The Australian Bureau of Meteorology uses “surrounding” thermometers to adjust for odd shifts in data (caused by things like long grass, cracked screens, or new equipment, some of which is not listed in the site information). The Bureau fishes among many possible sites to find those that happen to match up or , err “correlate” during a particular five year period. Sometimes these are not the nearest site, but ones… further away. So the BOM will ignore the nearby stations, and use further ones to adjust the record.
These correlations, like quantum entanglements, are mysterious and fleeting. A station can be used once in the last hundred years to “correct” another, but for all the other years it doesn’t correlate well — which begs the question of why it had these special telediagnostic powers for a short while, but somehow lost them? Or why a thermometer 300km away might show more accurate trends than one 50km away.
One of the most extreme examples was when Cobar in NSW was used to adjust the records at Alice Springs –almost 1500km away (h/t Bill Johnston). That adjustment was 0.6°C down in 1932 (due to a site move, we’re told). This potentially matters [...]
