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Below is an original web page built in early January 2012 to demonstrate the rounding errors common to the BoM's Fahrenheit and Celsius temperature recordings. See audit background.
Cape Leeuwin temperature audit
Cape Leeuwin 9518 min and max - Mar 1978 - Jul 1982 most but not all .5 and .0C rounded.
May 19 1998 - Jan 10 2003 min and max all rounded to .0C.
Cape Leeuwin 9518 min - within raw minima daily data, there were 38,370 days recorded from 1907 to 2011/12. Of these, 9,488 were either .5C or .0C = 24.7%. Of the 9,488 at .5 or .0C, 2,638 were before September 1972 = 27.8%. In total, 427 days had no temperature = 1.1%.
1907-1972 represented 62.9% of the time span but had only 27.8% of .5 and .0C min temps.
598 of the 2,638 pre 72 were 10C exactly (=50F exactly).
Cape Leeuwin 9518 raw minima fractions 1907 - 2011/12
.0 - 6,594
.1 - 3,441
.2 - 3,793
.3 - 3,475
.4 - 3,390
.5 - 2,894
.6 - 3,641
.7 - 3,653
.8 - 3,809
.9 - 3,253
Cape Leeuwin 9518 HQ minima daily fractions 1957 - 2011/12
.0 - 4,980
.1 - 1,452
.2 - 1,613
.3 - 1,473
.4 - 1,384
.5 - 2,585
.6 - 1,595
.7 - 1,577
.8 - 1,639
.9 - 1,291
9518 HQ mean annual minima
1961 13.6
1962 13.6
1963 13.5
1964 13.0
1965 13.6
1966 13.3
1967 13.6
1968 12.5
1969 13.1
1970 13.2
1971 12.9 - average 13.3
1972 13.7 - Metrication
1973 13.4
1974 13.7
1975 13.8
1976 14.1
1977 13.8
1978 14.3
1979 14.0
1980 13.8
1981 13.6
1982 13.9 - average 13.8
Cape Leeuwin 9518 had 23,808 minimum temperature readings from 1907 to September 1972, of which 15,819 were full Fahrenheit degrees rounded to Celsius = 66.4%. (e.g 65F=18.3C, 66F=18.9C, 67F=19.4C, 68F=20C, 69F=20.6, 70F=21.2, etc)
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Example of corrupt HQ data:
All raw min and max in 2001 are rounded to .0. The mean annual minimum of these 363 days is 14.4C (14.38 in Excel). The HQ minimum for 2001 is 14.4C. The raw data is obviously incorrect but is the base for the mean raw annual minimum and, after adjustment, also the mean HQ minimum for 2001.
Almost all daily temperatures before September 1972 since 1907 round to an exact Fahrenheit degree - (i.e. 72F, 73F, 74F, not 72.4F, 73.7F, 74.8F, etc)
Pictured to the right is is an example of HQ minima for Cape Leeuwin 9518.
This is the High Quality historic temperature record upon which Australia's carbon tax is based.
Cape Leeuwin 9518 station equipment history
Air Temperature
03/FEB/1993 INSTALL Temperature Probe - Dry Bulb (Type Rosemount S/N - NONE) Surface Observations
01/SEP/2004 REPLACE Temperature Probe - Dry Bulb (Now Rosemount ST2401 S/N - 0381) Surface Observations
01/JAN/1907 INSTALL Thermometer, Mercury, Dry Bulb (Type Unknown S/N - Unknown) Surface Observations
03/FEB/1993 REMOVE Thermometer, Mercury, Dry Bulb (Type Unknown S/N - Unknown) Surface Observations
Maximum Temperature
01/JAN/1897 INSTALL Thermometer, Mercury, Max (Type Unknown S/N - Unknown) Surface Observations
03/FEB/1993 REMOVE Thermometer, Mercury, Max (Type Dobbie S/N - Unknown) Surface Observations
27/NOV/1984 REPLACE Thermometer, Mercury, Max (Now Dobbie S/N - Unknown) Surface Observations
25/FEB/1985 REPLACE Thermometer, Mercury, Max (Now Dobbie S/N - Unknown) Surface Observations
23/SEP/1991 REPLACE Thermometer, Mercury, Max (Now Dobbie S/N - Unknown) Surface Observations
Minimum Temperature
01/JAN/1897 INSTALL Thermometer, Alcohol, Min (Type Unknown S/N - Unknown) Surface Observations
03/FEB/1993 REMOVE Thermometer, Alcohol, Min (Type Dobbie S/N - Unknown) Surface Observations
08/SEP/1985 REPLACE Thermometer, Alcohol, Min (Now Dobbie S/N - Unknown) Surface Observations
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