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Glen Koehler

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3450 on: July 26, 2020, 01:52:33 PM »
     Where are the instructions on how to post images to forum server?

blumenkraft

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3451 on: July 26, 2020, 02:18:37 PM »
Glen, that is pretty straight forward. Just click the 'Attachment and other options' below the input window. There you can choose a file from your computer to upload.

Generally, i would say it should be compressed (i.e. JPEG format).

A good way to compress images is to upload them to a website like lunapic.com. There you can compress/convert to JPEG/scale/crop/etc.

If you have an image that is 500 pixels or below of canvas size, it will be displayed by the forum software as it is. If it's bigger, the forum software would shrink it and only show the full resolution if you click on it.

There is also a posibility to load pictures from an external source. In this case, you copy&paste the image link, select the link, and click the 'Insert Image' button (above the input window).

Hope that answers your question. :)

Glen Koehler

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3452 on: July 26, 2020, 09:38:30 PM »
Glen, that is pretty straight forward. Just click the 'Attachment and other options' below the input window. There you can choose a file from your computer to upload.
   Thanks bk, good info.  ;D I completely missed the "Attachments and other options" line.  After being on the forum for years and even after reading your post I could not find it, and was looking for it among all the buttons above the input box.  Missing the obvious seems to be one of my strength areas.

blumenkraft

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3453 on: July 26, 2020, 09:54:42 PM »
Glen, it's not you! It's clearly the crappy UI of the forum software!

I would do it in a prettier and more intuitive way. Tell the Simple Machines guys to hire me. They really need a good CSS guy. ;)

KenB

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3454 on: July 27, 2020, 02:07:22 AM »
Glen, that is pretty straight forward. Just click the 'Attachment and other options' below the input window. There you can choose a file from your computer to upload.
   Thanks bk, good info.  ;D I completely missed the "Attachments and other options" line.  After being on the forum for years and even after reading your post I could not find it, and was looking for it among all the buttons above the input box.  Missing the obvious seems to be one of my strength areas.

Also note that once you click that line, the (more attachments) line below the Browse input box is a link to add more attachments, even though there's no indication whatever that it *is* a link at all until you get the mouse over it.  And, of course, attachments don't show up in previews, so you just have to hope for the best. 
"When the melt ponds drain apparent compaction goes up because the satellite sees ice, not water in ponds." - FOoW

Tor Bejnar

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3455 on: July 27, 2020, 05:06:09 AM »
After you see the live "what you've done", if you want to change it you can (see the "Modify" button above and to the right of your post).  I regularly see I didn't use the right screen print and delete the first one put up and replace it or add another image.
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blumenkraft

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3456 on: July 27, 2020, 07:54:57 AM »
A short addition to what Tor said: Deleting a file is done by unchecking the checkbox in front of the file name.

Also not the most intuitive way to do this...

glennbuck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3457 on: July 30, 2020, 01:24:27 AM »
What would a BOE just below 1 million km^2 look like on a map of the Arctic, anyone have a map marked out with 1 million km^2 to look at thanks? To visualise this seasons BOE, i mean for the 2100 BOE when none of us will be around to see it according to the IPCC.
« Last Edit: July 30, 2020, 01:31:43 AM by glennbuck »

KenB

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3458 on: July 30, 2020, 01:56:16 AM »
What would a BOE just below 1 million km^2 look like on a map of the Arctic, anyone have a map marked out with 1 million km^2 to look at thanks? To visualise this seasons BOE, i mean for the 2100 BOE when none of us will be around to see it according to the IPCC.

One handy bit of info that might help visualize this is that the entire cap north of 80 is an area about 3.8 M km^2, so 1M is roughly a quarter of that cap.  A quick calculation shows (I think), that the cap north of 85 would be about 1M km^2, but don't hold me to it.

"When the melt ponds drain apparent compaction goes up because the satellite sees ice, not water in ponds." - FOoW

glennbuck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3459 on: July 30, 2020, 02:42:02 AM »
What would a BOE just below 1 million km^2 look like on a map of the Arctic, anyone have a map marked out with 1 million km^2 to look at thanks? To visualise this seasons BOE, i mean for the 2100 BOE when none of us will be around to see it according to the IPCC.

