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 - JayW

Pages: [1] 2 3
1
Arctic sea ice / Re: MOSAiC news
« on: December 07, 2019, 08:25:37 AM »
Translation of the Arctic Drift Podcast #7 - Sturm
Release Date: 03 Dec 2019

STORM

<Narrator>

Arctic drift,  the audio log book.

The first big storm has afflicted the MOSAIC expedition in the Arctic. The ice camp around the icebreaker Polarstern was exposed to a hours lasting storm with wind speeds up to 9 (Beaufort scale). The head of expedition Markus Rex talks about the repercussions of the storm.

<Markus Rex>

Yes, last weekend we had our first big storm with harsh wind speeds up to 20 meters per second. Such a hefty blow. While the storm was forming we could see that a big crack developing but then the sight was too bad to see it. The next night the storm had clearly left some marks on the ice. The crack that developed the night before was now a shear zone, a fault zone with smaller floes and pieces of ice. All of a sudden, the whole other half of the camp magically drifted with high speed eastwards. It looked like a train scrolling by. First ROV city, then remote sensing site, then MET city passed the bow and then they vanished in the dark. This is, of course, a drastic event for our camp. After 600 meters offset it stopped.

<Narrator>

Because of the storm and the offset of the ice also the route of drift has changed. The Polarstern is still frozen to an ice floe and moves without its own engines.

<Markus Rex>

Since the storm, we moved north towards the pole but we will have westerlies according to the forecast. Which means that we are moving along the western part of our drift scenario. This is all still in a margin where we feel good about but we would like to come north more quickly. The overall way we made so far is in the upper expected range.

<Narrator>

Also, the infrastructure of the camp is partly damaged. Power and data cables are cut and need to be repaired. Until this is done fewer data can be gathered.

<Markus Rex>

Since the shear zone moved right through our camp and cut power lines, we installed emergency generators to power the equipment. But we are on a reduced measurement schedule. We are now in the process of developing a new town plan. We know what should be located where now and in the next days after we see some stabilisation we will deploy the new power and data infrastructure.

The future town plan will differ from what we have now. At the moment all the sites are in a linear line along the ice and a pressure ridge easily to protect with a tripwire against polar bears. We will though, out of necessity, have a radial layout in the future. This will be harder to protect against polar bears, but this is what nature has given us and we will live with it.

<Narrator>
Even though the negative aspects of this storm are plenty, there are also positive ones. Never before where measurements made from the inside of an Arctic storm so intensely.

<Markus Rex>

From a science perspective, such a storm is a thrilling event. This is why we are here. We want to find out how the weather systems in the Arctic work together. We have complete measurements of multiple parameters from before, during and after the storm. Energy flow, heat flux,  snow thickness, radiation, what it did to the ice. This is a unique dataset and we are amazed when we look at it. This will allow us to improve weather models. Yes, it's problematic that we will have a new town layout and that we have to rebuild a lot, but this data is what we are here for.

<Narrator>

Fortunately, there are parts of the camp that are undamaged and work fine.

<Markus Rex>

The storm has affected almost all of our sites but one. The core of our observatory, the Balloon town, which we call the town hall, is still in the same place and can be used as before even though the landscape has changed dramatically. We now have a big pressure ridge in the background and a crack in the ice behind it. I would say this has become a very attractive site with direct water access and mountains. And we can still launch our balloon.

The balloon can, of course, only be launched with moderate wind speeds, so during the storm, the balloon took no measurements.

<Narrator>

And again, this week a polar bear family visited.

<Markus Rex>

A mother with her two almost adult curbs came by. They tripped over the wire which caused two flare bombs to start. That startled them a little and the mother became cautious. They circumvented the camp in a wide bow and they did what they are supposed to do - move along in the dark. But while they were near one of the curbs couldn't resist exploring everything it could. It tried to overturn every flag and play with everything. The mother returned a few times to collect the imp. The other curb stayed with the mother all the time. You could see the curbs were only one year old but had their own personality already.

<Narrator>

When the work is done, the scientist have time for personal activities. May it be sports or just watching northern lights.

<Markus Rex>

Friday night we have opened the ice for personal use. Some played with the frisbee disc,  a soccer game took place, some went off with skis and made a tour. Of course, it was black outside, but a black with a few northern lights. We are too far north to see plenty of them, but sometimes we have them.

2
Arctic sea ice / Re: MOSAiC news
« on: November 24, 2019, 01:41:54 PM »
60 frames, 51-minute increments via SNPP, Day&Night band.

Click to play

3
Arctic sea ice / Re: MOSAiC news
« on: November 18, 2019, 06:38:46 PM »
update on drift speed of the meereis Pbuoys from nov14-18 ~03:30

Posting this for interest while I work out which is the wayward buoy in the middle.

4
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: November 11, 2019, 07:00:38 PM »
The Arctic is certainly a mix of different seas.

Some here believe there is no real difference.

5
Arctic sea ice / Re: The Rammb Slider Thread
« on: November 10, 2019, 09:46:29 AM »
The north pole in the middle.

60 frames, 51-minute increments, Band: M16

Click to play, big file.

6
Arctic sea ice / Re: MOSAiC news
« on: October 27, 2019, 07:10:00 AM »
I think this confirms it.

There are two bright spots on the 14th when the Fedorov was still there.

