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Messages - grixm

Pages: [1] 2
1
Arctic sea ice / Re: The 2020 melting season
« on: April 03, 2020, 11:19:22 AM »
Extreme Fram export continues:

2
Arctic sea ice / Re: The 2020 melting season
« on: April 01, 2020, 08:19:28 AM »
Has anyone else noticed this odd protrusion between northern greenland and Svalbard island. It has been there for a while and it looks like it should just break off but it hasn't. Or is it normal?

The ice is anchored to the seabed below. In 2012 there was a similar long and relatively thin protrusion, but even as it started to shatter in July, it still held on for a while even as the part connecting it to the mainland broke off: https://worldview.earthdata.nasa.gov/?v=269947.6895835763,-1001118.4511475239,925307.6895835763,-656030.4511475239&p=arctic&t=2012-07-20-T10%3A00%3A00Z

You can see there is an area of shallow water around there too:

3
Greenland and Arctic Circle / Greenland 2020 Melting Season
« on: March 24, 2020, 08:40:12 AM »
Since we clarified that the SMB thread should be for SMB data/discussion only, I am making a general-purpose melting season thread for Greenland like from last year.

I'd like to start by asking wtf is going on in the Freya Glacier webcam? Am my eyes deceiving me or was there a lot of snow melting yesterday despite being March and -20C?

Some resources:

SMB data: http://polarportal.dk/en/greenland/surface-conditions/ (And gerontocrat's thread)
Melt extent data and news: https://nsidc.org/greenland-today/
A webcam: https://www.foto-webcam.eu/webcam/freya1/


4
Arctic sea ice / Re: The 2020 melting season
« on: March 15, 2020, 06:09:51 PM »
Some fast ice in Laptev and Kara is starting to crack. Maybe just because of drift, not melting. Click to play.

5
Arctic sea ice / Re: The 2019/2020 freezing season
« on: March 12, 2020, 10:24:27 PM »
Has anyone notices that there is a large "valley" in the Fram strait in the DMI thickness map? If that's accurate then the ice near the pole could be unusually weak this year.


6
Antarctica / Re: PIG has calved
« on: March 08, 2020, 02:38:48 PM »
In case anyone is interested, I boosted and normalized the contrast of baking's gif


7
Antarctica / Re: PIG has calved
« on: March 03, 2020, 04:12:28 PM »
Is it just me or is the sentinel-2 photos posted so far really dark and hard to make out? No offence to the posters. Here is an overview of the ZOD, somewhat brighter.


8
Science / Re: 2020 Mauna Loa CO2 levels
« on: March 01, 2020, 06:37:18 PM »
Interesting drop. Central European vegetation is starting it's spring growth and manufacturing in China is pretty down. I haven't followed the progress of northern hemisphere's spring elsewhere, might be additional reasons for this decrease in the speed of the rise.

The reason likely has nothing to do with that, it's just pure chance. It takes months for CO2 from the mainlands to mix and reach the measurement station on Hawaii.

9
Consequences / Re: COVID-19
« on: February 26, 2020, 09:22:55 PM »
grixm, might it be about this guy: https://www.thelocal.no/20200226/norwegian-student-tests-positive-for-coronavirus-in-italy

"a Norwegian citizen in Italy has been infected with coronavirus"

"He has been based in Italy for around six months but may have been in Norway as recently as last week..."

Nope, it was a new one: https://translate.google.com/translate?sl=auto&tl=en&u=https%3A%2F%2Fwww.nrk.no%2Fnorge%2Fforste-tilfelle-av-koronasmitte-i-norge-1.14920058

10
Consequences / Re: Chinese coronavirus
« on: February 23, 2020, 03:06:31 PM »
43 people infected in Iran, and 8 fatalities. Let's hope it's not a mutation.

There are almost certainly far more people actually infected.


Also, Italy cases is spiking, now at 129: https://www.repubblica.it/cronaca/2020/02/23/news/coronavirus_italia-249329434/

11
Antarctica / Re: Where is D-28 headed?
« on: February 18, 2020, 08:31:15 AM »
It is speeding up. It has moved around 20km north in the last four days. Click to play.