One handy bit of info that might help visualize this is that the entire cap north of 80 is an area about 3.8 M km^2, so 1M is roughly a quarter of that cap.  A quick calculation shows (I think), that the cap north of 85 would be about 1M km^2, but don't hold me to it.

Ok thanks for the info, would be nice to see a map of what it looks like to, hope someone adds a map some time.

Tom_Mazanec

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3460 on: July 30, 2020, 02:43:21 AM »
But wouldn't the last 1M of ice more likely be along the Greenland and Canadian Archipelago coasts instead of around the Pole?
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oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3461 on: July 30, 2020, 03:21:19 AM »
Glennbuck, Worldview has an area measurement tool that enables you to create such a map on your own. At first try I got an area of 1.1 M km2. It's the icon that looks like a ruler at the lower right corner of my screen capture.
Yes Tom supposedly the ice will not be centered around the pole, assuming the general transport across the Arctic remains the same by the time we reach BOE.

Tor Bejnar

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3462 on: July 30, 2020, 04:58:52 AM »
What would a BOE just below 1 million km^2 look like on a map of the Arctic, anyone have a map marked out with 1 million km^2 to look at thanks? To visualise this seasons BOE, i mean for the 2100 BOE when none of us will be around to see it according to the IPCC.

See this post (Reply #68) in the Maps thread for what 1,000,000 km2 looks like.
« Last Edit: July 30, 2020, 07:41:07 PM by Tor Bejnar »
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Steven

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3463 on: July 30, 2020, 11:20:04 AM »
To visualise this seasons BOE, i mean for the 2100 BOE when none of us will be around to see it according to the IPCC.

For your information, the latest IPCC assessment report (published 7 years ago) says

Quote
For high GHG emissions such as those corresponding to RCP8.5, a nearly ice-free Arctic Ocean (sea ice extent less than 1 × 106 km2 for at least 5 consecutive years) in September is likely before mid-century (medium confidence). This assessment is based on a subset of models that most closely reproduce the climatological mean state and 1979 to 2012 trend of Arctic sea ice cover.

https://data.globalchange.gov/report/ipcc-ar5-wg1/chapter/wg1-ar5-chapter11-final

glennbuck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3464 on: July 30, 2020, 11:58:50 AM »
Glennbuck, Worldview has an area measurement tool that enables you to create such a map on your own. At first try I got an area of 1.1 M km2. It's the icon that looks like a ruler at the lower right corner of my screen capture.
Yes Tom supposedly the ice will not be centered around the pole, assuming the general transport across the Arctic remains the same by the time we reach BOE.

Thanks Oren, that will be an amazing and sad day to see 1 m km^2, i think we will all be around to see it, hoping after 2030 and not before 2025!

glennbuck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3465 on: July 30, 2020, 12:09:58 PM »
To visualise this seasons BOE, i mean for the 2100 BOE when none of us will be around to see it according to the IPCC.

For your information, the latest IPCC assessment report (published 7 years ago) says

Quote
For high GHG emissions such as those corresponding to RCP8.5, a nearly ice-free Arctic Ocean (sea ice extent less than 1 × 106 km2 for at least 5 consecutive years) in September is likely before mid-century (medium confidence). This assessment is based on a subset of models that most closely reproduce the climatological mean state and 1979 to 2012 trend of Arctic sea ice cover.

https://data.globalchange.gov/report/ipcc-ar5-wg1/chapter/wg1-ar5-chapter11-final

Ah ok to be fair the IPCC have there hands tied, censoring of there reports is common.
https://www.smh.com.au/world/ipcc-report-summary-censored-by-governments-around-the-world-20140414-zqugm.html

KenB

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3466 on: August 01, 2020, 11:36:31 PM »
Once upon a time (Ok, July 17, 2020), in the 2020 data thread, Gerontacrat wrote:

Quote
Kara Sea One year the convention will be that the Kara Sea is part of the Atlantic Front, so given the way this season is going why not anticipate events?
Sea ice area has been well below the 2010's average all melting season Apart from an obstinate lump of solid looking ice on the West side of the New Siberian Islands North Land isles, sea ice in the Kara Sea is basically kaput. But this sea never completely melts out. This year?
_________________________________
EDIT - Whoops Not the New Siberian Islands - 'tis the "North Land", consisting of 3 islands, Ostrov Bolshevik, Ostrov October Revolution & Ostrov Komsomolets (means member of the Young Communists League).
(I left the EDIT in because I thought it was, umm, edifying.)

