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Messages - uniquorn

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1
Arctic sea ice / Re: Latest PIOMAS update (August 2020)
« on: Today at 10:23:39 AM »
Thickness map compared with previous year and their differences.

2
Arctic sea ice / Re: Latest PIOMAS update (August 2020)
« on: Today at 10:08:20 AM »
Fram volume export graph.

3
Arctic sea ice / Re: Latest PIOMAS update (August 2020)
« on: Today at 10:05:52 AM »
The volume and volume-anomaly graphs.

4
Arctic sea ice / Re: Latest PIOMAS update (August 2020)
« on: Today at 09:56:26 AM »
PIOMAS gridded thickness data is updated to day 213 (31Jul/1Aug). The (calculated) volume on that day was 6.52 [1000km3], second lowest (behind 2019).

Here is the animation.

5
Arctic sea ice / Re: The 2020 melting season
« on: July 30, 2020, 01:07:41 PM »
As it appears (to my non-expert eyes) that clouds cause artifacts in the concentration products, the big question in my mind is whether they cause high-concentration streaks, or whether they cause low concentration streaks... Can some kind soul superimpose (and synchronize) the cyclone and the concentration images and prove it one way or the other?
p.s. Of course it's also possible the storm causes actual concentration changes that appear to be in its shape. Would love an expert opinion.

Another version, to add to uniquorns great work.

(Large file warning!)

6
Sorry for the delay, some trouble with the download caused a corrupted file (uice, the ice velocity data).

Here are the updated volume and volume-anomaly graphs. Worth a click for size.

7
PIOMAS has upgraded the gridded thickness data to day 197 (15 /16 July). Volume on day 197 was 9.04 [1000km3], which means an annual fourth lowest place for that day.

Fasten seat belts, here is the animation of July so far. Might need a click.

8
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 15, 2020, 12:54:38 AM »
For uniquorn, these are all the images that were available.

Second is just east of Nansen sound.  Lots of areas breaking up the CAA

Both need clicks.

9
The rest / Re: SpaceX
« on: July 08, 2020, 03:07:23 PM »
—- Starlink (+ Blacksky sats) launch today!
Quote
SpaceX (@SpaceX) 7/7/20, 6:06 PM
Falcon 9 is vertical on LC-39A ahead of our tenth Starlink mission, targeted for [today] at 11:59 a.m. EDT. Vehicle and payload look good; weather is 60% favorable → spacex.com/launches
https://twitter.com/spacex/status/1280624175590240256

SpaceX’s next batch of Starlink satellites back on the launch pad
July 7, 2020 Stephen Clark
https://spaceflightnow.com/2020/07/07/spacexs-next-batch-of-starlink-satellites-back-on-the-launch-pad/

Edit:
Quote
SpaceX (@SpaceX) 7/8/20, 11:01 AM
T-1 hour until Falcon 9 launches its tenth Starlink mission; team is monitoring weather conditions. Webcast will go live ~15 minutes before liftoff spacex.com/launches

SpaceX (@SpaceX) 7/8/20, 11:48 AM
Standing down from today’s mission due to weather; proceeding through the countdown until T-1 minute for data collection. Will announce a new target launch date once confirmed on the Range
https://twitter.com/spacex/status/1280891612088823808


——  Next customer launch targeting July 14th
Quote
Nathan Barker (@NASA_Nerd) 7/7/20, 1:55 PM
Before Falcon 9 and Starlink even gets off the ground, the next Falcon 9 launch hazard advisory is on the Range for July 14th. This advisory is covering a period from 4:55 pm EDT to 9:47 pm EDT. This launch will carry KMilSatCom 1 for the South Korean Military.
https://twitter.com/nasa_nerd/status/1280560997237997568

—- Starship
Quote
Michael Baylor (@nextspaceflight) 7/7/20, 6:07 PM
New road closures in Boca Chica! Starship SN5 static fire testing starts July 10. Then, the notice starting July 13 through July 15 says SN5 150 meter launch! Surely too soon? Windows are daily from 8 am to 5 pm local.
cameroncounty.us/spacex/
https://twitter.com/nextspaceflight/status/1280624400694341632

—-
SpaceX Super Heavy ‘high bay’ construction begins in South Texas
SpaceX began assembling the first building dedicated to Starship's Super Heavy booster on July 7th.
https://www.teslarati.com/spacex-starship-super-heavy-high-bay-construction/amp/


—-  NASA & SpaceX
Congress may allow NASA to launch Europa Clipper on a Falcon Heavy
New budget also offers some hope for Human Landing System.
Eric Berger
Quote
One of the big questions in recent years has been how NASA will get its multi-billion-dollar Europa Clipper mission to Jupiter's moon. In the past, Congress has said this must go on NASA's Space Launch System rocket, but this came with downsides. For one, the SLS rocket likely will cost NASA at least $1.5 billion more than a commercial rocket. Also, because it takes so long to build the large rocket, it's unlikely an SLS would be available for the Clipper before 2026.

