2014 sea ice area and extent data

[crandles]

Is there any other available daily area published, like NSIDC?

The overemphasis of low latitudes doesn't sound good, but it is a long record, consistently applied and seems to work pretty well, being a better guide to minimum extent than extent at least for some date ranges.

I am inclined to think I want something better before abandoning CT area.

[Wipneus]

Jim,

I believe ignoring the true grid size by CT is unique.

Including lake ice is strange (for a sea ice metric), but I have a suspicion that IJIS/Jaxa version 2 does that as well (while version 1 did not).

It is safe to assume that otherwise all sea ice is taken into account (including Baltic Sea, Norwegian Sea, Gulf of Maine, Yellow Sea, Gulf of Alaska) unless indicated otherwise.

The "home brew" amsr2 data that I reported daily last year is calculated using only the 14 main regions. I have not made up my mind yet if that should be changed, it would include more noise than signal was the idea.
 

[Wipneus]

Is there any other available daily area published, like NSIDC?

None that I know of that is also updated near-real-time. Yet there are several that produce gridded data every day nrt.

The overemphasis of low latitudes doesn't sound good, but it is a long record, consistently applied and seems to work pretty well, being a better guide to minimum extent than extent at least for some date ranges.

As long as you use CT area by itself, the problems are not so big. When comparing with other numbers there is an apples-to-apples problem.

I am inclined to think I want something better before abandoning CT area.

My idea is to make the numbers that I calculate available for you this season. Time available to me is limited though. I see if I can start with putting "NSIDC Area" online (that would be from 1979-present).

[Pmt111500]

So, that being the case, where to get climatology of sea ice area? (30 years of internally consistent data). It surely looks like CT SIA should be reworked to correct for the uneven sized grid. Of course the errors at both ends cancel each other out in winter somewhat but that's not necessarily the case in summer. Summer!

oops, Wipneus posted while i was typing.

[Wipneus]

So, that being the case, where to get climatology of sea ice area? (30 years of internally consistent data). It surely looks like CT SIA should be reworked to correct for the uneven sized grid. Of course the errors at both ends cancel each other out in winter somewhat but that's not necessarily the case in summer. Summer!

Actually I wonder about the consistency of this data. Have we any reason to think it is so good?

What I know is that the NSIDC concentration data is the result  from a (continuing) effort to produce such internally consistent data series,  fit for establishing long time trends. Using that data will, properly done, give the required consistent area (and consistent extent to go with it) figures.

[Neven]

Is there any other available daily area published, like NSIDC?

None that I know of that is also updated near-real-time. Yet there are several that produce gridded data every day nrt.

I prefer area numbers over extent numbers, because it gives the most accurate picture once excessive melt ponding from earlier in the season has ended.

Unfortunately, there are plenty of organisations that produce daily extent numbers, but CT is the only one doing daily area numbers. Still, like Wipneus says, CT is useful for interannual comparisons.

My idea is to make the numbers that I calculate available for you this season. Time available to me is limited though. I see if I can start with putting "NSIDC Area" online (that would be from 1979-present).

Hold on, are you saying you're going to produce daily area numbers (when you have the time)? That would be so awesome. If I can help in any way with that, I will also try and find the time.

[ghoti]

Wipneus since you've clearly demonstrated you have a complete handle on the way CT area is miscalculated have you considered producing a corrected sea ice area for the Arctic Sea Ice Graphs page? Would be amazing to see the actual area in years like this that have what has become rare and transient freeze up in the St Lawrence and great lakes.

Amid the crying about the ice's impact on shipping in Canada I finally heard someone point out on radio that 20-30 years ago this much ice was considered an average year.

[Wipneus]

Hold on, are you saying you're going to produce daily area numbers (when you have the time)? That would be so awesome. If I can help in any way with that, I will also try and find the time.

Yes, that seems the logical thing to do. As far as I can see I have everything needed. I will try to get something useful together not too long after the start of the melting season.

[ghoti]

Thing is, quite early in the melting season all the south ice which is distorting the ice area, is going to melt. I feel like this is going to look like the "flash melt" we normally see a bit later because of melt ponding. Once the ice on the lakes and gulf of St Lawrence is gone then the CT area will look much more "normal".

Main thing I see now is that most of the low ice area maximums we are comparing this year too didn't have much ice on the lakes nor the gulf. So we have a false sense of "recovery" while overestimating the amount of what is actually Arctic Sea Ice. Would feel difference if this year's maximum was the lowest of the last 30 years.

