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Messages - jdallen

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Arctic sea ice / Re: The 2019/2020 freezing season
« on: March 13, 2020, 09:08:53 PM »
Do we dare to say BOE?

I'm going to go out on a limb and say no. A BOE would require extent to be ~4Msqkm below the new normal come September, which I don't see happening even if we have a brutal melt season. Variability caused by weather is usually on the order of <1Msqkm.
Attached is a graph of the JAXA Arctic Sea Ice Monthly Averages since 1979 and the deviations from the linear trend.

You will see that the maximum -ve departure from the trend was in 2012 at just over 1.5 million KM2. 2nd was 2007 with an anomaly of -1.2 million km2.

A BOE (using BOE defined as sea ice extent of 1 million km2) would require melting of about 3 million km2 below the trend value for 2020 of about 4 million Km2, double the previous maximum deviation.

Data is such a bummer

Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: January 22, 2020, 05:06:03 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

January 21st, 2020:
     13,332,633 km2, an increase of 40,141 km2.
     2020 is 11th lowest on record.
     In the graph are the today's 15 lowest years.
     Highlighted the 4 years with September lowest min (2012, 2019, 2016, 2007) & 2020.

Arctic sea ice / Re: 365 day average extent poll
« on: January 19, 2020, 07:40:49 AM »
I'm going to call it - the majority of us, myself included, were probably wrong. I think there's too much ground to make up in the next two months with recent gains.

Arctic sea ice / Re: The 2019/2020 freezing season
« on: December 22, 2019, 01:00:39 PM »
Very readable overview of open ocean tides here:

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 07, 2019, 12:50:22 AM »
Apologies for taking so long to reply... I'll spare you my usual excuses, though I don't doubt they would impress you with their earnest sincerity and momentous import of the ways I manage to waste time ...

   Here is the reasoning why I proposed that the last 1 meter of ASI from 1m average thickness would melt to 0m faster than from 2m to 1m average thickness:
    -- As we lose the older thicker MYI, the remaining ice has higher percentage of younger, and thus saltier and easier to melt FYI.  Everybody seems to agree on that.

e.g. As interstitial noted at,2709.msg201895.html#msg201895
       Thinner ice, presumably with higher portion of First year Ice...
"has pockets with high salt concentrations in it. Some of the pockets even most may not of frozen solid.
   ...When the temperature climbs above -21C the pockets of high salt concentration melt first. The temperature is still too low to melt the pure ice.
   ... This is how multiyear ice is formed each freeze and thaw cycle of salty water can more and more salts out until it is pure ice with no salts. That makes the multiyear ice fresher and more melt resistant."

   -- But here is the main reason - the Thorndike (1975?) chart showing the differential rate at which ice of different thicknesses increases thickness, that Chris Reynolds posted to explain the Slow Transition hypothesis.  To me it says that unless there is some hysteresis effect, then that curve in reverse shows that thin ice also melts MUCH faster for the same amount of heat input.  For a given amount of heating energy, e.g. melting degree days in summer, more ice is lost per unit of energy in summer by thin vs. thick ice, just as more ice is gained by thinner ice for the same amount of freezing degree days during the winter.

      Here is the Thorndike chart

(And you know its good because it is Neven's account icon!)

     Here is my reversed version, with zoom into the last 2 meters.

     Seems to me that the Thorndike chart, when reversed, shows the amount of ice lost for the same amount of heat added to ice of different thicknesses.  Just as the original chart shows the amount of ice gained for the same amount of heat lost from ice of different thicknesses. 

     Thus, I am using Chris Reynolds' Slow Transition evidence to reach an opposite conclusion.

     This is a simple case of Teslacle's Deviant ("What comes in, must go out") to Fudd's First Law of Opposition ("If you push something hard enough, it will fall over") -- for you Firesign Theatre fans.  Seriously though, as a thermodynamic equation, what works in one direction should work in the reverse unless there is some hysteric effect at work.  (e.g. Teslacle was right!  This could be Vulvaire's Correlate to Teslacle - "What went out, comes back in.")

     Another chart adapted from an ASIF post by Jim Hunt,2709.msg201631.html#msg201631
shows the same phenomenon. I didn't reverse this one, but you can do that in your head.

     The only argument against a quicker final meter melt notion is that the because the CAB is at higher latitude, the melting process will stall as the Arctic ice melt reaches the high latitude end game.  And I might buy that idea if humanity was intelligent enough to stop pumping greenhouse gases into the atmosphere at an increasing rate, but not seeing evidence that we will, one can only suppose that warming will continue, and in fact that the rate of warming is increasing.

     I admit that gerontocrat's open water chart (up thread at,2348.msg235525.html#msg235525) requires a huge rate increase in CAB September open water to have a BOE anytime soon.

      But the cumulative evidence argues that that is indeed what will happen.  While gerontocrat's CAB volume trend chart shows it reaches zero a few years later (ca. 2040?) than the whole-Arctic Wipneus volume chart (2032), it is not that much later.  That suggests that the CAB does not have enough extra resistance against melt to combat the inexorable warming and Arctic amplification underway. 

   As Tor Bejnar noted at,933.msg113144.html#msg113144
"I have also long considered the 'quick' loss of summer ice in the non-CAB regions over the past 30 years (e.g., the Beaufort going, in August, from 2/5th coverage to none between 2013 and 2016) not to be predictive of how fast CAB ice will be lost.  I think this discussion of bathymetry adds some geophysical creds to Chris's theses.  This doesn't mean, however, that I'm 'now' convinced Chris is right.  I think other issues like CO2-equivalent, mobility and storminess (emphasis added GK) may well 'over' compensate for the bathymetry-related suppression of warm water currents remaining near the ocean surface."

     As Bruce noted at,778.msg32178.html#msg32178
"Chris, I don't see any reason for the rate of summer melt increase to flatline, slow down, or even be linear. As the ice thins, the surface/volume ratio increases, which should increase the rate of melt. The thick MYI held off major assaults in 2017 and 2012, but that ice is nearly gone. What we have now is this "mesh ice" that spreads out as the edges melt (which, though it is a negative feedback (because it keeps more of the ocean covered with ice), is a short-lived one). That spreading increases the surface (both top and bottom) that can melt."

