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Jim Hunt

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Re: What the Buoys are telling
« Reply #950 on: July 22, 2016, 12:29:05 PM »
In trying not to read too much into this, but are 2015I and 2015J trying to awake?

I think it's more that the CRREL has finally got around to processing some more of their data. Note that neither of them are up to date :(
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JayW

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Re: What the Buoys are telling
« Reply #951 on: July 23, 2016, 12:07:32 AM »

I think it's more that the CRREL has finally got around to processing some more of their data. Note that neither of them are up to date :(


Thanks Jim,  that's makes more sense. But there's hope  :) 2015J is current as if yesterday with some data apparently.  But looking at it cautiously for now.

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Andreas T

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Re: What the Buoys are telling
« Reply #952 on: July 23, 2016, 09:23:35 AM »
taking position from colocated ITP89 http://www.whoi.edu/page.do?pid=148096 which gives lat/lon to more precision than I ncan position the cursor in worldview I locate Obuoy14 where the red dot is in the image below. I marked south with an arrow, the best way I find to see which way the camera is pointing is from sun position and local time (UTC + 9:20 if I am doing my sums right)
Try it for yourself http://go.nasa.gov/2a4FSXq
and yes there are large leads in the area.
The ITP oddly gives the time of the position data as 13:16UTC when it is only 7:20 UTC now, so there is some doubt by how much image and position are misalligned.
« Last Edit: July 23, 2016, 11:10:36 AM by Andreas T »

Jim Hunt

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Re: What the Buoys are telling
« Reply #953 on: July 23, 2016, 10:53:24 AM »
2015J is current as if yesterday with some data apparently.

I was looking in the data file, which only goes up to July 5th.
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Andreas T

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Re: What the Buoys are telling
« Reply #954 on: July 26, 2016, 12:55:00 AM »
looking at the buoy data http://imb.erdc.dren.mil/irid_data/2015J_Proc_21Jul16.csv
today the last entry is dated 22/07/01:01
What I find very interesting is how the water temperature rises quite strongly, up to -1.0oC at the latest. There are also above zero temperatures near the surface, which appear to be in water since they do not follow the temperature fluctuations of the air temperature.
Whether the stong bottom melt shown by the sounder data is localized is impossible to say but at least the temperature profile is consistent with it.
The buoy is colocated with Obuoy13 which shows no new data since 29. April, before melting started in that vicinity.

Jim Hunt

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Re: What the Buoys are telling
« Reply #955 on: July 26, 2016, 01:28:16 AM »
today the last entry is dated 22/07/01:01

Yup, they've updated it again! It's a shame the data file's in a different format to 2015F though :(
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Andreas T

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Re: What the Buoys are telling
« Reply #956 on: July 27, 2016, 11:42:47 PM »
comparing with the earlier images http://forum.arctic-sea-ice.net/index.php/topic,327.msg84027.html#msg84027the AOFB is now sitting noticeably lower so some melting seems to be going on

Andreas T

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Re: What the Buoys are telling
« Reply #957 on: July 28, 2016, 09:22:06 AM »
ITP89 reports: Last position on 2016/7/28 1316 UTC : 76.9989° N, 140.7808° W (again, that time is several hours in the future)http://www.whoi.edu/page.do?pid=148096
looking this up on worldview of the 27th http://go.nasa.gov/2awjqde finds the same floe I identified on the 22nd  (see above) which makes me more confident that  this is the floe on which Obuoy14 sits together with its companions.
temperatures are up at about zero and there has been water on the lens.
Following on from the discussion with Rob on the season thread it fits what I said about radiative balance that surface temperatures are higher under clouds. Under clear skies with lower surface temperatures melt is nevertheless continuing below the surface from absorption of the incoming SW (which is lower under dense clouds).

edit: in the file http://www.whoi.edu/page.do?pid=148096 which shows hourly lat/lon position for ITP89 the time is given as day of year in decimals: 2016  210.00921  -140.7808  76.9989  which makes it 12 hours earlier than 13:16 and makes more sense, maybe a leap year thing?
« Last Edit: July 28, 2016, 07:31:50 PM by Andreas T »