So here's the question?  This "obstinate lump" is still there 2 weeks on, though it's starting to look very sickly indeed and I don't see how even a trace of it can possibly survive to the end of August.

What was it (or is it) that makes this lump so obstinate?  Are we seeing the end of some MYI holdover and now we should expect this area will behave more like the rest of the surrounding area, or is there something about this location, just W. of the islands, that lends itself to ice formation every year and this is likely always going to be the last spot in the area to go?


"When the melt ponds drain apparent compaction goes up because the satellite sees ice, not water in ponds." - FOoW

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3467 on: August 02, 2020, 12:10:41 AM »
I would assume this ice was pressured against the islands at some point and formed ridges, thus thicker and harder to melt, though melt it will. Take a look at some long term animation of the region, Ascat is best for winter, or Worldview.
The same happens in Hudson Bay, where the west side ice remnant are more resilient.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3468 on: August 02, 2020, 02:36:14 AM »
If you look at piomas and hycom models a few months back to now that ice is/was thicker ice almost certainly from pressure ridges. Looking back at the island thicker ice around 2.5 m thick forms almost every year but not necessarily on the same side. Their are other years where ice this thick had melted out. I have watched that section for much of the melt season and It seemed to be cloudy more than the surrounding areas. The adjacent ice cap was collapsing and that probably had some influence as well.

johnm33

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3469 on: August 02, 2020, 10:48:00 AM »
I'd guess a contributing factor would be that it's in the path of the river discharge so any cold ice keels would be bathed in easy to freeze fresh water.

wallen

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3470 on: August 02, 2020, 01:50:59 PM »
When looking at Worldview as it opens on a daily basis, if one adds the corrected reflectance 7,2,1, more of the image opens in the clockwise direction. Why??

glennbuck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3471 on: August 02, 2020, 03:16:07 PM »
Why do the Media make statements that the Arctic is warming twice as fast as the rest of the planet but not include the other countries declaring they are warming twice as fast as the rest of the planet.

Russia/Canada/Australia declared last year they are warming twice as fast as the rest of the planet. Europe declared there land temperatures are 2 C above Pre-industrial, land and sea temp around 1.25 C. So would the statement be more accurate if they said the Arctic is warming twice as fast as some parts of the planet. Unless the case is, most of the planet is warming twice as fast as we are reporting to the general public?

kassy

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3472 on: August 02, 2020, 07:07:29 PM »
Lookup some general physics on how global warming effects the world. There is a climate gradient across the globe. Russia and Canada are in or near it.

Local temps of 2C above pre-industrial are also not the same as warming twice as fast.
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The Walrus

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3473 on: August 04, 2020, 05:18:25 PM »
Why do the Media make statements that the Arctic is warming twice as fast as the rest of the planet but not include the other countries declaring they are warming twice as fast as the rest of the planet.

Russia/Canada/Australia declared last year they are warming twice as fast as the rest of the planet. Europe declared there land temperatures are 2 C above Pre-industrial, land and sea temp around 1.25 C. So would the statement be more accurate if they said the Arctic is warming twice as fast as some parts of the planet. Unless the case is, most of the planet is warming twice as fast as we are reporting to the general public?

I cannot speak for Australia, but Canada and Russia make up most of the land around the Arctic.  All but a small fraction of both countries is above the 45th parallel, and extend beyond the Arctic circle.  In a very simplistic form, the coldest areas have warmed the most.