    In a second instance of using Chris Reynolds' evidence to reach an opposite conclusion, I will reinterpret a chart he posted at at,933.0.html

   Read his post to see how he uses that to argue for the slow transition.  To me it shows that  September ASI volume hits zero ca. 2027, even earlier than the Wipneus chart.

   As for the hiatus, I think we've beat that to death.  I'll just repeat that 10 yearly data points is simply not long enough to make statistically valid conclusions for data with high interannual variability.  I will go out on a limb and bet that the 2012 minimum volume record has a 50% chance of being replaced in 2020, likely won't last beyond September 2021, and almost certainly won't last  beyond Sept. 2022. 

    That said by the guy who expected the October slow refreeze to continue based on GFS forecast showing continued high Arctic temperature anomalies over the last 10 days, when just the opposite happened.  I guess I was confusing the tail and the dog - my new guess is that the air temp. anomalies were high because the water transitioning to ice was giving off heat to warm the air above it. 

Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 07, 2019, 07:59:52 AM »
Still trying to understand how the *warmest* August on record, according to awesome +70N 925hPa temps chart produced by Zack Labe, led to such a poor loss of ice extent. No convincing explanation so far....
I am convinced that we had normal melting conditions in 2019.

WTF? Normal melting conditions? With warmest August, 2nd warmes June and 3rd warmest July (and it was quite sunny for a good part of the summer as well)? How can you call that normal? Based on temps, ice should have crashed to nil, but it held up very well, so I have the same question as the original poster: i wonder why we did not lose more ice?

My answers are:
- the GAC of 2012 was truly a powerful and rare phenomenon and simple warm weather is not enough to repeat it
- the Central Pack is really hard to crack
- the Arctic is a mystery :)

Arctic sea ice / Re: The 2019 melting season
« on: September 16, 2019, 11:50:44 PM »
Over on the ASIB, I've just posted the late(st) PIOMAS update, and I just wanted to share the final half here, because it's how I view this melting season. Normally, I don't like it when people post long texts, but I'm the exception to that rule, of course.  ;)

Last month, I wrote at the end of the PIOMAS update:

From what I've seen on the Arctic Sea Ice Forum, written by commenters I've known for years and highly respect, my gut feeling says this year won't be able to break the 2012 records.

But for weeks now, I've been thinking of those prophetic words uttered by Peter Wadhams, back in 2007: 'In the end, it will just melt away quite suddenly.' I don't think all of it will melt away quite suddenly in coming weeks, but maybe more than one would expect just looking at the data.

This year is a great test that will tell us a lot about the importance of melting momentum.

To be honest, I expected a clearer melting momentum signal during this final phase of the melting season. Melting momentum took off slower than years like 2012 and 2016, but when it did take off, it was fireworks (see June 2019, one hell of a month). David Schröder's melt pond fraction maps, the SMOS pixel chart, the compactness charts, the Albedo-Warming Potential graphs, the snow cover graphs, more and more they were pointing to a massive build-up of melting momentum. On top of that, PIOMAS was showing that this year was very competitive volume-wise, and for five months in a row, 2019 was in the top 3 when it came to temperature records (August coming in lowest on record):

It was clear that the spell of extremely sunny, warm weather was ending during August. That, to me, was the great test for my melting momentum theory. Weather conditions switched, but for a week or so extent loss was keeping up with 2012's pace, despite the boost provided by the GAC. But then halfway through the month, things slowed down to a crawl after all (see red trend line):

So, what happened? Of course, there was a cyclone that was in a perfect position to disperse the ice, but there was so much weak ice that in my view, momentum should have gone on for a while longer.

There are two possibilities:

1) There wasn't as much melting momentum as I assumed.

2) Melting momentum is less important than I think it is.

As said, it took a while for melting momentum to get going. Timing is of the essence when it comes to breaking melting season records. May was actually very sunny this year, but most of the radiation coming from a Sun at a still low angle, got bounced off the pristine white ice. It may sound counterintuitive, but before the real melt ponding gets going due to open skies, cloudy weather is actually worse for the ice, because with clouds comes humidity and the clouds also block outgoing radiation. This can cause the snow on top of the ice to melt just a tiny bit, deforming the structure of the snow, making it more prone to melt when the sun starts to shine in earnest. 2019 came short in this respect, as evidenced by visual inspection of satellite images. Never mind the fact that the 2018/2019 freezing season was much less spectacular compared to the previous three winters, when it comes to temperatures and extreme weather conditions.

I'm still convinced that without a decent amount of melting momentum no records will be broken. That's why in years like 2016, 2017 and 2018 it was possible to announce at an early date that the 2012 record was safe. But conversely, a massive amount of melting momentum doesn't guarantee records either. Initial ice conditions and late stage weather obviously play important roles as well.

Maybe I'm emphasizing melting momentum too much, but I still feel kind of vindicated by recent developments on the extent front. Over the last week, just a small amount of weather conducive to melting has helped nudge 2019 below the 2007 and 2016 minimums, with quite an impressive run of daily drops. Tomorrow or the day after, the 4 million km2 mark could even be breached. I always thought that this year would come in second whatever would happen, and it looks like it has:

Either way, after almost 10 years of blogging, I'm now clearly seeing the contours of that first year when ice-free conditions will be reached (in other words, an ice cover smaller than 1 million km2, which amounts to ice-free for all practical purposes). It is preceded by a freezing season similar to that of 2015/2016, starts with the melt onset 2012 saw, builds up the massive melting momentum of 2019, and ends with the crazy weather of 2016. It makes me shudder to think what the satellite images will look like then. It may take more time than most cryospheric scientists think it will take, but unfortunately, that's not much of a comfort.

The ingredients are there, AGW is the cook.

