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Messages - Nightvid Cole

Pages: [1] 2 3 ... 9
1
Arctic sea ice / Re: The 2019 melting season
« on: August 12, 2019, 03:16:55 PM »
What about evaporation?

The high Arctic usually has relative humidity values of at least 90% and often near 100%. This would largely suppress evaporative cooling.

2
Arctic sea ice / Re: The 2019 melting season
« on: July 23, 2019, 02:49:03 PM »
00z ECMWF shows big high pressure over central Arctic ocean around +120h. We'll finally have clear weather so we can see just what shape the ice is in on Worldview.

3
Arctic sea ice / Re: Subdividing the Central Basin
« on: July 23, 2019, 11:53:40 AM »
I suppose we could invoke the so-called Sector Principle and use terminology like "Chukchi-CAB", "ESS-CAB", "Laptev-CAB", etc.

4
Arctic sea ice / Re: The 2019 melting season
« on: July 21, 2019, 10:43:28 AM »
It's beginning to appear that the solid white area on this map is possibly the approximate region that will be ice-covered at minimum. Can anyone estimate the area?


5
Arctic sea ice / Re: The 2019 melting season
« on: July 19, 2019, 07:39:46 PM »
HYCOM Arctic ice thickness model July 19 - July 25

Looks like this year there wont be any thick ice at the end of the season. Guessing from this images, we could end up with that blue ice mass which could be only less than 1m thick :(



Is that hole near the North Pole real?

6
Arctic sea ice / Re: The 2019 melting season
« on: July 12, 2019, 11:56:06 AM »
I have been saying this for a few weeks now, and every time I do, very smart people tell me I’m silly and the ice in the Beaufort is moving into a kill zone and will melt out soon.

But it has still not happened.  I’m still thinking this might be a record year, but it won’t happen unless the Beaufort clears out.  We are now in mid-July and it is quickly running out of time. 

The Beaufort is the key to whether or not we hit a record.  If it warms up and melts all of that ice quickly, I agree we have a good chance of a new record. But, if all of those chunks of ice continue swirling around for a couple of more weeks, I think it will be hard for this year to beat 2012.

"Top surface melt" season has reached its peak for sure, but "bottom melt" season is only just beginning and often chews through a lot of ice in late July and in August. With such open water between the ice floes in the past 2 weeks or so, a lot of solar energy has been soaked up by the upper ocean layer, so everything is in place for an intense "bottom melt season" in the Beaufort...

7
Arctic sea ice / Re: The 2019 melting season
« on: July 07, 2019, 10:49:27 PM »
Is it just me or has the entire Northern Sea Route been reduced to "slush puppie" ice that doesn't require a heavy duty icebreaker to get through?

8
Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 05:02:08 PM »
I'm afraid a July cooldown is too late to save the ice. Apparently the amount of solar radiation reflected from the Arctic in June is almost a decisive determination of the final September extent (r = 0.91).  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JD025819

9
Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 11:41:57 AM »

10
I say 2.5 - 3.0 million km^2, I think we will beat 2012 because June was so exceptionally hot in the Siberian/Pacific sector and concentration is already dropping precipitously there. (previous hottest Junes were 2007 and 2012 in that region).

https://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=2000&lat1=90&lat2=68&lon1=90&lon2=225&iseas=1&mon1=5&mon2=5&iarea=1&typeout=2&Submit=Create+Timeseries


11
Arctic sea ice / Re: 2018 Melting Season - Predictions and Speculation
« on: March 26, 2018, 03:01:30 PM »
It looks to me like the PIOMAS ice volume is likely to join the pre-2017 years, since we have had such a "cold snap" this month (really just a return to near average!). Thus, I expect the volume and extent minima to be similar to 2011 this year, unless weather surprises come this spring or summer, which is quite possible...

12
Arctic sea ice / Re: Overdue for a 'monster' spring volume melt?
« on: March 06, 2018, 03:29:50 AM »
Looks like we'd get down to around 2,300 km^3 if this year gains and loses the same volume as 2010 (starting March 1st). That's a 35% drop from the minimum in 2012.