12
Antarctica / Re: PIG has calved
« on: February 15, 2020, 09:34:50 AM »
Calving in the cork area / ZOD. Line is approximate




13
Antarctica / Re: PIG has calved
« on: February 13, 2020, 09:33:41 AM »
The iceberg(s) are hardly even recognizable anymore.


14
Science / Re: 2020 Mauna Loa CO2 levels
« on: February 11, 2020, 03:17:38 PM »
Another record day: 416.08 ppm on February 11th

15
Consequences / Re: Weird Weather and anecdotal stories about climate change
« on: February 11, 2020, 12:27:13 PM »
We just broke the record for sea level in some parts of Norway, as well as close to the lowest ever surface air pressure. This is after a separate top-10-ever sea level event just a few weeks ago.

And january broke temperature and precipitation records as well. We've had exactly zero days of persisting snow in my city (Bergen) so far this winter even though there are usually weeks of it most years. It's been a weird start of the year.

16
Policy and solutions / Re: Bikes, bikes, bikes and more...bikes
« on: February 09, 2020, 11:47:26 AM »
Biking on compacted snow works fine on flat roads. But it's suicidal in a hilly city like mine. So sadly the lessons from that article is not applicable everywhere. "Luckily" it doesn't go below freezing that many days of the year anymore, though.

17
Arctic sea ice / Re: The 2019/2020 freezing season
« on: February 05, 2020, 07:39:22 PM »
RE grixm
https://forum.arctic-sea-ice.net/index.php/topic,2888.msg247928.html#msg247928

     I thought we were done with this, but I have another favor to ask.  Can you extend the early vs Sept. Extent comparison charts to April-August? 

    You showed above that there is no correlation of March to September, but surely there must be correlation by August.  This is probably in a journal article somewhere, but your charts are lovely and can be up to date to include 2019.  Seeing the data point spread would be really interesting.   

     For sporting interest, I'll wager such charts would show R2 around:
April 10%
May 20%
June 30%
July 50%
August 80%

    And if anybody did the same for Volume, that would be icing on the cake.

PS in case you zipped past binntho's post in the data thread at
https://forum.arctic-sea-ice.net/index.php/topic,2975.msg247842.html#msg247842
   The articles he cites there provide really nice long-term context for ASI variability and current situation.  Good stuff.










18
Arctic sea ice / Re: The 2019/2020 freezing season
« on: February 04, 2020, 08:11:40 PM »
Therefore, I experimented with instead normalizing the years to their predicted average extent from a linear regression of all the years.
Your method is skewed by the fact that the long-term extent losses are happening more rapidly in September than in January/February/March.

September extent in the last few years is about 40% lower than in the 1980s, whereas March extent has decreased by only 10%.  So your "normalized" March extent has an upward trend over the last few decades, whereas the normalized September extent has a downward trend.  So it's not surprising that you get a negative correlation between them.  But that correlation is spurious.

A more meaningful method is to detrend the data (see e.g. here for some background on detrending).  It turns out that the correlation between the detrended March extent and the detrended September extent is very weak: the correlation coefficient is  -0.029.

    Many thanks to grixm and Steven et al. for wrestling with the numbers.  It looks like the jury is still out on this one.  While counter-intuitve [more Extent early leads to less 8 months later (Jan-Sept), 7 (Feb-Sept.), or 6 March-Sept.)], the insulating ice theory at least sounds plausible. 
[..]

I normalized the months to the trend of its month alone, instead of to the whole year, like pointed out. And it seems Steven is correct. The correlation is gone..




19
Arctic sea ice / Re: The 2019/2020 freezing season
« on: February 01, 2020, 09:15:14 AM »
Overnight I realized that my graphs has a big flaw, the fact that the years are normalized with themselves can induce a lot of autocorrelation. For example, if it is the case that a low september minimum is completely random, that would still increase the ratio of normalized winter extent vs normalized september extent, because the low september extent would drag the average for the whole year down, thus increasing the normalized winter extent. Furthermore, since calculating the normalized extent requires knowledge of the average for the whole year, it is not possible to predict anything with it beforehand.