Some background research on Laptev shoals from A-Team
Here is more on incredible parallel to ESS shoals but on the Laptev side of the NSI. A bit of land remains today (Yaya island, now 0.5 m above sea level). Weird to see ice/rock feature not far from islands with conventional hard rock islands. The other mystery is the length ... requires a chain of pingos. Note the 5 ESS shoals are kinda in a line which would fit with a fault line and methane pingos along it,,_New_Siberian_Islands,_Russia,_Sentinel-2_satellite_imagery,_2-SEP-_2016.png?

google translation from  the russian wiki:Васильевский_остров_(Новосибирские_острова)

"Vasilyevsky is a former island (currently Vasilyevsky Shoal, Vasilyevsky Bank) in the southwestern part of the Novosibirsk Islands (the extreme west of the Lyakhovsky Islands), in the eastern part of the Laptev Sea. Before it disappeared, it was one of the smallest islands in the archipelago. Shoal (or bank) was named after the island. To the northeast is the Semenovskaya Bank, to the east is Stolbovoy Island. In 2013, a new island (Yaya) was discovered in the area.

Since its discovery, Vasilievsky Island has rapidly declined in size, until it completely disappeared by the mid-1930s due to the melting of ice mixed with rocks. The shallowest depth in 1965 was 0.8 m. Then, the increase in shoal depths continued due to melting of icy inclusions in the rocks of the bottom, chemical processes and under the influence of sea waves."


73.59'086 "N and 133.07'398" E. “It looks like a ridge of hummocks,” said Gukov. The results of the flight convinced the director of the reserve that "ice played a decisive role in the formation of the island, raking, like a bulldozer, in shallow sediment." “This is evidenced by the location of the hummocks,” Gukov said.

It was first noticed and mapped in 1814 by Yakut trappers who mined mammoth tusks in these places. According to the materials of the Hydrographic Expedition of the Arctic Ocean, in 1912 the length of Vasilievsky Island was  4.6 km in length, it had coasts 15-16 meters high. However, according to Gukov, even such a height of the coast did not save the island, and it was eventually washed out by the waves.

The new island is much smaller - about 150 by 150 m, and it rises above sea level by only half a meter. Vasilievsky Island belonged to the Lyakhovsky Islands archipelago, which, together with the Anjou and De Longa archipelago, are included in the large island association of the Novosibirsk Islands.

When first discovered, Vasilievsky Island was 7.4 km long and 0.5 km wide.

Semenovsky Island once joined it:

September 10, 1881 American expedition D.V. made a two-day stop De Longa, sailing after the death of her expeditionary ship "Jeannette" in the ice of the Laptev Sea to the mouth of the Lena River in three boats. In the diary of D.V. De Long recorded the island’s width of 1/8 mile and a height of 3 to 9 m and noted that the island was apparently being eroded. On the top of the hill dominating the island, he found the remains of deer horns and mammoth teeth.

August 19, 1912 icebreaker-transport  “Vaigach” anchored at a depth of 8.2 m at a distance of two miles from about. Vasilievsky.   Neupokoev noted that the islands of Semenovsky and Vasilievsky did not exceed 2.5 miles in length. He suggested that once instead of two islands there was one large island, which is confirmed by the presence of an extensive shallow extending to the east, northeast and southeast from the islands of Semenovsky and Vasilyevsky.

the Semenovsky and Vasilievsky islands consist of subsoil ice covered with a layer of silt and various kinds of tundra formations, two feet thick. The ice at the coastline is exposed and is rapidly being destroyed due to melting.

example of coastal ice/dirt decay
Worldview, ESS-1S, clear day, 2000-2018

Arctic sea ice / Re: Latest PIOMAS update (August 2019)
« on: August 06, 2019, 03:42:08 PM »
That highly anomalous steepening of the volume curve in mid-August 2012 is best explained, in my opinion, by Ekman pumping of heat from the Atlantic water layer into the surface ocean. Normal storms can't do this because they don't persist long enough to break up the strong density inversions. The GAC lasted ten days and was very intense at its peak. It was strong and persistent enough to break down the layering in a large volume of the Arctic ocean.

The buoy profiles were stunning. Ekman pumping by persistent high pressure areas has caused multiple episodes of upwelling along the continental shelf in the Beaufort sea, but I'm not aware of any storm other than the GAC causing a upwelling of mid-ocean water in the central Arctic ocean. There was a very large amount of energy involved in the rapid melting of ice in mid-August 2012. Because there were not large amounts of heat advected by the atmosphere, it must have come from the ocean.

This melting season atmospheric heat advection may be larger than it was in 2012, but so far storms are not persisting like the GAC, so we should perhaps expect less bottom melt from ocean heat than took place in August 2012. However, sea surface temperatures in the Arctic are very high this summer so there is a lot of ocean heat in the upper layers. Moreover, strong atmospheric heat advection has been persisting in the Arctic for months. We are going to get a chance to compare the effects of different processes on the melt minimum by comparing 2012 and 2019. The sea ice volume curves are a most important aspect of that comparison because they are a function of system enthalpy (heat).

Arctic sea ice / Re: The 2019 melting season
« on: August 05, 2019, 03:56:58 PM »
This thread becomes interesting. Fewer people are discussing on the state of ice right now. The greenhand may think the melt rate slows down and it will not break the record at this rate. The storm is not strong and the CAB ice seems to be pretty healthy compared with previous year(2016 and 2012). All the things seem to be predictable until mid September.

For those experienced person, they are just watching. They know the ice is not healthy as MODIS have shown. The ice is compacted but full of tiny cracks and could be completely disintegrated if strong wind comes. The high SST is the potential ice killer. They know the strong wind will not disappear in the melting season but delay because the arctic is too warm to form. The strong wind and storm really need cold air to distablize the upper troposphere. Once the thin ice meets strong wind at the end of melt season they know what it will mean to the ice with high SST surroundings(Ekman pumping). They also know the melt season will not stop as early as 2016 does because the Arctic is record breaking warm. It has the potential to extend the melt season to the mid September even the late September.

All these thinkings cause fewer people wants to discuss in this thread.

Arctic sea ice / Re: The 2019 melting season
« on: August 04, 2019, 02:28:43 AM »
Some further info ...,2278.msg170187.html#msg170187,2278.msg170206.html#msg170206,2417.msg215667.html#msg215667

Yale Researchers Find Heat Held in Arctic Ocean Doubles in 30 Years

Newly published research suggests the amount of heat stored in a vast section of the Arctic Ocean has doubled over the last 30 years, adding another blow to sea ice that helps regulate the planet’s climate.

