Hyping Maximum Daily Temperature (Part 4)

From Jennifer Marohasy’s Blog

By Jennifer Marohasy

John William Abbot vs. Director of Meteorology was heard at the Administrative Appeals Court, Brisbane, yesterday, Friday, 3 February 2023 – the focus of this blog post series. While it was a public hearing and I was an expert witness, before I could give my evidence, the case was brought back to the mediation stage and the public was asked to leave.

Now I am part of the reconciliation that is Are not solved yesterday. I am now legally bound to Are not comment on this ongoing mediation. That is set to continue on Tuesday.

I am grateful to Caroline, Gideon, Charles and Howard for attending yesterday’s public hearing – albeit briefly.

This sage has continued on me in some form since August 25, 2015 when I first requested parallel data for Cape Wilsons . Lighthouse from an electronic weather station based on platinum resistance probes since September 2000 and as a check from the original glass-liquid thermometers (including mercury), re-installed in 1872 and theoretically still recording the temperature. I specifically ask:

Can you also please provide me with a complete log of the temperature (maximum and min) measured from each of these different thermometers during their available recording period.

I particularly want to know if there is a continuous monthly record for mercury thermometers installed from 1872 to the present. [end]

This request was made through the portal [email protected], and I was contacted by phone calls, but my application was never officially recognized. We are aware it was discussed by Bureau staff as it was mentioned in correspondence that was made public following a partially successful FOI request by Mulholland (#FOI30-6142) regarding set limits. out about how cold temperatures can be recorded at Goulburn. correspondence is available online here.

Since a change in instrumentation has the potential to create a discontinuity in the temperature recording, it is Australian Bureau of Meteorology policy to place the new instrument recording parallel to the old one for at least a period of time. 2 years. This way, the readings from the new device can be compared with the readings from the old device, including checking that they are equivalent – ​​that there are no discontinuities. This is parallel data.

It is reasonable to assume that this data will be made public, but it is protected and kept secret by the Bureau. The Bureau also states that it has not been digitized and is only likely to be available as hard copies of A8Forms and that the Bureau lacks the resources available for scanning to provide this upon request. Access to this data for the Brisbane airport weather station was the target of John Abbot’s FOI request and thus the beginning of the current story.

In 2017, I succeeded in collecting some parallel data for Mildura. After many nights of staying up late, manually copying values ​​from the scanned Form A8 provided to me following the intervention of then-Minister of Energy and Environment Josh Frydenberg I chart the data and do some analysis.

This analysis shows that the first probe, which became official at Mildura on November 1, 1996, is recording too cold for mercury with some seasonal variation. On May 3, 2000, the Bureau changed the Stevenson monitor to a smaller design, and although there is no record of a change in transducer type, this is almost certainly the case based on the recording pattern. very different from mercury, see Figure 1.

Initially, temperatures were recorded at Mildura, from 3 May 2000 from what I assume to be a new second probe in the new shelter, which is more consistent with measurements from mercury thermometers. But then I could see from the data that the temperature from the probe started to cool down relative to the mercury thermometer in the period up to June 27, 2012. The cooling rate was close to 1°C. in 100 years.

Then, on June 27, 2012, the probe recorded official temperatures at Mildura for 12 years while drifting to record ever colder temperatures, which were altered. The limited available parallel data indicates that this third probe records overheating compared to the same mercury thermometer – typically 0.4 °C.

Here is the range of parallel data available and it suggests:

1. The change from mercury thermometer to probe makes a significant difference to the reliability of historical data.

2. This is important to understand climate variability and change – trends.

3. This information is in the public interest – as far-reaching public policy decisions are being made on a 1.5C tipping point basis.

4. We know the data exists because I received a scanned Form A8 for Mildura with records from both the probe and the mercury in 2017. We also know the data exists by reference and discussion of this data by the Bureau.

On 12 December 2019, John Abbot requested access to parallel daily minimum and maximum temperature data sets for the Brisbane airport weather station; those are measurements recorded using a mercury thermometer as a potential check against measurements from a platinum resistance probe.

That data has never been made available and is the source of the current story that will be continued on Tuesday through private mediation.