Sure the coming melt will depend on the weather but in reality it is starting the melt season at a low point.

[jdallen]

2) The NSIDC sea ice concentration data is specified on a polar stereographic  grid. This grid is non equal area, at 70^o latitude the grid cell measures 25x25 km=625 km². At the pole the true size is about 6% bigger, at the latitude of St.Lawrence it is a lot smaller: 66% of the nominal size.
CT ignores the true size and thus amplifies the St.Lawrence by a factor 3/2.

I didn't realise that, don't get the time to read everything here. It's not good. I'll have to reconsider whether I continue to use CT Area.

For that, and other reasons, I plan to retire my CT area logging and visualizations and switch to a different metric, perhaps within a month or so.

This is a very unfortunate revelation.  The inverse is, it would tend to understate (slightly) changes in the CAB.  At the very least, it introduces very high uncertainty (> 10%) into the numbers.  Would make Year over Year comparison difficult over short time frames.  Fortunately, over longer time frames, the nature of statistics and probability reduce that problem.

[idunno]

The climate average 1979-2008 CT ice area figure peaked 4 days back, on 11 March, (Day yyyy.1891)...

 2014.1836  -1.1562057  12.9566565  14.1128626
 2014.1863  -1.2448727  12.8873091  14.1321821
 2014.1891  -1.1286273  13.0077171  14.1363440
 2014.1918  -1.0726961  13.0525837  14.1252794
 2014.1946  -0.9525744  13.1593428  14.1119175
 2014.1973  -0.8094620  13.2780533  14.0875149

However, as I have previously noted, in recent years the curve has shifted to the right during winter, with huge negative anomalies in late Fall, and very small negative anomalies in early Spring.

I expect to see the negative anomalies (Column 1 above) shrink for at least the next 30 days. Peak WUWT Arctic Sea Ice coverage anticipated around the Ides of April.

See, for example; this recent year...

 201x.1836  -0.5227620  13.6094198  14.1321821
 201x.1863  -0.5292391  13.6071053  14.1363440
 201x.1891  -0.4820102  13.6432695  14.1252794
 201x.1918  -0.5290352  13.5828819  14.1119175
 201x.1946  -0.5559658  13.5315495  14.0875149
 201x.1973  -0.5618051  13.5200644  14.0818691
 201x.2000  -0.6080314  13.4446287  14.0526600
 201x.2028  -0.5867017  13.4490089  14.0357103
 201x.2054  -0.4630685  13.5609722  14.0240412
 201x.2083  -0.3832543  13.6294451  14.0126991
 201x.2109  -0.5139271  13.4831829  13.9971104
 201x.2137  -0.2741723  13.7006741  13.9748468
 201x.2164  -0.3097457  13.6579199  13.9676657
 201x.2192  -0.3677080  13.6005507  13.9682589
 201x.2219  -0.4103398  13.5414495  13.9517889
 201x.2246  -0.3774471  13.5757990  13.9532461
 201x.2274  -0.3973767  13.5457191  13.9430962
 201x.2301  -0.3739171  13.5517349  13.9256525
 201x.2329  -0.3198970  13.5742121  13.8941088
 201x.2356  -0.3085823  13.5586052  13.8671875
 201x.2384  -0.2130075  13.6367016  13.8497095
 201x.2411  -0.1403615  13.7085104  13.8488722
 201x.2439  -0.1256468  13.7064037  13.8320503
 201x.2466  -0.1731139  13.6488171  13.8219309
 201x.2493  -0.2383550  13.5509872  13.7893419
 201x.2521  -0.2680253  13.4791651  13.7471905
 201x.2548  -0.3105773  13.3990307  13.7096081
 201x.2576  -0.2124027  13.4671679  13.6795702
 201x.2603  -0.2683759  13.3804970  13.6488733
 201x.2631  -0.3800559  13.2370482  13.6171045
 201x.2657  -0.4217986  13.1631298  13.5849285
 201x.2684  -0.4025667  13.1420774  13.5446444
 201x.2712  -0.3506708  13.1437597  13.4944305
 201x.2739  -0.3651701  13.0986910  13.4638615
 201x.2767  -0.3785109  13.0444088  13.4229193
 201x.2794  -0.3267768  13.0428562  13.3696327
 201x.2822  -0.2355201  13.0951643  13.3306847
 201x.2849  -0.1749455  13.1154699  13.2904158
 201x.2877  -0.1364361  13.1236439  13.2600803
 201x.2904  -0.1163378  13.1125441  13.2288818
 201x.2931  -0.0739577  13.1254025  13.1993599
 201x.2959  -0.0594924  13.0958014  13.1552935
 201x.2986  -0.0811954  13.0136461  13.0948420
 201x.3014  -0.0981108  12.9725018  13.0706129
 201x.3041  -0.0458881  12.9906597  13.0365477
 201x.3069  -0.0384333  12.9621344  13.0005674
 201x.3096  -0.0304987  12.9304876  12.9609861
 201x.3124  -0.0363239  12.8770418  12.9133654
 201x.3151   0.0027094  12.8662653  12.8635559
 201x.3177  -0.0463200  12.7772894  12.8236094