7
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: October 25, 2019, 09:29:58 AM »
The article linked in my previous post predicts that two blocking highs will form over Greenland and Alaska, pumping cold Arctic air down Eastern Europe and Central N-America, and pumping hot air north over e.g. Siberia. So I'd venture to predict that the refreeze will be in trouble again next week.

8
Arctic sea ice / Re: MOSAiC news
« on: October 24, 2019, 12:01:14 AM »
Nice work on buoys! I didn't realize at first that it was a 2-frame animation. It looks good at the click-size. That is great to have the buoy network over a Sentinel base layer.

Compiled highlights (with edits and commentary in brackets) of the Polarstern cruise to Oct 23rd from screen scrapes of twitter, email, blogs, depts, BBC and newspapers. Too long but good to have it in one place (that won't get lost or deprecated to invisibility by google).

Most interesting information on thickness and near-loss of equipment and power line to ridging and shearing -- we knew from S1AB that things were morphing around on the selected floe but not exactly how. Is this going to get worse as time goes on, or will freezing solid help? (The too-fancy expedition web site does not allow text copying so screen shots have to be taken.)

First note a very important result  from R Kwok et a; about overall Arctic Ocean calibration of IceSat2 by simultaneous airplane lidar: measured elevations agree to within 2-4 cm. The April flights did not quite reach the Polarstern/Mosaic floe but more recent Icesat-2 orbits may have.

ICESat‐2 surface height and sea‐ice freeboard assessed with ATM lidar acquisitions from Operation IceBridge

https://www.nasa.gov/feature/goddard/2019/laser-precision-nasa-flights-satellite-align-over-sea-ice
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL084976  30 Sep 2019

Matthew Shupe: : how to get all of our different apparatus installations fitted into a limited and challenging space. Frozen melt ponds are to be avoided as they are likely to melt once again next summer. Plus some melted all the way through. Hummocks are safer for most equipment; the heavy stuff goes on the outer wall of the Fortress. with the Met Hut  tucked up against a big plate of ice jutting up 2m inthe air. This may cause a drifting challenge.

We flagged a power line path out to all of the major installations. The ‘Ocean City’ type  power hubs weigh 700 kg but are moveable as they are installed on top of 3 snowboards. The 700 m road out to Met City was smoothed out with picks and shovels.They are able to log in remotely from one station to the next to fix issues that arise.

Carrying a big breaker bar to probe the ice conditions, I learned back at SHEBA that if you lightly throw such a bar down to the surface from about 10 inches up and it DOES NOT break through, the ice is safe to walk on. Deep snow at places, making walking difficult.

But inside the Fortress was actually quite appealing. Nice courtyards of flat ice surrounded by sturdy walls. Eventually we made our way to a broad valley heading out to the far end of the floe, with a gateway to exit the fortress. Heading south we found wide, open and mostly flat plains made of frozen over melt ponds (30 cm thick ice) and some older hummocks (~100 cm thick). At the southern extreme we looked out over a narrow lead of open water, perhaps 15-20m across. 

Took the ship’s helicopter over to AkF to give a lecture on “coupled system research” to the MOSAIC School.

https://blogs.agu.org/thefield/2019/10/20/postcards-from-a-frozen-icebreaker-part-5/

October 16, 2019 Janek Uin, Brookhaven Lab/ARM Instrument
84° 45.440' N 133° 08.236' E

IThe ARM instruments are set up and will hopefully run smoothly for the rest of the campaign during the drift. In case of any trouble, our amazing technicians will be there to tackle any issues. Even today new cracks and pressure ridges appeared in the ice in the middle of a power line, challenging our efforts to set up our camp. We prepare ourselves for the next ARM adventure on Andoya, a Norwegian island located within the Arctic Circle.

October 5, 2019 Matt Boyer, Brookhaven Lab/ARM Instrument Mentor
85° 06.187' N, 133° 50.678' E


BBC x 2:
“With other floes we’ve encountered [data on 16 floes studied not released] we have clipped a piece off the edge with the ship to see how thick it is. A red and white two-meter stick, painted at 50cm intervals, sticks out from a lower deck to help judge how thick it is. The solid layer of blue ice in between snow on top and mushy rotten ice below [incompletely melted in summer, not newly forming], has rarely made it past 0.5 m.

The new layer [FYI from last winter not affected by past melt season] at the top can support equipment weight. The older rotten ice below [ice accretes to the bottom; this is newer than the ice above, is new ice on the floe edge meant?] is unreliable, although there is a question about whether a thicker layer of it helps or hinders refreezing during winter.

The investigated floe’s surface is level with the water that is freezing at its edges [freeboard should be 10% of total thickness if it were solid ice: Bernouli]. There is no protection or refuge. Instead, the floe merges seamlessly with the sea around it, rising in the distance to what could be a more rugged area towards the centre.

“The thing is, I’m not sure this piece of ice is even safe to walk on. That ridged area has holes and gaps. Take survival suits and floats,” says atmospheric physicist Markus Rex.

“In that ridged area there are holes and gaps,” says Rex, gesturing towards the central region. “It would be good to have those survival suits. Take flotation too.”

The Polarstern parks well away from a floe of interest so as not to damage it. A refrozen lead is covered by a thin layer of blackish-grey ice. The ship’s bridge radar augments what they can see. They don’t clip any ice off the edge with the ship to see how thick it is.

The edges of the "fortress" ice floe seem thin and waterlogged but in the distance the ice rises up and becomes thicker.

