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Topics - jdallen

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1
Arctic sea ice / Sea ice formation dynamics
« on: April 20, 2020, 08:06:03 PM »
Seeding the thread.  Moved from melt season.

Here's a link to a Chris Reynolds discussion on ice growth calculations, and another to a post in his "Slow Transition" thread about Lebedev and Billelo and related issues.
http://dosbat.blogspot.com/2015/01/the-simplest-model-of-sea-ice-growth.html
https://forum.arctic-sea-ice.net/index.php/topic,933.msg58049.html#msg58049

I would ask that further discussion of this very important issue continue in a different existing thread, or start a new one if needed.
Make a search for Lebedev and Billelo to help in locating a suitable venue.

Glen Koehler,
I think that the formula given by John_The_Elder in the previous post: "Thickness (cm) = 1.33 * FDD (°C)0.58", is relative to a starting situation without ice. If at the beginning there is already an ice thickness to use the formula you have to add to the FDD the value that gives the thickness already present (and the influence of the thickness in the formula is given by the exponent 0.58).
Nico Sun quotes this formula in his webpage for FDD   https://cryospherecomputing.tk/index.html

The source quoted is  "Lebedev - 1938". One wonders what research / testing has been on this formula since 1938.

I've posted the Lebedev formulat a couple of times previously over the years.  It's pretty empirical and does factor in the ice thickness.  Like many such things, it isn't precise, but does provide scale.

2
Arctic sea ice / 2018 Melting Season - Predictions and Speculation
« on: March 22, 2018, 09:17:04 PM »
Created to winnow down the 2018 Melting Season topic proper.

3
There is a lot of buzz right now about Trump and discussions about N. Korea. (April 24, 2017)

Some of us have picked up articles about substantial numbers of US vessels transiting the Canal starting a few days ago.  I've found some in various Spanish language site, but am keen to find as close to original source as possible.  I'm suspicious english language search engines may not be picking up the threads on this; certainly our news outlets are not.

Here's an example of what I found:
http://www.7dias.com.do/portada/2017/04/22/i227865_estados-unidos-moviliza-submarinos-nucleares-hacia-peninsula-coreana.html#.WP7metIrJqM

4
Consequences / Trump to eliminate climate change research.
« on: November 24, 2016, 02:44:40 AM »

5
Arctic sea ice / Polar Vortex/SSW effects on Ice
« on: November 17, 2016, 06:25:37 PM »
Greetings;  Started this as a placeholder to start capturing posts on this topic which have ended up in unlikely locations.

7
Greetings all;

I was recently challenged by someone regarding the observation that 2015 extent is the lowest for the date in the current record.  The individual tried to draw me into a fight (on someone else's page), which I refused for propriety's sake.  Among the things he asserted and posted was this:

http://adsabs.harvard.edu/abs/2007AGUFMPP11A0203F

He was using that to defend an assertion that 5-7000 years ago the Arctic was hotter, and that the current changes were no big thing.

I'm curious as to what people have to say about this, as I've got little understanding of it.  My gut says that the conclusions are (1) unsupported and/or (2) being misrepresented.  I'd rather not argue from my gut, however.

Feedback would be appreciated.

8
Arctic background / Arctic Wildfires
« on: April 14, 2015, 12:13:48 AM »

9
Greetings all;

The National Climate Assessment has been released.  Link here for access and download of a rather voluminous set of documents.

http://nca2014.globalchange.gov/downloads

11
Arctic sea ice / Fracturing event, Two point Oh
« on: January 08, 2014, 11:26:09 PM »
Last year late January/February, a fracturing event started in the Beaufort.  Thanks to Apocalypse4real, we have an image from last February 8th:
https://5fb597cc-a-62cb3a1a-s-sites.googlegroups.com/site/apocalypse4real/home/arctic-sea-ice-polar-avhrr/AVHRR%20020813%201353.png?attachauth=ANoY7corWCnjCiViXf0rL55WUKpt-SbjzovaqI5j_1iidP-f3iZLhlYx8fQsg_B6PDSHdB0Gmm2Hf3DWHBGqPDzduziUfA37jTgA5cHjVLqMDF_aUDA0L41lxcBv_HnQgSwZ3ATlihjWyaIukG2n6cZ_UH2X9Z-6KDmOJ2ExjldbVAEquDRS4M8Pmc3kEYqtnPoOnaSmJnvZ8cytsqD-8QbmF61euFRZjr9ZAgm76SLAuAmVnOTRZEHbQo8d30AqCL9RdCjprtqo4K29bMrAxBYtIgsuv6Ug8w%3D%3D&attredirects=0

At the time there was considerable expectation that this was dire news for the pack. But then came a cold spring and cool summer, and the ice was saved, against most peoples expectations.

Now, forward to the present.

Here's what it looks like currently:
http://weather.gc.ca/data/satellite/hrpt_dfo_ir_100.jpg

It seems to me this breakup is starting about 30 days earlier.  Predictions, anyone?

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