Because the spacecraft may be ready to launch as early as 2024, and storing it would lead to increased costs, NASA's Jet Propulsion Laboratory has studied alternative launch vehicles. Among the most promising is a Falcon Heavy booster with a kick stage.

In the House legislation, Congress says NASA "shall use the Space Launch System, if available, as the launch vehicles for the Jupiter Europa missions," and plan for an orbiter launch no later than 2025. Because few people at NASA expect an SLS vehicle to be available in 2025, this is a pretty big deal.

It remains to be seen how the US Senate will act—the biggest proponent of the SLS rocket, Alabama's Richard Shelby, chairs the Senate Appropriations subcommittee. …
https://arstechnica.com/science/2020/07/house-budget-for-nasa-frees-europa-clipper-from-sls-rocket/

—-
Excellent review of information from the web conference yesterday.  NASA admits they paid closer attention to SpaceX and its “new” approach, compared to the well known and trusted Boeing.
Quote
Thomas Burghardt (@TGMetsFan98) 7/7/20, 8:34 PM
Today, NASA released the final results of the Starliner OFT investigation. Now, Boeing teams will move to implement 80 recommendations ahead of OFT-2 later this year and crewed flight in 2021.

Quote
NASA and Boeing Complete Starliner Orbital Flight Test Investigation
https://www.nasaspaceflight.com/2020/07/nasa-boeing-complete-oft-investigation/
https://twitter.com/tgmetsfan98/status/1280661557614166017

Edit:  Here is a link to the audio briefing, which starts about five minutes in.
NASA Live: NASA Review of December 2019 Boeing Starliner Orbital Flight Test (July 7, 2020)
➡️https://www.youtube.com/watch?v=hsB1ZWrGero

10
Changes from June 15.

Laptev ... -64%
Hudson ... -58%
Baffin ... -46%
CAA ... -45%
Kara ... -44%
ESS ... -41%
Chukchi ... -34%
Barents ... -34%
Greenland ... -21%
CAB ... -15%
Beaufort ... -14%

11
Arctic sea ice / Re: Latest PIOMAS update (July 2020)
« on: July 04, 2020, 11:24:43 AM »
The thickness map for day 182, compared with previous years and their difference. All need a click for size.

12
Arctic sea ice / Re: Latest PIOMAS update (July 2020)
« on: July 04, 2020, 10:41:55 AM »
Volume and volume-anomaly graphs. Click for size.

13
Arctic sea ice / Re: Latest PIOMAS update (July 2020)
« on: July 04, 2020, 10:29:26 AM »
PIOMAS has updated the gridded thickness data. Last day (day 182, 30th June or 1st July) the calculated volume was 12.53 [1000km3], which is the fourth lowest for day 182.

Here is the animated thickness map, which seems to start only after a click.

14
Arctic sea ice / Re: The 2020 melting season
« on: June 30, 2020, 12:44:06 AM »
Some ridiculous soundings coming out of YLT and WEU (Alert and Eureka) the past couple of days. Below is an example from this morning at YLT. Aside from the lack of column moisture (due to crushing subsidence from the ridge) and near-surface inversion due to melt, this looks similar to subtropical soundings. Note the tropopause all the way up around 250mb and freezing level at 700mb (>3000m). Peak of +15C just a couple of hundred meters up.

15
Some people have good use for the updated regional data files.

daily:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

16
Updated Fram volume export graph.

17
Arctic sea ice / Re: The 2020 melting season
« on: June 13, 2020, 12:33:32 AM »
The 12z models and 00z EURO the 12z euro isn't out yet have backed off considerably with the dipole in the long range.

Instead of setting up a full or 3/4 dipole the models slide the Eurasian vortex over the pole/Atlantic side and merge it with the GIS vortex which won't budge.

This keeps the torching over the Pacific half.

It's not a good pattern by any means but it definitely is much better than the entire CAB getting the roast.

This kind of thing is what will keep 2020 from passing 2012 in the end.