But the ship has to cut through a neighboring piece of ice instead. Large fragments bob vertically next to the hull to reveal a cross-section over 1 m. The sea ice in the region where the Mosaic mission have been searching has turned out to be much thinner than they were expecting. Floes are large but drill easily and could easily have disintegrated. [Only anecdotal data from EmBird surveys and drilling has been released]. 

Foes identified as >80cm thick from satellite images [IceSat2? Smos?] have turned out <40 cm from sled EM transects and drilling “Put that ship alongside such a floe and the first storm will press this ship right through it sideways. We budgeted to look at 20 floes,” says Rex.

The selected floe has a strong central section, with ice depths of up to 5m. It appears to have been created from several floes merging under high pressure. It appears as a luminous, bright patch in the otherwise dark grey satellite pictures the team are using. The inhomogeneous rugged jumble has drop-offs of 3m.

Beyond the fortress, there are two large flatter zones. The larger of these two [south side] appears to be made of ice typical of the region. It would allow the expedition to study what is happening to the ordinary, fast-disappearing young Arctic sea ice.

The ice around the ship started forming about 300 days ago – around two months later than the usual onset of the Arctic winter freeze. Those two months of missing freezing make a big difference, reducing the ice thickness by around half.

After two days, the floe, clearly very dynamic, has already changed. A large crack runs through the ice from west to east, almost severing about a fifth of the floe beyond the northern edge of the fortress. The floe is in a shear zone, with currents [a misunderstanding: no water currents exist in the central AO] pulling it in different directions. This section of the floe is not expected to last long.

The Polarstern moors to the fortress floe at 85ºN, 137ºE on Oct 4th but not as originally planned by gently lining the ship up to an edge but instead by ramming 500m towards the fortress. The captain wants to the ship securely embedded to get the robust mooring. “This may be one of the last years we can do this kind of expedition,” says Matt Shupe.

Some ice terms: frazil, shuga, nilas, pancake, grease, cake ice and frost flowers.

As sea water freezes, it first forms crystal discs known as frazil, eventually forms a suspension in the water known as grease ice, which creates an iridescent sheen like an oil slick. Waves and wind can compress the ice crystals together to form pancake ice that floats on the ocean surface. As these pancakes grow bigger they become cakes. On calmer seas, the frazils grow to form a continuous expanse of dark, glassy layer of ice, like a windowpane on top of a black sea. Shuga ice is slushy mess created by spongy white lumps that bob in the water.

Researchers at Russia’s AARI have been tracking ice floes for Mosaic in the Central Arctic Ocean all summer. They have been using data from several satellites[?], hoping to find those which survive the storms and melting.

Rex points out a darker oval in the image – the darker the ice appears, the thinking goes, the thicker and more robust the ice should be. The ice in the target region is looking like it will be 80cm thick, according to the data available. “We’d prefer one meter, one meter 20 (3 to 4ft) – but 80cm can work,” says Rex.

They will drift with the floe on an unpredictable path across the polar region, creeping on average from east to west through the year. But, choose a bad floe, or even a good floe in the wrong place, and the camp is at risk of collapse.

“What happened to N-ice would be really, really bad [4 forced relocations as Atlantic swells and melt broke up their floes]. We need to avoid that. A large fraction of model trajectories ends up in the N-ice area [2º north of Svalbard].

But other drift trajectories end their year’s drift stuck at the North Pole. Another gets into a danger zone off the coast of Greenland. [Floes never pile up against land in Greenland; floes never pass through the Nares Strait from their starting position.]

Another promising floe has 30 cm of compact snow over a deep layer of translucent blue ice that transitions to  brownish mushy honeycomb that easily sloughs off as sludge. However the Akademik Federov has sailed straight through it leaving a track visible on satellite. However it turned out to be only 30 or 40cm thick so worthless for an ice camp.

Re-interpretation of radar imagery: the discovery of so many thin floes lead the team to rethink satellite imagery. Previously the idea was that the thicker ice absorbs more radar signal from satellites overhead and so appear darker in the resulting image. But tests on those floes shows that this interpretation is wrong. The dark patches on the images are in fact showing something else entirely.

On the first floe, there was very little freeboard. “When you remove the snow, the surface was wet,” says Stefan Hendricks. The floe was flooded with seawater. The layer of salt water reduces the reflection of the radar back to the satellite. “Our idea is dark floes are actually the thin ones having low freeboard.”

September 29, 2019
84° 29' 44.2" N 128° 44' 12.1" E
Last couple of days were spent retrieving four Ocean Bed Seismometers that had been collecting data for the past year at the bottom of the ocean, almost 4 kilometers (2.5 miles) deep. The scientists responsible for these devices had remotely triggered their release from the ocean bed and had to find them among the ice once they surfaced. It took almost two days, but finally all four were found and hoisted on board.

https://www.awi.de/en/science/geosciences/geophysics/methods-and-tools/ocean-bottom-seismometer.html

9
Arctic sea ice / Re: MOSAiC news
« on: October 09, 2019, 09:55:19 PM »
Quote
Polarstern drifting south and east
The ice shows no sign of getting its drift act together. Some of these autumn freeze season time series could be confused with spring melt season. Either way, great that the PS is out there observing it all.

10
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: September 30, 2019, 06:23:01 PM »
Well, when the current is off, i could imagine a freeze over to happen quite fast if the temperatures are low enough. But once the current starts picking up again, the ice needs to be thick enough to not get sucked away.

I would love to know some real numbers on those variables.

