Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - cesium62

Pages: [1] 2 3 ... 6
1
Arctic sea ice / Re: The 2020 melting season
« on: September 13, 2020, 01:35:29 AM »
Reminder that if 2012 wasn't a thing we'd all be blown away by this melting year. We are so far ahead of #3 in terms of extent.

We shouldn't be blown away.  This extent was predictable and predicted. https://www.arcus.org/sipn/sea-ice-outlook/2020/august

The narrative is not "omg, so much ice melted this year! What a surprise!".  The narrative is "Ayup.  a lot of ice melted this year, and probably a lot of ice will melt again next year.  Of course, we might get a once in 30 year perfect storm and a helluva lot of ice will then melt..."

2
Arctic sea ice / Re: The 2020 melting season
« on: September 12, 2020, 12:57:40 AM »
...
I stand corrected.  Thank you!  You bring me more hope for ice recovery in the future.  ....

I would not put too much hope into ice recovery, given sea ice temperatures.
I attach the latest SST anomaly : 2020 vs 2019,16,12. Those were very strong melt years, but 2020 still stands out by far. The Arctic Seas are crazy hot (except for the Beaufort) even vs. those exceptional years. I don't see how the Atlantic/Siberian side will ever freeze over. (of course it will eventually but still...). This is pretty amazing!

The important thing to remember is that 2019, and 2016 are not "very strong melt years".  If you run a trendline through monthly September extent, these years are barely below trend.  If you take into account the context of northern hemisphere June snow and ice area (per Dekker), these years had higher extents than expected.  2020 is also a typical melt year.

2007, 2011, and 2012 might have had some crazy weather conditions that made them very strong melt years, but recent years are hitting low extents without those rare weather conditions.

3
Arctic sea ice / Re: The 2020 melting season
« on: September 12, 2020, 12:30:53 AM »
::)
I ask that you indulge my bathymetry-and-ice-distribution fixation one more time. ...  The thing that jumps out here for me is how different this year is from all the others in terms of the Atlantic front, as others have noted.  2020 melt has advanced into the deep basin of the Arctic Ocean in a manner that seems qualitatively different..

As noted before, it is NOT unprecedented. 2013 had almost exactly the same depth on the Atlantic Front:

You bring me more hope for ice recovery in the future.   

2013 had a larger minimum extent than any subsequent year.  The ice might get blown around a little bit, but it isn't "recovering".

4
Arctic sea ice / Re: The 2020 melting season
« on: September 08, 2020, 12:39:39 AM »
In what region would you expect that rebound, gandul?
Check it out yourself above
Not his job to prove your point, please.

You made the assertion, your job to lay it out and describe your evidence for it.
Concur.  The amount of yellow+red in 2020 visually looks roughly the same as in 2019.  More to the point, the yellow and red for 2020 is closer to the CAA.  So the compaction and current flows over the next year is really going to thin out that band and stretch it through the Beaufort and Chukchi, where it will melt next year.  2021 is looking kinda scary on that front...



5
Arctic sea ice / Re: The 2020 melting season
« on: August 22, 2020, 09:14:24 PM »
Another element that this August weather has brought is significant cloudiness especially in the pacific half, which means heat excess retention and enhanced melting.
I’d be surprised if Arctic temperatures in August are not well above average.
You've looked at air temperatures just above the ice? This is either not accurate or a very small effect given the positive temperatures being concentrated on the Svalbard side and the negative ones on the Alaskan side

Air temperature just above ice is capped at the melting point of that ice and won't tell you anything about excess heat retention nor enhanced melting.  Looking at temperatures in the arctic that are not above the ice will give you some idea whether or not Arctic temperatures in August are well above average.

6
Arctic sea ice / Off Topic
« on: September 25, 2019, 06:23:51 AM »
This is the thread where one should discuss whether or not a posting to an Arctic Sea Ice thread is off topic.  Please remain on topic in this thread.  However, if you do go off topic, this is the thread to discuss that.