“The most likely outcome for this heat is that it will slow the growth of winter sea ice, which further compromises the Arctic sea ice pack,” said Mary-Louise Timmermans of Yale University.

That ocean is composed of layers divided by both salinity and temperature. One of those layers, beginning at about 50 metres of depth, is both more saline and warmer than the surface waters.

The paper calculates that sea is now absorbing five times more solar energy than it did before.

That sun-warmed water has created what Timmermans calls “archived” heat in the Canada Basin.

“That layer of water is both increasing in temperature and also increasing in thickness. Overall, it’s increasing heat content.”

The warmth under the ice hasn't dipped or varied significantly since the 1980s, she added. It's just kept marching upward "like a staircase."

Although that water has only been warmed to a maximum temperature of about 0 C, the paper calculates there is currently enough new heat stored beneath the ocean surface to thin the ice cover of the entire basin by nearly a metre. It notes the amount of such “archived” heat will continue grow as the Chukchi loses more ice.

... The study shows that climate change doesn't only threaten the Arctic through the direct melting of ice along the northern ice cap's edges, Timmermans said. Instead, all the extra heat now present in our planet presents a long-term threat to the northern ice, independent of year-to-year shifts in weather patterns. Over time, she said, that heat will break through the insulating fresh water above it and eat away at the planet's remaining northern sea ice from within.

What’s happening in the Canada Basin is an example of how losing sea ice in one area can contribute to further sea ice losses in areas hundreds of kilometres away, the paper says.

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 29, 2019, 01:23:18 PM »
Not free. I followed your link, had to log in ( give information) and then directly request access to the paper. Haven't received it yet.

Here is the abstract of the paper:
During recent decades, there has been dramatic Arctic sea ice retreat. This has reduced the top‐of‐atmosphere albedo, adding more solar energy to the climate system. There is substantial uncertainty regarding how much ice retreat and associated solar heating will occur in the future. This is relevant to future climate projections, including the timescale for reaching global warming stabilization targets. Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year. Assuming constant cloudiness, we calculate a global radiative heating of 0.71 W/m2 relative to the 1979 baseline state. This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years.

From here:

... or just use Sci-Hub to find papers <cough>

Looking at it...  this is a self evidently ridiculous paper.  It's a simple albedo calculation, based on the complete absence of ice from March through to September.

From their methods:
In the calculations of albedo and radiative heating presented here, we use data from the National Aeronautics and Space Administration's CERES Terra SSF Edition 4 monthly averaged 1 × 1-degree product, between March 2000 and October 2016, available online ( The Arctic Ocean is defined here as the land-free area poleward of 60◦N. Due to issues concerning polar night, we only consider the months of March to September of each year.

i.e. they account for extra incoming energy during an ice-free summer, but do not account for any extra outgoing energy during the winter.  This is effectively equivalent to assuming that the Arctic freezes over as normal each winter (i.e. insulating the surface and restricting heat loss) and then the ice magically disappears overnight some time in March.

It's completely unphysical and the only utility it has is giving a ballpark figure for HALF the energy equation resulting from an ice-free Arctic. Don't waste any time trying to interpret this one any further than that.

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)

   -- 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.

Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 03:55:56 AM »
4 more screenshots - Area, Concentration (opposite of Dispersion), Volume, Thickness


Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 03:41:39 AM »
Screenshots from
"Arctic Sea Ice Score Card: Extent, Area, Concentration, Volume, & Thickness - 2019 vs. 2012"
17-page PDF at
(but that server is misbehaving 7/27/2019, should be fixed by Monday).

2012vs2019 NSIDC concentration images

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 24, 2019, 06:37:52 PM »
Here's a link to a review article (an article that examines recent studies and summarizes them) published in the journal "Climate Change Reports" in December 2018. The article examines whether an ice-free Arctic leads to "tipping point" behavior and concludes that it doesn't.

Actually, it doesn’t. The limitations of the study are bounded by the conditions it studied. These include limitations to a data set of only variably ice covered Arctic, linearity in response in that regime, and omission of other factors not studied that might cause non-linearities and tipping points. They did go beyond those bounds in projecting an ice free arctic from July to December at +4C. But that projection too must be taken in the context of the studies limitations. In other words, that is a lower bound. Feedbacks and inputs leading to nonlinear behavior were excluded.

Said differently, the study creates a linear model based on the observational period. Arguments beyond the observational period conditions are at best speculative. To use the model to argue that tipping point behavior won’t occur falls victim of a self referential error in logic of the type: “We made a model. The model only includes linear response. The model doesn’t predict nonlinear response. Therefore nonlinear response is not possible.” Gack! 

Sadly, this sort of error is common, as is the error of extrapolating beyond the bounds of the data set and trying to apply the data set to regimes where it may not and likely does not apply.


Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 24, 2019, 03:05:54 PM »
I think that we could avoid a lot of unnecessary disputes over something many "somehow" agree, if we would invent (ADD) an additional term to our vocabulary:

We are now talking about "Blue Ocean Events" = BOE

I suggest to add the term "Seasonal Blue Ocean State" = either BOS or SBOS

what do other think about that, as mentioned i think by distinguishing single BOEs and
a general new state that will repeat each or almost each summer, many heated debates
could be avoided and at the same time we would be more precise for "noobs" about what is meant.

Arctic sea ice / Re: FireStorm in Siberia
« on: July 24, 2019, 08:40:24 AM »
The low was already predicted three days ago by ECMWF, see chart, weak low south of Kara. No way they predicted the fires, even I doubt they take into account all the physics needed to predict a fire-caused cyclone.
This is smoke caught by a normal atmospheric low. A lot of smoke yes, but it is not causing the low.

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 23, 2019, 11:49:07 PM »
Let's return to the central issues...

1) When the Arctic will go ice free
2) How that is likely to play out from first ice free day, to week, to month, to season, to year
3) What the consequences are of that, and hence why we should care

1) the trends in ice extent, ice area and ice volume are all headed to the same outcome, zero ice. Each points to a somewhat different potential date for that. The differences in those dates, though important from a human perspective in a single human lifetime, are essentially identical in geologic terms, and virtually identical in the lifetime of civilizations or nations.