Iceismylife

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Re: What the Buoys are telling
« Reply #958 on: July 28, 2016, 07:43:44 PM »
...
Following on from the discussion with Rob on the season thread it fits what I said about radiative balance that surface temperatures are higher under clouds. Under clear skies with lower surface temperatures melt is nevertheless continuing below the surface from absorption of the incoming SW (which is lower under dense clouds).
...
My thinking is that if you can see melt ponds or leads through the clouds looking down or they are bright on the bottom looking up then net warming. If they are dark then net cooling.

seaicesailor

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Re: What the Buoys are telling
« Reply #959 on: July 28, 2016, 07:52:12 PM »
The 2015F temperature profile since Jun 1 from the csv provided in the web page. The x-axis origin does not coincide with ice top. It is just thermistor number x 10.
During June, apart from the gradual rise in surface temps and warming of ice by heat conduction, there is a steady rise at the bottom not caused by heat conduction through the ice.
It changes a lot around the 5 to 8 of July. There is this sudden rise of temperatures around the 5 to 10 of July.

ghoti

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Re: What the Buoys are telling
« Reply #960 on: July 28, 2016, 08:16:47 PM »
Really fabulous way to present the time series! Thanks

seaicesailor

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Re: What the Buoys are telling
« Reply #961 on: July 29, 2016, 12:35:03 AM »
Really fabulous way to present the time series! Thanks
Thanks to you. I will be rerunning the script in some days to see how it goes. Maybe we can make some sense out of it.
Forgot to mention I filtered fluctuations below 30 cm scale and 1 day approx.

Jim Hunt

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Re: What the Buoys are telling
« Reply #962 on: July 29, 2016, 01:00:37 PM »
The 2015F temperature profile since Jun 1 from the csv provided in the web page.


Excellent stuff! I've taken the liberty of sharing it on my 2016 IMB page:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/summer-2016-imbs/#2015F-Anim

I hope that's OK with you? Please advise ASAP if not! Are you by any chance willing & able to share your code/methodology?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

seaicesailor

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Re: What the Buoys are telling
« Reply #963 on: July 29, 2016, 02:05:32 PM »
The 2015F temperature profile since Jun 1 from the csv provided in the web page.


Excellent stuff! I've taken the liberty of sharing it on my 2016 IMB page:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/summer-2016-imbs/#2015F-Anim

I hope that's OK with you? Please advise ASAP if not! Are you by any chance willing & able to share your code/methodology?

Thank you Jim! More than glad that you share it.
It is Matlab code but requires a few manual things yet. I will tidy it up and share it soon

Andreas T

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Re: What the Buoys are telling
« Reply #964 on: July 29, 2016, 11:06:59 PM »
Thank you seaicesailor for an excellent new way to "read" the huge amount of data from the IMB.

Not to be outdone, Obuoy14 also has a new video out, it has updated to the 26th July. http://obuoy.datatransport.org/monitor#buoy14/movie

seaicesailor

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Re: What the Buoys are telling
« Reply #965 on: July 30, 2016, 12:58:04 AM »
Thank you Andreas :-)
Looks to me that the buoy over the pond basculates as if it got loose just recently.

magnamentis

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Re: What the Buoys are telling
« Reply #966 on: July 30, 2016, 11:21:59 AM »
Thank you Andreas :-)
Looks to me that the buoy over the pond basculates as if it got loose just recently.

glad you said pond and not "melt pond" because this is an open water pond, not a melt pond anymore, the buoy is definitely "swimming" and not stuck in under water ice anymore :-)
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Andreas T