How cold must it be for how long to freeze a sustainable sea ice surface? How does an active current influence these numbers?
All I know is, don't go looking for those temperatures today.  For most of the last 48 hours the temperature in Alert has been above freezing, hitting a high of 4.7 degrees the morning of the 28th.  Everything outside right now is melting, there's water dripping from the roof of the lab.  The forecast says we're going to see continued high temperatures through most of the week.

Admittedly my experience is limited, but I've never seen weather like this so late in the season.  5 degrees is warmer than most days in the middle of summer, and we're only two weeks away from the final sunset of the year...

I'm up here until the first week of January, I'll be watching this thread closely in the meantime.  Judging by the large area of open water visible off the coast here, I have serious doubts about the ability of the ice bridge to form this winter.  The floes are simply too sparse and thin.

12
Arctic sea ice / Re: The 2019/2020 freezing season
« on: September 26, 2019, 12:41:16 PM »
Compaction is extreme, so there is no easy to freeze ice; SSTs are way above anything I have seen before, and there is warmer than average air over the Arctic the next few days. I would say that it is likely that 2019 will get to the first place some time October. Refreeze should be very very slow.
Or the Arctic will trick me again as it usually does :)

13
Mini calving

14
In cooperation with the Operation Ice Bridge Team and especially Sea Ice Scientist Linette Boisvert NASA who sent me many images and a few videos from their trip across Zachariae Isstrøm on September 5 2019, the delay in the publishing is due to the poor internet band width at Thule Airbase.
We start this round of images from the top of Zachariae Isstrøm including the giant meltponds then passing the calving front across the Zach Bay and at the end we reach the former glacier tongue of Zachariae Isttrøm, now a death piece of glacier ice, enjoy and again thanks to Linette:

15
Arctic sea ice / Re: The 2019 melting season
« on: September 15, 2019, 08:12:25 PM »
Hi weatherdude88,

I can't wait to hear your verification summary from this July prediction:

Despite all of the hyperbole and wish casting, 2019 will not be in the top 3 lowest sea ice minimums on record in area or extent. We may not end up in the top 5 in a sea ice area metric (looking at UH AMSR2 and NSIDC daily data and extrapolating).

The regions that will matter at the end of the 2019 melt season are the Central Arctic Basin, East Siberian sea, Beautfort sea, Greenland sea, and Canadian Archipelago.

For the most part, we are lagging the highest melt years in these regions (There are 5 years that lead 2019 in all these areas combined).

There is too much high latitude ice in the critical regions. All the subjective interpretation of data will not translate to reality, no matter how many members reiterate it.

By the end of the first week of August, it will become evident that 2019 will be ordinary, as it relates to sea ice minimums over the last decade.









16
Arctic sea ice / Re: The 2019 melting season
« on: September 13, 2019, 10:03:58 PM »
Aluminium + IWPD @ 850hPa (hindcast/forecast acquired 9/12 from Nullschool)

17
Arctic sea ice / Re: The 2019 melting season
« on: August 26, 2019, 07:14:29 AM »
It seems to me that the stall these last few weeks compared to 2012 is mostly due to dispersion. Late August 2012 saw the inner ice a lot more compacted, especially towards the Pacific side.

Dispersion obviously causes higher extent, but then area seems to be stalling as well. But how reliable are the area measurements, particularly with highly dispersed ice under cloudy skies? I don't know.

But it does seem to me that a good "compaction event" on the Pacific side could lose several 100 k's without any extra melt.

And that leads me to wonder if the difference between 2012 and now lies not so much in how much ice has melted as in how it is distributed - admittedly, 2012 had less ice, but the difference probably wasn't nowhere as big as the current extent numbers indicate.

18
Arctic sea ice / Re: The 2019 melting season
« on: August 25, 2019, 01:00:29 PM »
Looking at the entrance to the Nares strait shows snow-free conditions on the 14th and the following days. Then on the 23rd quite a lot of snow can be seen, but it is clearly melting away. I'm assuming that this is the same snow as can be seen melting rapidly between the 23rd and the 24th on the images above.

19
Arctic sea ice / Re: 2019 vs 2012
« on: August 22, 2019, 08:48:35 AM »
The Atlantic side near Spitzbergen shows more ice than the last couple of years currently.

In regards to 2012 I don't think 2019 is comparable at all due to the unusual weather in 2012  which 2019 has not had. 2019 is now following the general trend for August (so far) but will still be a very low year.

Personally I always ignore 2007 and 2012 as outliers and just look at the general trend.

Once the Arctic gets down to 2012 ice extent levels  repetitively, like it has compared to 2007 now, then that is worth noting.

20
Arctic sea ice / Re: Arctic Image of the Day
« on: August 12, 2019, 07:51:15 AM »
Here are a couple of photos I got while flying over the Arctic, from Toronto to Hong Kong on August 1st. (yes, I feel bad about flying due to emissions, but it's not a vacation, we've moved to Jakarta for my wife's work. we will also buy some offsets to try to compensate a bit.)

We were trying to sleep through the 15 hour overnight flight, but I managed to some how wake myself up at the right time to open the window blind and blind myself with the glare.

Again, taken on Aug. 1st, somewhere between Greenland and the North Pole. It seems like a lot of water visible in the leads for this area, even for this time of year. Maybe it's normal recently, but I can't imagine it would've been normal when this area used to be dominated by multiyear ice.

