreas T »

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Re: What the Buoys are telling
« Reply #1307 on: May 20, 2017, 05:13:31 AM »
It's great to see that we are about to hit 7 days of straight uptime on #14! It appears that the batteries started to really drop out about a month ago and are only providing slight power buffering from the solar panels, which are now benefiting from 24hr daylight.

Also, there have been quite a few blizzards or dense ice fogs over the last 2+ weeks. When we had some clear conditions a few days back, I feel like the drifts appeared a bit larger and more widespread.

Finally, some forecasts are calling for a more southerly flow and warmer conditions near #14 in a few days.

https://earth.nullschool.net/#2017/05/22/0300Z/wind/surface/level/overlay=temp/orthographic=-86.29,70.21,3000/loc=-106.572,74.151

Jim Hunt

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Re: What the Buoys are telling
« Reply #1308 on: May 23, 2017, 01:25:41 AM »
O-Buoy 14 currently reports temperatures above zero:

http://GreatWhiteCon.info/2017/05/facts-about-the-arctic-in-may-2017/#comment-221841

Unfortunately her webcam was still shrouded in mist when it last managed to upload an image :(
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woodstea

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Re: What the Buoys are telling
« Reply #1309 on: May 23, 2017, 05:05:30 PM »
It's great to see that we are about to hit 7 days of straight uptime on #14! It appears that the batteries started to really drop out about a month ago and are only providing slight power buffering from the solar panels, which are now benefiting from 24hr daylight.

Also, there have been quite a few blizzards or dense ice fogs over the last 2+ weeks. When we had some clear conditions a few days back, I feel like the drifts appeared a bit larger and more widespread.

When the view is obscured like this I am always wondering whether it's fog or whether something is obstructing the lens -- like a thin layer of frost. Fog seems like the right answer here considering that the humidity is high, and considering that we've had some back and forth between the foggy view and a clear view during the last month.

I understand that there's a difference between ice fog and freezing fog. This would be freezing fog, right? Supercooled droplets of water rather than ice crystals, since the temperature is near 0°C.

I am tremendously interested to see what the view looks like once it clears. Will we see evidence of melting? How long before we see melt pools like we did last year?
« Last Edit: May 23, 2017, 05:15:24 PM by woodstea »

magnamentis

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Re: What the Buoys are telling
« Reply #1310 on: May 23, 2017, 05:09:05 PM »
It's great to see that we are about to hit 7 days of straight uptime on #14! It appears that the batteries started to really drop out about a month ago and are only providing slight power buffering from the solar panels, which are now benefiting from 24hr daylight.

Also, there have been quite a few blizzards or dense ice fogs over the last 2+ weeks. When we had some clear conditions a few days back, I feel like the drifts appeared a bit larger and more widespread.

When the view is obscured like this I am always wondering whether it's fog or whether something is obstructing the lens -- like a thin layer of frost. Fog seems like the right answer here considering that the humidity is high, and considering that we've had some back and forth between the foggy view and a clear view during the last month.

I understand that there's a difference between ice fog and freezing fog. This would be freezing fog, right? Supercooled droplets of water rather than ice crystals, since the temperature is near 0°C.

I am tremendously interested to see what the view looks like once it clears. Will we see evidence of melting? How long before we see melt pools like we did last year?

while it can be both, this time it's fog because at times one can see the horizon which is not possible if the lense is layered with vapor, snow or anything of that kind. once the lense is covered one can see that very well. if you want to verify this just check several times a day until the light conditions allow to see the horizon, i think it's even there in one of the recently posted images but you'll see.

magnamentis

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Re: What the Buoys are telling
« Reply #1311 on: May 23, 2017, 10:08:32 PM »
in this (current [see time stamp]) image you can clearly see the horizon as well as some features in the foreground which as i said clearly indicate that the lense is not obscured this time ( but it has been in the past while one can see the difference with a bit of experience )

oren

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Re: What the Buoys are telling
« Reply #1312 on: May 24, 2017, 05:34:14 PM »
Finally a clear image

RoxTheGeologist

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Re: What the Buoys are telling
« Reply #1313 on: May 24, 2017, 06:12:13 PM »
Does the surface look slightly blue in places, or is it a trick of the light?