...culminating in the POSITIVE anomaly of 2.7km2 (a massive 2.7 BILLION m2, or 27 TRILLION cm2) which surely should have been the final nail in the coffin of the whole CAGW hoax, etc.

Er, until later the same year...

 2012.6959  -2.4786112   2.2620590   4.7406702
 2012.6986  -2.5096879   2.2397964   4.7494841
 2012.7014  -2.5251360   2.2340095   4.7591457
 2012.7041  -2.5055733   2.2648528   4.7704258
 2012.7069  -2.5101068   2.2799201   4.7900267
 2012.7096  -2.5759177   2.2444446   4.8203626
 2012.7123  -2.5797634   2.2379336   4.8176970
 2012.7151  -2.5071130   2.3031538   4.810266

[ChrisReynolds]

Hold on, are you saying you're going to produce daily area numbers (when you have the time)? That would be so awesome. If I can help in any way with that, I will also try and find the time.

Yes, that seems the logical thing to do. As far as I can see I have everything needed. I will try to get something useful together not too long after the start of the melting season.

I've been looking at using this data to calculate area daily:
ftp://sidads.colorado.edu/pub/DATASETS/nsidc0051_gsfc_nasateam_seaice/final-gsfc/north/daily/
However I need to be able to get Excel VBA to open files over the 'net, and that is far from trivial for someone with limited coding experience like myself.

Actually, I've just manually downloaded a few years, about 30 min per year. I'll do that over the next few weeks.

Those binary files have a 300byte header, followed by 136192 bytes, which is a 304X448 grid.

Grid box area masks available from here:
https://nsidc.org/data/polar_stereo/tools_geo_pixel.html
No need to bother with grid box location data - I do not intend to plot maps, these are already available. Although grid box locations may be useful for some other things I've been pondering.

Land/Ocean masks available from here:
http://nsidc.org/data/polar_stereo/tools_masks.html
Not sure if I need these...

I've already got the 25km grid box regions in a binary file derived from CT's region image.

I'll see if I feel like coding later today and may try doing a couple of years of calculating area and extent. See how the extent matches with NSIDC Extent. Shouldn't be too hard to do area, extent, and both with regional breakdowns.

Looks like essentially the same task as dealing with the PIOMAS gridded data.

Wipneus,
If you can see where I've gone wrong please do point out.

[Wipneus]

That looks about right Chris.

Plotting is real easy: the grid cells are the pixels and gives an acceptable image without bothering with the coordinates. Apart from getting a mirror- or up-side down image, that is.

Look for the aequivalent of:

writePNG( array, filename.png)

Values are coded as follows:

#0-250  concentration
#251 pole hole
#252 unused
#253 coastline
#254 landmask
#255 NA

[Jim Hunt]

However I need to be able to get Excel VBA to open files over the 'net, and that is far from trivial for someone with limited coding experience like myself.

I'll see if I feel like coding later today and may try doing a couple of years of calculating area and extent.

I have a sudden urge to do something similar, but with this data instead: http://osisaf.met.no/p/ice/

Is Excel really the best tool for the job? What software (suite?) do you use Wipneus?

[Neven]

Not that I mind you discussing it here (as it is relevant to the thread), but you could take the detailed discussion to the Developers Corner to make it easier to follow and find back.

[Wipneus]

Is Excel really the best tool for the job? What software (suite?) do you use Wipneus?

In my opinion it is the worst, but for Chris it is somehow the only option. We have decided not to discuss that anymore between us.

I am using at the moment R, great for interactive work on the desktop. For what I have in mind, some scripts running on a Raspberry Pi, I intend to rewrite the stuff in Python.