7
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 20, 2019, 12:11:35 AM »
Our friendly star is remarkably stable but the slight variation in energy received from the sun across solar cycle can nudge annual average global surface temperature up and down by ca. 0.1C. 

Link to a peer reviewed paper, please.  I ran the regression between solar cycle and september minimum extent.  There is no correlation.

8
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 09, 2018, 09:51:25 AM »
Also, graphing the trend lines through the minimum and the predicted minimum, suggests that the prediction is diverging from actual (getting larger) as each year passes.  Since both snow cover and minimum extent trend downward year by year, it might be interesting to add 'year' as a parameter to better explore how well snow cover helps explain minimum extent.

Overfitting a model based on year, snow area, and ice area to all data from 1979 through 2017, we get the second attached picture.  And a forecast of 4.58 M km2 for the 2018 min extent.  (With a 360 K km2 geometric mean error.)  (Overfitting Dekker's model gives a forecast of 4.76 M km2 with a 435 K km2 geometric mean error.)  (If I train the year-based model on just 1992 through 2015, the forecast is 4.64 M km2 with a 386 K km2 geometric mean error.)

My simple physical explanation for the year-based model would be: heat is accumulating worldwide year by year due to greenhouse gases; the snow and ice area (or lack thereof) takes into account how much insolation is absorbed in the northern hemisphere in June.  Together, this suggests the amount of heat available for melting ice, subject to the vagaries of weather.

Thanks, cesium. The 'year' variable is indeed very clear in the 1979-2017 record, so it is tempting not to use it. But there are three reasons not to give in to that temptation :

1) One could argue that the 'year' variable is indicative of the increase in greenhouse gases as you suggest. But we did not quantify the relation between greenhouse gas increase to sea ice loss yet, so this relation is kind of speculation at this point.

2) The 'year' variable is adding one more variable, which will increase the risk of "over-fitting". Remember the famous saying by John Von Neumann :
With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.

3) As pointed out above, the method I use is not very accurate in the 80's, and starting from the 90's the variability can be better explained by the physical measurable variables (snow cover, ice area and ice concentration). Even though each of these physical variable may ultimately be caused by (gradually increasing) greenhouse gasses in the atmosphere...

So that's why I wanted to stay away from including "year" (or "time") as a variable in the prediction method.

You really ought to avoid assuming that people you're talking with are idiots and patronizing them.  Since you've already thoroughly though through all aspects of this problem, I'll stop wasting your time.



9
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 09, 2018, 02:26:13 AM »
Edit: sorry, apparently you were using the daily minimum rather than the September monthly extent.  Perhaps that explains it.

Specifically: I grabbed
http://nsidc.org/arcticseaicenews/sea-ice-tools/
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Min_Max_Rankings_G02135_v3.0.xlsx
Then the nh-annual-5-day-extent tab.

Sounds like you're saying that SIPN is asking for the September average extent to be predicted instead of the minimum extent...

10
Arctic sea ice / Re: What's new in models?
« on: July 08, 2018, 11:29:45 PM »
At the risk of hi-jacking this old thread...

1)  Why does SIPN try to predict September minimum extent instead of area?  Seems like area would be slightly easier to predict and might be slightly more interesting?

2)  Is there a good data source for May Melt Pond fraction?  Pretty much any number that has been gathered over "many" years that describes may melt ponds in some fashion?

3)  Are there other easy-to-use data sources for simple parameters?  June SST say?

The motivation here is that Rob Dekker has an interesting model that incorporates june area, june extent, and june snow cover.  Kinda makes you wonder if there are some other easy to grab parameters to see if they might be as useful as snow cover in making forecasts.

11
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 08, 2018, 07:30:50 PM »
I think it is great that others are digging into data triggered by Rob Dekkers model but, if you change the graph, you should also change the title.
What title would you give to each of the two graphs?

12
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 08, 2018, 12:39:58 PM »
Normally for a hind-cast, that would include ALL the prior years available.