Andreas T

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Re: What the Buoys are telling
« Reply #1314 on: May 24, 2017, 06:36:19 PM »
scroll up to the image vigilius posted on the 16th, very similar lighting, very similar colours.
The first signs of melting I expect from watching these buoys for a few years is a slumping or sagging of the snow as it becomes coarser and denser (firn). There would be bluer tones in the shadows (because transparency increases) but the scenery in front of Obuoy14 is very flat this year. Its position in Canadian archipelago has meant there was (almost?) no movement around it over the winter, no ridges formed since September.
This has the advantage that we have a good idea what lies under the snow: the stuff we saw snow in in October. See these stills or watch the movie
 http://obuoy.datatransport.org/monitor#buoy14/movie

Jim Hunt

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Re: What the Buoys are telling
« Reply #1315 on: May 25, 2017, 01:07:39 AM »
The sun is now high in the sky. No melt ponds that I can see as yet however:
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vigilius

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Re: What the Buoys are telling
« Reply #1316 on: May 25, 2017, 02:00:51 PM »
Colder and clear this AM,  our heroic buoy puts in an appearance via shadow.

Tor Bejnar

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Re: What the Buoys are telling
« Reply #1317 on: May 25, 2017, 04:33:54 PM »
I think we can see land in the distance.  Do we know which island(s)? (Map from Obuoy website, annotated) [edit: per the next post, I've uncovered the marker.][edit: no, it isn't land we see]
« Last Edit: July 16, 2017, 11:14:58 PM by Tor Bejnar »
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Andreas T

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Re: What the Buoys are telling
« Reply #1318 on: May 25, 2017, 06:09:13 PM »
The map on the Obuoy monitor site oddly shows a track which ends short of the green position marker. If I read the position as 74.3N 103W out of the GPS display it fits the green marker position rather than the end of the red track which stops too far west. (I am using worldview https://go.nasa.gov/2r0VxCv to locate lat/ long position in relation to the surrounding islands.
This would put it about 70km from land in any direction. The direction the camera is pointing can be read from the picture vigilius posted: 11 UTC is 4 AM local time at at 105W, which give me a rough estimate of the camera direction as 240 deg clockwise from north (I don't know whether that is  azimuth or what) corrections welcome.
The images posted by Jim and vigilius also illustrate again that clear sky and sunshine brought lower temperature readings. Lower temperature does not necessarily equate to lower energy absorption, but with snow cover (still) intact, which shouldn't be surprising after a few hours of above zero temps, I don't expect much energy to go into the snow, ice and seawater below.
« Last Edit: May 25, 2017, 06:18:01 PM by Andreas T »

Tor Bejnar

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Re: What the Buoys are telling
« Reply #1319 on: May 25, 2017, 07:37:51 PM »
Quote
... which give me a rough estimate of the camera direction as 240 deg clockwise from north ...
So, WSW of the marker's pointer is Stefansson Island.

From Wikipedia:
Quote
Stefansson Island is an uninhabited island in the Canadian Arctic Archipelago in the Kitikmeot Region of Nunavut, Canada. It has a total area of 4,463 km2 (1,723 sq mi), making it the 128th largest island in the world, and Canada's 27th largest island. The island is located in Viscount Melville Sound, with M'Clintock Channel to the east. It lies just off Victoria Island's Storkerson Peninsula, separated by the Goldsmith Channel. Stefansson Island's highest mount is 267 m (876 ft).

The first European sighting of the island was in 1917 by Storker T. Storkerson who was travelling with Canadian explorer Vilhjalmur Stefansson (1879-1962), for whom the island was named.
(See interesting life of the explorer.)
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seaicesailor

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Re: What the Buoys are telling
« Reply #1320 on: May 26, 2017, 04:22:09 PM »
The latest 6 days or so available of the B 2017A temperature profiles. I am showing the non-filtered data (red dashed line) and the filtered data. The result of filtering is that some spatial wiggling is removed, but also that the profiles take a 24h-averaged temperature approximately.

I think this daily-averaged temperature, for the thermistors not covered by ice or snow, is skewed to higher values frequently and I don't find another explanation that they are heated by sun or by the buoy material being heated by sun...
« Last Edit: May 26, 2017, 04:57:13 PM by seaicesailor »

woodstea

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Re: What the Buoys are telling
« Reply #1321 on: May 26, 2017, 08:39:29 PM »
I think we can see land in the distance.  Do we know which island(s)? (Map from Obuoy website, annotated) [edit: per the next post, I've uncovered the marker.]
You may be right, but I do remember that as the buoy was working its way into the Parry Channel last year, I often thought I could make out land in certain photos, but then other photos with similar azimuth but different sun angle seemed to show no land. When this first started happening the buoy was just too far out for it to be possible. I suspect that's the case now, if it's true that the buoy is 70 km away from the nearest island and the highest point on that island is 267 meters.