13
Arctic sea ice / Re: AMSR2 Sea Ice Volume/Thickness
« on: March 04, 2018, 02:08:16 PM »
A few people already know the ADS/JAXA sea ice thickness and melt concentration product. It is derived from various AMSR2 scanning frequencies.

The melt concentration makes it hard to estimate the sea ice volume, because you can't just read out all individual cell values and calculate the sum. To overcome this issue I developed a melt algorithm which estimates thinning based on the melt concentration percentage and the number of days it occurred. The algorithm also estimates freezing of open water from the melt concentration.

My calculated Sea Ice Volume & Thickness:
https://sites.google.com/site/cryospherecomputing/amsr2-sea-ice-volume





Anyone interested in the details can look at my short documentation.
https://sites.google.com/site/cryospherecomputing/documentation/amsr2-sea-ice-volume-algorithm

Due to the JavaScript download-site from ADS I can't set up daily updates, but I'm able to download a whole month of sea ice thickness products and get rid of unwanted files and decompress the right ones for processing. With these scripts I can update it every month with a few minutes work.

The AMSR2 thickness isn't as accurate as PIOMAS for actual sea ice thickness. It's definitely affected by melt pond refreezing in August, which almost cancels out further volume losses and thickness increase is rather slow in October-November. As indicated with 2017 it counts snow cover as additional sea ice volume like CryoSat did.

If ones aware of these artefacts it's still a very useful tool to judge current sea ice conditions. Refreezing melt ponds mean a quick end to the melting season and additional snow has to melt in spring before the sea ice melts.

Further it has a higher spatial resolution (10km) than PIOMAS and a higher temporal resolution for the entire Arctic than CryoSat.

Attached is a comparison to PIOMAS

ADS Raw Data visualization:
https://ads.nipr.ac.jp/vishop/#/monitor

I'm a little bit puzzled on the physicality of your melt algorithm, which appears to diminish the thickness of thick ice much faster than that of thin ice. In actuality, the thickness has to decrease at a rate governed by the energy input into the ice (from sun, air above, and water below). None of these energy sources input energy at a rate proportional to the thickness of the ice. What gives?

By the way, you ought to open source this on Github!

14
I'm going with March 11th-13th, which just 'feels' right to my 'gut'.

15
Arctic sea ice / Overdue for a 'monster' spring volume melt?
« on: March 02, 2018, 04:08:08 PM »
It looks like we haven't really had a warm spring in the Arctic since 2010. Here is the April-June temperature for the region north of 75 degrees latitude:

https://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=Air+Temperature&level=1000&lat1=75&lat2=90&lon1=0&lon2=360&iseas=1&mon1=3&mon2=5&iarea=1&typeout=2&Submit=Create+Timeseries

It is also true that 2010 had the largest spring volume drop on PIOMAS of all time:

https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd3.png?attachauth=ANoY7cpnGfvdXIX8LPaNeN2TTx4i88IJgME3gaEISrD7kWYWSJVd5tV-ydfcVrf9SCEl1gGtWsFF5TRnxv5uUysZn_vqxQ_VP1LNk6OfFuXqUhDMvBt6t_jPO6SqEbt7dt0gd78wAP7d_3Cw1noBJW27uQ8EZxv6xy_Lffjc4H03QJmz8CBGYPCwz9KAOevGtyYtW9TnywFLHygz3JTssrAYBHzTT9HcD54MxB3NSmoKEO2X5trcoOqOXvoIMCB-3Hp3bmKOleBB&attredirects=0

Since the trend has been for warming springs since at least 1990, this raises the question of whether we are overdue for a monster spring volume melt. Even a spring melt identical to 2010 puts us on the fast track to shattering the 2012 volume minimum. If we have a spring warmer than 2010, it seems that we could approach near ice free conditions in a single year. What gives? 

16
Arctic sea ice / Re: The 2017/2018 freezing season
« on: February 08, 2018, 04:31:03 PM »
Unfortunately, I can't do images on my computer right now, but take a look at Climate Reanalyzer. The Arctic is ground zero for an absolute blowtorch starting within the next few days!!!!