Therefore, I experimented with instead normalizing the years to their predicted average extent from a linear regression of all the years. Now, it should be truly neutral, and also you can make predictions. Unfortunately, doing this does reduce the correlation a lot, but it is still there.

Now, we can make  a prediction for 2020 based on the january value. The high extent compared to the ever-decreasing trend makes this year stand out a lot, the normalized january extent is an all-time high: 1.322. See the red area on the january graph. Will this mean the september extent  will be very low like the graph suggests? Or does it mean the correlation will break down? If we trust the graph naively, the expected normalized september minimum average for this year is 0.42, which is 4.30 Mkm^2 (which is third lowest of all time, behind 2012 and barely 2007), with a lower uncertainty bound of ~2.97 Mkm^2 and a high bound of ~5.33 Mkm^2.




20
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 31, 2020, 10:39:56 PM »
Here I have plotted the normalized average extents in january, februrary and march, compared to september. Normalized meaning the value divided by the average value for the whole year. This means that the long-term trend of general melting is removed.

There seems to indeed be a strong correlation of high extent early season = low extent late season, for all three months graphed.






21
Antarctica / Re: PIG has calved
« on: January 29, 2020, 07:27:07 PM »
Just compared the Sentinel-1 images from this morning and yesterday, and yes it definitely looks like movement. See the gifs below. Notice how the southern edge appears to move, but the northern edge does not. It is rotating. I looked at the map scale and it looks like the southern edge surged around 100 meters. The cork also moved with it. Maybe some movement in the icebergs of rift 2 too.

22
Antarctica / Re: PIG has calved
« on: January 28, 2020, 10:12:57 PM »
Is it just me or is there significant movement of the whole front between the latest worldview image and yesterday's? 


23
Antarctica / Re: Melt lake on Nivlisen Ice Shelf
« on: January 28, 2020, 11:53:26 AM »
We got a cloud-free sentinel image on the 26th. And also the lake has mostly frozen over, or drained? I'm not experienced enough to tell the difference. If it has drained, does that have implications for future sea level? That's a pretty large meltwater drainage basin that would have found a way to the ocean.


24
Antarctica / Re: PIG has calved
« on: January 24, 2020, 05:03:15 PM »
Yep, tip fell off.

We'll have to tow it outside the environment.

25
Science / Re: 2019 CO2 emissions
« on: January 22, 2020, 07:30:40 PM »
Wow! Latest daily CO2 reading was 415.79 ppm, higher than at any date last year. And it's still winter!


26
Antarctica / Melt lake on Nivlisen Ice Shelf
« on: January 10, 2020, 06:34:29 PM »
Noticed this cool lake on Worldview, and thought I'd make a thread even if it may not be of any particular significance.

There is a surface meltwater lake growing on the Nivlisen Ice Shelf in Queen Maud Land. By now the main lake is almost 5km wide. It formed on around the 26th of December from rivers of meltwater originating dozens of kilometers further up the shelf.

I had a quick browse through worldview and I couldn't find any other year where the lake was this big. Most years a proper lake doesn't even form at all on this shelf. Also I think this might be the biggest meltwater body on the Antarctic right now.

Here is the coordinates on worldview: https://worldview.earthdata.nasa.gov/?v=224464.63410371373,1972163.5070182374,715984.6341037138,2225091.5070182374&p=antarctic&t=2020-01-10-T17%3A02%3A46Z

And here is a Sentinel picture from four days ago. The deep blue color is gorgeous, I think:


27
Consequences / Re: Heatwaves
« on: December 19, 2019, 09:27:21 PM »
Nullarbor weather station seems to have recorded 50C today, is that official?

http://www.ogimet.com/cgi-bin/gsynres?lang=en&ind=94651&ano=2019&mes=12&day=19&hora=18&min=0&ndays=30

28
Consequences / Re: Heatwaves
« on: December 14, 2019, 08:58:15 AM »
Quote
'Like a furnace': Massive heatwave could roast Australian records

Almost all of mainland Australia will be roasted in a huge heatwave next week, with the mercury likely to nudge 50 degrees in parts of the south.

https://www.smh.com.au/environment/weather/like-a-furnace-massive-heatwave-could-roast-australian-records-20191213-p53jps.html

29
Arctic sea ice / Re: The 2019/2020 freezing season
« on: November 13, 2019, 09:44:54 AM »
November 8-12.

2018.