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Re: What the Buoys are telling
« Reply #967 on: July 30, 2016, 12:34:03 PM »
You probably missed this on the melting season thread http://forum.arctic-sea-ice.net/index.php/topic,1493.msg84359.html#msg84359, these images show how the stem of the buoy can be freed of ice by increased melting near the buoy. This could be due to stronger absorption of sunlight by the buoy.
A gap around the buoy (is this what you mean by open water pond?) regardless of size means that the water surface in the pond is at the same level as the surrounding sea water. There was no large drop in water level when the gap opened (I take the dropping of the buoy as its first appeareance) so this indicates that the ice surface is not far above the sea level. That low freeboard in turn shows that the ice is not very thick.
As I have pointed out earlier ice thickness at installation was only 45cm http://imb.erdc.dren.mil/2015H.htm
Unfortunately 2015H soon was damaged by the shearing of the floe seen in the video so we do not have information on how much thickness grew over winter. IMBs 2015F, I and J had growth between 90 and 60cm.
Of course the ice surface is not flat, the place where the meltpool has formed is a low point so we can't actually derive ice thickness from these observations with any precision other than it confirms the ballpark of numbers quoted above. Some bottom melt will have taken place, more will be happening over the next month. I still think melt out is a possibility, but not a guaranteed event. But then there is little point in claiming to know in advance what we will see in mid September unless your main interest is who said what first  ;)

Andreas T

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Re: What the Buoys are telling
« Reply #968 on: July 30, 2016, 11:20:47 PM »
The AOFB has sunk deeper. I haven't saved images recently so can only compare with 27. and 24. when it was sitting higher in the water.
The melt pond is getting wider, I don't think this is a separation along the old fracture line yet but that is becoming likely to happen with so much of the melting season still to come and albedo reduced again.

seaicesailor

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Re: What the Buoys are telling
« Reply #969 on: August 01, 2016, 07:57:30 PM »
The 2015F temperature profile since Jun 1 from the csv provided in the web page.


Excellent stuff! I've taken the liberty of sharing it on my 2016 IMB page:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/summer-2016-imbs/#2015F-Anim

I hope that's OK with you? Please advise ASAP if not! Are you by any chance willing & able to share your code/methodology?


As promised I have posted the code. If Matlab not available, which is very possible, it may work in octave but probably needing some modifications.

http://forum.arctic-sea-ice.net/index.php/topic,1622.msg85130.html#msg85130

As an example, below the evolution of the last 15 days, in a very slow motion (6 profiles per day).

woodstea

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Re: What the Buoys are telling
« Reply #970 on: August 05, 2016, 05:32:25 PM »
I notice that AOFB 37, the one the O-Buoy 14 camera view, last reported on July 9:

http://www.oc.nps.edu/~stanton/fluxbuoy/deploy/buoy37.html

I wondered if it's stopped working, or if it uploads data infrequently. Looks like we'll have some sun today:


Andreas T

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Re: What the Buoys are telling
« Reply #971 on: August 05, 2016, 11:22:37 PM »
good call! With cloud cover when sun was low and clear sky towards local noon, temperatures are above 0 again after the recent cold spell. The AOFB has rotated slightly since the earlier picture, showing that it isn't frozen solid depite the snow drift covering ice on the melt pond. the clear sky gives us a view of this location when the AQUA image comes out later.


Andreas T

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Re: What the Buoys are telling
« Reply #972 on: August 06, 2016, 02:34:43 PM »
Taking position of Obuoy14 from colocated ITP89 again http://www.whoi.edu/page.do?pid=148096 with AQUA overflight assumed to be 20:00UTC approximately, I have marked the position: 2016  218.83352  -137.9446  76.5575
(correct me if I am getting this wrong)

the position marker is the small dot, the arrow points south to orient the images. The floe has turned about 60o since the 23. 7. (see GPS http://obuoy.datatransport.org/monitor#buoy14/gps) so everything fits although the shape of the floe has changed a bit, just not in front of the camera.

seaicesailor

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Re: What the Buoys are telling
« Reply #973 on: August 06, 2016, 06:11:03 PM »
Now that we are at it, 2015F webpage stopped reporting data again, this time on July 31.
The closest MODIS open view for the last reported location is on August 3, see below.
The ice looks "relatively healthy", so I really suspect the rapid melting reported by the buoy was due to a nearby crack or self-inflicted.
I hope the buoy is alive and kicking and survives the summer. Next year it may be in the stream of export toward Beaufort sea.

