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Author Topic: Meaningful artifacts in the Arctic data and their underlying causes  (Read 1631 times)

ajouis

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Meaningful artifacts in the Arctic data and their underlying causes
« on: July 19, 2020, 02:04:47 AM »
While most abnormal features can be chalked up to interferences or created by a momentaneous failure of the instrument or data gathering, some last too long to be explained away this easily, it then becomes interesting to try to see what is behind them, whether actual natural features, long-lasting cloud patterns or durable failure of the data. Their study would help on both data gathering accuracy and understanding of the arctic.

Images attached for the exemple described below.

Quote from: ajouis on July 19, 2020, 01:25:45 AM
That area, south of the pole towards the gaps between the atlantic islands but very close to the pole at about 86 North , also had meltponding around very white edges in 2019 (july 3-8) creating a weird thin rectangular artifact that seems to reappear in june 22-24 in 2020 [...] also of this year, and corresponds to a deeper basin in the bathymetry too, it is probably all linked but how is above my paygrade.
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After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

ajouis

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #1 on: July 19, 2020, 02:27:43 AM »
Artifact from high pressure/low pressure in Bremen shows the effect of the gaac.

While meltponding is often seen in bremen in strips and random areas, in how it artificially lowers bremen’s map concentration, the circular pattern you can see in the images show the cloudlessness from the gaac (clouds artificially increase bremen concentration) as opposed to the neighbouring areas with ice, as well as the spread, intensity and uniformity of the melt it causes.
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After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

ajouis

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #2 on: July 20, 2020, 09:30:58 AM »
Another hard to explain anomaly, sea ice detected in the middle of the Barents sea. Some of it corresponds to major sea ice break/meltout near the fjl, but it is too far too early (several hundreds of kilometers in a day) to be a fully satisfying explanation, and other footage is not assciated with particularly aggressive fjl breakout compared to the other islands who do not flash sea ice remnants far away south from their position.
Anyone has an explanation? Currents? ice cap flow from novaya zemla? Data Bug?
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After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

ajouis

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #3 on: July 22, 2020, 03:28:09 AM »
Slater’s model show ice where there isn’t currently any, in the Laptev, as well as between Svalbard and fjl, further those are separated from the main pack. This means that Slater predicts an early refreeze starting vy the island. Further an unusual long term inversion on the simpler model and slater’s prediction means that if anything close to what we are currently seeing carries on over to the minimum, slater’s model would be very poorly performing. Already we can see the forecasted pause isn’t comingto fruition at all, leaving a large gap between both models and reality, is it the time where actual conditions render modelisation obsolete? Would that extend to other models like Piomas?
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After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

ajouis

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #4 on: July 27, 2020, 09:29:59 AM »
Gif courtesy of Unicorn, at the end you can the ce close to the northern Greenland coast going north while the one farther away seems to go south. Could that be an eddy or contradictory winds pushing down ice from the southern CAB and north ice from the Greenland coast?

https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=3017.0;attach=277528;image
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After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

blumenkraft

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #5 on: July 27, 2020, 09:37:57 AM »
I think it has to do with the eddies and tidal forces occurring there.
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ajouis

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #6 on: August 06, 2020, 02:38:18 PM »
Another day, another anomaly.
I used to post Bremen graphs periodically but recently stopped due to this anomaly.
Bremen amsr2 often disagrees with jaxa and nsidc, because of its higher res, however the departure is now substantial, especially in terms of trends. While extent in low res has kept apace, and area was seeming to pick during the latest gerontocrat update, in high res they have both brutally slowed down.
This seems highly unusual especially with the Beaufort wrecking, and might be a result of cloudiness, either an underestimate during the gaac or an overestimate now, with the sensors recalibrated during the gaac. given how sensible it is to clouds I consider amsr2 more suspect but given the difference and divergence, either 1st or 3rd and already seeming to wrap up the season, it needs to be resolved beyond assumptions.
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After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

binntho

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #7 on: August 06, 2020, 02:42:50 PM »
Ajois, I think that there may be a normal explanation for this apparent "anomaly". If you look at the state of the ice in the Beaufort, the amount of dispersion is extremely unusual. I don't remember ever seeing such large areas with so very dispersed ice.

And I think that this is exactly the area where the higher resolution gets closer to reality - both in area and extent. So no anomaly, simply better measurements of a highly unusual state.
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because a thing is eloquently expressed it should not be taken to be as necessarily true
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uniquorn

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Re: Meaningful artifacts in the Arctic data and their underlying causes
« Reply #8 on: August 06, 2020, 03:50:38 PM »
Re dispersion, I agree with Binntho (becoming a habit ;) )
Re Slater. There is often an arm of thin ice close to SZ at minimum due to drift rather than refreeze. Maybe the model takes that into account?
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