> You seem to be exagerrating. The vast majority of the earth's surface
> is typically between -15 and +35 at any time. Try it again with a
> smaller range.
I've played a bit more with this, and the biggest relative impact on
temperature anomaly trends occurs when the average anomaly trend is
small, but it's driven by comparatively large local changes of
opposite signs at the extremes of the temperature range.
In one case, I've looked at, I assume 90% of the Earth at 16C, and 10%
at -30C, initially, and then make this go to 15.66C and -25C
respectively, and I get an anomaly of 0.2C using simple averages and
an anomaly of 0C using fourth powers.
What made me go for this example is that I've seen anomaly maps that
look a little like this, with the 10% being the Arctic in winter.
It's interesting, because an anomaly could be driven by a
redistribution of heat without any change in radiative forcing. Well,
ok, with so much heat capacity in the deep ocean over a 20 year time
scale, the world surface temperature could be cooled by 0.5C through
more heat being sunk into the deep ocean, also without any change in
radiative forcing.
I am not sure, whether something useful could be made out of this, but
I've been wondering for a while about what's driving natural 30, 10,
5, 1 year up and down cycles, and in how far it's possible to back out
"weather" from "climate", or
noise coming from redistribution of heat from changes in GHG forcing.
If "weather" was mostly about redistribution of heat (maybe it's more
driven by eg cloud albedo?), then it should be possible to get a much
smoother (and meaningful?) heating up line? This could then maybe also
be directly expressed in W/m2 (measured heat up take) and compared
with estimated forcing (also in W/m2)?
Might it be that monthly world temperature averages would be less
noisy using fourth powers?
Considering what else has been tried to smoothe data, fill in missing
data, correct for time of observation, urban heat islands etc..., it
seems useful to me to try what the effect of this averaging procedure
would be.
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