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Author Topic: Global Sea Ice Extent According to NSIDC  (Read 822 times)

Tigertown

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Global Sea Ice Extent According to NSIDC
« on: August 13, 2017, 10:38:34 PM »
I think this to be important overall, but especially interesting to watch over the next few months. As the extent around Antarctica sputters trying to making nominal gains, the Arctic chugs away at making losses. By the time the Arctic starts freezing, Antarctica's sea ice will start to drop in extent. If the Arctic freezing season is very slow at all about taking off, Wipneus' global extent chart could see larger gaps developed than ever imagined. I expect it(+related charts) to be a main feature in this thread, though if some one wants to do a JAXA chart, that would be great also.

Here we can see how the global extent starts to tail off over the last couple of years or so. I can't help but wonder what far reaching effects this may have on weather.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #1 on: August 13, 2017, 10:42:15 PM »
You really have to look at the year to year chart to get the overall idea, which is why it is the one seen the most.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #2 on: August 14, 2017, 05:51:16 AM »
JAXA numbers are in for the 13th and doing the math, roughly, global sea ice extent is down by another 70k plus. Will be interesting to see what the NSIDC numbers show when these come in. Any combination than has greater losses than gains leaves global extent down. Basic math, sure, but we are now in uncharted territory. This can easily continue with minor exceptions for a couple months.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #3 on: August 14, 2017, 04:17:44 PM »
Down another 48,000 km2 per NSIDC, leaving the total at 22.347 x 106.

gerontocrat

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Re: Global Sea Ice Extent According to NSIDC
« Reply #4 on: August 15, 2017, 12:22:13 PM »
 JAXA total extent as at 14 Aug is 22.228 million km2, some 0,12 million km2 less than the NSIDC figure, i.e. insignificant.

JAXA data says that on average (2007-2016) remaining Arctic extent loss is 0.2 million km2 greater than Antarctic extent gain. However, the end dates of freezing and melting are unlikely to be the same. This complicates matters. So it is with some trepidation, misgivings and a BEWARE notice that I include the little table below of some possible end of season outcomes.

added a graph
« Last Edit: August 15, 2017, 12:47:56 PM by gerontocrat »

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #5 on: August 15, 2017, 03:59:35 PM »
NSIDC is at 22.451 x 106 km2. Up somewhat, and the Arctic sea ice extent actually contributed to the increase.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #6 on: August 16, 2017, 05:36:30 AM »
JAXA extents add up to 22,226,175 km2. Down ever so little.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #7 on: August 16, 2017, 02:07:12 PM »
NSIDC is up, landing at 22.498 x 106. Antarctic sea ice gained more than the Arctic lost.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #8 on: August 17, 2017, 06:35:33 AM »
JAXA lands at 22,225,953 km2, down by a mere 222 km2.

gerontocrat

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Re: Global Sea Ice Extent According to NSIDC
« Reply #9 on: August 17, 2017, 01:01:17 PM »
A Confession:-

Two days ago I posted a table concerning Global Sea Ice Extent with the following warning.

JAXA data says that on average (2007-2016) remaining Arctic extent loss is 0.2 million km2 greater than Antarctic extent gain. However, the end dates of freezing and melting are unlikely to be the same. This complicates matters. So it is with some trepidation, misgivings and a BEWARE notice that I include the little table below of some possible end of season outcomes.

The table was arithmetically correct, but wrong. The methodology of just looking at remaining extent loss and extent gain misses further losses due to the timing of events.
The sequence of events over the next one to 5 weeks seems to be (on average) :-
- arctic extent loss exceeds antarctic extent gain up to the antarctic maximum. Global extent reduces.
- antarctic maximum is reached a few days before arctic minimum meaning further global extent reduction.
- for a few days after arctic minimum (until mid-September) arctic extent gain is still less than antarctic ice loss.
- Arctic freezing gets into high gear and exceeds antarctic extent loss until end-October/Mid-November, at which point Global Sea Ice Extent is at the maximum.
- Then the Antarctic Spring Summer ice extent loss far exceeds arctic winter gain. Global Sea Ice Extent drops.

However, the sequence of events is highly variable. The new table below shows that in the last 10 years the Autumn minimum of global sea ice has happened as early as 23 Aug and as late as the 20 September.

Methinks 'tis the Antarctic that will decide - if 2017 repeats the 2016 low maximum and early rapid extent that made it lowest in the satellite record by November 5th then........

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #10 on: August 17, 2017, 03:22:04 PM »
NSIDC numbers are in for the 16th. SIE for the Arctic is 5.310 x 106 and for the Antarctic is 17.171 x 106. Total being 22.481 x 106 km2. Again, down ever so little.

Looking at Antarctic SIE, mentally extrapolating the graph, I look for a peak very early in September.
« Last Edit: August 17, 2017, 03:31:21 PM by Tigertown »

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #11 on: August 18, 2017, 04:00:01 PM »
NSIDC total is 22.483 x 106 km2. JAXA comes in at 22,229,087 km2. Both up just a tad.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #12 on: August 19, 2017, 04:29:26 PM »
NSIDC totals to 22.44 x 106 km2 for the 18th. Down 43k.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #13 on: August 20, 2017, 11:37:19 AM »
JAXA lands at 22,263,805 km2 for the 19th.

NSIDC numbers total 22.466 km2 for the 19th.
« Last Edit: August 20, 2017, 02:35:31 PM by Tigertown »

gerontocrat

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Re: Global Sea Ice Extent According to NSIDC
« Reply #14 on: August 21, 2017, 02:29:02 PM »
From JAXA data
Since 14th August Arctic sea ice extent loss has been less than average, while Antarctic extent gain has been greater than average. This has resulted in global extent gains as opposed to "normal" global extent losses. This is obvious in the graph below.

In every year except one, the maximum global extent occurs in late October / early November.
The exception is 2016. The maximum global extent that year was on 7th July, at 23.76 million km2. The Oct/Nov minimum happened on 6th November at 23.64 million km2, within a day or two that Antarctic sea ice extent his a new low in the satellite record.
Is this the future? Are the patterns of global extent and gain changing for good ?

The first table shows some possible outcomes of the end of season (Aug/Sept) minimum.
The second table shows some possible outcomes of the Oct/Nov maximum.

Tigertown

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Re: Global Sea Ice Extent According to NSIDC
« Reply #15 on: August 21, 2017, 02:53:13 PM »
NSIDC totals in at 22.514 x 106 km2.