On Sat, 28 Sep 2013 00:52:14 -0700 (PDT)
exmetman wrote:

Graham

Interesting, certainly a curve that you could fit to but not a line!

I wonder were they get the stats for those years when satellite data
was just not available?


From satellites for a start! ;-) The 1979 start-date for 'satellite'
data is rather misleading. What it refers to is data from a particular
sensing system. When I started working in the Met Office Ice Unit in
1965, we were using ship reports, aircraft recces (including some
reports from commercial trans-polar flights), plus harbour and
sea-road reports. About a year later I started analysing Tiros satellite
pictures. Initially, these were visual only but a few years later we
started receiving infra-red pictures and, by about 1970,
minimum-brightness photos. The latter came by air-mail from USA along
with photographic strips of all polar-orbiting satellite data. We also
used satellite photos provided daily by the German DWR.

Danish records of Arctic ice conditions from 1893-1956 are available
from here in both PDF and jpeg format.
http://brunnur.vedur.is/pub/trausti/
The Met Office should have monthly charts available from 1959 to
1982(?).



--
Graham P Davis, Bracknell, Berks.
'In wine there is wisdom, in beer there is freedom, in water there is
bacteria.' - Benjamin Franklin