The map on the Obuoy monitor site oddly shows a track which ends short of the green position marker. If I read the position as 74.3N 103W out of the GPS display it fits the green marker position rather than the end of the red track which stops too far west.
The end of the red track is the last position of the buoy when it went dark for the winter. After that it continued to move with the ice to its current position, which has barely changed since the buoy woke up again.

Tor Bejnar

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Re: What the Buoys are telling
« Reply #1322 on: May 26, 2017, 09:21:09 PM »
Thanks, woodstea.  That explains the gap and the red dot at the bottom of the marker.

This calculator suggests one can see a 200 m tall mountain 50 km away.  at 70 km, the mountain would need to be at least 400 m tall. (250 m - 56.5 km)

Then there are false images (actual reflections) where one can see objects that are below the horizon.
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Re: What the Buoys are telling
« Reply #1323 on: May 26, 2017, 09:44:33 PM »
Is it my imagination, or is that water at the horizon?


magnamentis

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Re: What the Buoys are telling
« Reply #1324 on: May 26, 2017, 10:11:59 PM »
Is it my imagination, or is that water at the horizon?

you can verify this with  sat images, there is open water not too far out but what we see is the dark surface "mirroring" in the cloud base, one can observe that often in barrows, open water quite far out, hence not directly visible, but the clouds are darker over open water and at times there is some increased humidity in the air, at times even visible fog over open waters and that's what we see.

again you can verify this be measuring the distance to open water and will easily see that it's too far away to be "seen" directly. this, provided nothing has changed during the last 2 days as far as open water is concerned, i'm not checking such details on a  daily basis, just about twice a week.

woodstea

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Re: What the Buoys are telling
« Reply #1325 on: May 26, 2017, 11:03:28 PM »
Distant open water is also something I imagined I saw frequently last year during the freeze-up -- the mind sees what it wants (or expects) to see. I think it's an illusion in this case. I don't see open water anywhere near this buoy in Worldview or the uni-bremen ice concentration map. The buoy is closer to Stefansson Island I think than to open water.

magnamentis

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Re: What the Buoys are telling
« Reply #1326 on: May 27, 2017, 12:08:43 AM »
kind of fata morgana LOL there is open water exactly i that direction at the entrance of the main passage. has been more 2 days ago, currently has been closing up a bit.

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Re: What the Buoys are telling
« Reply #1327 on: May 27, 2017, 12:17:24 AM »
The latest 6 days or so available of the B 2017A temperature profiles. I am showing the non-filtered data (red dashed line) and the filtered data. The result of filtering is that some spatial wiggling is removed, but also that the profiles take a 24h-averaged temperature approximately.

I think this daily-averaged temperature, for the thermistors not covered by ice or snow, is skewed to higher values frequently and I don't find another explanation that they are heated by sun or by the buoy material being heated by sun...

Is that slow slow rising at the ice water interface indicative of bottom melt?
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Re: What the Buoys are telling
« Reply #1328 on: May 27, 2017, 06:43:30 AM »
@Hyperion not really, the interface does  not change within the noise of the data, not clearly. The www of the site does indicate a very slight bottom growth, if anything. I think that is going to change in any other day, being the buoy relatively in periphery location.
http://imb-crrel-dartmouth.org/imb.crrel/2017A.htm

Andreas T

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Re: What the Buoys are telling
« Reply #1329 on: May 27, 2017, 01:24:29 PM »
The temperature at which the bottom of the floe at 2017A will melt depends on salinity of the sea water there. I expect salinity to be below 30 (PSU) ITP profilers in the Beaufort show salinity under the ice in winter as low as 28.3  This would mean a melting point of -1.6oC, clearly above the dashed red line drawn in seaicesailors nice graph.
The freezing of water at that temperature raises the temperature of ice which is below that temperature.
Bottom melt can only be expected to start when ice temperatures have risen to the melting point.

