How Unstable Power Corrupts Australia’s Temperature Record

Since 1996 the Bureau of Meteorology has been replacing liquid-in-glass thermometers with electronic probes connected to automatic weather stations. The probes do not measure temperature directly; they measure electrical resistance, which is converted to a temperature value. That conversion is only as stable as the voltage supplied to the sensor.

At remote stations the power is often supplied by ageing lead-acid batteries. When those batteries are asked to do extra work—such as powering a satellite transmission—the voltage drops and the recorded temperature drops with it.

Browse Island (station 200784), 450 km off the Kimberley coast, is one of the most isolated automatic weather stations in the Australian network. It transmits via satellite at exactly 27 minutes past every hour. Request the one-minute data for 19–26 April 2016 and the pattern is unmistakable:

Every hour, on the 27th minute, the AIR_TEMP_MIN plunges by 1.5–2.0 °C while the concurrent AIR_TEMP and AIR_TEMP_MAX remain normal.

A few examples from the 219-page dataset (link below):

• 25 Apr 23:27 – 30.4 / 30.4 / 28.6
• 25 Apr 22:27 – 30.6 / 30.7 / 28.8
• 25 Apr 21:27 – 30.8 / 30.8 / 29.0
• 24 Apr 05:27 – 30.5 / 30.5 / 28.4
• 22 Apr 05:27 – 30.0 / 30.0 / 28.5

The spike is perfectly regular, perfectly predictable, and entirely artificial. It is caused by the momentary drain on the battery as the satellite uplink fires. The reference voltage falls, the probe reading falls, and a false minimum is written into the official record.

This is not ‘noise.’ It is a systematic, hour-after-hour corruption of the data at one of the stations least affected by urban heat or land-use change—the very stations that should be the cleanest.

The same electrical vulnerability was introduced more widely when the Bureau upgraded remote stations to one-minute satellite transmission in 2012. Preliminary analysis from that period showed the delta between the one-minute maximum and minimum increased at many sites once the new power arrangements were in place, and the delta grew as the batteries aged.

These measurement errors are smaller than the wholesale homogenisation the Bureau performs in plain sight, but they are still real, still ongoing, and still ignored. The same ideology that refuses to allow a new diesel refinery in Gladstone (because no bank will even open an account for an oil project) is content to use temperature records known to be electrically unstable to justify Net Zero.

The data from Browse Island is available. The pattern is clear. The only question is whether anyone in a position of authority is prepared to look at it.

Data set for article