Guest Post by Willis Eschenbach
As Anthony discussed here, some Australian climate scientists think that there was an “angry summer” in 2012. Inspired by the necromantic incantations in support of the Aussie claims coming from the irrepressible Racehorse Nick Stokes, I went to take a look at the Australian temperature data. I found out that in response to hosts of complaints about their prior work, in March of 2012 the Australian Bureau of Meteorology (BoM) released a new temperature database called ACORN-SAT. This clumsy acronym stands for the Australian Climate Observations Reference Network (overview here, data here)
It’s a daily dataset, which I like. And they seem to have learned something from Anthony Watts and the Surfacestation project, they have photos and descriptions and metadata for each individual station. Plus the data is well error-checked and vetted. The site says:
All scientific work at the Bureau is subject to expert peer review. Recognising public interest in ACORN-SAT as the basis for climate change analysis, the Bureau initiated an additional international peer review of its processes and methodologies.
A panel of world-leading experts convened in Melbourne in 2011 to review the methods used in developing ACORN-SAT. It ranked the Bureau’s procedures and data analysis as amongst the best in the world.
Methods and development
Creating a modern homogenised Australian temperature record requires extensive scientific knowledge – such as understanding how changes in technology and station moves affect data consistency over time.
The Bureau of Meteorology’s climate data experts have carefully analysed the digitised data to create a consistent – or homogeneous – record of daily temperatures over the last 100 years.
As a result, I was stoked to find the collection of temperature records. So I wrote an R program and downloaded the data so I could investigate it. But when I had just gotten all the data downloaded started my investigation, in the finest climate science tradition, everything suddenly went pear-shaped.
What happened was that while researching the ACORN-SAT dataset, I chanced across a website with a post from July 2012, about four months after the ACORN-SAT dataset was released. The author made the surprising claim that on a number of days in various records in the ACORN-SAT dataset, the minimum temperature for the day was HIGHER than the maximum temperature for the day … oooogh. Not pretty, no.
Well, I figured that new datasets have teething problems, and since this post was from almost a year ago and was from just after the release of the dataset, I reckoned that the issue must’ve been fixed …
… but then I came to my senses, and I remembered that this was the Australian Bureau of Meteorology (BoM), and I knew I’d be a fool not to check. Their reputation is not sterling, in fact it is pewter … so I wrote a program to search through all the stations to find all of the days with that particular error. Here’s what I found:
Out of the 112 ACORN-SAT stations, no less than 69 of them have at least one day in the record with a minimum temperature greater than the maximum temperature for the same day. In the entire dataset, there are 917 days where the min exceeds the max temperature …
I absolutely hate findings like this. By itself the finding likely make almost no difference for most applications. These are daily datasets, with each station having around 100 years of data, 365 days per year, that means the whole dataset has about 4 million records, so the 917 errors are 0.02% if the data … but it means that I simply can’t trust the results when I use the data. It means whoever put the dataset out there didn’t do their homework.
And sadly, that means that we don’t know what else they might not have done.
Once again, the issue is not that the ACORN-SAT dataset had these problems. All new datasets have things wrong with them.
The issue is that the authors and curators of the dataset have abdicated their responsibilities. They have had a year to fix this most simple of all the possible problems, and near as I can tell, they’ve done nothing about it. They’re not paying attention, so we don’t know whether their data is valid or not. Bad Australians, no Vegemite for them …
I must confess … this kind of shabby, “phone it in” climate science is getting kinda old …
Station, Bad days in record (w/ min. temperature exceeding the max. temp)
Alice Springs, 36
Cape Borda, 4
Cape Leeuwin, 2
Cape Otway Lighthouse, 63
Charters Towers, 8
Gabo Island, 1
Halls Creek, 21
Larapuna (Eddystone Point), 4
Low Head, 39
Marble Bar, 11
Melbourne Regional Office, 7
Mount Gambier, 12
Port Hedland, 2
Port Lincoln, 8
Rabbit Flat, 3
Richmond (NSW), 1
Richmond (Qld), 9
St George, 2
Tennant Creek, 40
Wagga Wagga, 1
Wilsons Promontory, 79