No.  To be a hind-cast you have to use the algorithm to predict data points that ARE NOT PART of the dataset used for the regression.

Forecasting is predicting future data.  Hindcasting is "predicting" data that already exists, which you do by not looking at it before you make your prediction. That graph contains three forecast points (2016-2018) and no hindcast points.

Note that I have now provided a hindcast for the years 1979 to 1991 for Dekker's model in one of my jpgs above...

13
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 08, 2018, 12:37:48 PM »
Rob: I think your model is fun and interesting, so I spent some time with it.

Assuming I've correctly re-produced your results...

The question above is, roughly:  what's the probability that the actual result is 0.7M km2 or more away from the predicted result?  This occurred in: 1980, 1982, 1983, 1986, 1988, 1991, 2001, and 2006.  That's 8 out of 39 years, or about a 20% chance.

Eyeballing the graph you published pretty much agrees that both 2001 and 2006 predictions are off by around 0.7M km2.


We can slightly simplify your approach by noting that you are predicting minimum extent as a linear combination of three variables: June snow area, June ice area, and June ice extent.  The multi-variable linear regression package that I'm using (XL miner in google sheets) notes that the 'extent' parameter isn't very useful in this prediction.  The software suggests there's a 6% probability that 'extent' should really be part of the equation.

Also, graphing the trend lines through the minimum and the predicted minimum, suggests that the prediction is diverging from actual (getting larger) as each year passes.  Since both snow cover and minimum extent trend downward year by year, it might be interesting to add 'year' as a parameter to better explore how well snow cover helps explain minimum extent.

Overfitting a model based on year, snow area, and ice area to all data from 1979 through 2017, we get the second attached picture.  And a forecast of 4.58 M km2 for the 2018 min extent.  (With a 360 K km2 geometric mean error.)  (Overfitting Dekker's model gives a forecast of 4.76 M km2 with a 435 K km2 geometric mean error.)  (If I train the year-based model on just 1992 through 2015, the forecast is 4.64 M km2 with a 386 K km2 geometric mean error.)

My simple physical explanation for the year-based model would be: heat is accumulating worldwide year by year due to greenhouse gases; the snow and ice area (or lack thereof) takes into account how much insolation is absorbed in the northern hemisphere in June.  Together, this suggests the amount of heat available for melting ice, subject to the vagaries of weather.




14
Arctic sea ice / Re: The 2018 melting season
« on: July 08, 2018, 07:59:31 AM »
Quote
You have a good track record and, given the current slow melt, I am inclined to agree that we will end this melt season around 5.00 M km2.

I think with the high snow cover, low level of melt ponding in May and June, the early cyclone over the Kara that brought in a lot of clouds and fresh show, that the amount of heat in the Arctic is probably less this year than in 2012, probably close to what it's been the past five years.  So I think a continuation of the long term trend is what we'll see, not anything exceptional this year.

What it's been in the past five years is pretty clearly less than 5M km2.  2013 and 2014 were barely above 5M km2.  4.5M km2 is much more in the middle of the past 11 years of minimums.  All other things being equal, we'ld expect 2018 to be a bit lower than the middle of the past 11 years given the amount of heat we've been pumping into the world's oceans.  A minimum of 4.75M km2 this year would make 2018 seem like a mildly exceptionally cold year to me.  A minimum of 5M km2 this year would seem exceptional.

15
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 08, 2018, 07:28:40 AM »
it is highly unlikely (less than 2.5% chance) that Sept 2018 will end up below 4.5 M km2.

You are saying that there is a <2.5% chance of this year's final outcome being about half a grid line below the prediction.  There are a couple of other years (2006, 2001, maybe 2010 and 2016) and  where the final outcome is about half a grid line away from the prediction.  It doesn't seem right that 10% of the years should display an event that should occur less than 2.5% of the time...

