On Sunday, Goulburn got colder than the BOM thought was possible (and a raw data record was “adjusted”).

The BOM got caught this week auto-adjusting cold extremes to be less cold. Lance Pidgeon of the unofficial BOM audit team noticed that the thermometer at Goulburn airport recorded – 10.4°C at 6.17am on Sunday morning, but the official BOM climate records said it was -10.0°C. (What’s the point of that decimal place?) This was a new record for Goulburn in July. (The previous coldest ever July morning was -9.1°C. Though there had been a colder day in Goulburn in August 1994 when it reached -10.9°C). Since colder temperatures have already been recorded in Goulburn, who thought it was a good idea to trim all future minus 10s as if they were automatically “spurious”?

Yesterday, the BOM have acknowledged the error and at first deleted the -10.0 figure, replacing it with a blank space. Then today, after Jennifer Marohasy’s post, they’ve corrected it.

You might think a half degree between friends is not that significant, but this opens a whole can of worms in so many ways — what are these “limits”, do they apply equally to the high side records, who set them, how long has this being going on, and where are they published? Are the limits on […]