17
I went higher this year, I think it will not go below 4.5 M. This is because I looked at NASA worldview and right now the Arctic is whiter than any other recent year at this time, even 2013 and 2014. This indicates very little melt ponding and the great majority of the sun's rays hitting the Arctic are bumped back out to space.

18
Arctic sea ice / Re: Latest PIOMAS update (June)
« on: June 03, 2017, 03:50:23 PM »
So it may get really close to 18k, because there is an accelerating trend

Perhaps you did not intend the x-axis label "MayDay" to contain the subconscious connotation of "doom", or did you?   ;)

19
Arctic sea ice / Re: Latest PIOMAS update (December)
« on: December 18, 2016, 06:15:14 PM »
What do you think? Will we end up with a new lowest December record?

Yes, given that the volume on December 1st was at a record low by a significant margin and the anomalous warmth has continued.

20
Arctic sea ice / Re: The 2016/2017 freezing season
« on: September 10, 2016, 04:28:22 AM »
New ice is forming around the "shoulder" area, filling in some of the holes.

21
Arctic sea ice / Re: The 2016 melting season
« on: September 07, 2016, 03:39:49 PM »
The amount of 100% ice cover for the 6th looks remarkably small.

Not significant. cf. July 12, 2015.


22
Arctic sea ice / Re: 2016 sea ice area and extent data
« on: September 05, 2016, 02:45:15 PM »
Can someone elaborate on this



http://www.iup.uni-bremen.de:8084/amsr2/extent_n_running_mean_amsr2_regular.png

This would actually seem to agree with IJIS that we are at the second lowest on record for extent, after 2012 which is mysteriously omitted from the graph...

23
Arctic sea ice / Re: 2016 sea ice area and extent data
« on: September 04, 2016, 04:02:58 PM »

The University of Bremen AMSR2 plot appears to have taken a scarcely credible nosedive.
http://www.iup.uni-bremen.de:8084/amsr2/extent_n_running_mean_amsr2_regular.png

A large sector has gone missing from the map as well.


24
Arctic sea ice / Re: The 2016 melting season
« on: September 03, 2016, 05:22:46 PM »
The area of low concentration ice now extends very near the north pole. Does anyone here think that it might be possible to make it to 88-89N in a small boat?

25
Arctic sea ice / Re: The 2016 melting season
« on: August 31, 2016, 08:45:39 PM »
The last six days have seen some appearance of new ice-free areas around the pole but mostly existing such areas just moving 'downward' towards the CAA. The animation shows the progression of lumped 0-10% sea ice concentration according to UHH AMSR2 3.1k.

Along with a surprisingly calm and content polar bear...

26
Arctic sea ice / Re: The 2016 melting season
« on: August 28, 2016, 07:29:22 PM »
Do you think the open water now is anykind of important in n80.
Im not an expert, but this region will have soon very low temperatures and no sun anymore, so it can give heat to atmosphere, better then warmed water driftet full with ice and then isolation during the hole winter.


Not sure I'm following completely - but wouldn't open water N of 80 with transient surface freezing pull the air temperature up towards freezing point, even in the absence of the sun? One might speculate that in rough seas this might go on for some time due to mixing down as far as 50-100m competing with the heat loss at the surface. If so, that would be a net loss of energy for the whole system, but warmer than usual low-level air temps. I'm far from an expert either, but I would think that the longer the period between sundown and the onset of the hard winter temp. inversion , the slower the refreeze overall?

From my old pasttime of looking at reanalysis data, I would say this is not significant until at least mid-September.

27
Arctic sea ice / Re: 2016 sea ice area and extent data
« on: August 26, 2016, 03:19:10 PM »
If so:


28
Arctic sea ice / Re: 2016 sea ice area and extent data
« on: August 26, 2016, 03:16:35 PM »
Is this real (from ASIG page) ?

