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Messages - AndyW

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1
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 12, 2019, 04:31:22 PM »
Atlantic side gone from one extreme to another for the start of the freeze season.

Normally freezing from less ice extent helps the accumulation  of ice but it will be interesting to sea how this runs up to December/ January, and then how quickly it melts next year.

The tongue of multiyear ice into the East Siberian Sea  being melted away this summer is probably the big conversation point nobody is talking about ...


2
Arctic sea ice / ICESat-2 data now available
« on: September 01, 2019, 08:17:29 PM »

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Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 27, 2019, 09:37:57 AM »
How many days of increase in a row count as a freezing season?? ;)

Also the 5-day average is lower than today's number.

I think we once all came to terms that we can use the best available but nevertheless debatable numbers for the sake of comparing apples with apples.

Nevertheless I suggest that you won't further insist that the melting season has ended 3 days ago because in that case I would suggest to label those numbers as misleading and rely on those with a higher resolution that show a drop in the range of the average for the day of the year.

On the other hand some may find it interesting to question and discuss everything but the propose that you open a separate thread to keep this one on track.

Neither temperatures nor forecasts nor events imply that a refreeze could happen except perhaps surface water (melt ponds) with fresh water but that would only ad to "Area" which apparently indeed happens.

It might have been easier just to say at this time of years winds can impact the extent more than at other times for periods of time :)

4
Arctic sea ice / Re: The 2019 melting season
« on: August 24, 2019, 05:23:04 PM »
Models are trending deeper and deeper. Below 970 hpa will as forecasted now make this complex looking like a GAC. Brace yourself for ice armagedon.....

I'm braced.

What are your predictions on the amount of sea ice lost in the next week in km2?


5
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 24, 2019, 05:17:15 PM »
Forgetting weather currently, the ice pack looks like it may get down to sub 4million km2 but not guaranteed.

August is a different kettle of fish compared to July unlike 2012, most years are.

I still don't think there is enough evidence for melt ponds etc giving a link to really low summer minimums from the Winter extent.

That might change in the next few years.


6
Arctic sea ice / Re: The 2019 melting season
« on: August 22, 2019, 09:20:08 AM »
I doubt this storm will provide much melt,  it is both geographically and temporally in the wrong place for a large melt caused by dispersion or compaction.

The 2012 storm was earlier and over the central Arctic  while this is later and mainly over land.

I'm new to this board and while there is a fantastic amount of data and science on here it surprises me that there is so much desire for melt and records rather than just watching it and learning; it should be about what happens, or potentially happens, not what you want to happen.

7
Arctic sea ice / Re: 2019 vs 2012
« on: August 22, 2019, 08:48:35 AM »
The Atlantic side near Spitzbergen shows more ice than the last couple of years currently.

In regards to 2012 I don't think 2019 is comparable at all due to the unusual weather in 2012  which 2019 has not had. 2019 is now following the general trend for August (so far) but will still be a very low year.

Personally I always ignore 2007 and 2012 as outliers and just look at the general trend.

Once the Arctic gets down to 2012 ice extent levels  repetitively, like it has compared to 2007 now, then that is worth noting.

8
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 15, 2019, 03:23:15 PM »
How many JAXA above 100k per day melts, so far, has 2019 got compared to 2012  and 2007?


9
Arctic sea ice / Re: September predictions challenge 2019
« on: August 15, 2019, 03:10:44 PM »
About 4 million

Not that it matters, the long term trends are what matters.  So I will not be losing any sleep over it.


10
Arctic sea ice / Re: When will the Northwest Passage "open" in 2019?
« on: August 15, 2019, 03:07:51 PM »
In regards to the NW passage being navigable I don't think this is a very interesting topic until year on year you can go north of Victoria Island  and do the direct route.

That would then equate to ships transversing the Northern passage on the eastern side easily, as per all the action currently.


11
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 11, 2019, 07:51:44 PM »
NSIDC Total Area as at 9 August 2019 (5 day trailing average)  3,570,381 km2

The 7 day turnaround has stopped.
On 8 August area loss collapsed.
On this day area loss collapsed even more.

Fascinating.  The collapse is running counter to everything we tend to expect from the current conditions. Consider for example the SST map from Climate Reanalyzer below. Consider also the current circulation and weather conditions.  What is happening is completely counter-intuitive.  It suggests we are missing some major factor.

This melt season is riveting. I think we have still not fully understood what a dramatically cloudier, wetter Arctic will behave like. Your observations about the current circulation and weather conditions is the right question to ask. I have none of the answers.

With all of the early open water and heat uptake, combined with the new cloudier Arctic holding that heat in, it would not surprise me if we have ridiculously warm autumn temps and a very slow refreeze.

Both 2007 and 2012 had very steep refreezes come mid October on the extent graphs. Statistically speaking you could argue 2019, if very low, will follow the same path, just because it is getting back up to to the norm of ice extent with Autumn temperatures at those high latitudes. Just like 2007 and 2012.

A corollary would be an extreme sea ice extent after winter would melt out at a greater rate come summer so a huge drop would be seen. Of course we have not had that recently.

Rate of increase after the summer minimum is not really any thing to go by IMO. Neither a rate of spring melt after a huge winter extent.


12
Arctic sea ice / Re: 2019 vs 2012
« on: August 11, 2019, 07:34:01 PM »
The interesting feature at the moment is that the tongue of ice into the east siberian sea, which had older ice due to failure to melt last few years,  has now almost melted out it seems.

Big loses extent wise always favourable to the Russian side.   




13
Arctic sea ice / Re: When will the Northwest Passage "open" in 2019?
« on: August 09, 2019, 06:45:18 PM »

The Canadian sea ice service bulletins need  to used for this.

To me though it does not matter, because commercial shipping uses the Northern passage and this is more important for a clear passageway.

NW is just for stuck yachts or historically inclined adventurers trying to get through. With 21st C commerce the Northern passage is far more important.

Andy


14
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 09, 2019, 03:34:14 PM »
Extent is 5.72 M sq km and area 3.90 M sq km. Therefore 1.82 is the water area of the 5.72
This represents 32 % of the 5.72 M sq km and so could be a measure of the slushiness of the total ice pack

Given JAXA and NSIDC have some significant differences in numbers, is it legit to mix and match their extents and areas? NSIDC extent for 8/4 is likely to be 5.97M km sq +/-30k with 82% certainty.

Did the math. Just a couple percentage points difference. Close enough for gov't work.

I was always under the assumption that NSIDC used a different algorithm to JAXA, which would perhaps explain the difference.

Neither are parts of the government.

Andy

15
Arctic sea ice / Re: 2019 vs 2012
« on: August 09, 2019, 03:23:51 PM »

We can dumb down the 2019 v 2012 argument simply to Occams razer, and that is that so far there in 2019 there has not been any severe  weather so far that could create enough of a change either way, up or down, to provide an outlier as 2007 and 2012 had.

2007 had an anomalously large number of sunny days coupled with a warm southerly wind from the Russian side,  2012 had warm conditions plus cyclonic wind that provided dispersion and melting.

It would be best to actually ignore these two outliers completely and instead concentrate on the other years in the last 15 years to compare 2019 to.


Andy

16
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: August 09, 2019, 03:16:17 PM »
Is there a multiyear version of this graph  available ?



It's a big melt season this year, but last two years have been quite the reverse.  It's the equivalent of the the Arctic graphs showing 2012 and this year and the medium.

Andy

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