16
Arctic sea ice / Re: The 2018 melting season
« on: July 06, 2018, 06:59:59 PM »
This year feels more 2013'ish all the time.
The Slater Projection has been dropping fast the past few days and is currently suggesting a 2016-like minimum.

17
Arctic sea ice / Re: The 2018 melting season
« on: July 03, 2018, 06:58:34 AM »
Thread A: only matter of fact observations and forecast based on well established patterns (maybe how this forum used to be).
You and I have been reading two different forums for the past few years.   ;D

18
Arctic sea ice / Re: The 2018 melting season
« on: July 02, 2018, 07:38:15 PM »
This morning's ECMWF forecast has the cyclone at 975 hPa now, starting the day after tomorrow, which then de-intensifies and slowly moves towards the Beaufort, all the while surrounded by high pressure. If the high pressure above the Kara Sea comes about, it's a new region that receives a solar blast.

That looks like at least two days of winds from the south blowing directly over the big thick blob of ice in the southern ESS...

19
Arctic sea ice / Re: The 2018 melting season
« on: June 30, 2018, 01:47:36 AM »
I played around a bit with those SMOS images. 

Just for fun, Here's the correlation between Steven's hard earned numbers and NSIDC Min Extent.  The dot at x=4.5 on the line is the projection for 2018.

20
Arctic sea ice / Re: The 2018 melting season
« on: June 29, 2018, 11:50:47 AM »
Interesting developments all around - the Chukchi warm water reared itd head and attacked the ice all around, I guess the winds shifted. Laptev polynia resumed its growth. And Fram export seems to have picked up. All signs of a melting season still not given up.

The Slater Probabilistic Prediction today looks like a Nuke went off on the Greenland half of the CAB.  It's currently predicting extent below the September minimum of 2013 and 2014, but in the middle of August of 2018.  No doubt the glitch will be gone tomorrow...


21
Arctic sea ice / Re: The 2018 melting season
« on: June 27, 2018, 11:49:02 PM »
I think zero Fahrenheit is defined as the temp of equal weights of salt and water with ice floating in it isn't it?

I think Wikipedia somewhat disagrees:
https://en.wikipedia.org/wiki/Fahrenheit

22
Arctic sea ice / Re: The 2018 melting season
« on: June 26, 2018, 06:54:01 AM »
Area is not effected by spread as much as extent is. Area loss has slowed because area loss has slowed.

Are you sure? I thought they where quite related. Or are you thinking of volume?
From Wikipedia:
"To estimate ice area, scientists calculate the percentage of sea ice in each pixel, multiply by the pixel area, and total the amounts. To estimate ice extent, scientists set a threshold percentage, and count every pixel meeting or exceeding that threshold as "ice-covered." The National Snow and Ice Data Center, one of NASA’s Distributed Active Archive Centers, monitors sea ice extent using a threshold of 15 percent."

So, start with one pixel's worth of fully covered ice.  Which is one pixel of area and one pixel of extent.  Fracture that into five pieces that go floating off into separate pixels.  You now have 5 pixels of extent and 1 pixel of area.  Fracture each of the five pieces into two that each go floating off.  You now have 1 pixel of area and zero pixels of extent.  So the area isn't being affected by spread here while extent is jumping around all over the place.

23
Arctic sea ice / Re: The 2018 melting season
« on: June 26, 2018, 06:44:23 AM »
I do appreciate that those posting it have cropped out the units of measurement in the scale legend - thereby removing any reference to purported thickness.

I seem to be seeing a thickness scale...  And, this raises the question, if we are displaying wetness, what do the colors mean?  Is the cropped "beige" color more wet or more dry?

24
Arctic sea ice / Re: The 2018 melting season
« on: June 22, 2018, 07:23:34 AM »
So I've been thinking about the apparent "slowness" of this year's extent behavior, and have come to the conclusion that a lot of it has to do with the Kara Sea.
...
Bottom line - 2018 has a "bank" of 300-400k km2 of extent that it could use to get back in the leading pack.