Andreas T

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Re: What the Buoys are telling
« Reply #974 on: August 08, 2016, 10:58:53 PM »
On the surface not a lot is changing at Obuoy14, temperatures have only briefly briefly been warm. Now it is looking a bit wetter, with the snow in the low lying parts becoming more transparent.
I am expecting bottom melt thinning the ice and because that reduces freeboard, water levels in the ponds should rise. At least that is true for the pond in which the AOFB sits. The buoy keeps turning so there must be a gap which connects the water in the pond to the ocean below the ice.

Adam Ash

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Re: What the Buoys are telling
« Reply #975 on: August 11, 2016, 10:41:43 AM »
Well if those ponds are at sea level (must be if 'connected') then the floe the buoys are on can only be about a metre thick, because there only looks like 10 cm free-board at the most! Another 30 days of bottom melt to go - they could all be adrift.

Andreas T

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Re: What the Buoys are telling
« Reply #976 on: August 12, 2016, 09:31:26 AM »
I expect thickness to be less than one metre. The floe has seen some deformation in the winter and has greater thickness in some places. I think bottom melt is continuing while surface temperatures now drop to lows which have not been seen for two months. The meltpond has frozen over again but is showing different behaviour from earlier in the season. It is widening even while some ice is on its surface. I attribute that to the lowering freeboard. Clear sky yesterday made the floe visible from satellites http://go.nasa.gov/2b1Fc5I and I have marked the buoy position again with a small red dot 138.22W 76.35N from http://www.whoi.edu/page.do?pid=148096.
Some ice has broken off at the far end from the buoys and there are darker lines visible (consistent with earlier images so not cloud shadows) which suggest further break up is imminent.
The floe is surrounded by plenty of open water which is still absorbing solar radiation. How quickly this is available to melt ice I don't know, but I suspect that some of the energy which was absorbed earlier is still making its way to the ice/water interface.

Andreas T

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Re: What the Buoys are telling
« Reply #977 on: August 12, 2016, 02:09:23 PM »
This confirms what I said before I think: despite low temperatures, the pond area is becoming more transparent again. On the horizon the ice which had drifted into view in the last image has drifted away again but also some of the ridged ice on the edge of the floe has gone, something that was seen in previous years (eg Obuoy9) with warmer sea water producing lateral melt as well as bottom melt.

vigilius

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Re: What the Buoys are telling
« Reply #978 on: August 15, 2016, 12:23:59 PM »
Lovely shot from #14, taken just now at 901 UTC. Though the temp is below freezing, our little meltponds seem to have re-melted.

Jim Hunt

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Re: What the Buoys are telling
« Reply #979 on: August 15, 2016, 09:17:06 PM »
I have just discovered via Andreas Muenchow's Twitter feed that another CRREL ice mass balance buoy is due to be deployed from RV Araon shortly:

http://www.ice-arc.eu/2016/08/11/blog-buoy-deployments-in-the-arctic/

It seems some British Antarctic Survey IMB's are out there too, but I haven't located any meaningful thermistor data from them as yet:

http://frazil.nerc-bas.ac.uk/ice-arc/index.php
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Andreas T

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Re: What the Buoys are telling
« Reply #980 on: August 16, 2016, 02:27:12 AM »
At Obuoy14 air temperature is up to just below zero again and more signs that the ice is getting thinner from below. That ice on the pond melts in these temperatures is a sign of saltiness of the water in the pond I think. Not sure how, but could water from below the ice be mixing with the fresher meltwater of the pond?
http://obuoy.datatransport.org/monitor#buoy14/weather


epiphyte

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Re: What the Buoys are telling
« Reply #981 on: August 16, 2016, 08:07:51 AM »
Is the buoy on the right floating in a hole? It's acquired something of a list to stbd over the past day or so...


Watching_from_Canberra

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Re: What the Buoys are telling
« Reply #982 on: August 16, 2016, 08:26:52 AM »
That pond looks like a polynya now...