29
Arctic sea ice / Re: The 2016 melting season
« on: August 24, 2016, 10:09:17 PM »
Are you feeling detached yet?


30
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 20, 2016, 08:48:34 PM »
The "regional graphs" on the Arctic Sea Ice Graphs page are all messed up :(

31
Arctic sea ice / Re: The 2016 melting season
« on: August 19, 2016, 05:47:12 PM »
...
Any ideas why the discrepancy?
Isn't it obvious? He compares _extent_ numbers to _area_ numbers. Like if it's same thing. It's not. And it's not. ;)

The question is why the 4km resolution for MASIE doesn't allow the extent numbers to be affected by all the open water areas that are in the interior of the ice pack. Or at least it's my question. If the grid cell size is small enough, eventually extent and area should be similar to each other, right?

32
Arctic sea ice / Re: The 2016 melting season
« on: August 19, 2016, 03:06:15 PM »
On our very own ASIG page, the CAB area is now at an all time low for this date:

While being a very different measure and not ideal for year to year comparisons, MASIE shows close to the opposite.



But does have the overall extent as lowest on record.



Any ideas why the discrepancy?

33
Arctic sea ice / Re: The 2016 melting season
« on: August 19, 2016, 02:17:37 PM »
On our very own ASIG page, the CAB area is now at an all time low for this date:


34
Arctic sea ice / Re: The 2016 melting season
« on: August 17, 2016, 07:48:07 PM »
Seems the cyclone is doing a number on the ice:


35
Arctic sea ice / Re: The 2016 melting season
« on: August 16, 2016, 01:49:18 PM »
Lots of holes in the NCEP map, which has a higher concentration cutoff for showing ice:


36
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: August 07, 2016, 03:29:09 PM »
Animation of the Chukchi corner is another illustration of the exiting changes going on.
It appears that yesterday's cloud bank produced phantom ice (the one-day straight-line-edge-between-higher-and-lower-concentrations) - one day there, the next day 'poof'. 

Would I be correct to think the reported sea ice area decrease is partly due to this lost phantom ice?

If it comes from the 89 GHz AMSR2 data, yes. At such a high frequency, cloud interference is a large effect.

37
Arctic sea ice / Re: The 2016 melting season
« on: July 28, 2016, 02:58:21 PM »
Latest ZMAW map:


38
Arctic sea ice / Re: The 2016 melting season
« on: July 27, 2016, 08:57:14 PM »
Here is an image from July 17th of this year, with less cloud obscuration of the satellite sensor.

39
Arctic sea ice / Re: The 2016 melting season
« on: July 26, 2016, 01:51:00 AM »
For some reason, Environment Canada's cloud free mosaic seems stuck on the week ending July 4. I looked at the ECMWF's forecast for the next 10 days and it shows that low just bouncing around the arctic, so it will likely be overcast for much of the time over most of the central Arctic. I badly wish we could get a few clear days to see what shape the ice is in on MODIS. :(

40
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: July 23, 2016, 04:05:08 AM »
Animation is of the Greenlands Sea, where the ice is having a hard time. The fast ice in NE Greenland can been seen dropping a little notch at the top. I expect bigger losses soon.

What are the pulses of white in this image? It looks like waves... is that related to weather or satellite coverage or something?

It's the satellite sensors picking up cloud cover.

41
Arctic sea ice / Re: The 2016 melting season
« on: July 22, 2016, 09:05:25 PM »
The ice looks like Swiss cheese on the Siberian side, to quite deep into the interior of the ice pack.

https://ads.nipr.ac.jp/vishop/#/monitor

Choose the RGB option under "product selection", and select July 21, 2016. Note that you can compare to other years on this date. Usually the Swiss cheese-ice at this time of year will be gone in mid-September. If this year follows that rule, it will end up much like 2012, maybe even a little worse. Time will tell...

42
Arctic sea ice / Re: The 2016 melting season
« on: June 09, 2016, 05:56:40 PM »
DMI has finally gone above the freezing mark for the first time this year.

43
Arctic sea ice / Re: Triple Point Of Water
« on: May 13, 2016, 06:45:16 PM »
I've been pondering arctic phase changes and etc for a while and kept getting confused by one thing...