I have a sudden urge to do something similar, but with this data instead: http://osisaf.met.no/p/ice/

I am aware of it, and intend to use it as well at some time. If I remember correctly it is on a 10x10km grid. Grid cell area of such  a grid is a nut that I have already cracked, when the time comes you need it contact me.

Not that I mind you discussing it here (as it is relevant to the thread), but you could take the detailed discussion to the Developers Corner to make it easier to follow and find back.

Yes of course, I will start a thread for follow ups.

[ChrisReynolds]

Wipneus,

Thanks for the tip regarding values used.

Jim,

But that data doesn't seem to go back to 1979, anway let us know what you come up with. I'm using Visual Basic, which is the same programming language used for Excel macros, all of my work with PIOMAS data is done using that combo.

Neven,

I did think that, but really there isn't much discussion needed.

[Jim Hunt]

I am using at the moment R, great for interactive work on the desktop. For what I have in mind, some scripts running on a Raspberry Pi, I intend to rewrite the stuff in Python.

You would seem to be a man after my own heart Wipneus! I have a cluster of Raspberry Pis and a UDOO quad amongst my other playthings!

[Jim Hunt]

But that data doesn't seem to go back to 1979

I'm more interested in recent data just at the moment Chris, to assist Snow White and I  in our current battle against the forces of darkness!

[Jim Pettit]

IJIS Extent:

14,329,192 km² (15 March, 2014)
(2014 maximum to-date)
Five years from 2004-2013 reached their maximum on or before this date. Five others, including four of the past five, did not.

Up 23,655 km² from previous day.
Up 245,853 km² over past seven days (daily average: 35,122 km²)
Up 303,820 km² for the month of March (daily average: 20,255 km²)

246,627 km² below 2000s average for this date.
98,284 km² below 2010s average for this date.
337,119 km² below 2012 value for this date.

Fifth lowest for the date (behind 2006, 2007, 2011, and 2005).

Fourth lowest March-to-date average on record (behind 2011, 2006, and 2007).

[Pmt111500]

Wipneus:

Excel: In my opinion it is the worst, but for Chris it is somehow the only option. We have decided not to discuss that anymore between us.

I am using at the moment R, great for interactive work on the desktop.

I'm not defending Excel as a tool for science, but Excel or similar spreadsheet-based thing is the easiest to access for most people outside science (such as accountants, economists, beginner social scientist etc.) so a version of a time series record in that sort of file format (or heaven forbid, some *.csv) would likely increase the number of people who have some statistics on climate variables much more than other formats. F.e. I have not installed R yet, though I know where to get it, partly since it's much easier to go wrong with power tools than hand tools and hurt oneself in the process.

[Wipneus]

I'm not defending Excel as a tool for science, but Excel or similar spreadsheet-based thing is the easiest to access for most people outside science (such as accountants, economists, beginner social scientist etc.) so a version of a time series record in that sort of file format (or heaven forbid, some *.csv) would likely increase the number of people who have some statistics on climate variables much more than other formats.

That is an entirely different matter, and I fully agree with you here. If the data is somehow tedious to import in spreadsheets, then that is something i would like to see fixed.

I am wondering: what is wrong with csv?

[LRC1962]

"Amid the crying about the ice's impact on shipping in Canada I finally heard someone point out on radio that 20-30 years ago this much ice was considered an average year."
Up until about 20 years ago, the Great lakes/Seaway was closed to all shipping Starting sometime in Nov/Dec I think. Used to hear the announcement on the radio.
That has now stopped I think more to do with changing ice then better ships.

[Pmt111500]

I am wondering: what is wrong with csv?

Nothing wrong with csv as long as it's easy to convert.

[Jim Pettit]

IJIS Extent:

14,388,611 km² (16 March, 2014)
(2014 maximum to-date)
Seven of the years from 2004-2013 reached their maximum on or before this date (both 2011 and 2012 reached their maximum on this day).

Up 59,419 km² from previous day. (NOTE: extent has increased on all but three of the past nineteen days).
Up 372,685 km² over past seven days (daily average: 53,241 km²)
Up 363,239 km² for the month of March (daily average: 22,702 km²) (NOTE: extent increased 384,065 km² during the entire month of February.)

160,788 km² below 2000s average for this date.
65,194 km² below 2010s average for this date.
304,473 km² below 2012 value for this date.