Andreas T

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Re: What the Buoys are telling
« Reply #983 on: August 16, 2016, 08:53:30 AM »
epiphyte, if you scroll up to post 965, there is discussion of this some way back. There often is increased melt of ice in contact with the buoy which then turns into a larger gap as water moves preferentially through the opening.
There is a stem below the visible float so that the buoy can be tilted by ice or water pushing against the lower part of that stem, see http://www.whoi.edu/page.do?pid=147717&tid=201&cid=116993&ct=362#
This buoy has had a list towards the side where a small mast with some instruments is mounted for a while and has kept rotating, so yes I think it sits in a hole of unknown size.

Watching_from_Canberra

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Re: What the Buoys are telling
« Reply #984 on: August 16, 2016, 11:35:53 AM »
Now you see it...

Watching_from_Canberra

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Re: What the Buoys are telling
« Reply #985 on: August 16, 2016, 11:37:02 AM »
Now you don't ...

Watching_from_Canberra

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Re: What the Buoys are telling
« Reply #986 on: August 16, 2016, 12:27:16 PM »
Is that it in the background??

Jim Hunt

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Re: What the Buoys are telling
« Reply #987 on: August 16, 2016, 12:31:49 PM »
Is that it in the background??

Yup! Do you suppose ITPs float?
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seaicesailor

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Re: What the Buoys are telling
« Reply #988 on: August 16, 2016, 01:49:26 PM »
Divergence best demo experiment

Jim Hunt

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Re: What the Buoys are telling
« Reply #989 on: August 16, 2016, 01:50:42 PM »
The next in the sequence:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

marcel_g

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Re: What the Buoys are telling
« Reply #990 on: August 16, 2016, 02:37:12 PM »
That ice looks more like slush than ice. Do you think this is the stage just before it goes poof? I wonder how much of the ice in the CAB looks like this, and how much of it will in fact go poof before mid-september?

bbr2314

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Re: What the Buoys are telling
« Reply #991 on: August 16, 2016, 02:38:00 PM »
Woooooooosh! There it goes. ;)

Metamemesis

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Re: What the Buoys are telling
« Reply #992 on: August 16, 2016, 02:43:28 PM »
It's the rapidity of the change in one day which amazes me. Compare the image in Reply #980 From Andreas to the latest image from Jim Hunt in Reply #989. Crumbs.

Watching_from_Canberra

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Re: What the Buoys are telling
« Reply #993 on: August 16, 2016, 02:46:46 PM »
Yep - that's 12 hours!

Jim Hunt

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Re: What the Buoys are telling
« Reply #994 on: August 16, 2016, 02:53:29 PM »
Make that 13?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Bruce Steele

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Re: What the Buoys are telling
« Reply #995 on: August 16, 2016, 04:00:39 PM »
I have been watching ITP93 salinity ( temp/salinity contours) shoal very rapidly over the last few days.
35.5 salinity water has shoaled from 75 meters to ~ 20 meters in a very short timeframe. ITP 93 may show Atlantic origin water upwelled to the surface within a few more days. The water is cold -1.8 C but the high salinity will undoubtably accelerate surface melt.

http://www.whoi.edu/page.do?pid=148496

Jim Hunt

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Re: What the Buoys are telling
« Reply #996 on: August 16, 2016, 05:30:03 PM »
I blinked and missed one:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

jdallen

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Re: What the Buoys are telling
« Reply #997 on: August 16, 2016, 06:08:26 PM »
I blinked and missed one:
WOW.
I think we've just seen visual testimony to the heat available in the water, the actual vulnerability of the ice, and the effect of ekman pumping.
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Jim Hunt

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Re: What the Buoys are telling
« Reply #998 on: August 16, 2016, 06:34:22 PM »
Here's a couple more. Plus O-Buoy 14 wind speeds:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

jai mitchell

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Re: What the Buoys are telling
« Reply #999 on: August 16, 2016, 08:53:46 PM »
Is that it in the background??

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