And it's not just the Kara.  Hudson Bay and Baffin Bay are still holding onto a lot of southern ice.  While those three cul-de-sacs might not heat up as much while the sun is high in the sky, they are also relatively isolated, so the current lack of heat in the cul-de-sacs shouldn't greatly influence the melt further north.

While the Pacific side might not be warming up as fast from the sun as in some years (the southern Beaufort, Chukchi, and ESS), the Atlantic side and Laptev has plenty of "momentum".

Certainly the Slater probabilistic prediction has 2018 with a bit higher extent than other recent years through early August, but 2018 is still well positioned to have a lower minimum extent than 2016 and 2007, especially if a hole opens up in the north Chukchi by the middle of August.

25
Arctic sea ice / Re: The 2018 melting season
« on: June 18, 2018, 01:10:56 AM »
True.  But as you will note Neven often talks about Melt Momentum.  2012 had it.  2018 is not exhibiting it.

This was very apparent in 2017 where the extreme early warm weather did not turn into extensive melting in the critical June/July period.  August melting can be fast, but there is simply not enough heat budget left to melt enough Ice to make records if June/July is not also in, or close to, record territory.

Not until the ice volume and thickness are low "enough" to make the difference.

It is not looking like we are there yet.  There is absolutely no doubt that we will get there.  It is just a matter of when.

Until someone defines "Melt Momentum" claiming that 2018 lacks it is meaningless.

In the meantime, as aperson points out, 2018 has a lot of open water in northern latitudes that acts like one big melt pond at that latitude.  2018 may have higher ice volume than some recent years, but a lot of that volume is in the south or is first year ice, and hence not directly comparable to volume in other years.

26
Arctic sea ice / Re: The 2018 melting season
« on: June 17, 2018, 11:41:29 PM »
Precisely my point.  The real Friv is *much* more exciting than that.   ;D

It's not really that exciting though is it?

My apologies for attempting levity.  Lesson learned.

27
Arctic sea ice / Re: The 2018 melting season
« on: June 17, 2018, 09:33:40 PM »
Unless a massively anomalous ridge of high pressure blows up and parks over the CAB,CAA, and GIS for the next 5 weeks there is zero chance for record low extent or area this year.

Volume is already past any chance for record lows

Who are you? and what have you done with our Frivolous?

Friv is just saying it as it is. 

Precisely my point.  The real Friv is *much* more exciting than that.   ;D

28
Arctic sea ice / Re: The 2018 melting season
« on: June 17, 2018, 08:55:04 PM »
Unless a massively anomalous ridge of high pressure blows up and parks over the CAB,CAA, and GIS for the next 5 weeks there is zero chance for record low extent or area this year.

Volume is already past any chance for record lows

Who are you? and what have you done with our Frivolous?

29
Arctic sea ice / Re: The 2018 melting season
« on: June 03, 2018, 11:32:16 AM »
The slater projection is functional once again. Predicting extent of 7.62 million kn^2 on July 22, 2018. Thanks to b.c. For prompting me to update from the meaningless thread.

I'd love to believe my nagging to University of Colorado had some impact

I'd say that is a helluvan optimistic Projection by the Look of Things now.

From Charctic, the extent on the 22nd (203rd day of the year) for the past 7 years has been in a fairly tight band from 7.2 to 7.9 mk2.  2016 extent was lower than 2018 at this time of year, but hit 7.65 on the 22nd.  So the Slater projection seems plausible based on Charctic trend lines.  On the other hand, the Kara typically loses 3/4ths of its ice by late July, and the Slater projection kind of shows it full of ice then.  And the Hudson typically loses 5/6ths of its ice by the time the Slater projection suggests it losing around half of its ice... 

30
Arctic sea ice / Re: The 2017/2018 freezing season
« on: March 14, 2018, 06:09:41 AM »
If you look at the plot of the daily range, both the upper and lower bounds are in decline by day 75. While this doesn't mean an individual year can't continue to climb, this might be something to watch. Also, only 6 or 21% of the yearly max's occurred after day 75.