Is it my imagination, or is that water at the horizon?

you can verify this with  sat images, there is open water not too far out but what we see is the dark surface "mirroring" in the cloud base, one can observe that often in barrows, open water quite far out, hence not directly visible, but the clouds are darker over open water and at times there is some increased humidity in the air, at times even visible fog over open waters and that's what we see.

again you can verify this be measuring the distance to open water and will easily see that it's too far away to be "seen" directly. this, provided nothing has changed during the last 2 days as far as open water is concerned, i'm not checking such details on a  daily basis, just about twice a week.

These observations are correct at Barrow where open water is not much more than 5km from the coast, here  open water is 500km away and land 70km  if one can be bothered to look at such "details" further up the thread.
Low clouds do reflect the brightness of ice or darkness of open ocean but at those distances they would be below the horizon. What is visible here are just variations in the density of clouds

edit: added graph after seaicesailors reply
source: http://sam.ucsd.edu/sio210/gifimages/dens.gif
« Last Edit: May 27, 2017, 03:03:05 PM by Andreas T »

seaicesailor

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Re: What the Buoys are telling
« Reply #1330 on: May 27, 2017, 02:16:11 PM »
@Andreas Yes I plotted the red -1.8 C line as typical reference, but not implying that ice is melting as soon as the bottom water temperature is over that line. In fact no bottom melting seems to be happening yet. Thanks for the info on melting temp for that salinity Andreas.

Andreas T

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Re: What the Buoys are telling
« Reply #1331 on: May 29, 2017, 02:42:26 AM »
after a week of cloud the sun is out again at Obuoy14. There is a glazed look to the snow surface which is an indication of some surface melt and refreeze I think.
With a slightly different sun angle there is no visible change from the image posted by Jim on the 25th.
Temperature dipped when cloud started to thin at low sun but is up again in the afternoon to just below zero.

oren

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Re: What the Buoys are telling
« Reply #1332 on: May 29, 2017, 07:16:24 AM »
As the movie is not updating unfortunately, here's a very crude animation of images saved on this thread. ImageJ forced me for some reason to go down to 8-bit color. In any case, the shifting lighting make it very hard to compare between frames. Needs a click.

oren

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Re: What the Buoys are telling
« Reply #1333 on: May 29, 2017, 07:20:29 AM »
And here's another one with just 3 frames which have similar shadows. Definitely something is going on in the foreground. Click.

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Re: What the Buoys are telling
« Reply #1334 on: May 29, 2017, 10:59:28 AM »
I tried to find some background information to give us an idea what to expect. Looking around on worldview I took this IR image from 13th Feb. I have marked the position of Obuoy14 within the accuracy the GPS graph data allows.
colourscale squashed to 220 -273K https://go.nasa.gov/2reCuEJ
The surface temperature shown in this image gives an indication of the thickness of the ice in that area and how stable it has been. Further east there was movement at that time but (as also shown from the buoys GPS) no movement near the buoy since then.

This leads me to expect little "action" for a while. This area was breaking up on between 15th and 25th of July in the last 5 years.
Snow cover is melting on the islands to the west quite quickly now and hillsides are warm and snow free nearby. Snow is also melting on ice further south (Cambridge bay)
In 2016 this area was starting to look blue around the 5th June, a week earlier than the previous 4 years.

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Re: What the Buoys are telling
« Reply #1335 on: May 29, 2017, 12:28:54 PM »
You're probably right that there will be little action for a while, OTOH as I look over at the main melting thread at comments #1550 & 1585 from Tigertown and comment #1560 from Bairgon, I am thinking the CAA might be throwing buoy #14 a little melting action at least earlier than last year.

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Re: What the Buoys are telling
« Reply #1336 on: May 29, 2017, 01:09:29 PM »
Vigilius, these areas have little connection with the part of the Parry channel where Obuoy14 is.
Lancaster sound is deeper and usually ice moves throughout the winter there, this is one of the polynyas where the movement of water into Baffin Bay keeps water surface open.
North of Resolute are other, smaller polynyas which are regular features, again flow from the Arctic ocean to the Atlantic is the cause, warmer temperatures now are enlarging the open water.
The water which opens is flowing towards Baffin Bay and has no effect on the vicinity of Obuoy14.

Next week warm air is expected to flow into the CAA from the south, this is when I expect major changes to the snow cover to show at the buoy, around the 3rd June, i.e. similar timing to last year.