If you have an ice floe or similar condition of both ice and liquid existing close to the freezing point, you also have water vapor existing, right?  But as I understand the usual phase diagram, in normal conditions (e.g., ~100kpA/1ATM pressure) you should only have liquid and solid states, the triple point being much lower.

What am I missing?

It is the PARTIAL PRESSURE of the water vapor that must be at the triple point, not the total pressure.

What I ultimately want to know is the equation for the water vapor capacity of air vs temperature even well below 0C.

Google "vapor pressure of water". Again we are dealing with partial pressure.

Another thing I've  been pondering, and quite related, is where the extra heat goes as one approaches a state where the arctic is increasingly ice free (since it doesn't go into melting the ice any more). The sun shines on the water and it absorbs heat (in the summer).  Presumably it loses heat to the atmosphere via evaporation, albeit at a much lower rate than would be the case in the tropics, but is this a meaningful number? And even if it is, where else can that heat go?  I assume the extra longwave radiation is not that significant. 

In other words, how much heat could be retained in the cryosphere season-to-season?

Mostly into warming the upper Arctic Ocean water. And a portion, but not all, of that heat will be released into the atmosphere in the early freezing season following the near ice free summer.

44
Arctic sea ice / Re: The 2016 melting season
« on: March 15, 2016, 07:51:49 PM »
More indications that this thread was started a bit...prematurely.

We have yet again a new high for the freeze season: 12.85966 m sq k for day 73, but still (barely) in record low territory for that date.

http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html

Meanwhile, NSIDC extent tells a different story...

45
Arctic sea ice / Re: The 2016 melting season
« on: March 09, 2016, 07:17:41 PM »
I didn't know whether to put it here or in the freezing thread. Anyway, the Arctic may get a strong late season surge as "ADA" (ADA - "Arctic Dipole Anomaly") seems to make a return by next week. The question is whether this is just temporarily or if a more persistent set up with high pressure building over the Arctic in tandem with a low over nortwestern Russia will start to emerge?
If so, we should see a high transport of ice through Fram Strait. At the same time the SIE numbers should rise quite sharp for a short period.

The GFS 06z run had a very strong ADA by the time of equinox. But GFS is as we all know just like may politicians e.g changing their views many times (sorry for the ironic).

Otherwise than that, it seems to me that Okhotsk will see considerably warmer temps by next week which should start the death of all "fish ice" there.

Is the wind also going to be out of the East, to push the ice edge Westward?

46
Arctic sea ice / The 2016 melting season
« on: March 08, 2016, 04:45:17 PM »
The sun is slowly returning to the Arctic, as we prepare for another melting season. The ice is thinner than last year on the Alaskan side, according to DMI, though there is less very thin ice around the North Pole:

http://ocean.dmi.dk/arctic/icethickness/thk.uk.php




47
Arctic sea ice / Re: The 2015 melting season
« on: September 06, 2015, 01:11:09 PM »
Higher sea levels due to warmer waters do not necessarily cause lateral water movements. That only happens if there is a horizontal pressure gradient. Sea level is higher because the water is less dense and is needed just to equalize pressure.

Like a block of styrofoam floating in water, it doesn't necessarily want to move sideways.

Not a good analogy because warmed ocean water is a liquid while Styrofoam is a solid. A better analogy would be to vegetable oil poured onto water. In this case, once a large amount has been added, it does not stay in one large blob where it was poured; rather, it spreads out horizontally.

48
I moved up one bin, to 2.0-2.25, because on the one hand the high-concentration region is not as small as in 2012, but on the other hand, the whole pack looks thinner, even near the CAA, based on MODIS images, plus CAB compactness tracked that of 2012 for much of the summer.

49
Regression mentioned in correlation thread leads me to 3.9 M km^2 as central estimate.

50
Unfortunately I am currently unable to access the computer my previous work was on, so the image size is different from before - however I still was able to project NSIDC extent for September as (3.90 +/- 0.17) M km^2. Image differs slightly from this figure due to non-ideal slope/intercept but should still represent a good guess for what we will see in September.

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