Also, on the NSIDC graph (charctic) 2017, 2016, and 2015 had converged around day 74 to 75 and split in interesting directions after that.  2018 is currently heading toward that convergence.  If extent doesn't drop dramatically in the next 4 or 5 days, I'd also like to see what happens on day 76 before calling the start of melting season.  2015 and 2016 each gained about 150K km^2 from day 71 to day 85 or 86.

31
Arctic sea ice / Re: The 2017/2018 freezing season
« on: March 12, 2018, 12:19:28 AM »
Slater's Projected Probabilistic Sea Ice Extent looks a bit interesting today.  It's projecting a hunk of ice in the southern Bering Sea with open waters further north.  Is that plausible, or just an interesting algorithmic anomaly?

32
Arctic sea ice / Re: The 2017/2018 freezing season
« on: March 08, 2018, 04:47:13 AM »
I think maybe we should sit back for a week and see what occurs next?

Opening topic for the thawing thread?

This might just be an early Spring at the North Pole...

Methinks the Guv'nor wants more evidence before opening the melting thread. Given the weirdness of this transition period, I am glad it is his problem.

Based on a poll of a small sample of recent warm winters, I'd give it an 80% chance that we haven't seen peak NSIDC extent yet.  Amongst 2017, 2016, 2015, 2011, and 2007, only 2017 didn't oscillate upwards by 64km^2 or more at some point in march after day 65.

33
Arctic sea ice / Re: The 2017/2018 freezing season
« on: March 08, 2018, 04:35:45 AM »
Expect the ice edge to melt and retreat 15 to 20 nm through
Thursday. After Thursday expect the pack to advect back to the south
10 to 20 nm

Wowza.  Tens of nanometers of melt and growth every few days.  Whiplash!
 :o
[Well, I thought it was funny...]

34
Arctic sea ice / Re: The 2017 melting season
« on: September 20, 2017, 05:13:03 AM »
We may simple by in a holding pattern.  The summer minimum in extent may be constrained by the water and air temperatures and circulation.

There could be a 'pause' (dare I use that term?!) in volume loss due to changes in global energy distribution

It's not clear to me how the Pacific and Atlantic can both get hotter without that heat transferring to the Arctic, but assuming it can happen, the Antarctic is screwed worse than I thought.

35
Arctic sea ice / Re: The 2017 melting season
« on: September 14, 2017, 12:51:56 AM »
I just meant sea ice is a following indicator not a leading one.

I thought albedo was supposed to be important to climate.  Are you saying that painting my roof white was a complete waste of time?  ;D

And then struggling to pretend I'm on-topic...  I guess I'm saying that the high (relative to recent lows) 2017 late summer ice extent suggests that the planet might not have cooled off warmed up quite as quickly this year as it did in past years.  But the overall impact probably isn't that large so late in the season...

36
Arctic sea ice / Re: The 2017 melting season
« on: September 04, 2017, 08:07:28 PM »
the relative widely spread slushy ice could make for an early relative jump in extent and area gains,

I still don't understand why refreeze of existing extent will lead to a jump in extent

37
Arctic sea ice / Re: The 2017 melting season
« on: September 02, 2017, 02:38:32 PM »
The weather conditions still warm enough to continue melting futhermore in September. (The pics below will update). There's not so much open water north of 80 latitude. The ice should continue to retreat on the edges and most likely the minimum extent should occur relatively late in September
I think the opposite.  All that slushy ice between the ESS and the pole will be easy to refreeze should the low temps come, as the water around it have not had a chance to mix. I think the balance of probability is more towards an early refeeze before Sept 15th, rather than a late one.
That's not the opposite.  Whether or not there is an early refreeze says nothing about whether or not there is a late minimum extent.
I'm with oren on this one.
If an early refreeze occurs (and the slush on the ice edge suggests so) then the minimum will be early, not late.