The most likely correct projection is the limiting projection based on the full suite of projections, not the average, not the last, but the first. And that is based on volume. The inherent oscillatory nature of the many linked earth and solar systems creates a form of variation that looks like and can useful be treated similar to randomness. And it has randomness in it. But it isn't truly random in the large scale.

That said, the outer bounds of the error band on projecting forward on ice volume suggest that we have already entered the outermost likelihood for an ice free summer day. Clearly this year won't be it. Next year could be. But most likely that won't be for a few years.

On the other end, the high band, we almost certainly will see it before 2030 even under the most unlikely combination of events. As a result, the first ice free day in September will almost certainly occur between 2022 and 2028.

2) with the progressive loss of ice cover, warming of the ice free ocean, thinning of the ice cover, failure of the tundra and clathrates, combined with mans continued and accelerating release of global warming gases, the lengths of time that the Arctic is essentially ice free will grow longer. There will be oscillation with temporary retreats, and with shocking extensions. The trend will remain for longer and longer ice free periods. That will happen quickly, even in human terms.

3) as that happens, the downwelling driving forces on both the ocean, driving the Atlantic and Pacific oceanic circulations will progressively grow weaker, and the down falling driving force for the atmosphere will simultaneously decline with it, and with that the motive forces for atmospheric circulation of the polar cell will decline.

As the oceanic driving forces collapse a whole suite of interlocking circulations will lose their motive force. New balances will come into play. The oceanic circulations will perhaps stall, and in some areas new broader slower circulations driven by corriolis forces and topography will take over. Areas will go anoxic. Species will move with the temperature and flow. Many will die.

As the atmospheric driving forces fail, the heat balance will shift. The tropopause will rise. The polar circulation will slow and become more chaotic before too be driven by lesser circulations and forces. As the polar cell fails, so too will the driving forces between the Ferrell and polar cells weaken and fail, then those between the Ferrell and Hadley cells. In time, those too will be overridden by other forces.

With an increased tropopause, single cell circulation becomes possible, though moving at slower speeds allowing drag to counter corriolis forces that would otherwise truncate the circulation. Exactly what happens with this is unknown and is a key question related to how the atmosphere circulates on Venus, and how it circulated on Earth during equable climate periods.

The oceanic and atmospheric circulations are however also interdependent based both on flow interactions and based on heat. With dramatic shifts in flow and consequent large shifts in heat balance, moisture shifts, clouds and the like, the problem is extraordinarily difficult to sort out.

That it will shift is certain.

As has already been noted, we are already seeing dramatic shifts in all of these, with dramatic consequences. However, the largest differences will no doubt come when the relative balance between the various forces reach near parity. At that point, if we had a non dimensional analysis to guide us, we might (and only might) have a better idea about how the transitions will occur, and precisely when we might expect hysteretic sorts of state change.

I haven't found a non dimensional analysis of the coupled ocean, air, ice thermodynamic system using the Buckingham Pi method that might aid there. If anyone does, that might be quite useful. It should tell us what the key dimensionless parameters are to monitor (essentially the ratios of various forces that drive the system as a whole).

What we can be certain of is that the Earth is a heat engine. During periods such as our recent several millions of years where we have ice at the poles, the heat differential between these and the solar inputs (dominant at the equator) act to stabilize the system like a giant engine. The ice acts as a huge buffer or battery holding the system in a sort of equilibrium. That oscillates annually and at longer periods. Still it is a buffer. With the loss of that buffer, the system loses its governor. It then is likely to change quite quickly to an alternate stable system governed by other dynamics. That is when we will,see and experience truly abrupt climate change. No one will need convincing then that it is real. But, no doubt, many will still need convincing that we are at fault, and that we need to urgently act.

That we don't know those dynamics sufficiently well to model them successfully is particularly troubling. That we know from geologic records just how different that system is is even more troubling. But, and this is especially important, people lose sight of the importance of the rate of change in converting from one to state to another. Prior geologic analogies seem tame and slow by comparison to our current predicament. And this may be why a period of ice free Arctic in and transition period between ice ages could exist without completely upending the system. Even then, the dynamics are such that the conditions must have been radically different from what we are acuustomed to.

In our case though, we don't have slow changes at work. Our case is more akin to a fully loaded 18 wheeler racing down a 12% grade, burning out its breaks and bashing through the guardrail into open air several thousand feet above the canyon floor. You might as well decide to enjoy the ever so brief ride, as no amount of steering or cranking on the breaks means anything at that point.

But in our analogy we are still on the road. We've begun to lose traction with the highway, the breaks are all but gone and the steering isn't working. Worse, we are making our decisions by committee with a crew in the cab that is, shall we say, less than up to the task.

We are in the ever so brief period before calamity where we cannot be quite certain whether we are going to inevitably go through the guard rail and plummet to our certain death, or miraculously gain the ever so small bit of control that allows us to steer onto the truck runaway ramp. Sure, it's going to rip the wheels off and all but destroy the rig, but at least we get to recover from it.

Now, if we can just get all of the monkeys in the cab to come to agreement that we need to act, and act together, maybe we might just barely survive this yet. But first we have to get them to stop biting each other and throwing their poo.


Arctic sea ice / Re: The 2019 melting season
« on: July 23, 2019, 10:19:44 PM »
A while back we had a section where various thoughts were presented on the dark ice bands in the ESS and elsewhere. A few competing ideas were presented with no conclusions, but the white in this image is probably more intact flows of ice with a bit greater thickness than the surrounding rubble.

The dark ice may have active algae growth, sea floor sediment, river sediment, particulate deposits from smoke, or simply be thin enough/fragmented enough to be absorbing more light/passing it through to the ocean below.

The sediment above would have been integrated into the ice either by wave action while it formed in shallow water, or picked up when the ice froze to the river delta/ocean floor.

Fundamentally, there are a lot of ways to make ice dark. There are considerably fewer ways to make ice white. More or less, it comes down to two options: relics of older ice embedded in a weaker matrix (such that they retain albedo while the surrounding material goes to slush) or the weathered remains of pressure ridges (for much the same reason). Or both.

The pattern of fairly small linear features in that ice near the New Siberian Islands suggests the latter.