We'll see

Yep, we've seen this time and again in the last 8-9 years. It's a pattern and I think part of the reason for this strong +PV tendency has been due to a marked increase in low-level baroclinicity and eddy kinetic energy as the mid-high lats warm faster in summer than the basin proper. It is providing a transient negative feedback by preferentially favoring storms over the basin during the summer months (on the cold side of the jet). This retards melt and slows down the year-to-year summer progression. Of course, eventually the warming signal will overwhelm this, but it may take another 20 years to do so (the occasional year like 2016 nonwithstanding). Eventually, increasing warming over land will cause the warm conveyor belts on these storms to start doing enough damage to offset the shielding effect and destroy ice cover anyways. We may end up seeing a fairly long period of not much change -- followed by a quick transient period to sea-ice free, followed by decoupling of the troposphere from the stratosphere in the autumn and subsequent large hits to winter ice volume recoveries. Nakamura et. al's BoE experiments suggested as such a few years back.

And I suspect 2007 and whatever future year(s) this happens will be seen as the turning points.

If you're looking for ocean-driven signals as well, simply look at the trend of shoaling along the Atlantic-inflow stream and heat content storage coming from the Chukchi. They're pointing to the 2040s as well. Incidentally, this is around the same time aragonite undersaturation in the Arctic begins to show up, too (aragonite undersaturation starts in the 2030s around Antarctica). Full-on ecosystem disruption seems pretty ripe around that time.

18

If one were to zoom in with a powerful enough microscope, they would see that the ice and the brine are discrete entities.

In liquid state, sea water is H2O molecules bound by hydrogen bonds (intermolecular bonds) with salt ions (Na+ and Cl-) dissolved in solution.

During the freezing process, the salt ions and some of the H2O molecules are separated from the rest of the H2O molecules. The crystal lattice of ice is composed of only H2O molecules bound together by intermolecular bonds. Consider this lattice to be similar to a house which is held together with wood and screws.

The brine exists in the spaces within the lattice, but is not part of the lattice itself. The brine is like a sofa inside a house. It fits inside the house, but it is not a component of the ice house and does not impact the strength (heat) required to dismantle the ice house.

As you indicate, the brine does exit the ice lattice over time... by escaping through the spaces in the lattice. Most of the brine exits within a year of ice formation.

The lattice portion of the ice house is the same in the Arctic as the ice in your freezer and melts at the same temperature.

As one who in my chemistry career used salt-ice baths to achieve lower than 0ºC temperatures I wish to correct the physical chemistry referred to in this post.

When water freezes into ice, the hydrogen bonds make a hexagonally shaped network of molecules inherent to the structure of ice.
When a solute is added to water the ordering of the solvent molecules is disrupted. This means that more energy must be removed from the solution in order to freeze it.
When salt is added to water, the resulting ions in the water disrupt the usual network of hydrogen bonds made upon freezing. As a result, the freezing point of the solution is lower than it is for the pure solvent. This is termed freezing point depression.  As the ice warms up the network of hydrogen bonds (referred to above as the lattice) requires less energy to be broken up so the melting point is lower.
Because the solubility of the salt decreases with temperature some of the salt is rejected, forming brine pockets.  These brine pockets get eliminated over time but some salt remains in the ice disrupting the structure. In multiyear ice the salt content will ultimately reach the solubility of the lowest temperature the ice has reached so in thick MYI you'd expect lower salinity at the top vs. the bottom.

Here's an amusing video illustrating the difference in melting between saline and pure water ice.


19
Arctic sea ice / Re: The 2020 melting season
« on: June 05, 2020, 08:56:06 AM »
Thick ice is rotating into Beaufort, so Amundsen may clear but my guess is the CAA coast needs to clear before Beaufort will. IF that means that Pacific waters are moving east into ESS then the ice there will weaken and cause losses as it moves north.

ice thickness and sssalinity courtesy of Hycom.

20
Arctic sea ice / Re: Latest PIOMAS update (June 2020)
« on: June 03, 2020, 11:10:57 AM »
Thickness map for day 152, compared with previous yeas and their diff's. Click for size.

22
Arctic sea ice / Re: Latest PIOMAS update (June 2020)
« on: June 03, 2020, 11:03:12 AM »
A large amount of ice crossed the imaginary line in the Fram Straight in the beginning of May.

23
Arctic sea ice / Re: Latest PIOMAS update (June 2020)
« on: June 03, 2020, 10:47:47 AM »
The volume and volume-anomaly graphs. Click to size.