It's nice that you think that if event A occurs, unrelated event B will also occur.  It's more interesting if you explain a causal link between the two events.

Oren suggests that slush refreezing north of 80-degrees, which will not change the extent (it will change concentration), will somehow prevent continued loss of extent further south.

I'm pretty sure the two of you can make the point you are trying to make more clearly and accurately.  The quick model that Pavel sketched allows for the ice north of 80 to refreeze early while still providing a late minimum extent.  Saying that you think the ice north of 80 will refreeze early is not "the opposite".

<Don't include so many nested comments; it clutters the forum, and makes replies difficult to follow. usually only the most recent comment in a sub-thread is enough to convey what you want.: JP>

38
Arctic sea ice / Re: The 2017 melting season
« on: September 02, 2017, 04:05:50 AM »
The weather conditions still warm enough to continue melting futhermore in September. (The pics below will update). There's not so much open water north of 80 latitude. The ice should continue to retreat on the edges and most likely the minimum extent should occur relatively late in September
I think the opposite.  All that slushy ice between the ESS and the pole will be easy to refreeze should the low temps come, as the water around it have not had a chance to mix. I think the balance of probability is more towards an early refeeze before Sept 15th, rather than a late one.

That's not the opposite.  Whether or not there is an early refreeze says nothing about whether or not there is a late minimum extent.

39
Arctic background / Re: Arctic Maps
« on: August 17, 2017, 01:08:09 AM »
https://www.ngdc.noaa.gov/gazetteer/
looks like a definitive interactive map of officially named undersea features.

40
Arctic background / Re: Bathymetry, Volcanoes and Upwellings
« on: August 17, 2017, 01:04:49 AM »
I think what's happening is a version of this, in the deep warm layer penetrating upwards, caused by movement of ice into and out of the basin, or the shift of high/low slp over the ridge or on/off shore.
Something similar happens at the far end of the basin but more diffuse given it's less focussed bathymetry, it shows in this gif.[for now]

These maps each have their own advantages but not quite everything you want, the first at least shows the lat/long of the cursor.
https://maps.ngdc.noaa.gov/viewers/fishmaps/
https://www.ngdc.noaa.gov/mgg/bathymetry/arctic/maps/version3_0/Ver3_Map_LetterSize_round.pdf

Thanks.  The 'fishmaps' has various named features on it.  The depression at 81.5N 120E doesn't seem to have a name.  The Shinkov Seamount, Sadko Valley, and Shaykin Hill are all nearby...

Searching for those features, I find
https://www.ngdc.noaa.gov/gazetteer/
which looks like a fairly definitive map of all officially named undersea features.

Anyway, I'ma call it Shugar Bowl until a better name catches on.  Laptev Polyna UnderBowl is just too long.

The hycom gif doesn't work for me.

The standing wave video is neat, and an interesting idea...

41
Arctic sea ice / Re: The 2017 melting season
« on: August 15, 2017, 05:21:37 AM »
moths of energy.

Just thank God it isn't receiving Butterflies of energy yet. :o

42
Arctic background / Bathymetry, Volcanoes and Upwellings
« on: August 14, 2017, 04:47:01 AM »
There appears to be a polyna in the Laptev at 120E 81N.  There is a large crater at the end of the Gakkel Ridge at those coordinates as well.  Is there a connection?

Does the Gakkel Ridge crater have a  name?  Do we have a good map that would show named features like that?

I can find reports of Volcanoes far to the northwest along the Gakkel Ridge; did the American research expeditions make it out to the end of the ridge?

In the Melting Season thread, Rathbone mentions that upwelling tends to occur over ridges.  Is the Gakkel Ridge Crater a known upwelling location?

[And is there a way to tag a forum thread to notify me when it gets updated?]

43
Arctic sea ice / Re: The 2017 melting season
« on: August 12, 2017, 09:48:23 PM »
Looks like the NSR is finally open now.

Judging by what Neil? See also:

https://forum.arctic-sea-ice.net/index.php/topic,854.msg122408.html#msg122408

et seq.