Is it possible to change the crop of the animation? I'd be interested in seeing Hudson and Baffin bay etc in the coming weeks

30
Arctic sea ice / Re: The 2019/2020 freezing season
« on: November 11, 2019, 03:30:32 PM »
http://ocean.dmi.dk/arctic/plots/meanTarchive/meanT_2019.png

it looks like we shall see the first autumnal fall below mean on the dmi80 chart since 2015 . b.c.

And then DMI80 is like "nah never mind":


31
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: November 08, 2019, 01:57:50 PM »
This is baffling to me. MAXIMUM extent in CAB?? Doesn't this scream BIG thickness for this vital area moving through the winter? This tells me that this ice is absolutely in great shape for the near future...and certainly multi-year probability.

The ice is not in great shape at all. Extent is only a small part of the story, the volume is still near record lows. The ice happens to be wide enough to cover the CAB, but it is very thin, especially near the greenland/canadian coast. Anyway lets take discussion to the freezing season thread and leave this one for data only

32
Consequences / Re: Hurricane Season 2019
« on: November 05, 2019, 07:20:57 PM »
Ridiculous intensification of Halong today. While JTWC only has it at 140 knots in the last advisory, AdjT and CI# numbers has reached almost 8.0, suggesting 170 knots is possible.

https://twitter.com/webberweather/status/1191740646022881281

33
The forum / Re: Forum Decorum
« on: November 02, 2019, 09:09:45 AM »
So what is the consensus about non-data posts in the data threads? I've heard many times that f.ex. only sea ice extent and area data should be posted in the sea ice extent and area data thread, and yet almost every day there are posts there with no such thing, just comments on the data or even unrelated season discussion. And they are almost never moderated. Are posts like that ok after all? If I want to comment on a chart, do I post it in the data thread or the freezing season thread?

34
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: October 08, 2019, 03:42:22 PM »
Daily gain 14k, 28 k less than the 2010's average of 57 k.
43k less. Also on the JAXA extent post, it seem the two bottom images are identical.

Don't mind me, just your friendly neighborhood nitpicker

36
The forum / Re: Forum Decorum
« on: September 20, 2019, 06:38:49 PM »

37
Arctic sea ice / Re: The 2019 melting season
« on: September 20, 2019, 10:34:56 AM »
At the risk of drifting off topic, JAXA/ViSHOP exent is now back above 4M.

4.01 to be precise!

Goodbye three, we hardly knew ye

38
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 15, 2019, 03:48:34 PM »

Meanwhile I don't see any serious attempts from the scientists in these organizations to get fancy with 3 or 4 or god forbid 5 parameter regression curves. Why do you think that is?

Really?

https://www.searcharcticscience.org/files/search/sea-ice-outlook/2011/07/pdf/pan-arctic/hamilton_panarctic_july.pdf

https://www.esrl.noaa.gov/psd/events/2014/arctic-predictions-science/presentations/wed/arctic-wkshp-051414-stroeve.pdf

Yes, there's a reason why I qualified my statement with the word "serious". Of course there will be the occasional reference to every kind of model just for experimentation's sake, it's only serious if they catch on and become the generally accepted way to model trends or is used in official outward-facing presentation of the data. And if those are the only such references you can find I'm especially unconvinced, as they aren't even particularly relevant to what makes the gompertz functions in this thread controversial, namely that they predict a slowing of the melt, while the ones in your links are only made to fit the accelerating melt up until around 2010 and remain fairly linear after that (and are only 3-parameter rather than 4 or 5).

EDIT: Also:

I want to emphasise all models are wrong. We don't know shape of trend; it could be anything between 4 parameter gompertz at one extreme, Tamino's 3 linear pieces, anything in between, or perhaps having a steeper trend now than Tamino shows.