Since we're on the topic... Pressure ridges are an extremely important aspect of Arctic sea ice, but don't get much discussion here because the large-scale models gloss over them. Basically, where floes are forced together by currents or winds, the ice shatters into blocks. Some of these blocks are pushed upward, in a small-scale equivalent of orogeny, to form visible ridges that can peak several meters above the floes' "ground level". But more importantly in many regards, this process also forces ice blocks below sea level, somewhat akin to the keel of an iceberg writ large. Leppäranta (2005) argued that these pressure ridges, in total, amounted for about half of ASI volume. We can quibble about that number, but the ridging process unquestionably provides for hidden stores of ice.

Also, these large pressure-ridge keels help to stabilize the pack against wind and current. The apparent cryosphere-scale rotation strongly suggests that there has been widespread erosion of this hidden volume store. In areas where sea ice abuts fast ice, the shallow water depth can allow pressure ridges to actually anchor to the sea floor. These structures are called stamukha; I suspect that the persistence of stamukha immediately north of the Sverdrup Islands is what has protected the Prince Gustav Adolf Sea and nearby channels from melt ... but that the shearing off of the sea ice from these anchors is what as allowed the CAA/CAB crack to torque open.

It's hard to back up any of my suspicions about pressure ridge keel behavior because these structures, despite historically being huge volume reserves, are individually too small-scale to be easily identified in the pack, and certainly too small-scale to be represented by most models. I suspect that, system-wide, most of that hidden volume is now gone, and the self-evident increases in motility and dispersion are the consequence.

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 22, 2019, 09:25:44 AM »
I attach CAB volume (rolling 12 months, PIOMAS) since 1980. As you can all see, it has not gone anywhere since about 2010, meaning that the central pack has different characteristics than the periphery. This "hiatus" is probably caused by the fact that by the time the periphery melts out (aug-sept) it is too late to attack the CAB which is thicker anyway. How long this state lasts is impossible to say. Eventually the meltout in the periphery will happen earlier (maybe by July) and there will be time to "attack" the CAB which might or might not kill it completely. This "hiatus" is obviously (considering the ever warmer seas) will end some time. Noone knows when though and linear projections are useless, especially that there are obvious state-changes on the graph.

Arctic sea ice / Re: The 2019 melting season
« on: July 22, 2019, 02:03:55 AM »
A trove of data for the split arctic polar vortex can been found here :

There is a very strong feedback loop between thin ice and the shape of the polar vortex

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 15, 2019, 02:42:53 PM »
BZZT - ambiguous pronoun referents detected!

"It is worse than we thought" = the "we" refers to the climate science community.

"It isn't as bad as we feared" = the "we" refers to members of this board.

Both statements are thus true, because this board is much more alarmist that the community in general.

Arctic sea ice / Re: 2019 vs 2012
« on: July 14, 2019, 09:44:22 PM »
I did an in-depth video analysis of 2012 vs. 2019 with regards to a portion of the Central Arctic Basin around 80N and 150W that borders on the Beaufort and Chukchi.

I think 2019 actually looks worse than 2012 in this important region.  Even without a Great Arctic Cyclone, 2019 may challenge 2012 everywhere outside of the CAA, where 2012 will probably have an edge.

I say 2.5 - 3.0 million km^2, I think we will beat 2012 because June was so exceptionally hot in the Siberian/Pacific sector and concentration is already dropping precipitously there. (previous hottest Junes were 2007 and 2012 in that region).

Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 02:11:40 PM »
It seems unusual to me the wind coming from south Asia to the Bering Strait. I don't see the normal jet stream. Instead, a flow south to north. It is coming a lot of heat to the Arctic, with this wind pattern?,61.11,316

Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 05:36:23 AM »
I've included a couple of archived Bremen concentration maps (earliest I could get for July was the 23rd), and as you can see, 2012 and 2016 don't appear definitively "holier" than 2019; at least from what I can tell. (edit - though 2019 has a lot more purely open water.)
Here's the Bremen map for the 3rd July 2012.

Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 11:33:25 AM »
I agree that the ice thickness in mid July determines who will survive in Sep.

Are we going to be shot if our predictions are wrong?  :o
No. Worse.

You will be trapped in the circular meta-discussion gyre with no parole.

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: June 21, 2019, 05:54:35 PM »
I've tried to keep quiet so as not to contribute to the noise, but please - the off-topic (though intelligent) discussions are cluttering this thread, please move them to the "meaningless season chatter" thread where they belong.
The on-topic discussions and rebuttals of Geron's boilerplate commentary should be held in the melting season thread.
(Neven - please punish me if I'm wrong. Please punish everyone else if I'm right)

Arctic sea ice / Re: Arctic Image of the Day
« on: June 21, 2019, 05:39:09 PM »
The Freya glacier (Greenland) webcam is online again. Snow cover looks very bad compared to previous years.

Really nice webcam images - I like the temp info as well - hits 11.9C on the 16th.  Noticeable that there are lots of blue-sky days as well.

Made an animated gif for the last 30 days:

Arctic sea ice / Re: The 2019 melting season
« on: June 21, 2019, 01:56:06 PM »
Following up on whoi itp110 buoy it's easy to see why extent and area might plateau or even rise. The large floe to the left of itp110 (circled) fractures into many smaller floes, covering a larger extent/area. That also happens to the smaller floes. It's not rocket salad. ;) The danger is that it happens earlier and earlier in the melting season as the years go by.
edit: This isn't just happening in open water. There are multiple small recently refrozen fractures all the way across the CAB.

worldview terra modis, beaufort, itp110 local area jun1-21
updated temp/sal/density charts for itp110 here,2417.msg207423.html#msg207423

note:had to move the worldview date during the crop to reduce size

Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 11:01:42 PM »
A 9 C dewpoint means that a brick on the ground that is 47 degrees F will get wet from water condensing out from the humid air. Now imagine what that warm humid air blowing at sustained 23 miles per hour will do to ice.

Frivolous is right. These are crazy melt conditions on the Siberian side.

And all the heat over Siberia means that there will be a surge of warm river water onto the Siberian shelf. The fast ice will be gone fast.

Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 04:33:31 PM »
~3 days ago, coords ~81.1, ~51.1: Counts as 100% extent eh.