If you want to see the full size images, DM me and I'll email them to you.

cheers,
m

21
Arctic sea ice / Re: The 2019 melting season
« on: August 04, 2019, 12:56:44 AM »
Indeed. A lot of ice is in the process of going "poof" in the Beaufort, including the largest floes. Expect large drops there in area and extent over a few days. I posted some graphics of it over in the RAMMB thread, if you're interested:

https://forum.arctic-sea-ice.net/index.php/topic,2649.msg218925.html#msg218925

Edit: And before-after as seen using WV spy mode: https://go.nasa.gov/2GKSOUB
This is the Worldview version. Only one day! Look at those big floes. Wave action?
https://go.nasa.gov/2GFDWqH

22
Arctic sea ice / Re: The Rammb Slider Thread
« on: August 03, 2019, 08:02:25 PM »
Similar to the one discussed earlier off Svalbard.
Yep, that one is still making it's daily appearance as well.  I misspoke when I initially posted that one and said it was at 80°N , 5°E, I had the latitude line confused on the slider, it's actually 82.5°N, 5°E.

Apparently, that underwater mountain below that feature is called Yermak Plateau.

23
Arctic sea ice / Re: The Rammb Slider Thread
« on: August 01, 2019, 10:16:44 PM »
Another interesting feature
Thanks. Here it is overlaid onto bathymetry. Rotation and scaling is not perfect.
Blue deeper than brown.

24
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: July 28, 2019, 06:18:57 AM »
I don't know the name of this glacier. These blocks that calved on the 26th are around 1 km across. It's at 75.572625,-58.237839

Many of these glaciers along the west coast of Greenland are calving.

(click to animate)


25
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 04:08:00 AM »
Last of 3 posts (and a half dozen updates to fix glitches).
   Yearly average ratios across Extent-Area-Volume-Thickness
...and the winner (so far) is.... (but you already knew)

 
Observations/Speculation: 
   -- 2012 stands alone as the lowest overall with two 1st place and two 2nd place rankings among the four categories.
   -- 2019 is second to lowest, with two 1st, one 2nd, and one 3rd place rankings.  2019 would require a lot of catching up in Extent and Area in the remaining weeks of melt season to take 1st place away from 2012.
   -- 2016 and 2011 are close to each other for 3nd lowest overall ranking, followed by 2017 and 2010 in a virtual tie. 
   -- The sequential rankings of 2010 (#6), 2011 (#4), and 2012 (#1) suggest that the 2012 minimum record was the culmination of a three year sequence of predisposing bad melt years vs. being entirely due to conditions in 2012 alone.
   -- Volume rankings are closely correlated with Extent and Area.  Thickness rankings less so.
   -- Nine of the 10 lowest ranking years have been in the last decade (all except 2007 at #9). 

Definition of terms, caveats, top 20 rankings for each category, and a few other things in the full PDF. Including a still photo from great video of what ice looks like at the edge of the Extent line.
Figure 2.  Ice condition near edge of the Extent limit.  Photo taken at 75N, 150W on October 29, 2016.  Credit: “Waves propagating through Arctic sea ice.”  By IBWOvids. 





Lots of calcs involved and done in a hurry, so errors possible.  Corrections and suggestions appreciated.  Now that the spreadsheet is set up, occasional updates should be pretty easy if folks are interested.


26
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 27, 2019, 08:36:51 PM »
I didn't look back too far but here is amsr2-uhh north of svalbard 2017 (high contrast, small, uncorrected). It's still there at times but I think the ice drifting over has been thicker in previous years so the lower concentration doesn't show.
I assume that it's warmer water forced to the surface over the shallower plateau

27
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 26, 2019, 11:47:28 PM »

14 hour loop of a channel in the CAA, I don't know its name so left the lat, lon in there. Rotated so that North is up.


Nansen Sound upper left, Greely Fjord to the center and right. Eureka is just to the left of the lower left '80'.

I didn't realize this stuff was moving around like that. It looks to me like melt runoff is driving it, but what do I know? :-)

28
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 23, 2019, 08:34:46 PM »

Better to evaluate the CAB based on bathymetry.

Do you think there's enough contrast there?

On the Atlantic side, there are shallow ridges that extend to ~ 83N and immediately adjacent to the CAA it's also shallow, but not necessarily too relevant.

Beyond that it's deep and deeper.... a nice seque to my next stupid question:

Does it make a difference if the water is 500m deep vs 2,000m deep in terms of impact on ice melt?

Someone (not sure who) draws arbitrary lines on the Arctic Ocean and labels a portion the CAB. We then measure the amount of ice at minimum in this area and while the metric is accurate and can be compared season to season, I would argue that looking at the whole and observing the behavior of the ice relative to the actual geology, oceanography, hydrology and atmospherics would be far more useful and contribute to our understanding of what is really happening.

It has been pointed out by some here that we are seeing more and more frequent open water to the north of FJI and Svalbard and this open water parallels closely the shallow shelf that extends from the Barents. As the Barents has warmed and become more salty, the flow of this water has intruded on what use to be more ice covered than not.

I have always been fascinated by the Lomonosov Ridge which rises spectacularly from the deepest portion of the Arctic basin.

https://www.ngdc.noaa.gov/mgg/bathymetry/arctic/Images/version11024.jpg

Portions of this ridge are less than 400 meters below sea level and this ridge is curiously located near the Laptev Bite which makes its annual appearance during the melt season. What, if any impact does this ridge have on the deep ocean currents? Could this pronounced ridge cause an upwelling of warmer, saltier water from depths and result in the Laptev Bite?