Sixth lowest for the date (behind 2006, 2007, 2011, 2005, and 2004).

Fourth lowest March-to-date average on record (behind 2006, 2001, and 2007).

[werther]

Well, it looks like a concerted attempt by the peripheral Seas to make it look like a recovery. Makes me wonder if they're on anybodies payroll?
Besides wonkyness, I've really checked NCEP/NCAR, up to 14 March. Whether there's a discernable cold snap in the Arctic. There isn't. It's just that the negative temp anomalies randomly work out over Bering, Okhotsk, Baffin, East Greenland Sea and Barentsz on the same time.
Won't last...

[ChrisReynolds]

This isn't turning out to be quite so straightforward as I expected.

The attached images show my calculated extent and the error with NSIDC Extent, both are for 2012.

Initially I left the 'Pole Hole' out, just to get things working, the result is shown in the first image. As concentration and area drops in the summer my calculated area drops substantially below NSIDC Exent (down to 4%). So following the description on this page:
https://nsidc.org/data/smmr_ssmi_ancillary/area_extent.html
Where it is stated:

There is a circular section over the Northern Hemisphere pole (known as the "pole hole") which is never measured due to orbit inclination. For the purposes of ice extent, pixels under the pole hole are always considered to be at least 15 percent. For total ice-covered area, the pixels under the pole hole are not used.

I simply take the 'Pole Hole' as being over 15% concentration. Now the error leaps to +6% in the summer, as seen in the second graph.

I've tried: Both V2 and V3 area files (psn25area_v3.dat and psn25area_v2.dat). Landmask has a negligible effect, but is now included in all calculations. The range of concentration is from 0 to 250, so 15% is 37.5, there is negligible difference between using 38 and 37 as the cut offs for including a grid cell area in the total extent calculation.

Wipneus,

Do you know if NSIDC Exent is calculated using the 25km grid, or if they use the 12.5km grid?

[Wipneus]

Chris, 25km is the one to use.

[Neven]

Gentlemen, best use the Calculating area and extent from gridded concentration data thread that Wipneus opened in the Developers Corner, as it will be easier to find there for others (and yourselves).

I've copied your comments and pasted them there. Now we have a backup. 

[Pmt111500]

with the last weeks unprecedented spurt up in CT SIA numbers the chances that 2014 has the lowest maximum area have vanished. It still looks that my original statistical estimate of the peak location could be correct. After Wipneus' revelation that the grid CT SIA uses is skewed in the north-south direction (http://forum.arctic-sea-ice.net/index.php/topic,743.msg21925.html#msg21925) and Werther (http://forum.arctic-sea-ice.net/index.php/topic,743.msg22099.html#msg22099) stating the current spurt occrued due increases on peripheral seas, I'm not very keen on saying anything of the accurate date of the peak ice. Though out of habit will probably do so anyway. (there goes the plan to use CT SIA on anything quantitative.) There's still slight chance of 2014 being the lowest in the monthly weighted series, if the real elusive peak is about today, but I'm not counting on it. If people can't get area numbers right, how do they do with volumes (rhetorical). and some people wondered why I didn't pursue a scientific career (this sort of thing goes on everywhere in science, at least it currently feels like it)

[Jim Pettit]

IJIS Extent:

14,419,194 km² (17 March, 2014)
(2014 maximum to-date)

Up 30,583 km² from previous day. (NOTE: extent has increased on all but three of the past twenty days).
Up 393,470 km² over past seven days (daily average: 56,210 km²)
Up 393,822 km² for the month of March (daily average: 23,166 km²) (NOTE: extent increased roughly the same amount--408,670 km²--over the entire month of February.)

116690 km² below 2000s average for this date.
33,615 km² below 2010s average for this date.
261,742 km² below 2012 value for this date.

Sixth lowest for the date (behind 2006, 2007, 2005, 2011, and 2004).

Fourth lowest March-to-date average on record (behind 2006, 2011, and 2007).

CT area:

13,402,321 km² (17 March, 2014)
2014 maximum to-date: 13,444,588 on 15 March (If it stands, this would be the fourth lowest maximum on record, behind 2011, 2007, and 2006)
NOTE: The recent five-day increase of 557,279 km² is by a huge margin the largest ever recorded in the month of March. In fact, only one similar increase has ever even been measured in the month of February, and that was in the first week of the month in 1997.)