Arctic sea ice / Re: "Stupid" Questions :o
« on: June 18, 2019, 03:16:17 AM »
RE Nanning #1886
     The guy who built and runs Climate Reanalyzier (CR) (Sean Birkel) is precise with his terminology.  While I can't be 100% certain since I have not asked him, I'm pretty sure if it was using median he would labeled it "median", not average.  So I can almost guarantee that "average" indeed is the average (mean) for both for 2M temperatures and for anomaly. 

     Furthermore, he says this in an explanatory note on multiple CR pages
"2m Temperature refers to air temperature at 2 meters above the surface. 2m Temperature Anomaly refers to the departure of the current day (or hour) forecasted temperature from a long-term mean for the same day (and hour) of the year. The anomalies here are based on a 1979-2000 reference climatology derived from the NCEP Climate Forecast System Reanalysis (CFSR). This 22-year baseline is used instead of the more common 1981-2010 climate normal because 1979-2000 represents conditions prior to rapid Arctic warming and sea-ice loss."

   Speaking of CR, note that it uses GFS, and that last week after the June 12 transition to the new version of GFS there was an issue with temperature values.   CR had a cautionary note to that effect last week, but now I can't find it, so perhaps the issue has been resolved.  But as of June 17 there is still a cautionary notice on Karsten Haustein's 2M temperature anomaly graph at

Arctic sea ice / Re: Global sea ice area and extent data
« on: June 16, 2019, 10:42:43 AM »
patiencia, calma...

Hmm i don't think humans are ever going to see 18m sq km of seaice area again.

Arctic sea ice / Re: "Stupid" Questions :o
« on: June 13, 2019, 08:19:35 PM »

Is warning of climate disaster counterproductive?

Wait, that's not the premise here.

The question is, do we understand the human psyche and use that to get to our goal.

As I understand the problem is two fold

1. Efficient and accurate messaging. Without a clear picture of the problem we have a very low chance to solve  it. For example if we focus on solving climate change by 2050, then we will not solve the problem by 2030, which about how long we have of climate order, could be sooner, depending on the ASI

2. message reception. This is the part Tom’s post addresses. Climate change is scary. If we tell it straight up some people will panic (ie: climate change deniers), but other people will recognize the danger and react properly with climate change action.

If we blunt the message to protect the people that are too scared to face climate change then we give up the people that will jump into action.

Arctic sea ice / Re: The 2019 melting season
« on: June 10, 2019, 08:19:10 AM »
Thanks ReverendMilkbone, the Mt Sinabung eruption is interesting.

It turns out that this might be expected to have only a negligible effect on the climate though. I base that on this tweet from volcanologist Simon Carn, reporting that only 11 kT of released SO2 has been detected:

For comparison, the 1991 Mt Pinatubo released about 20 MT of SO2, so ~2000x times as much. That cooled global temperatures by about 0.4 degrees C, for about 2 years.

There may be other factors in play but I presume that this eruption should have effects around 3 orders of magnitude down on that from the Pinatubo eruption, so negligible.

As Wallen has just indicated, volcanic ash - whether blocking the sunlight or darkening the Arctic ice - is a separate issue. Mt Sinabung is in Sumatra, Indonesia, so a long way from the Arctic.

Arctic sea ice / Re: September predictions challenge 2019
« on: June 09, 2019, 07:32:02 PM »
My prediction (JAXA Sep minimum): 3.75-4,25 M km², high confidence
My prediction (NSIDC Sep Average): 4.00-4.50 M km², high confidence

Arctic sea ice / Re: The 2019 melting season
« on: June 02, 2019, 08:25:51 AM »
Just nitpicking: while true that many years start bad and turn around, 2016 is not what I call "the ice was saved", with its ultra-low minimum area, the worst ever ice state around the Pole, and the very delayed refreeze that followed it. Ice saved only in the context that a new record was avoided, and that low compaction gave the impression of a better situation that it actually was.

Arctic sea ice / Re: The 2019 melting season
« on: June 01, 2019, 02:13:03 PM »
Except for the Siberian side (especially near the Lena delta), I wouldn't say the difference is very pronounced, but 2012 looks like it has more melt ponds overall. I think differences will show up more clearly in the next two weeks, when the ice pack starts to turn blue.

Arctic sea ice / Re: What's new in the Arctic ?
« on: May 31, 2019, 12:33:55 AM »
I made a quick and lightweight sea ice comparison page for the entire NSIDC data set. At the moment it's just for the 1st of the month, but soon I add the 15th of the month as well.

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 28, 2019, 10:46:31 AM »
Two thoughts:
- Although the anomalies go down, this does not mean the temperatures do especially at this time of the year. Otoh temperatures very high lat (75+N) start to approach the ceiling imposed by ice melting, which will be absorbing the heat.
- The high pressure dome for the first week of June is hardly a deja vu for the last 7 seasons. It may be less or more dangerous, I don't know, but it kind of breaks what I am used to since 2013. We'll see what happens later on.
My déjà vu is about the armageddon stuff. OK, this year it is a high pressure dome, last year it was something else. Nor am I saying melting will stop, rather that my guess is that it will not be that much above average for the next week or so.

So, in the sure and certain knowledge that it will be wrong, for now I am sticking with my guess of a September minimum of 4.00 million km2, just 2nd lowest in the satellite record. That is an average of the last 10 years remaining melt. Using the last 5 years average remaining melt gives a figure of more like 4.25 million, 6th lowest in the satellite record.

But - the PIOMAS May data should be out in a week or so. That could change my point of view entirely.

Arctic sea ice / Re: The 2019 melting season
« on: May 27, 2019, 02:30:10 PM »
Water vapor is a gas. Air does not hold water vapor. Water vapor is fully miscible in air.

The vapor pressure of water and ice increase non-linearly with temperature. It is a function of the physical properties of the water molecule, not the air around it. One tricky factor is that a parcel of air may become supersaturated with water vapor. Clouds need nuclei to form.

One other tricky factor is that under high pressure domes this time of year  thin low clouds can form over the ice and radiate heat directly down onto the ice. They can act like a white plastic greenhouse. Clouds can have very different effects on the ice depending on their optical thickness, reflectivity, and height.