As MYI has deteriorated north of the CAA, the ice seems to be separating in a more pronounced manner from the CAA during the melt season. What impact, if any, does the shallow shelf paralleling the north coast of the CAA contribute to this? If this shallow shelf is driving this phenomenon, what does this say about where the last remaining ice will hold out? We have always assumed this ice would hug the CAA but perhaps this highly fractured and mobile MYI will find itself swirling around the pole.

My problem in looking at the Arctic this way is that it only triggers questions in my mind and provides few if any answers, mere suppositions on my part, I fear.

29
Arctic sea ice / Re: The 2019 melting season
« on: July 22, 2019, 11:00:24 PM »
Yes, Rich...
 
But very likely the damage has been done well before this week. What happens in the next few weeks will probably not change much in the final outcome at Minimum. nor during "refreeze".

I have watched enough MODIS tiles during 2010-2015 to see on Worldview the state of the ice is deplorable everywhere. Even in the former "safe-haven" 1,5 Mkm2 North of the CAA/Greenland.

30
Lots of melting today, July 20.
I played around with the color balance to try to make this look more natural.

31
Arctic sea ice / Re: The 2019 melting season
« on: July 20, 2019, 03:44:06 PM »
There seems to be some extremely fast currents moving along the northern Greenland coast. We've all been seeing the crack that's opened up in the last week or so, and I'd earlier estimated a drift rate of some 10 - 20 km based on EOSDIS imagery.

But playing around with the RAMMB slider, a 15 hour loop from yesterday shows the small floes cloes to the coast simply racing away. One of the small ones seems to move around 40 km in 15 hours, that makes for 65km per day, amazing speed for a place where there are no documented currents?

(Click to run, less than 1MB).

32
Arctic sea ice / Re: 2019 vs 2012
« on: July 17, 2019, 09:47:59 AM »
Uni Bremen misses pics from 2012, the first available is 2012 July 23 (shown on second pic). I compared it to 2019 July 16 (first pic). I know there is still one week to go and the comparison is therefore not totally fair but I would say that 2012 looked much-much worse than 2019

33
Arctic sea ice / Re: The 2019 melting season
« on: July 17, 2019, 12:34:32 AM »
An imperfect overlay of the ice aging map with July 15 UH AMSR2
I guess the Beaufort branch is not really that far from the edge anymore

34
Arctic sea ice / Re: The 2019 melting season
« on: July 16, 2019, 05:28:36 PM »
Clear skies at the pole.  Shot is centered on the North pole. 30°E is straight up. One pixel is just about 375m.

16 hour loop, "natural color"
Click to run
Using this calculator, i see that now (day 196) surface albedo of ~36% would mean equilibrium surface temperature of ~1°C there at the North Pole from insolation alone (before any greenhouse effects). Same calc lists ice albedo as 60%, water albedo as 6%. For the latter, equilibrium surface temperature would be ~29°C. And the place looks rather bluish, to me.

35
Arctic sea ice / Re: The 2019 melting season
« on: July 14, 2019, 11:20:09 PM »
Rather than rely on the profiles, lets look at the microcats mounted at a fixed 6m depth and also 7m where there are two. The salinity drops are likely to be associated with melting. As mentioned before, temperature directly beneath the floe is likely to be lower due to melt.
Buoys posted in the same order with gifs where there are two cats.
Note that itp103 hits 0C at 6m and 7m with large drops in salinity despite being slightly further north.
data thanks to woods hole oceanographic institute https://www.whoi.edu/page.do?pid=163356

36
Minor calving in the center of the Zachariae. The images have been scaled fro 10m->5m per pixel. The calving lies on its "side", allowing an estimation of local ice thickness: 380m.

37
Arctic sea ice / Re: The 2019 melting season
« on: July 13, 2019, 11:01:40 PM »
The heat has to travel much farther and faster (away from shore) than it has previously in order to maintain the melting. momentum. Otherwise, we're looking at a relatively inert body of warm water.

It really couldn't be much closer. (maybe I drew the area a little too far west, since it is overlapping with some ice. but that kinda proves the point.)

38
Another calving and an advance between the 9th and 13th. It looks like there was a big burst of water released? I haven't really looked around much yet, but it looks very different from recent events.

click to animate

39
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 13, 2019, 09:52:47 PM »
Quote
A shear line can be seen bisecting the image horizontally.
I see two shear lines, actually.  First a shear line in the lower/center part of the GIF, then it stops and a shear line further up (still center) immediately takes over.

I've watched this sort of team-tag movement in Lincoln Sea ice (mostly on the Greenland side of the Sea) many times.

40
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 13, 2019, 07:08:15 PM »
  • and the small floes getting ground to nothing
  • and the swirling mixing the shallow water (at least raising salinity a spot at the surface, if not temperature)
  • and the spots of open water with low albedo

41
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 13, 2019, 05:04:20 PM »
... and the thick floes getting ground in the process.

42
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 13, 2019, 10:28:38 AM »
Another one.

Ellesmere on the right, M8 band, enhanced contrast.