A couple of ways of deciding which to prefer between these include:
What has least parameters while still giving a good fit.
What looks like most of the models as a physical explanation for what is likely to happen.

Of course this is true, I'm not saying that I am absolutely certain that a gompertz trend is definitely going to be inaccurate in the future, we don't know for sure. I am just saying that with those very two criteria you post on the bottom of the quote, a linear fit seems very much like the most reasonable assumption for a future trend, and based on what the expert institutions use in their presentations they seem to largely agree.

39
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 15, 2019, 09:12:16 AM »
Statisticians weep when they see people trying to fit 4-parameters functions to series with so few data points that vary so much.

That's another argument for the linear fit instead. To just see what the real experts use. I already posted the official PIOMAS graphs, which includes linear trend lines:

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1.png

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAprSepCurrent.png

And then there is the graphs in NSIDC's official extent discussions, such as this:

http://nsidc.org/arcticseaicenews/files/2019/09/Figure-3.png

Arctic Data archive System allows you to overlay a linear trend line but no other forms of trend line:

https://i.imgur.com/MbD14S3.png

JAXA includes a graph with a linear trend line in their Satellite Monitoring for Environmental Studies front page:

https://kuroshio.eorc.jaxa.jp/JASMES/climate/data/graph/JASMES_CLIMATE_SIE_197811_000000_5DAVG_PS_9999_LINE_NHM_201.png

And NOAA:

https://arctic.noaa.gov/Portals/7/easygalleryimages/8/412/arc18_seaice_perovich_fig2.png

Meanwhile I don't see any serious attempts from the scientists in these organizations to get fancy with 3 or 4 or god forbid 5 parameter regression curves. Why do you think that is?

40
The forum / Re: GIF size, your Internet, and what is usable?
« on: September 14, 2019, 05:49:07 PM »
I have massively reduced my time on the forum lately . I did not realise just how much of my monthly data was being eaten by gifs . Freegrass has been costing me a small fortune as I race toward the inevitable data squeeze for the last week then fortnight of the month.
  I know blumenkraft and others have demonsrated there is no difficulty in providing gifs etc that do not self load or run automatically ; but most regular high megabyte uploaders ignore these options and go for maximal consumption options , obviously in a 'to hell with the planet' approach to warning us of impending doom .
 I will continue to appeal to people to consider those with low data provisions and more importantly the people who come after us .
  lol .. I just looked at the last 3 posts on the melt thread .. 8000kbs of data just gobbled . I can but try / cry .. b.c.
 
 

Are you aware that the forum has a WAP2 mode? Here you can browse in in text only, each visit only costing you 3-4 kB: https://forum.arctic-sea-ice.net/index.php?wap2

41
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 11, 2019, 04:13:15 PM »
Except that your graph shows anomalies throughout the year.  While volume has continued dropping at other times of the year, that cannot be said for the Sept. minima.  Check what others posters have presented regarding volume at minimum.

The whole point was that I think anomalies through the year is a better indicator than minima.

For the general state of the ice in the Arctic, I would agree.  However, when we talk about an ice-free Arctic, we are specifically talking about the ice at minimum.  Therefore, ice at minima is more relevant to this thread.

What I'm saying is that the general state of the ice is a better indicator for future minima including an ice-free arctic, than past minima is. The actual minimum just comes down to luck because weather is noisy, but the odds of that luck is decided by the overall state of the ice, which can be studied throughout the year, not just at peak melt season.

Maybe past minima could have been useful in analysis if we simply had more of them, but since 2012 and the supposed slowdown started, there have only been 6 or 7 such data points. That's not statistically significant and thus can't really be used to make any sort of conclusion or prediction. It is much more meaningful to use the continuous streams of ice data we have from the rest of those years too.

42
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 10, 2019, 10:09:16 PM »
I'm rather new to this but personally I am not convinced that melt have slowed down, certainly not stalled completely. The last few years can all be explained by simple noise around a linear downwards trend, as seen in this image which I think has been posted here before. Even though we've been (un?)lucky at the times of minima, the average level keeps dropping and we regularly see different times of year with record low ice, both extent and volume.