Longer term outlook is of course very dependent on uncertainties in the weather, but we saw inflow of older ice through McClure strait (together with Obuoy14) in the autumn which has collected where my IR image shows the lowest ice temperatures. I think this is more substantial than last year, how it will play out I don't claim to know.

oren, temperatures were still below -10C on 1st May and  several days after, so snow will have drifted then. Now I expect it to have fused into a harder firn at least on the surface and without fresh snow fall there will be no movement by wind.
« Last Edit: May 29, 2017, 01:19:35 PM by Andreas T »

Andreas T

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Re: What the Buoys are telling
« Reply #1337 on: May 29, 2017, 02:01:29 PM »
taking up oren's idea I couldn't resist the opportunity of closely matching lighting 25th/29th.
Shortening of the buoys shadow over just 4 day is striking, but there are slight changes in the snow texture. I think this is consistent with what in engineering terms would best be called sintering of snow crystals, finer crystals partly melting and refreezing into coarser grains of ice. I don't think temperature of the ice below would allow formation of the water accumulations which will become meltpools.
Without a clear reference (like the ablation stakes we have seen at other buoys) it is of course not possible to say  how much snow depth has changed, but we know that in the middle distance there are small piles of ice which would melt more slowly than snow and therefore will stand out more when the snow starts to melt. This is what I am looking for as a sign of substantial melt.

click to animate
« Last Edit: May 29, 2017, 03:10:09 PM by Andreas T »

vigilius

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Re: What the Buoys are telling
« Reply #1338 on: May 30, 2017, 04:08:21 AM »
Quote
Vigilius, these areas have little connection with the part of the Parry channel where Obuoy14 is. Lancaster sound is deeper and usually ice moves throughout the winter there, this is one of the polynyas where the movement of water into Baffin Bay keeps water surface open.

Thanks for helping me understand this better. (You know, I keep wanting to pipe up with exclamations of amazement and alarm, something like what forum member friv used to contribute, but I don't think I could ever come with anything better than "gee, willikers")

Watching_from_Canberra

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Re: What the Buoys are telling
« Reply #1339 on: May 30, 2017, 03:02:40 PM »
The attached image is from Worldview, 28 May.  OB14 is roughly in the centre of the image.  There do seem to be some largish cracks developing in the area.

Andreas T

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Re: What the Buoys are telling
« Reply #1340 on: May 30, 2017, 05:24:50 PM »
these too are old cracks, look at the 17th Feb https://go.nasa.gov/2shNwGH

I think they are just east of Obuoy14, I should have mentioned those too, sorry for posting too hastily. Thanks for spotting. Combining observations and checking up is a good thing in science!

2017A has updated, shows temperatures rising above 0oC
« Last Edit: May 30, 2017, 05:30:58 PM by Andreas T »

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Re: What the Buoys are telling
« Reply #1341 on: May 30, 2017, 05:45:35 PM »
Thanks for the heads up
The lastest 10 days of the 2017A temperature profile. Red: unfiltered data. Blue: soft filtering to remove wiggles and diurnal variations as possible
Note I placed the red dashed horizontal line at -1.6C (an arbitrary number as any other one).

Andreas T

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Re: What the Buoys are telling
« Reply #1342 on: May 30, 2017, 05:58:28 PM »
Snow depth has gone up. This fits the observation that after the storm passed through Jay W showed and the darkening in Wipneus' AMSR animation worldview 7,2,1 is not showing the darker blues of wet surfaces. This could have been wet snow falling rather than surface wetting by rain or melt, but those air temps should still start melting at the surface.

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Re: What the Buoys are telling
« Reply #1343 on: May 30, 2017, 10:23:48 PM »
I do think Algae growth under the floe is starting to melt it from below. antifreeze compounds etc.
Wish they had a webcam looking up.
Policy: The diversion of NZ aluminum production to build giant space-mirrors to melt the icecaps and destroy the foolish greed-worshiping cities of man. Thereby returning man to the sea, which he should never have left in the first place.
https://en.wikipedia.org/wiki/McGillicuddy_Serious_Party

vigilius

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Re: What the Buoys are telling
« Reply #1344 on: May 31, 2017, 05:47:42 PM »
I am relating in my own way to the discussion of "firn"

At the risk of being seriously off-topic I am thinking of the Chicago Art Institute, the room with the Monet grainstacks. The sixth one in the series. (Okay, he painted a zillion of them, I am thinking specifically of the sixth in the series displayed in Chicago in the permanent collection) The man could paint "firn" by which I mean ground which has frozen, been snowed on, thawed and partially melted, then refroze. (I can feel the crinkling under my feet as I say this)

For those of us less in the quant fields, is this what you mean by "firn"?

