On Aug 19, 10:33 pm, crandles <[EMAIL PROTECTED]> wrote:
> On Aug 14, 10:55 am, Alastair <[EMAIL PROTECTED]>
>
> > Using that spreadsheet, in the first 13 days of August this year the
> > average ice loss has been 83,000 sq km per day compared with the same
> > 13 days last year when it was 77,000 sq km. On 13 Aug last year the
> > total area was 5.3M sq km. Yesterday it was 6.1M sq km. So this years
> > melt is now faster by 6,000 sq km per day, but has to catch up by
> > 800,000 sq km which would take it 130 days at the current rate of
> > progress. W.'s bet money seems safe :-)
>
> > Cheers, Alastair.
>
> 6 days later the gap should be down circa 36000 sq km but has actually
> fallen to under 600000 sq km - down 204000 sq km. At that rate it
> would only take 19 days and there are more than 19 days of the melt
> season left.
>
> However, I still think W.'s bet money is pretty safe :-)
> I don't think that extrapolation makes much sense:
> 6 days is way too short - almost certainly weather noise.
> Even if you insist on using that 6 days of data it makes more sense to
> say max fall from 18 Aug to minimum in last 5 years is 0.9m sq km from
> 2007. At 72% faster in last 6 days, this still isn't sufficiently
> large a fall.
>
> Area anomaly graphs make an area record look more reachable - even
> likely.
Crandles,
You are correct. My calculations did not allow for the the rate of
melt slowing from mid August in 2007, but the melt rate this year
remaining at around -80,000 sq km per day this year.
This year that rate IS reducing and now approaching -70,000 sq km per
day, but since on a daily basis it is variable it is difficult to be
precise about the rate far less predict its future, but what have I to
lose :-?
There are several factors which affect melt rate such as the intensity
of solar radiation which varies with latitude, and salinity and
temperature of the surface water which can be changed by storms. But
there is also a third factor, and that is thickness of the remaining
ice. I am arguing that with less multi-year ice than last year (since
that was when much of it melted) this year the melt rate will remain
higher than the historical average for this time of year. On that
basis I expect the minimum ice area to be close to last year's. But
who knows :-(
Cheers, Alastair.
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