43
Arctic sea ice / Re: The 2019 melting season
« on: July 12, 2019, 12:33:33 PM »
Regarding bottom melt in the Beaufort. whoi itp103 is currently tethered to one of the many floes north of the mclure strait. Two microcats are mounted at 6m and 7m depth which measure temperature, salinity and pressure. Temperature has risen significantly over the past week while salinity has dropped (not shown, please see https://www.whoi.edu/page.do?pid=163356 )

44
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 10, 2019, 05:59:40 PM »
Mostly melt in that animation with the possible exception of the CAB near Beaufort which shows some compacting.

I'm not sure how much faith I have in that compaction. The area near the Beaufort/CAB/CAA boundary has been under increasingly heavy cloud for the past several days. It's especially evident on Worldview if you look west and northwest of Prince Patrick Island. However, what's visible through holes and breaks in that cloud isn't inspiring.

A cloud-free window at 150°W 80°N shows rubble with quite a bit of open water, and several visibly identifiable floes near Borden Island have broken apart over the last few days (in addition to displaying nontrivial westward movement).

That's not to say that there isn't some extent loss due to compaction and the way that extent is determined. But I certainly don't think there's good news for the ice in the northeast Beaufort.

45
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 09, 2019, 05:35:45 PM »
Nice. You found what you were looking for, and reasonable agreement with mercator.

46
Arctic sea ice / Re: The 2019 melting season
« on: July 09, 2019, 10:08:51 AM »
Judah Cohen appears to be anticipating a gradual shift towards a neutral or slightly negative AO for the remainder of the month (as opposed to more strongly negative in recent weeks), so this suggests average or slightly above average surface air pressures generally across the Arctic ocean.
However, he is also suggesting that the NAO will remain in its negative state, which means higher air pressure around Greenland.

Looking at the anomaly charts for geopotential height, which you can roughly take as a guide to surface pressure patterns, high pressure remains around Greenland and stretching back towards the Beaufort sea, with low pressure across the Eurasian side of the Arctic.

6-10 day


11-15 day


Rather than a general period of storminess, this suggests a switch to a more dipole like patterns, which a chances of some depressions around the ESS, Laptev and Eastern side of the central Arctic ocean.
While it might not bring the exceptional heat the last 2 months, the potential for compaction and export from such a fractured pack is very high, and leaves little reason to suggest the weather will save the ice.

47
Arctic sea ice / Re: Updating the ASIG
« on: July 08, 2019, 11:31:43 PM »
I've finally come around to updating the ASIG front page, and it just keeps looking better and better.  :)

- I've kicked off the NRL stuff.
- I've added a few links at the top (RAMMB SLIDER)
- I've added a new category called 'melting momentum', with Tealight's AWP graphs, Wipneus compactness and melt extent ratio graphs
- Speaking of Tealight, he helped me out in a fantastic way with a script that allows me to hotlink to maps/graphs with dynamic links. That way I was able to add a lot of Polar Portal stuff in the Greenland category, as well as DMI ice thickness map and graph. Maybe the OSI-SAF sea ice drift map can be added as well, but the URL is more difficult to script.
- I've also made some changes to the Regional Graphs page, removing the compactness graphs, and adding NSIDC regional graphs, as well as the Arctic Basin area and extent graphs.

That's it for now.

48
Arctic sea ice / Re: The Rammb Slider Thread
« on: July 08, 2019, 06:16:52 PM »
Mesmerizing...

49
Arctic sea ice / Re: The 2019 melting season
« on: July 08, 2019, 02:13:50 PM »
A big P.S. also to my post, beyond the fact that June 2019 was abysmal, I wanted to show also, even though it was not explicitly state, that Sun input is increasing bigly in Arctic, with an increase of 1 W/m² in June every four years. It could perhaps have been better to wait MERRA, but the topic was brought again in this discussion so go. But even more importantly, no matter if 2019 is at record or not, we are witnessing the effect of increase Sun input, with Chukchi, Beaufort and Bering running like bats out of hell after records. Of course, it is a progressive state change, but I fear we are nearer and nearer to the point that Bering sea will be perennially open, and even Chucki sea looks to be already in bad state for a good refreeze this winter. If ocean is warm enough, I think that it could supply enough moisture to create a positive feedback with longwave radiation. The warmer, the moister, the moister, the less heat can escape to space. And the warmer, the longer it takes to cool down, and if heat is not able to radiate back to space, it will take even longer. And if a melt season can give hand to the next like it was almost the case last three years, Sun input in summer is going to go trough the roof, etc... Up to now, Arctic was more or less able to erase its memory of the latest melt season during winter, but when I see the SSTs going trough the roof and Arctic pounded by relentless warmth and sun, and the last 3 years, I fear we are reaching the point where it is no longer the case.

50
Arctic sea ice / Re: The 2019 melting season
« on: July 08, 2019, 01:43:15 PM »
...
I think what is missing here is a discussion of the impact of increased solar irradiance.
...

Are you talking about the reduced albedo, low cloud cover, something else?

Looking at only solar irradiance I believe we are at a solar minimum right now with a lower irradiance than in 2012 and most of the rest of this decade (even then that difference is tiny).

The low solar minimum that the earth is presently experiencing is not the key issue that I am talking about. Rather, the key issue is the amount of solar energy entering the system as a result of reduced albedo in the arctic. This difference far offsets the difference in energy coming from the sun due to the solar cycle.

I broadly agree, I have also the feeling that incoming solar radiation is probably a bit an understate factor. It is of course a know fact, and a spoken one, that lower albedo implies a greater heat accumulation. But perhaps that the big train of heat ready to ram us is not fully acknowledge. By the way this is why I'm back here, at ASIF. I'm like a vulture, when I smell the good fragrance of a water bath I am here.