<Removed wrong text and the attachment of winter temps up to 1995. O>
« Last Edit: August 04, 2020, 07:47:44 PM by oren »

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3474 on: August 04, 2020, 07:45:50 PM »
Why do the Media make statements that the Arctic is warming twice as fast as the rest of the planet but not include the other countries declaring they are warming twice as fast as the rest of the planet.

Russia/Canada/Australia declared last year they are warming twice as fast as the rest of the planet. Europe declared there land temperatures are 2 C above Pre-industrial, land and sea temp around 1.25 C. So would the statement be more accurate if they said the Arctic is warming twice as fast as some parts of the planet. Unless the case is, most of the planet is warming twice as fast as we are reporting to the general public?
It's not "the media", but science that says so. The Arctic has been warming at more than twice the global average. Maybe for some countries this has happened as well, remember that land temps warm faster than ocean temps.
Here are a couple of excerpts from the NOAA report card for 2019 that might help. Note the first chart is for land stations only. Note the second chart is the anomaly compared to 1981-2010, a baseline that is already badly affected by global warming and Arctic amplification.
In order to really see the warming signals, a baseline prior to 1970 is highly recommended, IMHO.

https://arctic.noaa.gov/Portals/7/ArcticReportCard/Documents/ArcticReportCard_full_report2019.pdf

glennbuck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3475 on: August 05, 2020, 09:27:51 AM »
Hypothetically what are the implications of the CAB breaking in half and 1-2 million km^2 heading for the Russian cost. How long would it take to float to the Russian coast or melt in the warm waters in the ESS/Laptev sea?

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3476 on: August 05, 2020, 10:02:10 AM »
Hypothetically what are the implications of the CAB breaking in half and 1-2 million km^2 heading for the Russian cost. How long would it take to float to the Russian coast or melt in the warm waters in the ESS/Laptev sea?
Best not deal with hypothetical scenarios too much. Why would only half be transported? And what would be the mechanism transporting it? Ice doesn't just float away. Also bear in mind the CAB is not an ice sheet, and is not cohesive. Breaking in half is not a good metaphor. All in all, I find the question meaningless.

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3477 on: August 05, 2020, 11:34:50 AM »
Hypothetically what are the implications of the CAB breaking in half and 1-2 million km^2 heading for the Russian cost. How long would it take to float to the Russian coast or melt in the warm waters in the ESS/Laptev sea?
Increased melting until that ice melted or the waters next to the ice melted. I am beginning to think a great deal of churning in water is required for it to melt the ice for long.

wallen

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3478 on: August 05, 2020, 01:29:12 PM »
What is the causing the rich Aqua like blue color in the Barents sea. Is obvious a very large area, seen easily on Worldview today. Could it be an Algae Bloom??

Tor Bejnar

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3479 on: August 05, 2020, 07:04:03 PM »
... How long would it take to float to the Russian coast or melt in the warm waters in the ESS/Laptev sea?
A couple years ago in the Test space thread, A-Team posted GIFs (link to an example)  that show sea ice 'drifting' during the winter.  It takes about 6 months to go half way across the Arctic (typically from near Siberia to the North Pole). For the ice to systematically go the other way would take quite a change in the dominant weather/climate system.

If I think the ice is moving fast, I need to put it in the context that the Arctic Ocean is larger than my bathtub.  Only in Nares Strait in the early winter do floes move up to 500 km in a week.  Pretty much everywhere else the ice takes its time to get to where it is going.  (Woyaya)
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Villabolo

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3480 on: August 06, 2020, 01:31:05 AM »
What will happen to Northern Hemispheric weather when the Arctic Sea ice melts completely?

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3481 on: August 06, 2020, 04:29:48 AM »
This has been discussed in a few threads, for example:

Potential effects caused by loss of sea ice

The Climatic Effects of a Blue Ocean Event

Note this doesn't mean anyone has the answer...

Rod

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3482 on: August 06, 2020, 04:51:53 AM »
What is the causing the rich Aqua like blue color in the Barents sea. Is obvious a very large area, seen easily on Worldview today. Could it be an Algae Bloom??

This is a good and very important question. These phytoplankton blooms are becoming more and more common. They have ecological impacts and have an impact on carbon uptake.