I think also extent is very misleading compared to volume. Melt keeps going relentlessly the whole season, but sometimes we may not see this in extent because it's spent making the ice thinner. Then suddenly when an area reaches 0 thickness, large extents can disappear almost at once. I think the CAB can act the same way when a BOE happens, taking everyone by surprise. Funny thing, I heard a military commander describe the fight against ISIS like that too. They could surround one of their occupied cities for weeks or months with seemingly stalled progress. But what was happening was just that ISIS's reserves of soldiers were slowly diminishing, until suddenly they didn't have enough left to maintain the frontlines, and the whole city fell in days.

Exactly when we get an ice-free minima, I'm hesitant to guess, but it becomes more and more likely every year. I think even next year it may be theoretically possible if absolutely everything aligns, even if the chance is just 0.1%. But then in 10 years it may be a 10% chance per year, and in 20 years maybe 50% chance per year. And so on until it becomes inevitable.




43
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 07, 2019, 01:11:03 PM »
What's up with this site? Seems to be at odds with JAXA. Glitch showing massive losses lately???

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

It 5-day average. Daily values are posted in this thread. https://forum.arctic-sea-ice.net/index.php/topic,2533.msg227125.html#msg227125

44
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 05, 2019, 06:31:22 PM »
Analysis of seas with (almost) no ice Aug 31-Sep 04:
Okhotsk - 6,25 M km² (-78%)
Hudson - 7,05 M km² (-54%)
Bering - 0.40 M km² (-35%)
Barents - 1.21 M km² (-14%)
Baffin - 3.26 M km² (-27%)
sum      -18,17 M km² → looking at the small changes since Aug 20 these 18 M km² are relevant.

Will they finally find out that these seas are ice free? (at least Okhotsk and Bering?)

They are well aware that those are ice-free. Kara too. But they can't manually adjust the readings because that would introduce subjectivity which ruins a lot of the scientific worth of the data.

45
Arctic sea ice / Re: The 2019 melting season
« on: September 02, 2019, 02:38:38 PM »
@Freegrass: When every other post is a forecast animation, it might be a bit much. It takes a lot of space. Maybe you can just post links to the animations hosted at a different place?

46
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 02, 2019, 09:51:03 AM »
Is there a structural reason for the massive discrepancy of -10k from Juan G and - 73k NSIDC daily from Alphabet Hotel.  i.e one is yesterday vs today? 


In which case can we expect one to "catch up" tomorrow?

Juan's is based on JAXA which is much higher resolution than NSIDC. This will cause them to be somewhat different, even long-term so it's not a necessity that one catches up to the other.

47
The water in the rifts is definitely sea water, it may enter from the sides or the rifts may extend to the bottom of the glacier where there's also water because it's floating. Here are some different perspectives on how rifts in the petermann glacier look close up:





48
Arctic sea ice / Re: The 2019 melting season
« on: August 17, 2019, 07:59:50 AM »
It looks, very tentatively, like "normal" flow (clockwise, leading to south export) is trying to reassert itself in the PGAS, but I'm not going to make any definitive proclamations on one day of satellite images.

On the other hand, I will make proclamations about Massey Sound, which is just a brutal place for the ice to die right now.

What is the PGAS? It's not in the glossary thread and I find nothing by googling it.

49
Arctic sea ice / Re: meaningless freezingseason/melting season chatter.
« on: August 09, 2019, 08:44:46 AM »
Eye of a hurricane? No, this strange looking cloud is located in Baffin Bay!


50
Arctic sea ice / Re: The 2019 melting season
« on: August 04, 2019, 07:23:56 PM »
Except for an area of the northern Barents sea between Svalbard and FJI which has been cooled by advection of ice into the waters, SSTs are anomalously high on the Atlantic side.<snip>

Yes, SST anomalies have gone crazy recently, on both the atlantic and the pacific side. Animation below for the past 6 weeks.


My naive reaction is that those anomalies around the CAA suggest that a complete melt out is possible there.

The thickness in most of the CAA is already very low according to PIOMAS, so I agree.

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