So to continue this discussion, I will try something (each word of this sentence is important XD ). NCEP/NCAR Reanalysis is easier to manipulate and is update with a lag of a few days only. So I already us it, but radiations data are not as good as other dataset. Good enough to say something about big trend and to beat some dead horses, but probably not good enough for details -like the exact magnitude of the June 2019 crash-. MERRA is probably better but will not be available until mid or late July for the month of June. As already state, solar heat input in June above 70°N is a big factor : https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JD025819
With MERRA data up to June 2018 I am going to back up this claim and give some order of magnitude, and with reanalysis up to June 2019 I am going to show that this year things are worst than worse. I will update the analysis when June 2019 data from MERRA will be available in late July -when nobody will no longer care as sea ice extent will be many thousands squared kilometers below 2012 and the crash will be beyond obvious XD -. Perhaps MERRA datas are going to show a little miracle, against the reanalysis, but is not really likely.

I am going to use two different flux. With MERRA, I am using net downward flux at surface (SWGNT for short). State an other way, it is the solar input wich is really accumulating at surface. The part of the Sun wich is not absorbed can be reflected by atmosphere and surface, wich is going back to space as a outgoing shortwave radiation (RSR for Reflected Sun Radiation). And Sun can also be absorbed by atmosphere. I stick with SWGNT cause looking at RSR implies giving weight to heat absorbed by atmoshere, but I don't think this part of the flux is really important. Its variations year over year are not as important, and heat absorbed by atmosphere is probably going to be mixed all over the hemisphere in a few days (as a side note, aerosols and soots -also known as black C- implies that Sun is more easily captured by the atmosphere, wich also have implications for global warming. But, looking only at sea ice year over year, the Sun captured by the atmosphere is not looking like a big factor). So, with MERRA dataset, is is going to be SWGNT. But Reanalysis as not an easy dataset for this flux. I could be possible to mix surface albedo with the downward shortwave flux at surface, but it is starting to look a bit too shaky, given the accuracy of reanalysis. So, with this lad, I am sticking with shortwave outgoing flux at TOA (RSR in the state paper above). Of course, the higher the heat absorbed by the surface, the lesser the heat making an escape to space. As a consequences, many graphs are going to have a left hand y axis, and a reversed right hand y axis. So far, the brains already hurts XD

The first graph is September SIE and SWGNT. The latter is reversed, meaning that the more the Sun is absorbed at surface in June, the less ice survived in September. Correlation is looking quite good, so let's check this.

The two datasets are quite correlated, with a decrease of the September SIE of 1 million square kilometers if absorbed radiation increase by 7 or 8 W/m². It should be note also that extrapolating the trend brings plausible results, with a zero SIE if June heat input is up to around 150 W/m². Definitively in the realm of possibilities.

So now that we have checked we are able to replicate the results of the above study, and that sea ice is screwed if Arctic is pounded by Sun in June, let's look at what the reanalysis is saying about June 2019. Was it bad, or worse than worst ? Short answer, acording to reanalysis June 2019 is abysmal. Values from reanalysis for outgoing solar flux at TOA are correlated with values from MERRA for solar input at surface. Correlation is not so bad (R² 0.45), but 2019 is not a record low point (caramba ^^). This said, it is looking like reanalysis is not going down enough. What I'm going to do is to artificially increase the trend for USWRF. Not for the pleasure of making things looking worst, but because, without MERRA data for June yet, we can only guess what happened. And an educated guess will be that reanalysis is to shy (not a surprise here...). Correlation is improved (R² 0.55) and 2019 is to the basement. Again, this is not intended to manipulate data to prove that June 2019 is a nightmare, but it is really because it is quite probable that reanalysis is not going down enough. Correlation with September SIE is also vastly improved (R² up to 0.43, from 0.20 with bulk values). Again, it is not a surprise that adding a trend to a datset to compare it with a dataset -SIE- where the trend is overwhelming everything vastly improves the correlation -if the slope of a dataset is way higher than its variability, we can correlated it with about any dataset having also a big slope-. But I do think this as a physical meaning.

I let you also the values for SWGNT in June in W/m², and with a conversion to "how many meters of ice could be melt by such and heat input ?" to give a sense of the energy in play.

   SWGNT      Thickness elt
1980   107   0.90
1981   109   0.92
1982   103   0.87
1983   103   0.87
1984   108   0.92
1985   113   0.96
1986   99   0.84
1987   108   0.91
1988   109   0.92
1989   99   0.84
1990   117   1.00
1991   111   0.94
1992   102   0.87
1993   116   0.99
1994   108   0.92
1995   109   0.93
1996   100   0.85
1997   109   0.92
1998   114   0.97
1999   102   0.87
2000   112   0.95
2001   114   0.97
2002   112   0.95
2003   108   0.92
2004   107   0.91
2005   113   0.96
2006   107   0.90
2007   118   1.00
2008   117   0.99
2009   111   0.94
2010   115   0.97
2011   117   0.99
2012   118   1.00
2013   109   0.92
2014   112   0.95
2015   113   0.96
2016   113   0.96
2017   116   0.99
2018   108   0.91



So, if I am not fooling myself, if I did not make any basic calc errors, etc... June 2019 has sucked up a lot of Sun, and probably is the leading horse in this race. Put in another way : die sea ice, die ! And see you again when MERRA will update.

Pages: [1] 2 3