Up 40,517 km² from previous day
Up 515,012 km² over past seven days (daily average: 73,573 km²)
Up 357,894 km² for the month of March (daily average: 21,053 km²)

219,751 km² below 2000s average for this date.
51,179 km² below 2010s average for this date.
158,651 km² below 2012 value for this date.

Fifth lowest for the date (behind 2006, 2011, 2007, and 2005)

Third lowest March-to-date average on record (behind 2011 and 2006).

[davidsanger]

IJIS Extent:
Seven of the years from 2004-2013 reached their maximum on or before this date

Jim, it looks to me that only 2010 (March 31st) was later in that period.

and also 2003 (March 21st)

[Jim Pettit]

IJIS Extent:

14,437,490 km² (18 March, 2014)
(2014 maximum to-date)

Up 18,296 km² from previous day. (NOTE: extent has increased on 17 of the last 21 days).
Up 318,943 km² over past seven days (daily average: 45,563 km²)
Up 412,118 km² for the month of March (daily average: 22,895 km²) (NOTE: extent increased less--408,670 km²--over the entire month of February.)

92,466 km² below 2000s average for this date.
1,290 km² above 2010s average for this date.
242,486 km² below 2012 value for this date.

Sixth lowest for the date (behind 2006, 2007, 2011, 2005, and 2004).

Fourth lowest March-to-date average on record (behind 2006, 2011, and 2007).

CT area:

13,393,762 km² (18 March, 2014)
2014 maximum to-date: 13,444,588 on 15 March (If it stands, this would be the fourth lowest maximum on record, behind 2011, 2007, and 2006)

Down 8,559 km² from previous day
Up 386,044 km² over past seven days (daily average: 55,149 km²)
Up 349,335 km² for the month of March (daily average: 19,407 km²)

234,851 km² below 2000s average for this date.
70,839 km² below 2010s average for this date.
235,684 km² below 2012 value for this date.

Fifth lowest for the date (behind 2006, 2011, 2007, and 2005)

Third lowest March-to-date average on record (behind 2011 and 2006).

[Shared Humanity]

Looks like we have a real sea ice recovery going on.   

[epiphyte]

Looks like we have a real sea ice recovery going on.   

I assume you mean that in the same sense that "the Charge of the Light Brigade"  was a territorial gain!

Half a league, half a league,
  Half a league onward,
All in the valley of Death,
  Rode the six hundred.

[it seemed an apt analogy since Crimea is in the news again these days...]

[Jim Pettit]

IJIS Extent:

14,448,299 km² (19 March, 2014)
(2014 maximum to-date)

Up 10,809 km² from previous day. (NOTE: extent has increased on 18 of the last 22 days).
Up 214,470 km² over past seven days (daily average: 30,639 km²)
Up 422,927 km² for the month of March (daily average: 22,259 km²) (NOTE: extent increased less--408,670 km²--over the entire month of February.)

62,263 km² below 2000s average for this date.
39,020 km² above 2010s average for this date.
214,470 km² below 2012 value for this date.

Eighth lowest for the date.

Fourth lowest March-to-date average on record (behind 2006, 2011, and 2007).

CT area:

13,369,513 km² (19 March, 2014)
2014 maximum to-date: 13,444,588 on 15 March (If it stands, this would be the fourth lowest maximum on record, behind 2011, 2007, and 2006)

Down 24,249 km² from previous day
Up 316,929 km² over past seven days (daily average: 45,276 km²)
Up 325,086 km² for the month of March (daily average: 17,110 km²)

279,481 km² below 2000s average for this date.
53,875 km² below 2010s average for this date.
113,670 km² below 2012 value for this date.

Fifth lowest for the date (behind 2006, 2011, 2007, and 2005)

Third lowest March-to-date average on record (behind 2011 and 2006).

[Phil.]

Looks like we have a real sea ice recovery going on.   

I assume you mean that in the same sense that "the Charge of the Light Brigade"  was a territorial gain!

Half a league, half a league,
  Half a league onward,
All in the valley of Death,
  Rode the six hundred.

[it seemed an apt analogy since Crimea is in the news again these days...]

Indeed, my grandmother's uncle took part in that fiasco, and survived it!

[BornFromTheVoid]

A busy few days, sorry for the delay.

Update for the week to March 15th

The current 1 day extent is 14,867,750km2, while the 5 day mean is on 14,780,270km2

The daily anomaly (compared to 79-11) is at -566,420km2, an increase from -954,690km2 last week. The anomaly compared to the 07, 11 and 12 average is at +118,663km2, a change from -262,620km2. We're currently 6th lowest on record, compared to 1st lowest last week.