Phytoplankton Bloom in the Barents Sea

Quote
Clear skies over northern Russia and Scandinavia reveal magnificent swirls of blue and turquoise in the Barents Sea. This true-color image, captured by the NOAA-20 satellite on July 30, 2018, shows a large phytoplankton bloom, made up of millions of tiny plant organisms that thrive in the nutrient-rich waters of the Arctic. Phytoplankton blooms are common in the Barents Sea in late July and August, thanks to a combination of 24-hour sunlight, minimal ice cover and relatively warm surface waters.

https://www.nesdis.noaa.gov/content/phytoplankton-bloom-barents-sea

Sebastian Jones

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3483 on: August 06, 2020, 07:02:52 AM »
What will happen to Northern Hemispheric weather when the Arctic Sea ice melts completely?
As Oren indicated, nobody knows for sure, but, stick around and you'll be among the first to know.

Villabolo

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3484 on: August 06, 2020, 03:08:06 PM »
Thanks Oren and Sebastian.

El Cid

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3485 on: August 08, 2020, 07:12:31 AM »
Ok, I tried this in the main thread but nothing came up, so I try it here:

Does anyone know of a good site (with data and/or graphics) where SSTs can be compared day by day for the Arctic?

This year's crazy high temps in the Siberian Seas are as high as I have ever seen them but I want to check my memory and see the anomalies vs previous years


blumenkraft

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3486 on: August 08, 2020, 08:00:58 AM »
Does anyone know of a good site (with data and/or graphics) where SSTs can be compared day by day for the Arctic?

I'm using Mercator >> http://bulletin.mercator-ocean.fr/en/PSY4#2/62.7/-85.1

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3487 on: August 08, 2020, 08:58:40 AM »
Hycom also offers SST's though they only show surface sst's and mercator offers 6 depths

johnm33

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3488 on: August 08, 2020, 10:07:54 AM »
If it's just the surface why not nullschool? for other stuff i occasionally look at https://resources.marine.copernicus.eu/?option=com_csw&task=results which is a bit clunky but once you get to advanced tools quite flexible. For instance here you can just change the numbers 4887and 11 for say 36 and 20 and the depth to suit.

El Cid

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3489 on: August 08, 2020, 12:29:42 PM »
Thank you all, but unfortunately (unless I am mistaken) these still do not allow comparisons to the same date in 2007, 11,12 and the like. mercator goes back to 2019 and Copernicus to 2016.

Nonetheless, these links are great! ty again

johnm33

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« Last Edit: August 08, 2020, 02:05:27 PM by johnm33 »

El Cid

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3491 on: August 08, 2020, 03:24:29 PM »
Ok, thx again!

I was trying to find actual sea surface temperature but I guess potential temperature should be just as good for comparisons

Général de GuerreLasse

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3492 on: August 09, 2020, 02:33:27 PM »
If it's just the surface why not nullschool? for other stuff i occasionally look at https://resources.marine.copernicus.eu/?option=com_csw&task=results which is a bit clunky but once you get to advanced tools quite flexible.

Thanks you Jhonm33, it is it's a wonderful toy, I will never master it like you (it's in English and far too complex for me). But such as I already make beautiful discoveries. :)
« Last Edit: August 09, 2020, 06:37:28 PM by oren »
La cravate est un accessoire permettant d'indiquer la direction du cerveau de l'homme.
Un petit croquis en dit plus qu'un grand discours, mais beaucoup moins qu'un gros chèque.
Pierre DAC

johnm33

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3493 on: August 09, 2020, 03:06:33 PM »
Général de GuerreLasse since it's an EU/ French site i'd be amazed if it didn't offer at least as good a service in French. https://www.mercator-ocean.fr/

Général de GuerreLasse

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3494 on: August 09, 2020, 04:45:39 PM »
Général de GuerreLasse since it's an EU/ French site i'd be amazed if it didn't offer at least as good a service in French. https://www.mercator-ocean.fr/

