Bureau Can’t Dodge Differences in Temperature Data

Chart2 1024x658 1

by Jennifer Marohasy via wattsupwiththat.com

Since Graham Lloyd’s article ‘Mercury Rising in BOM probe row’ was published on the front page of The Weekend Australian earlier this month, there has been some confusion regarding the availability of the parallel temperature data.

These are the temperatures handwritten into the Field Books of Meteorological Observations, both the temperatures as recorded by a mercury thermometer, and from the platinum resistance probes, at the same place and on the same day.

I spent the first of several minutes of a prerecorded interview with Michael Condon from ABC NSW Country Hour earlier this month arguing with him about this. He was repeating wrong information from the Bureau of Meteorology’s Chief Customer Officer, Peter Stone.

Specifically, Condon incorrectly claimed that the bureau makes all its temperature data publicly available on its website, including the parallel data. This claim, that is apparently being repeated across university campuses, flatly contradicts the opening paragraphs of Lloyd’s article. Lloyd correctly explained that it was only after a Freedom of Information request and three years of arguing with the Bureau (including over the very existence of these Field Books/A8 reports and whether their release was in the public interest), and then the case eventually going to the Administrative Appeals Tribunal on February 3, that some of the parallel data for Brisbane Airport was released.

As Lloyd reported early this month, only three years of the 15 years of data for Brisbane airport was released to John Abbot on the Thursday before Easter and this is just a fraction of the 760 years of parallel data the bureau holds for 38 different locations spread across the landmass of Australia.

I’ve had several academics phone and email me over the last few days asking for assistance in locating the parallel data for Brisbane Airport online. I have explained that this was never provided to me in an electronic form, but as over a thousand handwritten pages. I manually transcribed the handwritten entries over Easter and undertook preliminary analysis of this data.

My analysis of the three years of parallel temperature data from Brisbane Airport shows that 41% of the time the probe is recording hotter than the mercury, and 26% of the time cooler. The difference is statistically significant (paired t Test, n = 1094, p < 0.05). The differences are not randomly distributed, and there is a distinct discontinuity after December 2019.

I initially thought that this step-change from an average monthly difference of minus 0.28C in December 2019 to plus 0.11 in January 2020 (a difference of 0.39C) represented recalibration of the probe.

The bureau has denied this, explaining there was a fault in the automatic weather station that was immediately fixed and operating within specifications from January 2020 onwards. Yet even after January 2020, the probe was recording up to 0.7C warmer than the mercury thermometer at Brisbane Airport.


Leave a Reply