Furcifer
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- Apr 30, 2007
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OK then, find me a single use of "20th century average" which includes data from before 1900 or after 2000. It doesn't have to be to do with temperature, it doesn't even have to be from a scientific source. Just one example of anyone anywhere using it the way you wrongly thought NOAA was using it.
I suppose you mean other than this thread?
You're the one insisting there's a specific definition. If you look at the first paper I believe they refer to the data set from 1900-1997 as the "20th Century Average". Will that suffice? Or are you now claiming the "scientific definition" can be less than the 100 year period from 1900-2000 but never more? I'm just trying to nail down these goal posts before I bother searching for something that's just going to be dismissed.
I never insisted anything of the sort.
It's the average of all the data that's available for the 19th century, as has been explained to you multiple times. It just so happens that, for global temperatures, that data begins in 1880.
The average given in the paper is for the "full period", which as I've explained numerous times I thought was what NOAA was referring to as the "20th Century Average".
For any quantity where data is available for the whole of the 19th century, the 19th century average would mean the average from 1801-1900.
That's just your opinion. It's probably the most logical opinion and I'm sure you'd be correct more often than not in assuming as much, but the notion that this is some sort of "scientific principle" is completely absurd.
It's the average of all the data that's yet available for the 21st century, as has already been explained to you multiple times. Prior to 2000, anyone who referred to the 20th century average would likewise have meant the average for the century so far.
There go the goal posts. You're just making this up as you go along.
Yes there is, it's the average from (x-1)01-x00 or, where the available data covers a period shorter than that, the average for the years for which data is available. It never, ever, covers a period of more than a century.
Again, this is just your opinion. I don't know why you think this is some universally accepted convention? I know you've convinced yourself, but I don't think anyone else is actually buying this. If you've got data from 1884-2002 and you take the average, what do you think is stopping anyone from calling it the "20th Century Average"? Especially when it's an indirect reference.
You thought very very wrong. Again: improvements to or extensions to the NOAA data set is never ever going to change the way they define "20th century average". Why should it? It's just a convenient, universally understood (by everybody but you) baseline against which to calculate temperature anomalies. For some things NOAA chooses a different base period, for example on the temperature anomaly maps they use a base period of 1961-1990. They're not going to change that one every time they improve or extend their data set either.
Nonsense. The base period is just a preference. I seem to recall from my reading the MLOST based period was just recently changed to the 1971-2000 period. Next year it could change to 1980-2010 just like that.
As it happens, this particular dataset only covers a few years either side of the 20th century, but that doesn't mean that it would ever have been correct to use "20th century average" to describe the average over the whole period. If NOAA had ever done so they would have been a laughing stock.
Again, this is just your opinion and has no basis in fact.
Edited by Gaspode:
Edited for moderated thread.
Every time another full year's data became available all the previously published temperature anomalies would have had to be recalculated, which would be absurd.
You obviously didn't read the papers and follow the discussion if you believe that.
No it doesn't and that's why they don't do it.It makes sense to pick a fixed period in the past for which data is available and calculate anomalies wrt the average of it, and continue to use the same base period as more data becomes available, and improvements are made to the analysis of existing data.
We use a variety of base lines. The 1961-90 period is most often used because it is the period recommended by the WMO (World Meteorological Organisation). This period is also used for UK data so that information for the UK is directly comparable to data from other parts of the world.
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