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 26, 2019, 11:20:30 PM »
The extent declines have been slow because all the easy ice on the Pacific side was gone very early and because the ice margins have large areas of dispersed ice.

If the weather in June and July is like 2017 expect a similar outcome. Most of the melting season is ahead of us. We know the ice is in trouble on a decadal scale, but we cannot predict reliably what July's weather will be.

I made my guesses at beyond June 10th below

1st image is ESRL 1000mb air temperature anomalies month by month, 2012-2018 compared to 1979-2000.  This shows that the temperatures have dropped significantly around Hudson Bay, especially in March April May.  The big signal here is that in recent years, the Polar Cell has elongated toward Hudson Bay and Siberia.  Meanwhile, ridging from both oceans has taken turns reaching into the Arctic and delivering those bursts of high temperature we all get excited about, the DMI 80N movers.  However, those Arctic incursions have always came singly, and not from both sides of the planet at the same time.

Dr Judah Cohen has published AER's summer temperature forecast.

2nd image attached is AER's GEFS Polar Cap Height including forecast.  The current conditions are updated here:

3rd image is now a 7 day composite of the 500 mb anomaly from ESRL, and the 18Z GEFS 5 day averages tacked onto the end, which is what I stare at to guess where in the Arctic will get hit by these recurring short circuit ridges.  Looks like once this Bering Blast wears out, another long reaching ridge coming across the Kara Sea brings another big block of high pressure right to the pole.

Gav's weather vids on YouTube has been doing analogs and seasonal models of interest in the UK.  The analogs have been extremely interesting.

Michael Ventrice on Twitter: "With a strong suppressed phase of a Kelvin wave to pass the Western Hemisphere during early June, I'm thinking severe thunderstorm activity in the U.S. quiets down. Good news for parts of the Plains.  Early June likely meaning June 7-20+"

Michael Ventrice regularly reports on the synoptics and there's a great image here.  Little bit over my head with the MJO.  He's been "bearish" on El Nino lately.

I've been staring at models until I can see it with my eyes shut.  I've been doing this because it seems like something is very wrong.

Firstly, GFS runs hot & is a little bit fast at the end.  When I see a high 500mb anomaly, the resulting action is much more diffuse and less sharp.  The GFS paints a bright dot on an area, reality waters it down.  Same amount of ink, just spread out.

The timing of GFS is a little bit fast in the 10-16 day.  Whatever it was developing speeds up at the smaller resolution and the temperature and speed runs away.  What is depicted turns out to be less energetic.

I like how it is "sensitive" and one run van vary widely from the next, but you get great indications of major moves 16-20 days out in the hour 384.

Yeah and it will suffer a heat wave right over the Beauforts area, above zero temps with high pressure in 15-20 days.  I guarantee it.

Ask me how I know

Someone asked me how I knew the Beaufort would be buried in high pressure & heat May 21-26.  I wanted to say something pithy about the value of long range GFS.  I mean, it's working.  But there's more to it. 

Hurricane Oscar, the last named hurricane of the 2018 Atlantic Season was turned out to sea and became and extratropical cyclone.  It entered the Arctic on November 1.  500mb charts from GFS and ECMWF showed it entraining with the polar cell and landing right at the north pole around November 5th.  Within days, the stratospheric polar vortex began ping ponging around the Arctic.  Displacement eventually yielded elongation, splitting, and a notable 3 PV setup.  The PV split worked its way down to the ground for 5 weeks, and then we had the major arctic air outbreaks of last winter.

Since all this happened, the flow has been often split and two major sections of polar cell depart the Arctic for colder land.  The two cells find separation while the jet stream reaches up from both oceans and short circuits at the pole.

4th image.  Big time separation.  There are now two areas of polar cell instead of one.  It is a repeating pattern of meandering, pinching in half, churning in heat at the pole, and then slapping back together again.  It repeats and repeats coming every 6 or 8 weeks.

Now you can expect there will be ridging from opposite sides of the planet at the same time, nearly reaching the pole simultaneously.  The aggressiveness of GFS often shows waves crossing the Arctic and landing on the other side of the planet.  In reality, it's a little bit less simultaneous, a little bit less of a short circuit.

So, what we can all see in the models is a new block of high pressure forming in Russia and then curling into the Arctic, buring the Kara Sea in high pressure and warmth incursion, and delivering another parcel of high pressure to the Arctic.  This is shown in the June 1-9 period.  It is accompanied by a ridge from the Pacific reaching toward the Beaufort.  Models are showing this one a little less energetic and low pressure begins to deepen in the region of Greenland & Baffin Bay around June 10.

Arctic sea ice / Re: HYCOM vs ASMR2 Imagery
« on: May 26, 2019, 11:54:07 AM »
Bumping this thread to point out that the ACNFS/NOGAPS section of the US Navy's web site seems to have disappeared. However ACNFS/NAVGEM can still be found at:

GOFS 3.0 is at:

and the current GOFS 3.1 is at:

The GOFS 3.1 reanalysis goes back to 2014.

Comparing MODIS, AMSR2 and GOFS 3.1 for yesterday reveals:

Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 03:17:09 AM »
Subsidence is a pretty useful precise term in meteorology. Would you also complain about a pilot using precise jargon like "elevator" or "horizontal stabilizer" or "trim" to explain an aviation concept? If you want explanation using layman's terms, feel free to ask, preferably in a different thread. This thread watches the ice and the weather etc. Mackenzie delta.

Arctic sea ice / Re: The 2019 melting season
« on: May 25, 2019, 09:07:05 PM »
Sarat - it's hard to gauge thickness from ASCAT. Someone like Jim probably has a more trained eye that can better interpret the shades of grey.

I'm not sure about that! The ASCAT "shades of grey" are dependent on the porosity and salinity of the ice, and perhaps the surface "roughness" as well:

That's a reasonable proxy for age, but perhaps less so for thickness? However as A-Team revealed, the boundary between the two reveals the sea ice movement towards the Atlantic over the last few months.

So does the movement of snow buoy 300234066342810, which is now almost at the North Pole:

BTW, comparing the US Navy's 2012 (ACNFS) and 2019 (GOFS 3.1) model outputs is apples versus oranges:,1602.msg201189.html#msg201189

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