It's not weighted by area but by degree, hence the circle 89-90 has the same weight as the much larger circle 80-81.
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Peter Ellis wrote:
Easiest way to visualise this is to appreciate that DMI are effectively calculating the average temperature across a Mercator projection of the globe.The further North you go, the bigger the distortion.
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litesong wrote:
Yes, as the explanatory notes state:
"Plus 80N Temperatures - explanation.......Therefore, do NOT use this measure as an actual
physical mean temperature of the arctic. The 'plus 80 North mean temperature'
graphs can be used for comparing one year to an other."