Yes indeed Mercator is in French, but not (it seems to me)
Arctic Ocean Physics Analysis and Forecast
and the user guide is in english.
But it doesn't really matter, I have a lot of tools that, although in English, are perfectly understandable. And if I need clarification on a post, I can always ask. :)
Thanks again.
La cravate est un accessoire permettant d'indiquer la direction du cerveau de l'homme.
Un petit croquis en dit plus qu'un grand discours, mais beaucoup moins qu'un gros chèque.
Pierre DAC

johnm33

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3495 on: August 13, 2020, 09:18:31 PM »
What temperature is methane, both as clathrate and as gas, whilst it's in shelf or deep sea deposits? is there a threshold temp. at which it has to expand and rise? how much energy can it take from the ocean as it rises to the surface?

igs

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3496 on: August 13, 2020, 10:50:07 PM »
What temperature is methane, both as clathrate and as gas, whilst it's in shelf or deep sea deposits? is there a threshold temp. at which it has to expand and rise? how much energy can it take from the ocean as it rises to the surface?

Hope it's what you were looking for ;)
« Last Edit: August 13, 2020, 11:06:40 PM by igs »

johnm33

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3497 on: August 13, 2020, 10:59:16 PM »
Thanks now here's why

grixm

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3498 on: August 15, 2020, 08:19:20 AM »
Help settle a debate on how concentration data is produced and whether or not we can measure concentration based on features smaller than the concentration data resolution. Here is their argument for why we can't:

Quote
As my second reply pointed out, my understanding is that concentration maps - like the DMI (Or was it NOAA - I believe they actually use the same data source but are slightly different models...) one I believe you posted - are derived from plugging in satellite telemetry to a model and based on that, assigning a concentration value based on the signal return strength in that data.  That is resolved to a binary "On (covered with ice)/Off (no ice)" toggle.

The resolution of that data is pretty coarse. In the case of the NOAA data, the grid cell used is 25km by 25km - basically the size of a large city.

By necessity that means the sensitivity of the measurement is regional rather than local - like seen in the image I posted from Polarstern.  My core argument is,that  if you took the ice quality you see around Polarstern in that image, and covered a 25x25km2 block with it, the return *and* the model output would show that section of sea surface as covered with ice.  It would not see the 10-15% of that surface which is actually open water between the mish-mash of small floes that caused the model to return a positive signal.

And my argument for why we can is that the sensors used for concentration data do not resolve individual pixels to a binary on/off. The microwave imagining sensors functionally work much like normal camera imaging sensors work in that each pixel gets a value on a scale based on the strength of the signal it receives, and this value can be processed into a percentage of ice concentration. Just like how a normal camera gets a value on a scale for each color channel based on the brightness, not just a binary on/off.

And what happens if you have features smaller than the resolution? Well if you for example draw a white and black checkerboard where each square is 1 mm wide, and take a picture from such a distance so that the resolution of one pixel is 10mm, how does the checkerboard pattern look? It doesn't look black, or white, but gray, in other words a 50% brightness value. That's because the sensor naturally averages out the signal from all the colors found inside the pixel. And if we have more black than white squares, the pixel turns into a darker shade of gray. Meaning that we have successfully measured the concentration of black vs white even though the patterns of black and white is smaller than our pixel resolution.

In the same way, if you have tiny cracks or melt ponds on the ice, they affect the total signal brightness that the microwave sensor picks up even if those features are smaller than the pixel size, and thus it can successfully measure the concentration anyway.

NB: Remember that we are talking about concentration/area data here, not extent. I know that extent maps do have a binary ice/no ice value for each pixel. (But this is still derived from the same analog sensor tech though)

We've gone back and forth with the same reworded arguments and are making no headway so I ask you guys which of us are correct. The other guy can chime in as well if he wants, I didn't post his username just in case he wants to stay private.

jdallen

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #3499 on: August 15, 2020, 08:33:44 AM »
Help settle a debate on how concentration data is produced and whether or not we can measure concentration based on features smaller than the concentration data resolution. Here is their argument for why we can't:


These might be germane in this argument:

https://nsidc.org/data/NSIDC-0081/versions/1

https://nsidc.org/data/polar-stereo/ps_grids.html
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