24
Arctic sea ice / Re: Latest PIOMAS update (June 2020)
« on: June 03, 2020, 10:28:16 AM »
PIOMAS gridded thickness data has updated to day 152 (~1 June). Calculated volume was 19.6 [1000 km3], 6th lowest on that day of year.

Here is the May animation.

25
Arctic sea ice / Re: MOSAiC news
« on: May 27, 2020, 01:55:36 PM »
PS probably struggling to make headway against the drift over the last 2 days. T61 is the Tbuoy on 7m ice. I'll keep monitoring its drift till it stops reporting
animation rotated 45deg

really not a big deal at all but when I had to blow-up ggplot figures for a conference poster I found anti-aliasing hugely useful

Install the R Cairo library and add type=cairo when you render

26
Arctic sea ice / Re: Latest PIOMAS update (May 2020)
« on: May 05, 2020, 10:08:02 AM »
The Fram volume export got into trouble the second half of the month.

27
Arctic sea ice / Re: Latest PIOMAS update (May 2020)
« on: May 05, 2020, 10:05:33 AM »
The volume and volume-anomaly graphs. Needs clicks for size and clarity.

28
Arctic sea ice / Re: Latest PIOMAS update (May 2020)
« on: May 05, 2020, 10:03:30 AM »
PIOMAS has updated once again. Last date corresponds to day 121 of this year, which in the PIOMAS data is the first of May (ignoring the leap year). Volume (calculated from thickness) was 22.52 [1000km3], the sixth lowest for day 121.
The maximum seems to have been reached on day 105 (15th April) with a volume of 22.96 [1000km3].

Here is the monthly animation.

29
And of course I updated the regional volume data, for those that have a good use for it.

daily:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

30
The updated Fram volume export graph, shows average export levels not abnormal for April.

31
The updated volume and volume-anomaly graphs (which get bigger when clicked upon).

32
PIOMAS has updated the gridded thickness data up-to day 106 (15 or 16 April, see previous announcements for the explanation). On that day volume was 22.94 [1000 km3], 6th lowest for the day.

Here is the animation for the first half of April.

33
Updated Fram volume graph.

34
Updated volume and volume-anomaly graphs.

35
PIOMAS has updated gridded thickness data to day 75, which would normally be the 15th of March. Because a PIOMAS has no leap years, it ends in some graphs at the 16th.
Any way volume calculated from this thickness was 22.10 [km3], 8th lowest for day 75.
Here is the animation of March sofar.

36
Im posting the main bulk working here.

It would be great to spot any errors in this at the moment and not later on. If anyone disagrees with  any of the lines I will be happy to change it.

37
Here they are matched, im working on a time series at the moment

39
Arctic sea ice / Re: Latest PIOMAS update (March 2020)
« on: March 04, 2020, 07:06:43 PM »
Thickness map, compared with previous years and their diffs.
That is on the 29th of Feb, admittingly looks a bit silly for the other years.

Images to click for size.

40
Arctic sea ice / Re: Latest PIOMAS update (March 2020)
« on: March 04, 2020, 06:58:37 PM »
Fram volume export was above average this month.

41
Arctic sea ice / Re: Latest PIOMAS update (March 2020)
« on: March 04, 2020, 06:41:40 PM »
Volume and volume-anomaly graphs. Click for larger and clearer images.

42
Arctic sea ice / Re: Latest PIOMAS update (March 2020)
« on: March 04, 2020, 06:29:58 PM »
PIOMAS has updated. Last date was actually day 60 of 2020. Now that would be entirely consistent with 29th of February, except that the PIOMAS year has only 365 days every year. So it could be tagged as 1st March in PIOMAS time scale. For now, I stick to 29th of February. That may change silently later this year.

Anyway here is the animation.

43
Arctic sea ice / Re: MOSAiC news
« on: February 22, 2020, 06:20:13 PM »
A steady tailwind bearing for 56 hours produced the incredible straight drift of the proxy buoys for the Polarstern seen in Uniq's #635 animation above. Chasing down the stats, the ice pack moved at 2.1% the speed of the 1000 hPa wind (confirming what 'they' have been saying for years).

This wouldn't be possible without unresisting exits for the ice such as Fram, Nares and SV-FJL gap because the ice pack cannot compress further against land. (Over-rafting pressure ridges provide too much pushback when the ice is thick.)