The average daily change over the last 7 days was +48.7k/day, compared to the long term average of -6.8k/day, and the average of the last 5 years of +1.1k/day.

The average long term change over the next week is -12.4k/day, with the average of the last 5 years being -8.3k/day.

The change so far this month is the 3rd most positive on record. The record the largest March gain, at least +8.6k/day is needed, while the largest loss requires -44.6k/day for the remainder of the month.

[Jim Pettit]

IJIS Extent:

14,448,415 km² (20 March, 2014)
(2014 maximum to-date)

Up 117 km² from previous day. (NOTE: extent has increased on 19 of the last 23 days, including the last 11 consecutive ones).
Up 147,908 km² over past seven days (daily average: 21,130 km²)
Up 423,044 km² for the month of March (daily average: 21,152 km²)

41,560 km² below 2000s average for this date.
66,065 km² above 2010s average for this date.
212,194 km² below 2012 value for this date.

Eighth lowest for the date.

Fourth lowest March-to-date average on record (behind 2006, 2011, and 2007).

CT area:

13,443,448 km² (20 March, 2014)
2014 maximum to-date: 13,444,588 on 15 March (If it stands, this would be the fourth lowest maximum on record, behind 2011, 2007, and 2006)

Up 73,935 km² from previous day
Up 284,105 km² over past seven days (daily average: 40,586 km²)
Up 399,021 km² for the month of March (daily average: 19,951 km²)

188,247 km² below 2000s average for this date.
17,617 km² below 2010s average for this date.
257,226 km² below 2012 value for this date.

Sixth lowest for the date.

Third lowest March-to-date average on record (behind 2011 and 2006).

[BornFromTheVoid]

New max on the NSIDC data of 14,960,310km2 for the 20th, making it (provisionally) the 5th lowest maximum of record.

[Jim Pettit]

IJIS Extent:

14,408,834 km² (21 March, 2014)
(2014 maximum to-date: 14,448,416 km²[/b] on 20 March)

Down 39,582 km² from previous day. (NOTE: first decrease in extent since 09 March, and only the fourth since 25 February).
Up 103,297 km² over past seven days (daily average: 14,757 km²)
Up 383,462 km² for the month of March (daily average: 18,260 km²)

63,852 km² below 2000s average for this date.
69,448 km² above 2010s average for this date.
189,992 km² below 2012 value for this date.

Eighth lowest for the date.

Fourth lowest March-to-date average on record (behind 2006, 2011, and 2007).

CT area:

13,451,423 km² (21 March, 2014)
2014 maximum to-date (If it stands, this would be the fourth lowest maximum on record, behind 2011, 2007, and 2006)

Up 7,974 km² from previous day
Up 173,368 km² over past seven days (daily average: 24,767 km²)
Up 406,995 km² for the month of March (daily average: 19,381 km²)

144,597 km² below 2000s average for this date.
26,661 km² above 2010s average for this date.
206,498 km² below 2012 value for this date.

Seventh lowest for the date.

Third lowest March-to-date average on record (behind 2011 and 2006).

[Pmt111500]

and with that value for CT SIA the chase for the lowest maximum, on longest sensible averaging procedure I recognize (lunar month), is finally over. Value for march 7th is now (I think) the second lowest maximum (after 2011) 13,035 Mkm2, this is ~8000km2 more than the value for 2011, but as there are some issues of north-south distribution of grid cell sizes, I'm tempted to call it even. With a quick turn around the monthly average won't rise much, and any higher figures might fit in to the error limit of this. I might use +-100000km2 (chosen arbitrarily) to say values are even. Meh, accurate yeah.

[Jim Pettit]

IJIS Extent:

14,325,446 km² (22 March)
(2014 maximum to-date: 14,448,416 km² on 20 March) (NOTE: despite the fact that two of the past four years [2010 & 2012] have seen extent increases after this date large enough to set a new maximum were they to happen this year, the forecast says that's not likely, so I'll be not-all-that-brave, and call that this year's maximum. But I'll keep a pot of crow stew simmering on the back burner just in case.)

Down 83,388 km² from previous day. (NOTE: second-largest one-day decrease this year).
Down 3,746 km² over past seven days (daily average: -535 km²)
Up 300,074 km² for the month of March (daily average: 13,640 km²)

132,465 km² below 2000s average for this date.
14,087 km² above 2010s average for this date.
255,377 km² below 2012 value for this date.

