Frostgate 1 – Australian Bureau of Meteorology altering temperature data – rewriting Melbourne climate history by eliminating many frostsJune 25th, 2012 by Warwick Hughes
Jointly with Ed Thurstan.
Since the mid 1990′s the BoM has produced several adjusted versions of Australian temperature history – these add more warming trend than the raw data show and many climate sceptics have been rightly critical of these BoM “high quality” (HQ) versions – what could be termed “stroked and tweaked” data.
In March the BoM released its latest version of adjusted temperature data termed ACORN SAT and time series of daily max and min ACORN data for 111 stations can be downloaded.
There has been criticism of the way BoM HQ or ACORN data reduces hot days from the past – particularly pre mid 20th Century – which increases the warming trend. But fancy arguments can be raised as to whether the temperature in the distant past was measured in an exactly equivalent manner to modern data. However frosts are a different matter – constituting a marker of air temperature independent of thermometers.
Examining both the ACORN daily minimum temperature data for Melbourne Regional Office (BoM Station 86071) and the raw BoM data we found many frost mornings in the raw data (minimums below 0 degrees C) that were altered to non-frost days in the ACORN version (minimums above 0 degrees C) – see this example from August 1944 where the BoM in their 2012 ACORN data wipe out 3 frost days.
However in this case it is bad luck for the BoM that the online newspaper archive of the National Library of Australia has the Argus newspaper for the 9th August 1944 reporting the “THIRD SUCCESSIVE FROST”.
These inconvenient facts expose the BoM as writers of climate fairy stories -
from what should be the best maintained set of weather instruments in the Nation – expertly observed.