Data from awiMet should someone wish to refine the estimate by providing the std error:
wind m/s,bearing 12,110 12,110 12,110 11,110 11,110 12,110 12,120 13,110 12,110 12,110 11,110 12,100 12,100 12,110 13,110 14,110 14,110 13,110 13,100 13,100 14,100 14,100 14,100 15,110 16,110 16,110 16,110 16,110 16,100 14,110 15,100 14,100 12,100 12,110 12,110 12,110 12,110 12,110 13,110 11,110 11,110 9,110 10,110 10,100 10,110 11,100 10,90 9,90 9,90 8,90 9,90 8,90 

Both ImageJ and Gimp offer image enhancement by convolution kernels, both canned (Process -> shadows) and roll-your-own DIY. They have a very beneficial effect on the Kaleschke SIC lead product (and downstream overlays), enhancing lead visualization without blowing up the grayish white interstitial background like linear contrast change, local adaptive (clahe) or histogram equalization.

To the extend the leads are anisotropic -- and they will be from TPD or during passage of a cyclone -- the choice of convolution 'direction' matters. The mp4 below used 'northeast'. No rocket science is involved automating out from the canned convolution to converge onto a quasi-optimal element of GL(3,R) wrt to frame average and that extends to a rolling window of GFS winds.

While some people are twittering from the KD, others are not. Kaleschke did not have time to describe productions methods but it is clear from Uniq's remarkable match-up in#635 of microwave leads with WorldView infrared that SIC leads just takes a longer radar wavelength approach to heat escaping through the ice. The images can't help but agree.

In other words, low Ghz radar meets up with long wavelength infrared in the electromagnetic spectrum, the difference being WV infrared is at the mercy of cloud cover while low Ghz sees through them better (in winter). It benefits from processing to darken warmer regions (ie the leads). We don't know what processing steps were taken but clearly they can be improved for the purpose of overlays on GFS weather,  Ascat scatterometry etc etc which don't see the leads but have other, complementary strengths.

The tripods have proven a planning and operational fiasco. Just drill through the ice, freeze in some 5 m fiberglass poles with no guy wires, hang slack electric and data cables off them, your pressure ridge problems are over. And where did Mosaic get their no-go snowmobiles, out of a museum?

44
Some people have good use for the updated regional data files.

daily:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

45
The gridded velocity data was not updated (yet?), so Fram export graph cannot be updated.

Here are the volume and volume and volume-anomaly graphs. Colors have been a bit tweaked, a light grey background added to make the yellows a bit readable, and shared with existing area/extent graphs.

[edit: gave 2020 a thicker line as suggested by charles_oil]
 

46
PIOMAS has updated the gridded thickness data upto the 15th. Calculated volume at 2020-2-15 was 19.67 [1000km3], This is fifth lowest for the day, exactly the same as the volume on that day in 2016, the "final official" volume data may change that exact match.

Here is the animation for February so far.

47
Arctic sea ice / Re: Latest PIOMAS update (February 2020)
« on: February 04, 2020, 08:19:07 PM »
Here are volume and volume-anomaly graphs.

It is getting harder to find a new color for a new year. I am trying a new color scheme that I found here:
https://sashat.me/2017/01/11/list-of-20-simple-distinct-colors/

Have a look, I am not sure myself yet, comments are welcome.


48
Arctic sea ice / Re: Latest PIOMAS update (February 2020)
« on: February 04, 2020, 07:21:45 PM »
Thickness map on 2020-01-31, compared with recent years and the diff's. Click for full size.

49
Arctic sea ice / Re: Latest PIOMAS update (February 2020)
« on: February 04, 2020, 07:11:15 PM »
PIOMAS has updated. Volume on 31st January was 18.282[1000km3], this is fifth lowest behind 2011,2013,2017 and 2018.

Here is the animation.

50
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: January 25, 2020, 11:48:22 PM »
Worth the read. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JC010310
"We conclude that tidal shear stresses at the bottom and the ice‐ocean interface facilitate the transport of warmer and saltier AW to the surface layers, while the effects of tides along the Siberian shelf result in mixing of fresh river runoff waters with saltier water below the eroding halocline. Mixed layers, being much thicker due to the effects of the critical latitude on the clockwise component of tidal currents, entrain saltier waters to the surface boundary layers. Along the Siberian coast with strong river runoff, thicker boundary layers result in mixing in halocline and penetration of freshened waters to depth. Finally we find that, in this particular model, tides are responsible for ∼15% of the ice volume reduction and the presence of more salt waters at the surface in average by ∼1–1.7 PSU (Figure 14). Tides significantly modify the freshwater pathways along the Siberian shelf, resulting in saltier water along the Greenland coast. Tides affect the fresh water and heat content in the AO, with a reduction in the former by 7% in the upper 100 m"

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