Um, yeah, there's that little patch of 10-30% probability ice with a couple of small patches of 50% probability ice at 78 degrees north on the right side of the chart, which, on worldview, don't look too scary.  But I'm not a sailor and don't play one on tv.

44
Arctic sea ice / Re: The 2017 melting season
« on: August 09, 2017, 01:15:55 AM »
However pretty the hue of blue ice ponds are in June , my feel is that this is the most important time of year at this stage in the evolution of the new Arctic .
The story this year has been low volume.  The warm winter was not able to restore the ice lost last summer.  Therefore the relatively few melt ponds in June and the relatively high snow cover weren't able to make up for the weak and mobile ice.  December or January may well be the most important time of year at this stage in the evolution of the new Arctic.


45
Arctic sea ice / Re: The 2017 melting season
« on: August 06, 2017, 08:21:55 PM »
Is it true to say that it was around Aug. 7th-8th that 2012 started to go way off track? What caused it? A storm? A series of storms? Persistent heat?
Any documentation or observations of what caused it?
http://www.huffingtonpost.com/2013/02/03/arctic-cyclone-2012-august-sea-ice_n_2611336.html

Quote
The Great Arctic Cyclone of August 2012” arose in Siberia on Aug. 2 and crossed the Arctic Ocean to Canada, lasting an unusually long 13 days. The cyclone hit a pressure minimum of 966 millibars on Aug. 6, the lowest ever recorded for an Arctic storm. The stronger the pressure gradient, or difference in pressure, the stronger the winds associated with a storm.

Since the storm, which was equal in strength to a hurricane, tore across the Arctic, scientists have wondered whether its winds and waves were a guilty party in the disappearing Arctic sea ice.

46
Arctic sea ice / Re: The 2017 melting season
« on: August 01, 2017, 07:59:38 PM »
It barely rises above freezing, and for less than three months.

The summer temperature north of 80 degrees is clamped to the melting temperature of the ice.  It occurs to me that the slight drop in summer temperature over the past few years suggests that the ice contains more salt than it used to, which is what we would expect from a loss of MYI.  Or am I reading too much between the lines?

47
Arctic sea ice / Re: Northern Sea Route thread
« on: July 30, 2017, 09:56:47 PM »
But since Yamal is an icebreaker, does this really count as the northern sea route being open? To me it seems we still have a few days to wait before it can be described as open in the colloquial sense.

And then, do we need to consider whether it actually broke (or pushed aside) any ice, versus just being along for extra insurance?

48
Arctic sea ice / Re: The 2017 melting season
« on: July 30, 2017, 09:52:37 PM »
Very little in the Beaufort looks safe right now.


Nice 15 m/s wind right now and staying like this for a while (Earth nullschool).

From that view, it looks to me like the ice on the Pacific side will compactify to the northwest and be  kept safer.  Are animations of low pressure systems misleading?

The most unsafe ice looks north of the Barents sea.

The 49km/h, 2.7C southerlies over the Nares strait look interesting...

49
Arctic sea ice / Re: The 2017 melting season
« on: July 30, 2017, 09:20:20 PM »
... looking at the 'area' numbers ...
... 'albedo' numbers ...
... Slater's model ...

The Slater model and Area numbers look like they are oscillating more than usual, suggesting that our traditional graphs don't understand the high area and low volume of this year's ice.  But this coming week has traditionally been rather informative.

Climate Reanalyzer suggests that heat will tend to be over the thickest ice north of the Archipelago and Greenland, which might trash volume while leaving extent and area largely unaffected.

50
Arctic sea ice / Re: The 2017 melting season
« on: July 30, 2017, 12:08:57 AM »
and your overlay in places is quite optimistic, i'm sure we won't see the perry channel entrance closed in september or end of august even.

The Slater Projection is similarly optimistic in that locale, and a bit more optimistic elsewhere.

Pages: [1] 2 3 ... 6