On Dec 19, 2009, at 12:28 PM, Dave Wallace wrote:
> My net overall from Rich's note is that while I see problems in averaging temperatures over a large area like Siberia I am not convinced that looking at anomalies is necessarily correct either.
It's not. If your area is too big even the anomaly analysis breaks down. That's why when the real calculation is done 5x5 weighted grids are used. That's one reason why I picked the smaller area around the North Pole to avoid this problem. The fact that all the anomalies line up indicated that the area I chose was not too large. The fact that the absolute temperatures did not line up indicated for absolute temperatures even my smaller area was too large to average. As my example shows anomalies allow you to extend the distance between stations to cover larger areas. At some point this breaks down, however, and you need to grid. Averaging a whole continent without grids -- no matter how clever your averaging technique is -- is clearly silly.
This is how the gridding is done:
http://www.ncdc.noaa.gov/oa/climate/research/Smith-Reynolds-dataset-2005.pdf
Rich Blinne
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Received on Sat Dec 19 15:03:47 2009
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