Ken Stewart, June 2010
Western Australia, the largest state in Australia ( 33 % of Australia’s land area) is the source of much of Australia’s mineral wealth. It is physically isolated from the eastern states, and during the politicking for the Federation of the colonies in the 1890s, the vote for Federation was only carried after the Trans Australian Railway was promised. After seeing what the Bureau of Meteorology has done with their temperature figures, Sandgropers may well want to secede.
BOM develops its climate Trend Maps and Time Series graphs form 100 sites nationwide, comprising the High Quality Australian Site Network. 25 of these are in Western Australia.
As you can see, Western Australia has a warming trend of 0.09 degrees C per decade, or 0.9 degrees per 100 years.
As part of my survey of the data from the whole High Quality series, I have analysed the Western Australian data. I averaged maxima and minima for all stations at each site, then compared with the High Quality means. A spokesperson for BOM has asserted that:
“On the issue of adjustments you find that these have a near zero impact on the all Australian temperature because these tend to be equally positive and negative across the network (as would be expected given they are adjustments for random station changes).”
44% warming bias! Even rounding conservatively, the warming bias is 28.57%.
Notice that there is a strong positive bias.
The HQ data has been subjectively and manually adjusted, and makes no allowance for Urban Heat Island effect, apart from not including (some) Urban sites.
However a closer examination of the WA HQ dataset reveals even more basic flaws:
- 4 of the 25 sites (Port Hedland, Roebourne, Geraldton, and Albany) were listed as Urban by Torok and Nicholls in 1996, and should therefore not be included, as BOM says that
- 4 sites (Giles, Newman, Meekatharra, Jarrahwood) have many years of data missing. High Quality sites are supposed to have a long record of at least 80 years, with few gaps.
The official Trend Map and Time Series Graph for Western Australia cannot be relied on as an accurate record of the Western Australian climate over the past 100 years. This is because they are derived from the High Quality Annual Temperature Network. This is plagued by subjective, manual adjustments that in many cases cannot be justified, sites with years of missing data, sites that should not have been used because of Urban contamination, and a large warming bias. If this is High Quality, I’d hate to see Low Quality. What does it say about the rest of the Australian temperature observations?
Progress report on the Australian High Quality Site Network:
Sites checked: 55 out of 100
Raw trend: +0.73 degrees C/ 100 years
High Quality trend: +0.96
Average difference: +0.23
Warming bias: 30.77%
No doubt the remaining 45 stations will show a large cooling bias!
Appendix: WA Sites and comments
Missing data for the first 47 years, and no sites around for hundreds of km!
This graph shows BOM did the same but made the first 15 years colder.
Note the four datasets (Bidyadunga is 93km away, Anna Plains is 163 km away) are very close for most of the period with a trend of 0.2C:
Note the small cooling adjustment, but the airport shows the possible UHI effect.
The trend of 0.2C has been adjusted to… 0.9! Where does that leave the record?
Gives a trend of 0.3C changed to 1.0C.
0.2 to 0.8!
From 0.1 to 0.8! But nearby Northam is about 0.2.
Given an extra 0.4C of warming, though Narrogin is almost identical to Wandering.
Cape Leeuwin Lighthouse:
Why not call it Donnybrook? Because Donnybrook has a rating of 4 (Poor) due to poor Stevenson screen siting during some of the record. That’s how they get around that little problem. Fortunately, the trend has been reduced by 0.4C.
Adjusted with an extra 0.3C warming.
I reduced the second town record by 0.3 to match the airport. Notice where the BOM adjustment matches this splice and where it is different- they do a very rough splice then warm the first few years. The result is a 0.1C increase in warming, and a dodgy record.