Meanwhile I have my eye on significant cracking just a bit east of 14 in the Parry Channel, maybe the buoy will have something to tell of this in the next few weeks.

Andreas T

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Re: What the Buoys are telling
« Reply #1345 on: May 31, 2017, 09:21:13 PM »
I should probably put this in the NWP thread but I think I can indulge a bit of OT once in a while:
There is a bit of the NWP route 1 which is intriguing me at the moment, not sure whether its called Lancaster sound or Parry channel at that point. There is a stretch of sea ice along the coast which is actually melting (arrow "M") rather than cracking (arrow "C") . Scanning back on worldview shows this was a crack in February, which looks as if nothing happened by the end of March. Beginning of May a faint shadow appears and on the 20th the first hole. Further enlargement isn't by the usual moving apart but by a gradual eating away of ice. No sign of surface melt (in bands 7,2,1)
Clearly the ice which grew since February was not very thick, but as at the polynyas north of Cornwallis island (I marked Resolute with R) the water flowing through the CAA from the arctic ocean is capable of melting from below. I suspect upwelling along than coast hitting a weak spot.

Even more OT: My experience of firn is limited to the Alps, I only know the North from what I read on ASIF (and its links and searches inspired by what I read here). There it can be quite abrasive grainy stuff which greatly shortens the time to descend from mountains in early summer (that I am able to write this shows I managed to stop before those shortcuts turned into steeper drops).
In spring off piste skiing crunching through the crust can be a almost as nasty as getting bicycle tyres caught in street car tracks.
The drifting of snow in the winter probably makes the snow on sea ice less fluffy even  before firn sets in. Something which I have encountered too in the Alps, drifted snow even at cold altitudes can be quite compact.
I allways considered Firn to be a german word, but could be wrong, german being my native tongue. Firniss is the german word for varnish, so there's a connection to Monet after all (I agree, if there was more snow in Paris or Rouen he would have done a great job of painting it)

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Re: What the Buoys are telling
« Reply #1346 on: May 31, 2017, 11:38:21 PM »
Even more OT: My experience of firn is limited to the Alps, I only know the North from what I read on ASIF (and its links and searches inspired by what I read here).

My notion of firn, comes from the firn line (https://www.google.com/search?q=firn+line+glacier+definition&rlz=1C1CHFX_enUS590US590&oq=firn+line&aqs=chrome.2.69i57j0l5.23591j0j7&sourceid=chrome&ie=UTF-8).  Probably much the same as in the Alps.

The firn line is where above it the glacier is adding material, and below it the glacier is losing material.

I'm guessing that the use of the term firn here has some sort of relationship -- but I must admit to not understanding it.

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Re: What the Buoys are telling
« Reply #1347 on: May 31, 2017, 11:41:55 PM »
There is a stretch of sea ice along the coast which is actually melting

I posted about that over in the melting thread:

The last one is of an area of Parry Channel which appears to be melting out rather than breaking up (though other areas further down have broken up).

It's certainly been interesting since then; though it looks like the ice will soon collapse as a large area has cracked.

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Re: What the Buoys are telling
« Reply #1348 on: June 01, 2017, 11:09:15 PM »
The predicted warming has arrived at Obuoy14 it seems.
On the 29th temperatures dropped with clear sky as usual, but when at 15:00 UTC clouds arrived again the rise in temperature which had happened on previous occasions was small and then dropped back down to -5C. It has remained cloudy since then.
I think the reason has been that these clouds have come from the north where temperatures at that time were still low (see IMB2017B) I have made an animation of band31 images both night and day TERRA
« Last Edit: June 01, 2017, 11:20:56 PM by Andreas T »

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Re: What the Buoys are telling
« Reply #1349 on: June 02, 2017, 05:18:05 AM »
The odd bouncy temperatures today are mirrored by bouncing battery voltages, high battery current and power draw. Obuoy 14 is struggling to stay alive I think.