Seventh lowest for the date.

Fifth lowest March-to-date average on record.

CT area:

13,487,337 km² (22 March, 2014)
2014 maximum to-date (If it stands, this would be the fifth lowest maximum on record.)

Up 35,915 km² from previous day
Up 42,749 km² over past seven days (daily average: 6,107 km²)
Up 442,910 km² for the month of March (daily average: 20,132 km²)

71,358 km² below 2000s average for this date.
86,362 km² above 2010s average for this date.
113,214 km² below 2012 value for this date.

Eighth lowest for the date.

Fourth lowest March-to-date average on record (behind 2011, 2006, and 2011).

[davidsanger]

IJIS/JAXA drop of -169,382 sq km  seems to be the largest daily drop of any day before June 1st in the 2003-2014 time period

[leaving aside a really bizarre drop/rebound on feb 29,2012]

[BornFromTheVoid]

Update for the week to March 22nd

The current 1 day extent is 14,757,080km2, while the 5 day mean is on 14,882,700km2

The daily anomaly (compared to 79-11) is at -589,980km2, an increase from -566,420km2 last week. The anomaly compared to the 07, 11 and 12 average is at +93,220km2, a change from -118,663km2. We're currently 5th lowest on record, compared to 6tht lowest last week.

The average daily change over the last 7 days was -15.8k/day, compared to the long term average of -12.4k/day, and the average of the last 5 years of -8.3k/day.

The average long term change over the next week is -12.2k/day, with the average of the last 5 years being -1.2k/day.

The change so far this month is the 4th most positive on record. The record the largest March gain, at least +34.3k/day is needed, while the largest loss requires -101.7k/day for the remainder of the month.

At this stage, it's probably safe to call the daily maximum as 14,960,310km2 on the 20th, and the 5 day maximum as 14,912,600km2 on the 21st.

[Jim Pettit]

IJIS Extent:

14,156,064 km² (23 March)
(2014 maximum to-date: 14,448,416 km² on 20 March) (NOTE: No previous year has seen a post-March 23 increase anywhere near the 292,000 km² it would take to to supersede this to-date maximum.)

Down 169,382 km² from previous day. (NOTE: largest one-day decrease in at least a year [more info to come]).
Down 232,547 km² over past seven days (daily average: -33,221 km²)
Up 130,692 km² for the month of March (daily average: 5,682 km²)

297,252 km² below 2000s average for this date.
120,964 km² below 2010s average for this date.
414,335 km² below 2012 value for this date.

Fifth lowest for the date.

Fifth lowest March-to-date average on record.

CT area:

13,438,232 km² (23 March, 2014)
(2014 maximum to-date: 13,487,337 km² on 22 March. If it stands, this would be the fifth lowest maximum on record.)

Down 49,106 km² from previous day
Up 76,428 km² over past seven days (daily average: 10,918 km²)
Up 393,805 km² for the month of March (daily average: 17,122 km²)

108,904 km² below 2000s average for this date.
75,774 km² above 2010s average for this date.
103,218 km² below 2012 value for this date.

Eighth lowest for the date.

Fourth lowest March-to-date average on record.

[Jim Hunt]

At this stage, it's probably safe to call the daily maximum as 14,960,310km2 on the 20th, and the 5 day maximum as 14,912,600km2 on the 21st.

Thanks BFTV. Would you like to add another pot of crow stew to the back burner on Jim's stove?

[Buddy]

This is setting up to be a WILD year of Arctic melt and Greenland melt.....  In larger context, it is just one of MANY crazy "melt years" to come over the next hundred years.

As always....thanks to Jim P for these updates.....they are timely and fascinating as history continues to unfold....

[Shared Humanity]

At this stage, it's probably safe to call the daily maximum as 14,960,310km2 on the 20th, and the 5 day maximum as 14,912,600km2 on the 21st.

Thanks BFTV. Would you like to add another pot of crow stew to the back burner on Jim's stove?

A generous man would have made enough stew for everyone.

[BornFromTheVoid]

Thanks BFTV. Would you like to add another pot of crow stew to the back burner on Jim's stove?

Sure why not! A slight increase today of 6,770kkm2.  I'd say we're more likely to be below 14.5 million km2 by next weekend than to set a new maximum.