"N_Cook" wrote in message
...


Every day seems to be 7 paces forward and then next day 6 paces back.
I can see that with different sat passes and different traverses and
different sun angles , then sea ice cliffs could be included as surface
area
in some passes and not other passes and broken ice appearing as solid in
some passes. Then an average taken , but why the implied 7 figure
accuracy.


New result are now available with yesterday's figure going up from
3,595,781 to 3,674,844 and today's figure given as 3,593,750, a new
record. But today has still another twelve hours to go so the value
they quote for that is unlikely to remain true.

I think that you are taking these values too seriously. They are only best
estimates using a satellite designed to measure wind speeds, now that the
original satellite has packed up. The values they are publishing are only
the results of their calculations, not a true value for the ice extent, if
such actually exists! Across at NSIDC, http://nsidc.org/arcticseaicenews/ ,
the data they use:
ftp://sidads.colorado.edu/DATASETS/N...th/daily/data/ gives
values of 3,488340 and 3,576,350 for Thursday and Friday compared with
3,676,406 and 3,664,531 from JAXA.

Near the botom of their web page JAXA do say :

"In general, sea-ice extent is defined as a temporal average of several days
(e.g., five days) in order to eliminate calculation errors due to a lack of
data (e.g., for traditional microwave sensors such as SMMR and SSM/I).
However, we adopt the average of latest two days (day:N & day:N-1) to
achieve rapid data release. Only for the processing of WindSat data (Oct. 4,
2011 to the present) the data of the day before yesterday (day:N-2) is also
sometimes used to fill data gaps." and "... SIC data could have errors of
10% at most ..."

Using the JAXA data and my algorithm, it now seems unlikely that their
value will drop below 3,500,000 sq km THIS year.

Cheers, Alastair.